DPS 42nd Meeting Abs..

Session Time: 10/4/2010 8:30 AM

Session Number: 01Session Title: Iapetus and MimasSession Type: Oral01.01: Iapean Tectonics: Despinning, Respinning, Contracon, Or Something Completely Different?Author Block: Kelsi Singer 1 , W. B. McKinnon 11 Washington University in St. Louis.Presentaon Time: 10/4/2010 8:30 AM - 8:40 AMLocaon: Ballroom BCAbstract: Saturn’s moon Iapetus is unique in that it has apparently despun while retaining a substanal equatorial bulge. Lineaments (linear surface features)on Iapetus were mapped, updated from Singer and McKinnon (LPSC XXXIX) to cover both bright and dark hemispheres. Lineament orientaons are compared tomodel stress paerns predicted for spin-down from a rotaon period of 16 hours, or less, to its present synchronous period, and for a range of lithosphericthicknesses. Many lineaments are straight segments of crater walls, which may be faults or joints reacvated during complex crater collapse. Most striking areseveral large troughs on the bright, trailing hemisphere. These troughs appear to be extensional and are disncve because the interior floors and walls containdark material. Globally, no specific evidence of strike slip or thrust offsets are seen, but this could be due to the age and degraded nature of any such features.Observed lineament orientaons do not correlate with predicted paerns from despinning on either hemisphere (the equatorial ridge was excluded from thisanalysis). Modest evidence for preferred orientaons ~20-40° from north could be construed as consistent with respinning, but the laer is physically unlikely.Assuming the rigidity of unfractured ice, predicted maximum lithospheric differenal stresses range from ~1 MPa to ~200 MPa for the elasc spheroid and thinlithosphere approximaons, respecvely (although it is only for thicker elasc lithospheres that we expect a nonhydrostac state to be maintained over geologicme). The tectonic signature of despinning may have been obscured over me as the surface of Iapetus is very ancient, or the thick lithosphere may haveinhibited its full expression. Several prominent lineaments strike E-W, and are thus parallel to the equatorial ridge (though not physically close to it), but atectonic or volcanic origin for the ridge is highly problemac.01.02: Impact basin relaxaon on IapetusAuthor Block: Guillaume Robuchon 1 , F. nimmo 1 , J. roberts 21 UCSC, 2 APL.Presentaon Time: 10/4/2010 8:40 AM - 8:50 AMLocaon: Ballroom BCAbstract: The evoluon of the icy satellites is complex and currently poorly understood. Here we combine thermal evoluon models with basin relaxaoncalculaons to place ghter constraints on the early history of these bodies.We have coupled the results of a model for the internal evoluon of Iapetus (Robuchon et al, 2010) with a computaon of the surface relaxaon (Zhong et al,2003). The evoluon of Iapetus is calculated using a 3D model with a temperature-dependent viscosity, while the relaxaon is computed with a Maxwellviscoelasc rheology. Our relaxaon model was benchmarked against the analycal results given by Melosh (1989) . At each mestep we recompute the effecveice viscosity using the parameters of Goldsby and Kohlstedt (2001). We also invesgate the effect of a cutoff in effecve viscosity (cf. Dombard and McKinnon,2006).Our baseline simulaon assumes 72ppb of 26Al, consistent with the results of Robuchon et al. (2010). Bigger basin relax more rapidly than smaller ones, becausethe inferred thickness of the ice shell of Iapetus exceeds the diameter of even the largest basins considered. Due to the cooling of Iapetus, the younger basinsrelax less than the older. Our results show a maximum relaxaon of less than 20% for the older and bigger basins and less than 5% for the smaller. These resultsare in good agreement with measurements of basin depth (Schenk and Moore, 2007) assuming that basin formaon occurred about 900 Myr aer the formaonof the Solar System.By linking models of internal evoluon and basin relaxaon, we can place ghter constraints on the histories of the Saturnian icy satellites. For instance, ourinial results are consistent with basin formaon at the me of the Late Heavy Bombardment. A crical observaonal requirement is the ages of the largestimpact basins on the icy satellites.01.03: Crical Spin as a Possible Origin of the Iapetus RidgeAuthor Block: Mikhail A. Kreslavsky 1 , F. Nimmo 11 University of California - Santa Cruz.Presentaon Time: 10/4/2010 8:50 AM - 9:00 AMLocaon: Ballroom BCAbstract: Iapetus has a significant non-hydrostac oblateness ("equatorial bulge") and an enigmac ridge that encircles a significant poron of the equator. Anumber of hypotheses involving a higher past spin rate of Iapetus have been proposed to simultaneously explain both features, but they have difficultyaccounng for the exceponal straightness and regularity of the ridge.We suggest that by the end of its accreon Iapetus gained an extremely high spin rate, close to the crical rate, when gravity at the equator is equal tocentrifugal acceleraon. The small crically-spinning asteroid 66391 is known to have an oblate shape with a prominent equatorial cusp. A model of acohesionless crically-spinning rubble pile with dry fricon [e.g., Harris et al., Icarus 199, 310-318, 2009] accurately reproduced this shape. This model cannot bequantavely applied to a crically-spinning Iapetus, because for a large body the implicit assumpon of infinite shear strength of rubble-pile-forming parclesfails; the overall shape of a crically-spinning Iapetus would be closer to the hydrostac soluon. However, near the surface, especially in the equatorial region,the material behavior would likely be described by cohesionless dry fricon, and an equatorial cusp would form by the same sliding mechanism as for rubble pileasteroids. Tides would then reduce the spin rate down to synchronous, but, due to lithospheric strength, the relaxaon stopped before it reached the hydrostacstate, accounng for the present-day relic equatorial bulge [Casllo-Rogez et al., Icarus 190, 179-202, 2007]. The equatorial cusp would remain as a ridge, bedisrupted by a few early basin-forming impacts, degrade due to small-impact-iniated surface creep, but preserve its original unique straightness. Othersatellites would not have similar ridges, because they are closer to Saturn, hence their despinning is quicker, and they had no chance to gain an extreme spin rateduring accreon.01.04: Carbon Dioxide Sublimaon on Iapetus: Exploring the Kinec PossibiliesAuthor Block: David G. Blackburn 1 , E. G. Rivera-Valenn 1 , R. Ulrich 11 University of Arkansas.Presentaon Time: 10/4/2010 9:00 AM - 9:10 AMLocaon: Ballroom BCAbstract: Although Cassini did not map the northern pole of Iapetus to test the claims of a CO 2 polar cap (Palmer and Brown, 2007, Astrophys. Jour., 666, L125-L128), further modeling can determine its likelihood. Recent spectral analysis of the 4.26 micron CO 2 absorpon feature in the dark material on Iapetus

Abstract: Cloaked in light from Saturn and its rings, the medium-sized Saturnian satellite Mimas is difficult to observe form Earth, and it was the only majorsatellite not to have a close encounter by the Cassini spacecra. Observaons of the moon during Ring Plane Crossing in 1995 and by the Hubble SpaceTelescope established that the moon has a visual geometric albedo of greater than unity (Verbiscer et al. 2007, Science 315, 815) and a brighter trailing side(Bura et al. 1998, Icarus 136, 223), suggesng it is being coated by the E-ring. Observaons at opposion obtained by the Cassini Visual Infrared MappingSpectrometer (VIMS) instrument between 0.4 and 5.2 microns show the moon has a surge similar to that seen on other icy bodies, increasing in brightness by over30% in the last five degrees. During the closest nontargeted flyby by Cassini on February 13, 2010, when the Cassini spacecra approached within 9500 km ofMimas, maps of the moon were obtained by VIMS. Water ice absorpon bands in the central peak and crater rim of Herschel are deeper than those in thesurrounding regions. Preliminary results indicate the water ice grain size decreases as the distance from the apex of moon increases. No constuents other thanwater ice have yet been idenfied.Funded by NASA.01.09: Mimas: Preliminary Evidence For Amorphous Water Ice From VIMSAuthor Block: Dale P. Cruikshank 1 , G. A. Marzo 2 , N. Pinilla-Alonso 1 , T. L. Roush 1 , R. M. Mastrapa 1 , C. M. Dalle Ore 1 , B. J. Bura 3 , K. Stephan 4 , VIMS Team1 NASA Ames Research Center, 2 Bay Area Environmental Research Instute, 3 Jet Propulsion Lab., 4 DLR - German Aerospace Center, Germany.Presentaon Time: 10/4/2010 9:50 AM - 10:00 AMLocaon: Ballroom BCAbstract: We have conducted a stascal clustering analysis (1,2) on a mosaic of VIMS data cubes obtained on February 13, 2010, for Saturn’s satellite Mimas.Seven VIMS cubes were geometrically projected and re-sampled to a common spaal resoluon. The clustering technique consists of a paroning algorithmcoupled to a criterion that prevents sub-opmal soluons and tests for the influence of random noise in the measurements. The clustering technique is agnoscabout the meaning of the clusters, and scienfic interpretaon requires their a posteriori evaluaon. The preliminary results yielded five clusters, demonstrangthat spectral variability across Mimas’ surface is stascally significant. The raos of the means calculated for each of the clusters show structure within the 1.6-µm water ice band, as well as the shape and the central wavelength of the strong ice band at 2 µm that map spaally in paerns apparently related to thetopography of Mimas, in parcular certain regions in and around Herschel crater. The mean spectra of the five clusters, show similaries with laboratory spectraof amorphous and crystalline H 2 O ice (3) that are suggesve of the presence of an amorphous ice component in certain regions of Mimas, notably on the centralpeak of Herschel, on the crater floor, and in faults surrounding the crater. This may represent a mixture of both ice phases, or perhaps a layer of amorphous ice ona base of crystalline ice. Another possible occurrence of amorphous ice appears southwest of Herschel, close to the south pole.1. Marzo, G. A. et al. J. Geophys. Res. 111, E03002, 20062. Marzo, G. A. et al. J. Geophys. Res. 113, E12009, 20083. Mastrapa, R. M., et al. Astrophys. J. 701, 1347-1356, 2009

Session Number: 02Session Title: Solar System Origin, Planet and Satellite FormationSession Type: Oral02.01: Protoplanetary Disks: Variable Rates of Photo-Evaporaon due to Stellar MoonsAuthor Block: Henry B. Throop 1 , J. Bally 21 SwRI, 2 Univ. Colorado.Presentaon Time: 10/4/2010 8:30 AM - 8:40 AMLocaon: Ballroom DAbstract: Photo-evaporaon sculpts protoplanetary disks during their earliest 1-5 Myr. Tradional models of photo-evaporaon have assumed that the distnacebetween the disk an an external UV-bright star is fixed, typically at 0.1 pc. However, the star clusters in which these disks form are dynamic, with orbital crossingmes of 0.1-0.5 Myr. The UV flux from a central star is therefore highly variable.We will present our simulaons of photo-evaporaon in a dynamic star cluster. We show that the UV flux received by disks varies by a factor of 10 - 1000 x duringa disk's first several Myr. Most of the flux is deposited during brief, intense close-approaches to the central star. Photo-evaporaon during this me readily affectsa disk's final mass and architecture. Furthermore, the diversity of orbits through the cluster implies a broad diversity of final mass configuraons for disks, evenfor disks with idencal ages and inial condions.02.02: Coupling Dynamical And Collisional Evoluon Of Dust In Protoplanetary DisksAuthor Block: Sebasen Charnoz 11 Universite Paris Diderot, France.Presentaon Time: 10/4/2010 8:40 AM - 8:50 AMLocaon: Ballroom DAbstract: Gaseous circumstellar disks are rich in dust and are thought to be both accreonaly and dynamically acve. Unfortunately large bodies that could beembedded in these disks are sll difficult to observe and their putave properes are indirectly inferred from the observable small dust content. It is whyconstraining the size distribuon coupled with dust-dynamics is so crical. Unfortunately, coupling effects such as a realisc me-dependant dynamics,fragmentaon and coagulaon, has been recognized as numerically challenging and almost no aempt really succeeded with a generic approach. In these disks,the dust dynamics is driven by a variety of processes (gravity, gas drag, radiaon pressure..) inducing a size-dependant dynamics, and, at the same mecollisional evoluon changes the local size distribuons. These two effects are inmately coupled because the local dynamics and size-distribuon determinesthe local collision rates, that, in-turn, determines the size-distribuon and modifies the parcle’s dynamics.Here we report on a new algorithm that overcomes these difficules by using a hybrid approach extending the work of Charnoz & Morbidelli (Icarus, 2004, 2007).We will briefly present the method and focus on gaseous protoplanetary disks either laminar or turbulent (the me dependant transport and dust evoluon will beshown) .We will show how the taking into account of a 3D dynamics helps to determine disantengle the dust size-distribuon in the disk's photosphere and in themidplane and thus may provide observaonal signatures of accreon. We will show how the coupling of turbulence with fragmentaon may significantly affectthe dust/rao for the smallest bodies.Finally, we will show that an accurate descripon of the me dependant dynamics of larger dusts (those with Stokes numbers >= 1) may provide a possible pathto the formaon of bodies larger than the accreon barrier, through accreon in a transitory regime.02.03: Formaon of Kuiper Belt Binaries by Gravitaonal CollapseAuthor Block: David Nesvorny 1 , A. N. Youdin 2 , D. C. Richardson 31 SwRI, 2 CITA, Canada, 3 University of Maryland.Presentaon Time: 10/4/2010 8:50 AM - 9:00 AMLocaon: Ballroom DAbstract.Abstract: A large fracon of 100-km-class low-inclinaon objects in the classical Kuiper Belt (KB) are binaries with comparable mass and wideseparaon of components. A favored model for their formaon was capture during the coagulaon growth of bodies in the early KB. Instead, recent studiessuggested that large, 100-km and larger objects can rapidly form in the protoplanetary disks when swarms of locally concentrated solids collapse under their owngravity. Here we examine the possibility that KB binaries formed during gravitaonal collapse when the excess of angular momentum prevented theagglomeraon of available mass into a solitary object. We find that this new mechanism provides a robust path toward the formaon of KB binaries withobserved properes, and can explain wide systems such as 2001 QW322 and mulples such as (47171) 1999 TC36. Notably, the gravitaonal collapse is capableof producing ~100% binary fracon for a wide range of the swarm's inial angular momentum values. The binary components have similar masses (~80% havethe secondary-over-primary radius rao >0.7) and their separaon ranges from ~1,000 to ~100,000 km. The binary orbits have eccentricies from e=0 to ~1,with the majority having e<0.6. The model inclinaons are consistent with the observed general preference for prograde binary orbits. Our binary formaonmechanism also implies that the primary and secondary components in each binary pair should have idencal bulk composion, which is consistent with thecurrent photometric data.02.04: Chondrites as Samples of Differenated PlanetesimalsAuthor Block: Linda Elkins-Tanton 1 , B. P. Weiss 1 , M. T. Zuber 11 M IT.Presentaon Time: 10/4/2010 9:00 AM - 9:10 AMLocaon: Ballroom DAbstract: Chondric meteorites are unmelted, variably metamorphosed samples of the earliest solids of the solar system. The variety of metamorphic texturesin ordinary chondrites movated the “onion shell” model in which chondrites originated at varying depths within a parent body heated primarily by the short-livedradioisotope 26 Al, with the highest metamorphic grade originang nearest the center (Jeffrey Taylor et al. 1987). Allende and a few other chondrites possess aunidireconal magnezaon (Butler 1972, Weiss et al. 2010) that can be best explained by a core dynamo on their parent body (Funaki and Wasilewski 1999,Weiss et al. 2010), indicang internal melng and differenaon. Here we show that a parent body that accreted to >~200 km in radius by ~1.7 Ma aer theformaon of calcium-aluminium inclusions (CAIs) could retain a solid undifferenated crust overlying a differenated interior, and would be consistent withformaonal and evoluonary constraints on the CV parent body. This body could have produced a magnec field lasng more than 10 Ma. This hypothesismodifies the image of some chondrites as the least processed of early solar system materials, and presents them instead as the unprocessed crusts of internallymelted early planetesimals. Further, the shapes and masses of the two largest asteroids, 1 Ceres and 2 Pallas, are consistent with differenated interiors,conceivably with small iron cores with hydrated silicate or ice-silicate mantles. This research is funded by an NSF Astronomy CAREER award and a NASA/Dawnco-invesgator grant.

02.05: Magnec Evidence for a Parally Differenated Carbonaceous Chondrite Parent Body and Possible Implicaons for Asteroid 21 LuteaAuthor Block: Benjamin Weiss 1 , L. Carporzen 1 , L. Elkins-Tanton 1 , D. L. Shuster 2 , D. S. Ebel 3 , J. Gaacceca 4 , R. P. Binzel 11 Massachuses Instute of Technology, 2 Berkeley Geochronology Center, 3 American Museum of Natural History, 4 CNRS/Universite Aix-Marseille, France.Presentaon Time: 10/4/2010 9:10 AM - 9:20 AMLocaon: Ballroom DAbstract: The origin of remanent magnezaon in the CV carbonaceous chondrite Allende has been a longstanding mystery. The possibility of a core dynamolike that known for achondrite parent bodies has been discounted because chondrite parent bodies are assumed to be undifferenated. Here we report thatAllende's magnezaon was acquired over several million years (Ma) during metasomasm on the parent planetesimal in a >~20 microtesla field ~8-9 Ma aersolar system formaon. This field was present too recently and direconally stable for too long to have been the generated by the protoplanetary disk or youngSun. The field intensity is in the range expected for planetesimal core dynamos (Weiss et al. 2010), suggesng that CV chondrites are derived from the outer,unmelted layer of a parally differenated body with a convecng metallic core (Elkins-Tanton et al. 2010). This suggests that asteroids with differenatedinteriors could be present today but masked under chondric surfaces. In fact, CV chondrites are spectrally similar to many members of the Eos asteroid familywhose spectral diversity has been interpreted as evidence for a parally differenated parent asteroid (Mothe-Diniz et al. 2008). CV chondrite spectral andpolarimetric data also resemble those of asteroid 21 Lutea (e.g., Belskaya et al. 2010), recently encountered by the Rosea spacecra. Ground-basedmeasurements of Lutea indicate a high density of ~2.4-5.1 g cm -3 (Drummond et al. 2010), while radar data seem to rule out a metallic surface composion(Shepard et al. 2008). If Rosea spacecra measurements confirm a high density and a CV-like surface composion for Lutea, then we propose Lutea may bean example of a parally differenated carbonaceous chondrite parent body. Regardless, the very existence of primive achondrites, which contain evidence ofboth relict chondrules and paral melng, are prima facie evidence for the formaon of parally differenated bodies.02.06: Reconciling Giant Planet Formaon With the Origin and Impact History of the Parent Bodies of Differenated MeteoritesAuthor Block: Nader Haghighipour 1 , E. R. D. Sco 1 , G. J. Taylor 1 , D. O' Brien 21 Univ. of Hawaii, 2 Planetary Science Instute.Presentaon Time: 10/4/2010 9:20 AM - 9:30 AMLocaon: Ballroom DAbstract: The extraordinary number of different parent bodies of iron meteorite, and the dearth of asteroids and meteorites derived from the silicate mantlesand crusts of these objects is beer understood if these bodies accreted at 1-2 AU during the first 2 Myr when 26Al melted all ice-free planetesimals larger than20-km. It has been suggested that planetary embryos at 1-2 AU dynamically excited the differenated planetesimals and scaered their fragments into theasteroid belt where they were captured by planetary embryos. The scaering and accreon of planetesimals has occurred during the me that giant planets weregrowing. If the mescale for the formaon of giant planets is comparable with the me of the accreon of parent bodies of iron meteorites (e.g. as short as in therecent version of the core-accreon model), or if it is as small as suggested by the disk instability scenario, the perturbaon of growing giant planet(s) may affectthe scaering, collision, and accreon of planetesimals. We have studied these effects in order to compare the results with meteoric data to constrain the meof giant planet formaon. We have numerically integrated the moons, collisions, and accreon of a large baery of planetesimals and planetary embryos in theregion between 0.5 and 4 AU during the growth of two giant planets in orbits of Jupiter and Saturn. Results indicate that the perturbaons of growing giantplanets decrease the efficiency of planetesimals scaering when these objects grow to approximately 50 Earth-masses. For larger values of mass, this efficiencydrops drascally suggesng that very short mescales for the growth of giant planets may not be favorable for models of the formaon of the parent bodies ofiron meteorites. We present the results of our simulaons and discuss their implicaons for the me of giant planet formaon.02.07: Formalism for the Impact Rate of Comets on the Inner Satellites and Rings of the Giant PlanetsAuthor Block: Henry C. (Luke) Dones 1 , E. B. Bierhaus 2 , K. J. Zahnle 3 , D. Nesvorný 1 , H. F. Levison 1 , C. R. Chapman 11 Southwest Research Inst., 2 Lockheed Marn, Space Exploraon Systems, 3 NASA Ames Research Center.Presentaon Time: 10/4/2010 9:30 AM - 9:40 AMLocaon: Ballroom DAbstract: Determining the rate at which eclipc comets have struck the satellites of the giant planets throughout the history of the Solar System is importantfor understanding the formaon and evoluon of satellites and planetary rings (e.g., Charnoz et al. 2009, Barr et al. 2010). Impact rates are oen calculated usingÖpik's equaons (Shoemaker and Wolfe 1982), which give the impact probability of a small body with a satellite in terms of the small body's pericenter distance(q), orbital eccentricity (e), and inclinaon (i). Zahnle et al. (1998, 2003) performed Monte Carlo simulaons that implement Öpik's equaons and have tabulatedimpact rates for a wide variety of satellites. These simulaons assume a distribuon of present-day encounter speeds (U) based on simulaons by Levison andDuncan (1997). However, encounter speeds probably would have been larger during the era of heavy bombardment (Charnoz et al. 2009). We have developed ananalycal approach to calculate satellite impact rates, relave to the rate on their parent planet, as a funcon of U. Our approach assumes that the orbitaldistribuon of eclipc comets that encounter a planet is isotropic in the frame of the planet (Levison et al. 2000). Our results agree well with those of Zahnle etal. (1998, 2003), and with numerical integraons carried out with the 'scaer3' roune in STARLAB (hp://www.sns.ias.edu/~starlab/). We thank the NASA CDAPand Origins programs for support.··········Barr, A.C., Canup, R.M., Nature Geoscience 3, 164-167 (2010)Charnoz, S., et al., Icarus 199, 413-428 (2009)Levison, H.F., Duncan, M.J., Icarus 127, 13-32 (1997)Levison, H.F., et al., Icarus 143, 415-420 (2000)Shoemaker, E.M., Wolfe, R.F., in Satellites of Jupiter, pp. 277-339 (1982)Zahnle, K., Dones, L., Levison, H.F., Icarus 136, 202-222 (1998)Zahnle, K., et al., Icarus 163, 263-289 (2003)02.08: Constraints On Satellite Formaon From Io's Low InclinaonAuthor Block: Douglas P. Hamilton 1 , C. Philpo 11 Univ. of Maryland.Presentaon Time: 10/4/2010 9:40 AM - 9:50 AMLocaon: Ballroom DAbstract: The Laplace resonances between the satellites Io, Europa, and Ganymede has had a profound effect on the evoluon of the jovian system. In itscurrent configuraon, the resonances enable some of the spin energy of Jupiter to be tapped to power the volcanos on Io. But when, and equally importantly, atwhat distance from Jupiter did this resonance first originate? Were the satellites pushed together by dal forces or by an earlier phase of inward migraon? Havethe satellites ever been deeper in resonance than they are today? Some of these quesons can be addressed by considering clues contained in the current orbital

configuraons. In parcular, the anomalously-low inclinaon of Io (0.04 degrees) rules out several otherwise plausible scenarios.The dal forces that strongly affect orbital semimajor axes and eccentricies only weakly influence inclinaons. In addion, slow enough (adiabac) crossings ofthe strongest first- and second-order resonances can only increase inclinaons. Lowering inclinaons, by contrast, is extremely difficult. It is possible with aparcular class of weaker third-order resonances, although the condions under which these resonances occur are somewhat limited. Other scenarios, such assimultaneous interacons with mulple resonances can, at least in principle, also lower inclinaons.So inclinaons, once induced, are not easily erased. Making the assumpon that the inclinaon of Io never rose above 0.04 degrees is quite diagnosc andallows us to rule out several scenarios including evoluon from deep within the resonance to today's condions. The inclinaons of Europa and Ganymedeprovide further constraints. In this talk, I will report the progress to date of our ongoing invesgaon.02.09: Origin Of Saturn’s Rings Via Tidal Stripping From A Primordial Massive Companion To TitanAuthor Block: Robin M. Canup 11 Southwest Research Instute.Presentaon Time: 10/4/2010 9:50 AM - 10:00 AMLocaon: Ballroom DAbstract: Saturn’s main rings are > 90% water ice by mass. Because bombardment of the rings by micrometeoroids increases their rock content over me, therings’ current composion implies that they were essenally pure ice when they formed, a much different composion than the roughly half-rock, half-ice mixtureexpected for a solar abundance of solids. The two leading ring origin theories involve the collisional disrupon of a small moon, or the dal disrupon of a cometduring a close passage by Saturn. However, disrupon of a small moon would generally lead to a mixed rock-ice ring, while dal disrupons of comets wouldoccur much more oen at Jupiter, Uranus and Neptune than at Saturn (Charnoz et al. 2009). I here explore a new alternave. Saturn’s sole large satellite contrastsnotably with Jupiter’s four Galilean satellites. Canup & Ward (2006) propose that Saturn has only one large satellite because large satellites interior to Titanspiraled into Saturn due to density wave interacons with the gaseous protosatellite disk at the end of the satellite formaon era. As a large, Titan-sized satelliteapproached Saturn, it would likely be differenated due to the combinaon of the energy of its formaon and strong dal heang. Planetary dal forces thenpreferenally strip mass from the satellite’s outer layers prior to its collision with Saturn, leading to the producon of a massive, pure ice ring. Over me the ringviscously spreads, its mass decreases, and icy moons are spawned from its outer edge. In this way, ice rings and ice-enhanced inner moons originate as aprimordial byproduct of the same process that produces Saturn’s regular satellite system, removing the need to invoke a later, and potenally low-probability, ringforming event.Support from NASA’s Outer Planets Program is gratefully acknowledged.

Session Number: 03Session Title: Comets: Taxonomy and Coma ObservationsSession Type: Oral03.01: A Composional Taxonomy of Comets and Narrowband Photometry of EP OXI Target 103P/Hartley 2.Author Block: David G. Schleicher 1 , A. N. Bair 11 Lowell Obs..Presentaon Time: 10/4/2010 8:30 AM - 8:40 AMLocaon: Ballroom EAbstract: Comets are widely believed to be the most prisne objects available for detailed study remaining from the epoch of Solar System formaon, and canbe used as probes of the protoplanetary material incorporated at that me. Variaons in chemical composion can indicate either differences in primordialcondions or evoluonary effects. The actual cause of specific differences in properes can be determined by stascal analyses of the chemical and orbitalproperes of a large number of objects. We are now compleng a new uniform reducon and set of analyses of 34 years of narrowband photometry of the 165comets that form the Lowell comet database. Cluster and principle component analyses reveals about 8-10 composional groupings, several of which are subgroupsof the original carbon-chain depleted class as defined by A'Hearn et al. (1995). All evidence connues to indicate that the carbon-chain depleted class isprimordial in nature and not associated with evoluon. Unexpectedly, 4 comets are idenfied as being depleted in ammonia but not depleted in carbon-chainmolecules. Details will be presented.A narrowband photometry observing campaign of Comet 103P/Hartley 2 was just begun in support of the EPOXI flyby on November 4. Water producon on July 12(r=1.74AU) was 7e26 molecules/s. Based on observaons from Hartley 2's 1991 and 1997 apparions, and the assumpon that there are no secular variaonsbetween apparions, a significant seasonal effect exists with peak producon taking place several weeks following perihelion. We esmate that the waterproducon at perigee (Oct 20; 8 days prior to perihelion) will be about 2e28 molecules/s, while at the me of the EPOXI encounter (Nov. 4; 7 days followingperihelion) we ancipate a value 50% greater, or 3e28 molecules/s. We will present addional on-going results.This research is supported by NASA's Planetary Astronomy and Planetary Atmospheres Programs.03.02: The Parent Volale Composion of 103P/Hartley-2: Results from Pre-perihelion Observaons at 1.6 AU.Author Block: Michael J. Mumma 1 , M. Lippi 2 , J. Keane 3 , B. P. Bonev 1 , G. L. Villanueva 1 , H. Boehnhardt 2 , M. A. DiSan 1 , E. L. Gibb 4 , K. Magee-Sauer 5 , K. Meech 3 ,L. Paganini 1 , T. Riesen 31 NASA's GSFC, 2 M PI-Solar System Research, Germany, 3 Univ. Hawaii, 4 Univ. Missouri, 5 Rowan Univ..Presentaon Time: 10/4/2010 8:40 AM - 8:50 AMLocaon: Ballroom EAbstract: We searched for parent volales in comet 103P/Hartley-2 using high-resoluon infrared spectroscopic observaons with NIRSPEC at Keck-2 andCRIRES at VLT-1 in late July 2010, when the comet was at heliocentric distance 1.62 AU pre-perihelion. We targeted our usual suite of parent volales: H 2 O,CH 3 OH, C 2 H 6 , CH 4 , CO, HCN, H 2 CO, NH 3 , and C 2 H 2 . This presentaon will report rotaonal temperatures and producon rates for the detected species, and upperlimits for those not detected.This work was funded by NASA’s Planetary Astronomy, Planetary Atmospheres, and Astrobiology Programs, by the NSF Astronomy and Astrophysics Program, andthe German-Israel Foundaon for Scienfic Research and Development.03.03: Organic Depleon and Low Rotaonal Temperatures in Comet 2P/Encke, Revealed Through Infrared SpectroscopyAuthor Block: Yana L. Radeva 1 , M. J. Mumma 2 , G. L. Villanueva 1 , M. A. DiSan 2 , B. P. Bonev 11 The Catholic University of America, NASA Goddard Space Flight Center, 2 NASA Goddard Space Flight Center.Presentaon Time: 10/4/2010 8:50 AM - 9:00 AMLocaon: Ballroom EAbstract: We present high-resoluon infrared spectra of the eclipc comet 2P/Encke, acquired on 4-6 Nov. 2003 with the Near Infrared Echelle Spectrograph onthe Keck II telescope. Comet 2P/Encke has the shortest period (3.3 years), among comets studied through infrared spectroscopy, and is a valuable addion to oursample. We extracted rotaonal temperatures and producon rates for the following parent volales: H 2 O, HCN, CH 4 , C 2 H 2 , C 2 H 6 , H 2 CO, CH 3 OH and CO.2P/Encke is depleted in C 2 H 6 , C 2 H 2 , HCN, CH 4 and CO, and is normal in H 2 CO and CH 3 OH. Rotaonal temperatures extracted for H 2 O and HCN are very low (20 -30 K), compared to other comets. We report rotaonal temperatures, water producon rates, and mixing raos of organic volales, and present the overallcomposion of comet 2P/Encke in perspecve (compared to organics-enriched, organics-normal, and organics-depleted comets). This contributes to the study ofcomposional diversity of cometary nuclei, which hold important clues to the origin and evoluon of our Solar System.03.04: Comet 29P/Schwassmann-Wachmann Observed with the Herschel Space Observatory: Detecon of Water Vapour and Dust Far-IR ThermalEmissionAuthor Block: Dominique Bockelee-Morvan 1 , N. Biver 1 , J. Crovisier 1 , M. de Val-Borro 2 , T. Fulton 3 , P. Hartogh 2 , D. Hutsemékers 4 , C. Jarchow 2 , E. Jehin 4 , M.Kidger 5 , M. Kueppers 5 , E. Lellouch 1 , D. Lis 6 , J. Manfroid 4 , R. Moreno 1 , M. Rengel 2 , B. C. Swinyard 7 , S. Szutowicz 8 , B. Vandenbussche 9 , HssO Team1 LESIA, Observatoire de Paris, France, 2 Max-Planck-Instut für Sonnensystemforschung, Germany, 3 Blue Sky Spectroscopy Inc, Canada, 4 Instut d'Astrophysiqueet de Géophysique, Université de Liège, Belgium, 5 ESAC, European Space Agency, Spain, 6 CALTECH, 7 STFC Rutherford Appleton Laboratory, United Kingdom,8 Space Research Centre PAS, Poland, 9 Instuut voor Sterrenkunde, Katholieke Universiteit Leuven, Belgium.Presentaon Time: 10/4/2010 9:00 AM - 9:10 AMLocaon: Ballroom EAbstract: The distant comet 29P/Schwassmann-Wachmann was observed with the HIFI, PACS and SPIRE instruments aboard the Herschel Space Observatory, aspart of the guaranteed me key programme "Water and related chemistry in the Solar System" (KP-GT HssO). Supporng observaons of the 230 GHz CO linewere carried out with the IRAM 30-m telescope. The HIFI observaons of the 557 GHz H2O line were performed on 19.05 April 2010, about 2 days aer a majoroutburst, and on 11.02 May 2010, when 29P was in a more quiescent phase. H2O was detected on both dates with a producon rate corresponding to about1/10th the CO producon, assuming near-nucleus producon. The H2O line shape is consistent with release of water vapour from icy grains. PACS and SPIREimaging data from 70 to 500 micrometers were acquired mid-June 2010 when the comet was in a quiescent phase. The connuum emission detected in the 70-μm and 160-μm PACS images is weakly extended with respect to the PSF, suggesng a major contribuon from the nucleus or from slowly moving large grains.03.05: Comet 10P/Tempel 2 Outgassing and Composion from Herschel and Ground-based Sub-millimeter ObservaonsAuthor Block: Nicolas Biver 1 , S. Szutowicz 2 , D. Bockelée-Morvan 1 , J. Crovisier 1 , R. Moreno 1 , P. Hartogh 3 , M. de Val Borro 3 , M. Rengel 3 , D. C. Lis 4 , M. Kidger 5 , M.Küppers 5 , HssO Team

1 LESIA, Obs. de Paris, France, 2 Space Research Centre, PAS, Poland, 3 M PIS, Germany, 4 Caltech, 5 ESAC, Spain.Presentaon Time: 10/4/2010 9:10 AM - 9:20 AMLocaon: Ballroom EAbstract: Comet 10P/Tempel 2 was observed between 15 June and 29 July 2010 with the HIFI instrument of the Herschel Space Observatory, as part of theguaranteed me key programme "Water and related chemistry in the Solar System" (KP-GT HssO). The observaons with Herschel were carried around the lastperihelion passage of the comet (4.9 July 2010) at 1.42 AU from the Sun, at the maximum of its acvity.Several water lines were observed to map and monitor the mid and short-term acvity of the comet. Complementary observaons were obtained from the IRAM30m radiotelescope on 7-11 July 2010. Both HERSCHEL and IRAM observaons suggest that the outgassing is mostly dominated by a strong jet (at ~0.9km/s),directed towards the observer and the north.The gas temperature is esmated to ~30K from the observaon of methanol lines. The water outgassing peaked around 2.5E28 molec./s. Abundances of HCN,CH3OH, CS, H2S and NH3 will be presentded.HCN and CH3OH were also detected two perihelions ago at CSO and JCMT and displayed similar strongly blueshied lines illustrang the recurrent apparion ofthis strong jet.03.06: Detecon of Water Vapor in Comet 81P/Wild2 by HerschelAuthor Block: Miguel de Val-Borro 1 , P. Hartogh 1 , J. Crovisier 2 , D. Bockelée-Morvan 2 , N. Biver 2 , D. C. Lis 3 , R. Moreno 2 , C. Jarchow 1 , M. Rengel 1 , S. Szutowicz 4 , H.HssO Team 51 Max Planck Instute for Solar System Research, Germany, 2 LESIA, France, 3 Caltech, 4 Space Research Centre, Poland, 5 Herschel, Germany.Presentaon Time: 10/4/2010 9:20 AM - 9:30 AMLocaon: Ballroom EAbstract: Comet 81P/Wild2 was observed with HIFI on the Herschel Space Observatory in the framework of the guaranteed me key programme "Water andrelated chemistry in the Solar System" (KP-GT HssO). The observaons were obtained in February 2010 about 20 days before perihelion at heliocentric distance of1.61 AU. We mapped the fundamental 557 GHz ortho and 1113 GHz para rotaonal transions of water with five point scans. We derive a mean water produconrate of 1.0 x 10 28 molecules/s in agreement with producon rates measured from observaons of the 18-cm OH lines at the Nançay radio telescope. The line shiand excess emission in the blue wing of the profiles suggest preferenal outgassing towards the Sun.These results are complemented by observaons of HCN, CH3OH, H2S and CS obtained at the IRAM 30m telescope on 12-14 February and HCN observed at CSOin early January 2010.03.07: Highly Depleted Ethane and Slightly Depleted Methanol in Comet 21P/Giacobini-Zinner: Applicaon of Empirical g-factors for CH 3 OH near 50 KAuthor Block: Michael A. DiSan 1 , B. P. Bonev 2 , M. J. Mumma 1 , G. L. Villanueva 21 NASA-GSFC / Goddard Center for Astrobiology, 2 The Catholic Univ. of America / Goddard Center for Astrobiology.Presentaon Time: 10/4/2010 9:30 AM - 9:40 AMLocaon: Ballroom EAbstract: We report high resoluon (λ/Δλ ~ 24,000) observaons of Comet 21P/Giacobini-Zinner (21P) between ~ 2.85 - 3.54 µm, obtained with NIRSPEC atKeck 2 on UT 2005 June 03 (R h = 1.12 AU, Δ = 1.45 AU). These simultaneously sampled mulple emissions from the ν 7 band of C 2 H 6 and the ν 2 and ν 3 bands ofCH 3 OH, together with several hot bands of H 2 O, perming a direct measure of parent volale abundances in 21P. Our spectra reveal highly depleted C 2 H 6 (0.13-0.14 percent relave to H 2 O) and CH 3 OH/C 2 H 6 ~ 10, consistent with previously published abundances from observaons in the IR [1,2] and millimeter/sub-mm(reporng CH 3 OH/H 2 O [3]) during its previous apparion in 1998.We observed similarly high CH 3 OH/C 2 H 6 , and also similar rotaonal temperature to that measured for 21P, in Comet 8P/Tule [4,5]. We used our (higher signalto-noise)NIRSPEC observaons of 8P to produce effecve (empirical) CH 3 OH g-factors for several lines in the ν 2 band. These will be presented together withinterpretaon of our results, including constraints on the spin temperature of water. We acknowledge support from the NASA Planetary Atmospheres, PlanetaryAstronomy, and Astrobiology Programs and from the NSF Astronomy and Astrophysics Research Grants Program.References: [1] Weaver et al. 1999 Icarus 142:482; [2] Mumma et al. 2000 ApJ 531:L155; [3] Biver et al. 2002 EMP 90:323; [4] Bonev et al. 2008 ApJ 680:L61; [5]Boehnhardt et al. 2008 ApJ 683:L7103.08: Near-nucleus Photometry Of Outbursng Comet 17p/HolmesAuthor Block: Rachel Stevenson 1 , D. Jewi 11 Dept. Earth and Space Sciences, UCLA.Presentaon Time: 10/4/2010 9:40 AM - 9:50 AMLocaon: Ballroom EAbstract.Abstract: The outburst of comet 17P/Holmes was the largest in recorded history, causing the comet to brighten by a factor of almost a million in under24 hours. We observed the aermath using the wide field camera MegaCam on the 3.6m Canada-France-Hawaii telescope atop Mauna Kea between 2007 Nov. 6UT and 2008 Feb. 12 UT. The nucleus and coma faded systemacally in the months following the outburst, with one apparent brightening occurring on 2007 Nov.12 UT, suggesng the surface of the nucleus remained unstable and acve. We will present photometry of the near-nucleus region and the surrounding coma andan analysis of the me-dependent surface brightness profile. An analysis of the morphological (as opposed to photometric) aspects of 17P/Holmes from the sameCFHT data-set has recently been published (AJ (2010), 139, 2230-2240).03.09: Interferometric Imaging of the Outburst of Comet 17P/Holmes with the Submillimter ArrayAuthor Block: Chunhua Qi 1 , M. R. Hogerheijde 2 , D. Jewi 3 , M. A. Gurwell 1 , D. J. Wilner 1 , J. P. Williams 41 Harvard Smithsonian, CfA, 2 Leiden University, Netherlands, 3 UCLA, 4 U. of Hawaii.Presentaon Time: 10/4/2010 9:50 AM - 10:00 AMLocaon: Ballroom EAbstract: We present high angular resoluon (2" or 2400 km) Submillimeter Array observaons of the Jupiter-family comet 17P/Holmes during its huge outburstfrom October 26 through October 31 2007, including detecons of CO 3-2, HCN 4-3, H13CN 4-3, CS 7-6, H2CO 3 1 ,2-2 1 ,1 and H2S 2 2 ,0-2 1 ,1, and associated dustconnuum at 221 and 351 GHz. We find two components from the molecular emissions: one from isotropic outgassing and the other from gas jets.The emissions of CO, CS, H2S and H2CO are much stronger in the gas jet component. Using a molecular excitaon code that accounts for the effects of collisionswith water and electrons, we determine disnctly different CO/HCN raos: within the isotropic outgassing component we find CO/HCN < 25, while in the gas jetcomponent, CO/HCN > 100. This difference might reflect the volale nature of the nucleus material brought out by the outburst.

Session Time: 10/4/2010 10:30 AM

Session Number: 04Session Title: Solar System Origin, Planet and Satellite FormationSession Type: Oral04.01: The Importance Of Planetesimal-driven Migraon And Collisional Grinding In Terrestrial Planet FormaonAuthor Block: David A. Minton 1 , H. F. Levison 11 Southwest Research Instute.Presentaon Time: 10/4/2010 10:30 AM - 10:40 AMLocaon: Ballroom DAbstract.Abstract: Planetesimal-driven migraon has come to be understood as an important process in the evoluon of the orbits of the giant planets. Weinvesgate here whether planetesimal-driven migraon may have been important while rocky planetary embryos were accreng within in a massive swarm ofplanetesimals in the inner solar system, where "embryo" is defined to as lunar to Mars-mass bodies. Planetesimal-driven migraon becomes important if embryoscan migrate through a planetesimal disk at a faster rate than the rate of embryo growth; migrang embryos can reach embryo-free zones of the disk before newembryos have a chance to grow there. Migraon rates of Mars sized embryos are comparable to embryo formaon rates in a planetesimal disk containing ~2mes or greater the surface mass density of the standard Minimum Mass Solar Nebula model. A more massive disk is not a problem, because we show thatcollisional grinding and mass loss due to embryo growth is an important but heretofore neglected process. Planetesimal-driven migraon allows growing embryosto be far more mobile during the runaway stage than has been assumed, leading to very different outcomes for planet formaon than have been modeled to date.One possible outcome of a migrang embryo model of terrestrial planet formaon is that the outward migraon of Mars may have been responsible for keepingits mass small. A consequence of this outward migraon is that Mars may have populated the inner asteroid belt with planetesimals, directly analogous to theresonant Kuiper belt objects that were presumably populated by Neptune's outward migraon. These resonant objects may have been an important contributor toterrestrial planet impacts when they became unstable due to the later migraon of the outer giant planets.04.02: Origin of the Asteroid Belt and Mars' Small MassAuthor Block: Kevin J. Walsh 1 , A. Morbidelli 1 , S. N. Raymond 2 , D. P. O'Brien 3 , A. Mandell 41 Observatoire de la Cote D'Azur, France, 2 Observatoire de Bordeaux, France, 3 Planetary Science Instute, 4 NASA Goddard Space Science Center.Presentaon Time: 10/4/2010 10:40 AM - 10:50 AMLocaon: Ballroom DAbstract: Reproducing the small mass of Mars is a major problem for modern simulaons of terrestrial planet accreon (Raymond et al. 2009). Terrestrialplanet formaon simulaons using a planetesimal disk with an outer edge at 1.0 AU have been found to form good Mars analogs (Hansen et al. 2009). However,these inial condions appear inconsistent with solar system evoluon and the asteroid belt. Hydrodynamical simulaons show that the evoluon of Jupiter andSaturn in a gas-disk generically leads to a two-stage, inward-then-outward migraon (Masset & Snellgrove 2001, Morbidelli & Crida 2007, Pierens & Nelson2008). We present simulaons showing that if Jupiter's minimal orbital radius was 1.5 AU, this evoluon both truncates the planetesimal disk at 1.0 AU andrepopulates the asteroid belt from two disnct parent populaons. Our model links the origin of the inner solar system - explaining both the mass of Mars andthe properes of the asteroid belt - to a realisc evoluon of the giant planets.This scenario represents a paradigm shi in our understanding of the early evoluon of the inner solar system. Previously S- and C-type asteroids were thought tohave both originated in the 2--3 AU region, with comets forming far away beyond the giant planets. This posed problems in explaining the vast physicaldifferences between S- and C-type asteroids, and the physical similaries between comets and C-type asteroids as shown by Stardust and micrometeoritesamples (Brownlee et al. 2006, Gounelle et al. 2008). Our presented scenario finds that S-types likely formed in the 1--3 AU region, with C-types and cometsforming in the outer regions of the disk. This provides a much beer qualitave explanaon of the observed differences and similaries.This work is part of the Helmholtz Alliances "Planetary Evoluon and Life", which KJW and AM thank for financial support.04.03: Early Giant Planet Migraon in the Solar System: Geochemical and Cosmochemical Implicaons for Terrestrial Planet FormaonAuthor Block: David P. O'Brien 1 , K. J. Walsh 2 , A. Morbidelli 2 , S. N. Raymond 3 , A. M. Mandell 4 , J. C. Bond 11 Planetary Science Instute, 2 Observatoire de la Cote d'Azur, France, 3 Laboratoire d'Astrophysique de Bordeaux, France, 4 NASA Goddard.Presentaon Time: 10/4/2010 10:50 AM - 11:00 AMLocaon: Ballroom DAbstract: A new terrestrial planet formaon model (Walsh et al., this meeng) explores the effects of a two-stage, inward-then-outward migraon of Jupiterand Saturn, as found in numerous hydrodynamical simulaons of giant planet formaon (Masset & Snellgrove 2001, Morbidelli & Crida 2007, Pierens & Nelson2008). Walsh et al. show that the inward migraon of Jupiter truncates the disk of planetesimals and embryos in the terrestrial planet region. Subsequentaccreon in that region then forms a realisc system of terrestrial planets, in parcular giving a low-mass Mars, which has been difficult to reproduce insimulaons with a self-consistent set of inial condions (see, eg. Raymond et al. 2009). Addionally, the outward migraon of the giant planets populates theasteroid belt with disnct populaons of bodies, with the inner belt filled by bodies originang inside of 3 AU, and the outer belt filled with bodies originangfrom beyond the giant planets.From a geochemical and cosmochemical point of view, this scenario differs significantly from the "standard model" in which essenally all of the material in theinner Solar System inially formed there. Specifically, the assumpon that the current radial distribuon of material in the inner Solar System is reflecve of theprimordial distribuon of material in that region is no longer necessary. This is important for understanding the chemical and isotopic diversity of the inner SolarSystem as inferred from studies of the terrestrial planets, asteroids, and meteorites, as well as for understanding the origin of Earth's water. We will discuss thegeochemical and cosmochemical implicaons of this model in relaon to available constraints, as well as to previous models of terrestrial planet formaon.Masset & Snellgrove (2001), MNRAS 320, L55. Morbidelli & Crida (2007), Icarus 191, 158. Pierens & Nelson (2008), A&A 482, 333. Raymond et al. (2009), Icarus203, 644.04.04: Tilng Saturn without Tilng Jupiter or Ejecng an Ice Giant: Constraints on migraonAuthor Block: Douglas S. McNeil 1 , M. H. Lee 11 University of Hong Kong, Hong Kong.Presentaon Time: 10/4/2010 11:00 AM - 11:10 AMLocaon: Ballroom DAbstract.Abstract: The obliquies of the giant planets preserve informaon about their migraon and encounter histories. Are the classic Nice models (Tsiganiset al. 2005) or the resonant Nice models (Morbidelli et al. 2007) compable with Jupiter's 3 degree lt and Saturn's 27? Here we consider the obliquity evoluonof the giants during the planetesimal-driven migraon phase using two methods: (1) a purely secular integraon of the Laplace-Lagrange equaons with spin,and (2) a hybrid N-body scheme with full interacons between the Sun and the giants but imposed prescripons for migraon and eccentricity and inclinaondamping. We find that it is difficult to reproduce today's obliquity values as migraon mescales sufficient to lt Saturn via the Hamilton &amp; Ward (2004)

secular spin-orbit resonance mechanism generally suffice to lt Jupiter more than is observed. Moreover, long migraon mescales which make lng Saturneasier simultaneously reduce the survival fracon (to below 20% for mescales longer than 20 Myr.) We discuss the constraints these observaons provide on thedynamical history of the giant planets, and the remaining possibility of lng Saturn during a late very slow migraon of Neptune to its present locaon aer themain phase of migraon is complete. [This work was supported by Hong Kong RGC grant HKU 7024/08P.]04.05: A Crical Lunar and Planetary Period ~ 4 Gy Ago - Independent of Dynamical Cataclysm ModelsAuthor Block: William K. Hartmann 11 Planetary Science Instute.Presentaon Time: 10/4/2010 11:10 AM - 11:20 AMLocaon: Ballroom DAbstract: Lunar crater counts at various landing sites show that the lunar cratering rate was declining from about 3.8 to 3.3 Gy ago, as found independently bydifferent workers [1,2,3]. This means saturaon cratering was reached in much shorter intervals around 3.8 Gy ago (and probably 3.9-4.1 Gy) than today. Thiscreates a crical period in terms of surface sample properes.Geometric consideraons alone show that as crater densies approach saturaon levels, the depth of pulverizaon, reworking, and regolith producon increasesexplosively [4,5]. Thus, while some 5 to 20 meters of regolith have been produced on mare surface in the last 3.5 Gy, such depths would have been reworkedmany mes over in intervals as short as 30 My at mes around 3.8 Gy and probably before - whether a Nice-style cataclysm happened or not.The conclusion is that rocks placed on the surfaces of airless inner solar system worlds before 3.8-4.1 Gy ago have much lower probability of surviving intact unltoday, than rocks delivered aer 3.8 Gy ago. This statement explains some properes of rock collecons from surface sites of different ages.References: [1] Hartmann, W.K. 1972. Astrophysics and Space Sci. 12:48-64. [2] Neukum, Gerhard 1983 Habilitaon Dissertaon, Ludwig-Maximilians-University,Munich. [3] Neukum, G., Boris Ivanov, and W. K. Hartmann 2001. Space Sci. Rev., 96:55-86. [4] Hartmann, W. K. 1980. In Proc. Conf. Lunar Highlands Crust, ed. J.Papike and R. Merrill. (N.Y.: Pergamon Press), pp. 155-171. [5] Hartmann, W. K. 2003. Meteorics and Planet. Sci. 38:579-593.04.06: The Structure of the Pre-Lunar DiskAuthor Block: William R. Ward 11 Southwest Research Inst..Presentaon Time: 10/4/2010 11:20 AM - 11:30 AMLocaon: Ballroom DAbstract: In the giant impact model of lunar formaon (Cameron & Ward 1976), the Earth is surrounded by a debris disk composed primarily of silicate materialimmediately following the impact event (e.g., Canup 2004). The dynamical evoluon of the disk is driven by gravitaonal instabilies that generate an effecveviscosity, causing the disk to spread (Ward & Cameron 1978; Takeda & Ida 2001). A poron of the material expands across the Roche boundary where it caneventually accrete into the Moon, while the remaining material is re-accreted by the Earth. The spreading rate is regulated by the disk's radiaon budget througha complex two-phase gas/magna equilibrium state that maintains the radiaon temperature near 2000 K (Thompson & Stevenson 1988). The vercal structure ofthe disk must sasfy the Clausius-Clapeyron phase equilibrium equaon as well as equaons of hydrostac and convecve equilibrium. The two phase disk has amodified sound speed that depends on the mass fracons of gas versus liquid, and consequently, there is a range of possible structures that depend on thesefracons. We will examine under what condions different disk structures are likely to have prevailed during the early history of the system. The resulngconsequences of various disk histories on the dynamics and ming of the Moon's accreon will also be considered.This research is supported by funds from the NASA Lunar Science Instute (NLSI) and from NASA's LASER program.04.07: Minimal Lunar Cataclysm from Tidal Disrupon of Mesosiderite Parent BodyAuthor Block: Maja Cuk 11 Smithsonian Astrophysical Observatory.Presentaon Time: 10/4/2010 11:30 AM - 11:40 AMLocaon: Ballroom DAbstract: The Lunar Cataclysm 3.9 Gyr ago is sll a controversial subject more than 30 years since its discovery. Researchers are sll divided over theinterpretaon of crater counts and the provenance of Apollo samples. Surprisingly, lunar basin magnezaon has not been used yet to constrain basin formaonhistory. I will show that basin magnezaon data strongly support a minimal cataclysm (which includes only Hertzsprung and Imbrian basins). Available craterSFD data are also consistent with this picture. This event is not consistent with delayed planetary migraon but may indicate a disrupon of a single body. Wecalculate that a survival of a Vesta-sized primordial Mars-crosser unl this era is possible if the inial populaon was about 0.01 Earth masses (Boke et al.2007, in contrast, studied only bodies with q

1 Charles University, Czech Republic.Presentaon Time: 10/4/2010 11:50 AM - 12:00 PMLocaon: Ballroom DAbstract: We study long-term orbital evoluon and also physical properes of the resonant family among Hilda asteroids (located in the J3/2 resonance withJupiter). In case of 1st order resonances a systemac dri in eccentricity occurs due to the Yarkovsky/YORP effect, which enables us to determine the age morethan 3.5 Gyr for the Hilda family. We constructed an N-body model for this purpose, which includes gravitaonal perturbaon of planets, Yarkovsky dri and anupdated YORP model for the evoluon of spin axes.The dynamics of the oldest asteroid families might be driven by planetary migraon, which likely occurred ~3.8 Gyr ago, and we test this possibility by variousmigraon scenarios. The Hilda family is perturbed mainly by secondary resonances between Jupiter-Saturn 1:2 frequency and frequency of libraons in the J3/2resonance. Our results indicate that: 1) the family was created at the me, when Jupiter and Saturn were already far from a compact 1:2 configuraon; 2) themigraon of Uranus and Neptune was very fast, with a few Myr mescale.We finally address two alternave hypotheses: 1) inial velocity field was extremely anisotropic; 2) small members of the family have higher albedos, but we findneither of them likely.

the HIPPAROCS satellite, it appears that the number of injected comets is less than 20% of the total flux for semi-major axis smaller than 25 000 AU.On the contrary, the stars which could be observed by the future GAIA mission will allow to obtain more than 80% of the total flux forsemi-major axis smaller than 40 000 AU and more than 90% for semi-major axis smaller than 25 000 AU.In conclusion, because the stellar perturbaons allow to inject comet at smaller semi-major axis than with only the des, our view of the Oort cloud size andpopulaon may change.We have also shown that it is hopeless to perform a backward integraon over one orbital period of the known "new comets" in order to esmate this size sinceour knowledge of the stellar neighborhood of the Sun is sll too incomplete. However, future spaal mission like GAIA may fill this gap and allow us to performsuch a study.MF is grateful to PNP 2010 for financial support.05.06: Capture of the Sun's Oort Cloud from Stars in its Birth ClusterAuthor Block: Harold F. Levison 1 , M. Duncan 2 , R. Brasser 3 , D. Kaufmann 11 Southwest Research Inst., 2 Queen's University, Canada, 3 Nice Observatory, France.Presentaon Time: 10/4/2010 11:20 AM - 11:30 AMLocaon: Ballroom EAbstract: Oort cloud comets are currently believed to have formed in the Sun's proto-planetary disk, and to have been ejected to large heliocentric orbits by thegiant planets. Detailed models of this process fail to reproduce all of the available observaonal constraints, however. In parcular, the Oort cloud appears to besignificantly more populous than the models predict. Here we present numerical simulaons that show that the Oort cloud could have been captured from otherstars while the Sun was in its birth cluster. Our results imply that >~90% of the Oort cloud comets that we have seen are from the proto-planetary disks of otherstars. This includes some of the most famous comets in history, including 1P/Halley and C/1995 O1 (Hale-Bopp). We thank NASA's Astrobiology Inst, and Originsand OPR programs for support.05.07: Detecon of Nongravitaonal Acceleraons on Comet 133P/Elst-PizarroAuthor Block: Steven R. Chesley 1 , H. Kaluna 2 , J. Kleyna 2 , K. Meech 2 , J. Pichová 2 , D. Yeomans 11 JPL/Caltech, 2 Inst. for Astronomy, Univ. Hawaii.Presentaon Time: 10/4/2010 11:30 AM - 11:40 AMLocaon: Ballroom EAbstract: Comet 133P/Elst-Pizarro is the best observed of the main belt comets, with astrometric measurements now spanning more than 30 years and for thisreason is so far the only main belt comet confirmed to have recurring periods of acvity. Here we report the detecon and measurement of nongravitaonalacceleraons acng on the nucleus of Elst-Pizarro.Using the so-called g(r) formalism of Marsden et al. [1] we esmate the radial and normal nongravitaonal parameters of Elst-Pizarro as, respecvely,A1=12.6±4.1 and A3=7.5±6.3 in units of 10 -10 AU/d 2 . Stated uncertaines are formal. The observaonal data do not reveal stascally significant transverseacceleraons (i.e., A2). The stascal significance of the out-of-plane acceleraon is poor, and should be interpreted merely as an indicaon that theacceleraons are likely posive, suggesng a possible predominance of southern hemisphere acvity in the case of direct rotaon. On the other hand, the 3-sigma significance of the radial acceleraon gives good confidence in the esmate, and indeed the esmated value of A1 is stable across a range of fit spans anddata treatments.The above parameters imply a peak acceleraon of 2.5×10 -10 m/s 2 at perihelion. Assuming reasonable values for nucleus mass and gas velocity leads to a massflow rate roughly of order 10 kg/s. However, the applicability of the Marsden et al. model is dubious in this case where there is good evidence that the outgassingis governed primarily by seasonal factors rather than the simple g(r) funcon [2]. Thus the out-gassing could be considerably more spread in me andhave a lower maximum, especially if it takes place far from perihelion. The ulity of alternate out-gassing models will be considered.Refs: [1] Marsden et al., AJ 78, 211--225, 1973. [2] Hsieh et al., AJ 127, 2997--3017, 2004.05.08: Temporal Evoluon of Water and Dust in Comet 9P/Tempel 1 aer the Deep Impact Event, as Observed from SpitzerAuthor Block: Adeline Gicquel 1 , D. Bockelée-Morvan 1 , M. S. Kelley 2 , C. E. Woodward 3 , D. H. Wooden 41 Observatoire De Paris, France, 2 Department of Astronomy, University of Maryland, 3 Department of Astronomy,School of Physics and Astronomy, 4 NASA AmesResearch Center, Space Science Division.Presentaon Time: 10/4/2010 11:40 AM - 11:50 AMLocaon: Ballroom EAbstract: The Deep Impact (DI) spacecra encountered comet 9P/Tempel 1 on July 4th, 2005. The spacecra released an impactor that collided with the cometnucleus and excavated (possibly unprocessed) cometary material in a prominent ejecta plume. Spectral maps covering 20'' x 67'' (1.85''/pixel) were acquired withthe IRS instrument on the Spitzer Space Telescope at different mes around the DI event: twice before impact (TI-41.3hrs and TI-22.9hrs) and twelve mes aerimpact (between TI+0.67hrs and TI+1027hrs). These IRS observaons are stored in the Spitzer data archive and presented by Lisse et al. (2006, Science 313, 635).We present the interpretaon of 5.2-7.6 micrometer spectra obtained in the second order of the short-wavelength module (SL2). To reduce the contribuon ofarfacts in the spectra, 5x5 pixel extracon apertures (9.25''x9.25'') were used. The underlying connuum in the spectra provides informaon on the grain sizedistribuon and color temperature of the dust ejecta. In order to determine the grain size distribuon, we assumed that ejecta consist of a composion of bothamorphous carbon and silicates. The grains are assumed to be spherical with sizes in range from 0.1 to 100 micrometers. We used the Mie theory to calculate theopcal properes of each material and the temperature of the grain. We constrained the grain size distribuon and velocies from the spectra and the temporalevoluon of the dust flux. The dust mass and dust/gas rao in the ejecta cloud are also derived and compared with other values published in the literature.05.09: Crystalline Water Ice In Outburst Comet P/2010 H2Author Block: Bin Yang 1 , G. Sarid 11 Astrobiology Instute, Univ. of Hawaii.Presentaon Time: 10/4/2010 11:50 AM - 12:00 PMLocaon: Ballroom EAbstract.Abstract: The Quasi-Hilda comet P/2010 H2 (Vales) underwent a remarkable outburst on UT April 16, 2010. The brightness of this object increased by afactor of 1000 in less than 15 hours. Near-infrared (0.8 to 2.5 micron) spectroscopy of this new comet was performed using the 3.0-m NASA Infrared TelescopeFacility atop Mauna Kea on UT April 20 and 22, 2010. Two broad absorpon bands were detected in the reflectance spectra of Vales, centered at 1.5 and 2.0micron at depths of 4% and 8% of the connuum, respecvely. These features, which were detected on the both nights, are consistent with abundant water icegrains in the central coma. Moreover, a narrow absorpon feature was observed at 1.65 micron, indicang the presence of crystalline ice. We will present the NIRspectra of comet Vales and the best-fit synthec models. We will also discuss a dynamical analysis which constrains the lifeme and the likely source regions ofthis new outburst comet. This was supported by the Naonal Aeronaucs and Space Administraon through the NASA Astrobiology Instute under Cooperave

Agreement No. NNA08DA77A issued through the Office of Space Science.

Session Number: 06Session Title: Icy Moon CornucopiaSession Type: Oral06.01: Composion of Jovian Outer Irregular Satellites from Reflectance Spectrophotometry: New MMT DataAuthor Block: Faith Vilas 11 M M T Observatory.Presentaon Time: 10/4/2010 10:30 AM - 10:40 AMLocaon: Ballroom BCAbstract: The “Nice model” describes a scenario in which the Jovian planets experienced a violent reorganizaon ~3.9 Gyr ago. One discrepancy, however, isthat the Nice model predicts that transported KBOs should dominate the outer part of the main asteroid belt. Reflectance spectra of these objects are expected tolook like the spectra of the D-class asteroids: dark plus increasing reflectance with increasing wavelength (“reddening”). The outer main asteroid belt, however, isdominated by the grossly spectrally neutral (“grey”) C-type asteroids from 2.6 to 3.2 AU. Perhaps 50% of these C-class asteroid spectra also show absorponfeatures in the ~ 0.4 - 3.5 µm range suggesng aqueous alteraon. Boke et al. (LPSC XXXIX , 1447, 2008) argue that more than 90% of the objects captured inthe outer main belt could have been eliminated by impacts in the violent reshuffling episode, if they had been weakly-indurated objects. These disrupted objectsshould have le behind pieces in the ancient regoliths of other - presumably stronger - asteroids. The observed aqueous alteraon absorpon features havegenerally not been detected in spectra of D-class asteroids. Now, the existence of features aributed to aqueous alteraon products is suggested in thereddened photometry and spectra of outer irregular jovian and saturnian satellites, and some outer-belt D-type asteroids (e.g., Vilas et al., Icarus 180, 453, 2006).To invesgate further, VNIR narrowband spectroscopy was obtained of irregular satellites JVI Himalia, JVII Elara, JVIII Pasiphae, JIX Sinope, JX Lysithea, JXI Carme,JXII Ananke in 2006, 2008, 2009, 2010 using the MMT Observatory facility Red Channel spectrograph centered near 6400 Å to cover the 0.7-µm feature enrely.These spectra sample the prograde (i = 28 o ), two retrograde (i = 149 o , 165 o ) and independent satellites. These data will be discussed in the context ofcomposional similaries with C and D type asteroids.06.02: Earth-based and Cassini-spacecra Observaons of Irregular Moons of Jupiter and SaturnAuthor Block: Tilmann Denk 1 , S. Moola 2 , T. Roatsch 2 , H. Rosenberg 1 , G. Neukum 11 Freie Universität Berlin, Germany, 2 DLR Berlin, Germany.Presentaon Time: 10/4/2010 10:40 AM - 10:50 AMLocaon: Ballroom BCAbstract: We observed irregular satellites of Jupiter and Saturn with the ISS camera of the Cassini spacecra [1] and with the 1.23-m telescope of the CalarAlto observatory in Spain [2]. Scienfic goals are the determinaon of rotaon periods, rotaon-axis orientaons, spin direcons, size parameters, colorproperes, phase curves, and searches for binaries.Himalia (J6), the largest of the irregular jovian moons, has been imaged by Cassini on 18 Dec 2000; a body size of 120±5 km x 150±10 km and an albedo of0.05±0.01 have been measured [3,4]. Earth-based observaons revealed that Himalia's rotaon period is probably 9.3 h, which is in agreement with the 9.2 to 9.8h suggested by [5], although periods of 7.8 or 11.7 h cannot be ruled out yet.In the saturnian system, 10 irregular moons were scheduled for Cassini ISS observaons over me spans >9 hrs unl end-of-August, 2010. Observaon distancesvary between 5.6 and 22 million km, corresponding to ISS pixel scales of 34 to 130 km. For the objects measured so far, the rotaon periods vary significantly. Forinstance, Siarnaq (S/2000 S3; size ~40 km) and Ymir (S/2000 S1; ~18 km) exhibit rotaon periods of ~6.7 h and ~7.3 h, respecvely, while Kiviuq (S/2000 S5; ~16km) might take about 22 h for one rotaon. First results from the observaon campaigns will be presented at the meeng.References: [1] Porco, C.C., et al. (2004), Space Sci. Rev. 115, 363; [2] hp://www.caha.es/CAHA/Telescopes/1.2m.html; [3] Denk, T. et al. (2001), Conference onJupiter (Planet, Satellites & Magnetosphere), Boulder, CO, 25-30 June 2001, abstracts book p. 30-31; [4] Porco, C.C., et al. (2003), Science 299, 1541; [5] Degewij,J., et al. (1980), Icarus 44, 520.We gratefully acknowledge funding by the German Space Agency (DLR) Bonn through grant no. 50 OH 0305.06.03: Clues to Hyperion's Interior from its Rotaonal BehaviorAuthor Block: Rebecca A. Harbison 1 , P. D. Nicholson 1 , P. C. Thomas 1 , B. Carcich 1 , M. S. Tiscareno 11 Cornell University.Presentaon Time: 10/4/2010 10:50 AM - 11:00 AMLocaon: Ballroom BCAbstract: Saturn's moon Hyperion is known for its non-synchronous rotaon, unlike the other regular moons of Saturn, but for changing its rotaon state over amaer of orbits. The Voyager flyby showed a moon in non-principal axis rotaon, with a spin axis near the moon's long axis and a rate of over four mes theorbital rate.Dynamical studies by Wisdom et al. (1984) predicted that the strongly-varying solid-body torques on Hyperion from Saturn would result in a moon with no loworder,stable spin-resonant states, with chaos over several orbits (about 50 days). Using models constructed with ground-based and Voyager data, Klaveer(1989) and Black et al. (1995) confirmed the chaos and concluded their models were consistent with a uniform-density Hyperion.In 2005, Cassini made three close passes of Hyperion. Changes in the spin rate of the moon are observable between fly-bys, but Hyperion appears to be in asimilar quasi-periodic state to the one observed by Voyager. While Hyperion is likely too small to be differenated, the large porosity inferred from its bulk density(Thomas et al., 2007) allows for an uneven distribuon of voidspace not apparent from surface features. We modeled Hyperion's rotaon during 2005, whichallowed esmaon of moments of inera, giving insight on its interior in a way that can be done with few other moons of its size.We conclude that the moment of inera raos of Hyperion do not agree well with those predicted from Thomas's shape model. Furthermore, models that place aprincipal axis nearer to the spin axis than the shape implies fit the data much beer than simply varying the moments of inera and fixing the principal axes tothe shape. This indicates that Hyperion may have large-scale inhomogeneies within its interior.06.04: Rhea: Sll RinglessAuthor Block: Mahew S. Tiscareno 1 , J. A. Burns 1 , J. N. Cuzzi 2 , M. M. Hedman 11 Cornell Univ., 2 NASA Ames.Presentaon Time: 10/4/2010 11:00 AM - 11:10 AMLocaon: Ballroom BC

Abstract: We have conducted an intensive search for any material that may orbit Rhea, using images obtained by the Cassini ISS narrow-angle camera. We findno evidence for any such material, contradicng an earlier and surprising inference that Rhea, the second-largest moon of Saturn, possesses a system of narrowrings embedded in a broad circum-satellite disk or cloud (Jones et al. 2008, Science).If one accepts the calculaons of the previous authors, our results would require any narrow rings around Rhea to be composed of objects no smaller than 10meters in radius, in order to be massive enough to account for the observed charged-parcle absorpons but diffuse enough to evade detecon in our images.Such a parcle-size distribuon is unrealisc given that erosion processes will break down 10-meter objects to smaller sizes, which would then have been seen inour images.Furthermore, Jones et al. (2008) assumed that the absorpon of electrons by hypothecal circum-Rhea parcles is proporonal to the volume of the parcles,even when they are much larger than the electron penetraon depth (van Allen 1983, 1987, JGR). If we assume instead that large parcles can only absorbelectrons efficiently near their surfaces, then our results rule out any solid material orbing Rhea as the explanaon for the absorpons detected by Jones et al.(2008), regardless of parcle size, by a margin of four (for narrow rings) or two (for a broad diffuse cloud) orders of magnitude.We conclude that the anomalous electron absorpons reported by Jones et al. (2008) are the signature of a new and hitherto unknown magnetospheric process.06.05: Metallic Iron and Iron Oxide as an Explanaon for the Dark Material Observed on Saturn's Icy Satellites and Rings with Cassini VIMSAuthor Block: Roger Nelson Clark 1 , D. P. Cruikshank 2 , R. Jaumann 3 , R. H. Brown 4 , C. Dalle Ore 2 , K. Stephan 3 , T. M. Hoefen 1 , J. M. Curchin 1 , B. J. Bura 5 , G.Filacchione 6 , K. H. Baines 5 , P. D. Nicholson 71 US Geological Survey, 2 NASA Ames, 3 DLR, Germany, 4 University of Arizona, 5 JPL, 6 INAF-IASF, Italy, 7 Cornell U..Presentaon Time: 10/4/2010 11:10 AM - 11:20 AMLocaon: Ballroom BCAbstract.Abstract: The Visual and Infrared Mapping Spectrometer (VIMS) on Cassini has obtained spaally resolved spectra on satellites of Saturn. The CassiniRev 49 Iapetus fly-by on September 10, 2007, provided data on both the dark material and the transion zone between the dark material and the visually brightice. The dark material has low albedo with a linear increase in reflectance with wavelength, 3-micron water, and CO2 absorpons. The transion between brightand dark regions shows mixing with unusual opcal properes including increased blue scaering and increasing strength of a UV absorber in areas withstronger ice absorpons. Similar spectral effects are observed on other Saturnian satellites and in the rings. We have been unable to match these spectralproperes and trends using tholins and carbon compounds. However, the dark material is spectrally matched by fine-grained metallic iron plus nano-phasehemate and adsorbed water which contribute UV and 3-micron absorpon, respecvely. The blue scaering peak and UV absorpon can be explained byRayleigh scaering from sub-micron parcles with a UV absorpon, or a combinaon of Rayleigh scaering and Rayleigh absorpon as has been aributed tospectral properes of the Moon. A new radiave transfer model that includes Rayleigh scaering and Rayleigh absorpon has been constructed. Models of ice,sub-micron metallic iron, hydrated iron oxide, and trace CO2 explain the observed spectra. Rayleigh absorpon requires high absorpon coefficient nano-sizedparcles, which is also consistent with metallic iron. The UV absorber appears to have increased strength on satellite surfaces close to Saturn, with acorresponding decrease in metallic iron signature. A possible explanaon is that the iron is oxidized closer to Saturn by oxygen in the extended atmosphere ofSaturn's rings, or the dark material is simply covered by clean fine-grained ice parcles, for example, from the E-ring.06.06: A 3-D General Circulaon Model of Triton's AtmosphereAuthor Block: Melanie Vangvichith 1 , F. Forget 1 , R. Wordsworth 1 , E. Millour 11 LM D, France.Presentaon Time: 10/4/2010 11:20 AM - 11:30 AMLocaon: Ballroom BCAbstract: The Triton's atmosphere circulaon and surface frost distribuon remain poorly known. To improve our understanding of these charactericcs, wehave developed the first 3D General Circulaon Model of Triton's Atmosphere which has been adapted from a GCM of the Maran atmosphere [1].In pracce, the dynamic part of the Maran GCM has been kept and the physical part has been modified to suit specific properes of Triton's atmosphere. Therepresentaon of the large-scale dynamics is based on a grid point model composed of 32 longitudes and 24 latudes that is a resoluon about 170 km and with25 layers distributed from the surface to above 45 km. The physical parameterizaons of the GCM include N2 condensaon and sublimaon both in theatmosphere and on the ground, the vercal turbulent mixing and the convecon in the planetary boundary layer, the thermal conducon with a prescribed flux atthe top of the model represenng heang from the upper atmosphere. We have introduced radiave processes due to methane and carbon monoxide, using thecorrelated k method to generate radiave transfer simulaon.With the GCM, we have tried to reproduce the Voyager 2 observaons. Some simulaons have been run supposing several realisc surface frost distribuons.The temperature profiles exhibit a clearly defined tropopause and just above a thermosphere, as expected from the Voyager observaons. However, this modeldoes not reproduce the wind direcon inferred from the plumes. The implementaon in the GCM of a topography on Triton or a flux varying with the latude andthe season could be behind this mystery.[1] Hourdin et al. (1993), J.A.S 50, 3625-3640 ; Forget et al. (1999), J.G.R 104., NO.E10, PP.24, 155-24, 175

Session Time: 10/4/2010 1:30 PM

Session Number: 08Session Title: Planetary Mission HighlightSession Type: PlenarySession Description: 1:40-1:45 pm, Eberhardt Prize Awarded to George Musser (Scientiic American)08.01: Rosea’s Encounters With Asteroids (2867) Steins And (21) LuteaAuthor Block: Rita Schulz 1 , A. Accomazzo 2 , M. Küppers 3 , K. Wirth 31 ESA Research and Scienfic Support Department, Netherlands, 2 European Space Operaons Centre, ESA/ESOC, Germany, 3 Science Operaons Department,ESA/ESAC, Spain.Presentaon Time: 10/4/2010 1:45 PM - 2:20 PMLocaon: Plenary BallroomAbstract.Abstract: On cruise to its main target, the Jupiter-family comet 67P/Churyumov-Gerasimenko, the ESA Rosea spacecra has performed close fly-bysat two very different main-belt asteroids. The first encounter took place on 5 September 2008, when Rosea flew by the 5-km sized asteroid (2867) Steins at adistance of 802.6 km. Then on 10 July 2010 Rosea passed its main asteroid target, the 100-km sized asteroid (21) Lutea, at a distance of 3162 km. In each casethe fly-by strategy was arranged such that it allowed for connuous observaons of the asteroid before, during and aer closest approach whilst the spacecrapassed through phase angle zero. Most of the scienfic instruments on board Rosea were switched on for invesgaons of the asteroids and their surroundingenvironment. Mul-wavelength observaons were obtained covering the electromagnec spectrum from the UV to radio wavelengths. On top of this theasteroids' gas, dust, plasma, magnec, and radiaon environments were characterized in-situ by various instruments on board Rosea. Both targets wereselected aer careful evaluaon of the scienfic significance of all reachable asteroids constrained by the available fuel budget, and have turned out to beextraordinarily interesng objects for close inspecon. This is not just because (21) Lutea is the largest asteroid, and (2867) Steins is the only E-type asteroidever visited by a space mission, but rather the results reveal the complex morphology, dynamics, and composion of both. Aer compleon of the detailedanalysis of the data obtained by Rosea these two objects will be among the best-studied asteroids and as such will add significantly to our understanding of thedifferent types of asteroids. This in itself will help to solve the puzzle of how the solar system has formed and evolved.08.02: Recent Scienfic Results From the Mars Exploraon ProgramAuthor Block: Ray Arvidson 11 Washington University in Saint Louis.Presentaon Time: 10/4/2010 2:20 PM - 2:55 PMLocaon: Plenary BallroomAbstract.Abstract: Landed and orbital plaorms connue to show that Mars has had a diverse geologic history rich in informaon about past fluvial, lacustrine,and hydrothermal environments. For example, Spirit rover's wheels broke through a thin soil crust and exposed sands enriched in hydrothermal sulfates. The soilcrust is enriched in relavely insoluble minerals, indicang ongoing aqueous leaching and transport of soluble species into the subsurface. Opportunity connuedto explore the ancient reworked lake beds in Meridiani Planum and is currently driving toward the rim of the Noachian-aged Endeavour crater. CRISM observaonsshow that the rim exposes clay minerals and hydrated sulfates unlike those found thus far by Opportunity are exposed nearby. These examples, and others, willbe used to illustrate the compelling science associated with past wet environments and enhanced habitability potenal of Mars as compared to many solarsystem objects.08.03: Cassini-Huygens in the Saturn System: Recent Science Highlights and the Solsce MissionAuthor Block: Linda J. Spilker 11 NASA Jet Propulsion Laboratory/Caltech.Presentaon Time: 10/4/2010 2:55 PM - 3:30 PMLocaon: Plenary BallroomAbstract: The Cassini-Huygens exploraon of the Saturn system has returned a wealth of scienfic data on Titan, Enceladus, and the other icy satellites,Saturn, the rings, and the magnetosphere. Cassini-Huygens arrived at Saturn in July 2004, roughly two years aer the northern winter solsce, and it has been inorbit around Saturn through spring equinox (August 2009), to date compleng its Prime and Equinox Missions.During the Equinox Mission, the Cassini orbiter watched as Titan’s northern hemisphere lakes were illuminated by sunshine, producing a specular reflecon in thenear infrared. Ethane was detected in Ontario Lacus, a south polar lake, and its shoreline receded, evidence for evaporaon. The most detailed temperature mapever made of Mimas showed completely unexpected hot and cold sides. High-resoluon images revealed numerous new small jets in Enceladus’ ger-striperegion. Curtain-like aurorae were caught flickering over Saturn’s north pole. The rings were seen at low solar incidence angle (equinox) and their threedimensionalstructure was revealed, including a spiral wave throughout the C and D rings, large clumps at the outer edge of the B ring and km-sized wavescreated by the moon Daphnis along the edges of the Keeler gap.Cassini-Huygens is now entering a seven-year phase called the Solsce Mission, returning science in a hitherto unobserved seasonal phase from equinox tosolsce. The Solsce Mission will provide new science; first, by observing seasonally and temporally dependent processes on Saturn, Titan, Enceladus and othericy satellites, and within the rings and magnetosphere; second, by addressing new quesons that have arisen during the mission thus far, for example providingqualitavely new measurements of Enceladus and Titan which could not be accommodated in the earlier mission phases; and third, by conducng a close-inmission at Saturn that would provide a unique comparison to the Juno observaons at Jupiter.

Session Time: 10/4/2010 3:30 PM

Session Number: 09Session Title: Saturnian and Other Icy Satellite PostersSession Type: Poster09.01: The Radial Distribuon Of Water Ice And Reddening Material Across Saturn's Icy Satellites And Rings Retrieved From Cassini Vims ObservaonsAuthor Block: Gianrico Filacchione 1 , F. Capaccioni 1 , P. Cerroni 1 , R. N. Clark 2 , R. H. Brown 3 , J. N. Cuzzi 4 , B. J. Bura 5 , A. Coradini 6 , F. Tosi 6 , M. Ciarniello 1 , D. P.Cruikshank 4 , R. Jaumann 7 , P. D. Nicholson 8 , K. Stephan 7 , K. H. Baines 51 INAF-IASF, Italy, 2 USGS, 3 University of Arizona, 4 NASA-AM ES, 5 NASA-JPL, 6 INAF-IFSI, Italy, 7 DLR, Germany, 8 Cornell University.Presentaon Time: 10/4/2010 3:40 PM - 3:42 PMLocaon: Exhibit HallAbstract: In the past few years we have retrieved the amount of water ice and red contaminant materials distributed across the Saturnian Icy satellitessurfaces and Ring regions using Cassini-VIMS observaons. These measurements highlight very striking differences among the Saturn system objects, which varyfrom the almost uncontaminated and water ice-rich surfaces of Enceladus and Calypso to the metal/organic-rich and red surfaces of Iapetus leading hemisphereand Phoebe. In this framework we have developed a method to compare surface composion versus radial distance from Saturn and satellites' densies. In the Fring environment, the inner minor satellites (Prometheus, Pandora, Janus and Epimetheus) have in average surface water ice abundance similar to C ring andCassini division parcles but with much less reddening contaminant. Although their orbits are close to the F-ring, Prometheus and Pandora have very strikingdifferences in surface composion, Prometheus being very water ice-rich but at the same me very red at VIS wavelengths. These properes make it very similarto A-B ring parcles while Pandora is bluer. Moving outwards, we see the effects of E ring parcles generated by Enceladus plumes contaminated surfaces fromMimas up to Rhea. We found some differences between Tethys’ lagrangian moons, Calypso being much more water ice-rich and bluer with respect to Telesto.Among outer satellites (Hyperion, Iapetus and Phoebe) we observe a linear trend in both water ice decrease and in reddening, Hyperion being the reddest objectof the populaon. This research is supported by an Italian Space Agency Grant.09.02: The Shapes of the Saturnian Satellites Pallene, Methone, and AntheAuthor Block: Morgan Rehnberg 1 , M. M. Hedman 2 , J. A. Burns 2 , M. S. Tiscareno 2 , C. D. Murray 3 , M. W. Evans 21 Beloit College, 2 Cornell University, 3 Queen Mary, University of London, United Kingdom.Presentaon Time: 10/4/2010 3:42 PM - 3:44 PMLocaon: Exhibit HallAbstract: We have analyzed photometrically the several hundred available unresolved images of the small Saturnian moons Pallene (S/2004 S2), Methone(S/2004 S1), and Anthe (S/2007 S4) in an effort to constrain their shapes and orientaons. Variaons in the moons’ brightness with viewing geometry areconsistent with those expected for synchronously rotang bodies with their long axes pointed at Saturn and their short axes normal to the orbital plane. Themoons were modeled as tri-axial ellipsoids with principal axes a (long), b (intermediate), and c (short). The equatorial axis rao (a/b) is moderately wellconstrained with values for all three moons likely exceeding 1.3, indicang that all three moons are roughly prolate. Our result for Pallene is within one standarddeviaon of a previously published value calculated from two resolved images (Porco et al. 2007, Science). The polar axis (c) is poorly constrained for all threemoons, due to the lack of high-latude images. However, we have set lower limits on the c/b rao for the three moons. We have also constrained the linearphase coefficients for these moons and have sought possible forced libraons and/or axial offsets due to internal density inhomogeneies.09.03: Improved Radio Emissivies for Satellites of SaturnAuthor Block: Paul Ries 11 University of Virginia.Presentaon Time: 10/4/2010 3:44 PM - 3:46 PMLocaon: Exhibit HallAbstract: The size distribuon of TNOs is one of the most important constraints on the history of the early solar system. However, while TNOs are mostdetectable in the visible and near-IR wavelengths, their albedos vary substanally, thus creang uncertainty in their sizes when determined from reflected lightalone. One way of determining the size distribuon for a large number of TNOs is to measure their thermal emission, such as has been done with Spitzer andHerschel. However, in just a few year's me, ALMA will be coming online, and will be able to detect thermal emission from even more TNOs.However, thermal emission from Solar System bodies in the millimeter and submillimeter, such as that which ALMA will detect, is not that of a pure blackbody.Pluto, the Gallillean satellites, and Vesta have all shown deviaons from unity emissivity. However, the cause of this variaon is not well understood.Here we re-analayze data from the Cassini RADAR instrument at 2.5 cm. Cassini RADAR measured the brightness temperature and emissivity of several ofSaturn's icy satellites, at least one of which, Phoebe, is thought to be a captured TNO. Previous emissivity determinaons relied on relavely simple thermalmodels. We recalculate emissivies using thermal models based on recent data obtained with the CIRS (infrared) instrument on Cassini which account for, amongother things, diurnal effects and the rotaon during the RADAR observaons. For one important result, we demonstrate that deviaon from unity emissivity onIapetus is due solely to surface depth effects at long wavelengths when RADAR data at 2.5 cm is combined with data obtained at 3.3 mm on the Green BankTelescope (GBT).This research is supported by a grant under the NRAO Student Observing Support program.09.04: The Shielding Effect of Small Regolith Grains on Photodissociaon of Carbon DioxideAuthor Block: Eric Palmer 11 Lunar and Planetary Laboratory.Presentaon Time: 10/4/2010 3:46 PM - 3:48 PMLocaon: Exhibit HallAbstract: CO 2 has been detected on most of the satellites of Saturn (Bura et al. 2005; Clark et al. 2005; Brown et al. 2006; Cruikshank et al. 2007). The CO 2absorpon feature is strongest on Iapetus indicang an effecve thickness of ~30 nm (Palmer 2009). However, the photochemical me scale for CO 2 on Iapetus isshort, ~6 months, suggesng that CO 2 is acvely produced on Iapetus’ surface. Lab experiments have shown that CO 2 can be produced from a mixture of waterand carbon (Palmer 2009). However, to constrain the producon rate of CO 2 , we evaluated the shielding effect of small grains on the absorpon of differentwavelengths of light.Photodissociaon of CO 2 is dominantly driven by Ly-α UV photons, but the detecon of CO 2 by Cassini VIMS was done by near-IR photons, 4.2 μm. We evaluatedthe possibility that a layer of CO 2 could exist that was be detected by Cassini VIMS, but was shielded from UV photons by small parcles. We report the results ofnumerical simulaons to test this possibility using a randomly generated regolith surface. The surface was created with a log parcle size distribuon toapproximate observed regoliths. The grains were randomly scaered, then allowed to sele down the gravity gradient.

09.05: Color Photometry of the Small Saturnian Satellites: Global and Regional Variaons on Prometheus and CalypsoAuthor Block: Sarah J. Morrison 1 , P. Helfenstein 1 , P. C. Thomas 1 , J. Veverka 11 Cornell University.Presentaon Time: 10/4/2010 3:48 PM - 3:50 PMLocaon: Exhibit HallAbstract: We invesgate color variaons of Prometheus and Calypso using recent high resoluon calibrated Cassini Imaging Subsystem (ISS) images with theNarrow Angle Camera (NAC) broadband filters UV3 (338 nm) , GRN (568 nm), and IR3 (930 nm) in comparison to those of Pandora, Janus, Epimetheus, and Telestoexamined previously (Morrison et al., 2009, DPS 45.04). The average UV3/IR3 rao values are as follows: Prometheus- 0.47, Pandora- 0.53, Janus- 0.57,Epimetheus- 0.58, Telesto- 0.95, and Calypso- 0.77 with formal uncertaines < 0.01 due to noise. While both Prometheus and Calypso connue the trend ofincreasing blueness toward the E-ring, Calypso differs in color from Telesto with a lower UV3/IR3 rao and a mean UV3/GRN rao value of ~0.7 compared toTelesto’s mean UV3/GRN value of ~0.9 despite both being Trojans of Tethys. Calypso’s surface also exhibits wider color and albedo variaons than on Telesto anddisnct UV3-bright units undergoing downslope transport with UV3/IR3 rao values of ~0.05 greater than the mean. Calypso's mean global CLR (611 nm) albedoat normal incidence and 35° phase is ~13% higher than Telesto's, but its albedo range is broader and overlaps Telesto's. The color differences between these twomoons may reflect varying degrees of surface burial and contaminaon from ring parcles.09.06: Mapping the Thermal Inera of IapetusAuthor Block: Edgard G. Rivera-Valenn 1 , D. G. Blackburn 1 , R. Ulrich 11 University of Arkanss.Presentaon Time: 10/4/2010 3:50 PM - 3:52 PMLocaon: Exhibit HallAbstract: Nighme temperatures on a slow rotang airless body, such as Iapetus, are a crical indicator of the surface thermal inera since during this methe only acve heat source is the stored thermal energy within the surface material. During a PRIME data set for ISS in 2007, the Cassini CIRS instrument wasgiven the opportunity to record data at such a me. Surface temperatures deduced from thermal emissions are thus far the lowest recorded for Iapetus. Toaccount for the observed low temperatures, a much lower thermal inera than previously esmated is required. Surface thermal inera is expected to vary if darkmaterial overburden thickness varies on the surface of Iapetus. This arises from the finding that for a heterogeneous mixture where the surface material has alower thermal inera than the underlying layer, the surface proximity of the high thermal inera material strongly affects the observed surface thermal inera(Mellon et al., 2004, Icarus, 169, 324-340). Indeed, it has been suggested that albedo is a funcon of dark material thickness (Spencer and Denk, 2010, Science,327, 432-435) thus it can be shown that surface thermal inera is a funcon of albedo. Via the use of a heat transfer model and the recently published Iapetusbolometric Bond albedo map (Blackburn et al., 2010, Icarus, Submied), surface thermal inera can now be extrapolated for several albedo points on Iapetus.This allows for an esmate of the albedo/thermal inera relaonship and thus the development of a global thermal inera map. We will discuss the implicaonsfor surface material composion focusing on the material properes of the dark terrain.09.07: Resonant Structure and Chaoc Diffusion of the Jovian Irregular Satellites.Author Block: Julien Frouard 11 IM CCE/LAL - Paris Observatory, France.Presentaon Time: 10/4/2010 3:52 PM - 3:54 PMLocaon: Exhibit HallAbstract.Abstract: The dynamical region of the Jovian irregular satellites presents an interesng web of resonances. Along with secular and mean moonresonances which shape the stability regions, we report a number of resonances involving the Great Inequality which are present in the system thanks to thewide range of the frequency of pericenter value available for the satellites in the stable regions. Using extensive numerical integraons of the satellites alongwith an indicator of chaos (MEGNO), we give global and detailled views of the retrograde and prograde regions for various dynamical models and show theapparion of the different types of resonances. The chaoc diffusion of the satellites is also studied and shows the long term stability of the Ananke and Carmefamilies, in contrast with the Pasiphae family.09.08: Towards a Comprehensive Explanaon of Iapetus' Albedo AsymmetryAuthor Block: Charles A. Peterson 11 Atmospheric & Environmental Research, Inc..Presentaon Time: 10/4/2010 3:54 PM - 3:56 PMLocaon: Exhibit HallAbstract: Saturn’s satellite Iapetus, which is 6 mes brighter on its trailing hemisphere than on its leading hemisphere, has an albedo asymmetry that is uniquein our Solar System. From the me of its discovery by Cassini in 1671 unl the present, no explanaon for this extreme appearance has gained generalacceptance. An updated hypothesis, originally proposed in 1975 (Icarus 24, 499-503) and revisited in light of recent observaons, is presented with the centralassumpon that Iapetus started out with a dark surface that connues to be coated asymmetrically with bright reflecve water ice. This ice is stable for longperiods of me in the region of the outer Solar System that includes Saturn and, therefore, can be conveyed to the satellite’s surface by three disnct populaonsof exogenic impactors whose sources are all exterior to Iapetus’ orbit. Evidence for the existence of these populaons is provided by the recent discovery by theSpitzer Observatory of a very large dust ring orbing Saturn at the distance expected for ejecta from its 38 known irregular satellites including Phoebe. Althoughjust one parcular impactor populaon could account for a hemispherical albedo asymmetry, the combined effect of all three populaons acng togetherenhances and characterizes this asymmetry even further. Relevant aspects of impact dynamics involving the collision of these ice-bearing parcles with Iapetus’surface will be summarized. Proving this revised hypothesis will require the extensive modeling of ejecta modificaon and transport on the surface of Iapetus.Such an effort should contribute significantly towards not only resolving this 300-year old problem in planetary science, but also providing a beer understandingof the much less extreme hemispheric asymmetries observed for most other regular satellites in the Solar System.09.09: Heat Conducon: An Important Process for the Shape of Iapetus’s Dark Spots?Author Block: Goetz Galuba 1 , T. Denk 1 , G. Neukum 11 Freie Universität Berlin, Planetology & Remote Sensing, Germany.Presentaon Time: 10/4/2010 3:56 PM - 3:58 PMLocaon: Exhibit HallAbstract: The saturnian moon Iapetus is famous for its global black-and-white dichotomy. While its leading side (Cassini Regio) is covered by very darkmaterial, the poles and trailing side are relavely bright. However, craters and troughs with dark floors are located within the bright area, especially at lowlatudes. The boundaries of these smaller-scaled dark areas are very sharp. Even within the best-resolved images from the Cassini imaging experiment (ISS), thetypical length of a drop-off in albedo is below the resoluon limit.

Thermal segregaon, driven by a feedback process, has been proposed as the cause for the global dichotomy (Spencer and Denk 2010; Denk et al. 2010). Inaddion, for local features like craters and troughs, we explain the local darkening by an increased amount of insolaon caused by the concave curvature of thesefeatures. We studied the insolaon geometry using varying reflectance models. A model of linear interpolaon between lunar and Lambert-like scaeringreproduces the dark paerns relavely well. However, the increased insolaon by itself neither explains the abundance of darkened terrain, nor the temporalbehavior of darkening of fresh bright craters from the outside inward within the Cassini Regio area.A comparison of me scales and spaal scales shows that heat conducon might act as a major contributor to the growth of local dark areas within the brightterrain, despite its short range. Due to the repeve nature of the processes needed for the growth of darkened terrain, the significant processes should not be aslong-ranged as saltaon of ice or CO2.We gratefully acknowledge funding of this work by the German Space Agency (DLR) Bonn through grant no. 50 OH 0305.09.10: Segregaon Of Ice And Dark Materials On The Saturnian SatellitesAuthor Block: Gary B. Hansen 11 Univ. of Washington.Presentaon Time: 10/4/2010 3:58 PM - 4:00 PMLocaon: Exhibit HallAbstract.Abstract: The water ice on the Galilean satellites is segregated spaally from the darker non-ice materials by a well known thermal process thatdepends on the temperature of the different materials (for the Galilean satellites, pure water snow has temperatures under full sun of 120-130 K while thesegregated dark materials reach 160 K. The Saturnian satellites with the darkest materials (1-3 % albedo), i.e., Iapetus, Phoebe, and Hyperion, also have beenshown to have spaally segregated dark material which reaches ~130 K. But the bright material need not be pure water ice, and in fact is mostly slightly dirty icewith an albedo of 30-50%. This is evident from the overall albedo of extended bright areas such as on the trailing hemisphere of Iapetus, and from the lack ofweak bands of water ice near 1.04 and 1.25 microns in its near-infrared spectrum. These bands are the first to disappear when you mix water ice with darksubstances. We will run radiave transfer models to show how much dark material needs to be mixed into the ice to remove these bands (we expect &lt;&lt;0.1%mass rao) and calculate the modified area of icy material in models we have done for Phoebe using Cassini-VIMS data, where we assumed pure water snow asthe icy component. Such modeling, even for these segregated terrains, is complicated because the amount of dark material in the ice can vary a lot and sllachieve segregaon. We will esmate the maximum dark material mixing rao beyond which the albedo is to low for effecve segregaon, while nearly pure icesnow can also exist (isolated locaons on Phoebe do show the short-wave ice bands, and are therefore purer ice than typical). Models of the areal fracon of icymaterial may have large uncertaines because of this effect.09.11: 3-D General Circulaon Model Simulaons of an N 2 Microbar AtmosphereAuthor Block: Charles Miller 1 , N. J. Chanover 1 , J. R. Murphy 11 New Mexico State University.Presentaon Time: 10/4/2010 4:00 PM - 4:02 PMLocaon: Exhibit HallAbstract: Both Triton and Pluto are known to possess thin N 2 atmospheres with surface pressures in the range of 10 microbars in vapor pressure equilibriumwith N 2 surface frosts. We present inial results of a 3-D dynamical model of a microbar N 2 atmosphere using an adaptaon of the Ames Mars GeneralCirculaon Model (GCM) version 2.0. The Ames GCM incorporates several physical processes crical to modeling the atmospheres of Triton and Pluto, includingcondensaon and sublimaon of the main atmospheric constuent gas as well as subsurface storage and release of heat. We altered the Ames GCM to simulatecondions found on Triton. These alteraons included changing the size, rotaon rate, orbital inclinaon, surface gravity, and distance to the Sun of the parentbody, which produced the appropriate insolaon at the top of the atmosphere. We also changed the gas properes from those of a CO 2 atmosphere in the originalAmes GCM to those of an N 2 atmosphere, including values for latent heat, specific heat, and the proper vapor pressure-temperature relaonship for N 2 frosts. Wechose albedo and emissivity values for the surface substrate and N 2 frost from published values based on global thermal simulaons of Triton. We ransimulaons covering 70 Triton days (or 411 Earth days) to allow for the establishment of equilibrium between the surface pressure and the temperature of thesurface frosts. We examine the role of albedo and emissivity on the paern of surface frosts aer inial spin-up of the GCM. We also present results ofsimulaons that employ a Newtonian cooling algorithm based on published temperature-pressure profiles from stellar occultaons by Triton. This study wasfunded by a NASA Earth and Space Science Fellowship through grant number NNX09AQ96H.09.12: The Effect of the Satellite/Planet Mass Rao on the Co-orbital Congenital Formaon ModelAuthor Block: André Izidoro 1 , O. C. Winter 1 , M. Tsuchida 11 UNESP, Brazil.Presentaon Time: 10/4/2010 4:02 PM - 4:04 PMLocaon: Exhibit HallAbstract: There are several known bodies in the solar system that share the same mean orbit. This kind of moon is denominated co-orbital and ischaracterized according to the center of libraon of the cric argument θ=λ- λ', where λ and λ' represents the mean longitude of the minor and major bodiesrespecvely. When the body librates around L4 or L5 the orbit is said tadpole, when oscillates around θ=180, involving L3, L4 e L5 the orbit is called horseshoe,and when the oscillaon occurs close to zero, the body is a quasi-satellite. In this work we studied the effects of different satellite/planet mass raos anddifferent satellite-planet distance during the formaon of co-orbital objects through of the congenital formaon model. The dynamic system studied consists of acentral body, a secondary body and a cloud of planetesimals randomly distributed in a sector around L4 or L5. The sector is delimited by an arc of 70°, centered onthe Lagrangian point, and the extreme orbital radii of the largest tadpole orbit. The preliminary results show that for satellite-planet mass rao equals to 1e-3occurs the formaon of bodies with relave mass larger than 0.6e-6 of the central body's mass, which is a the limit found by Beaugé et al. (2007). However, inthis case, we used a radial distance much smaller than Beagué et al. (2007). This shows that the liming mass of larger body created is not dependent only onthe satellite-planet mass rao.09.13: The Strongest Opposion Surges: Products of Ejecta Exchange?Author Block: Anne J. Verbiscer 1 , T. M. Fisher 1 , R. G. French 21 University of Virginia, 2 Wellesley College.Presentaon Time: 10/4/2010 4:04 PM - 4:06 PMLocaon: Exhibit HallAbstract: Recent evidence suggests that strong opposion surges are not necessarily correlated with albedo. We have measured the opposion surge of thebinary Trans-Neptunian Object (TNO) 2000 YW134 and find that its R-band reflectance increases by ~2 magnitudes/degree between phase angles of 0.3 and 0.05degrees. Another binary TNO, 1997 CS29, exhibits a similarly large opposion surge [1]. Spitzer Space Telescope and Herschel Space Observatory observaons

indicate that both of these are relavely dark objects with albedos ~0.10 or less [2,3]. Rabinowitz et al. [1] suggest that ejecta exchange [4] between the twocomponents could account for these strong opposion surges. Dobrovolskis et al. [5] find that the Tethys Lagrangian satellites Telesto and Calypso, two bodieswith extremely high albedos [6] also exchange ejecta. Hubble Space Telescope WFPC2 observaons of Telesto and Calypso at small phase angles and CassiniImaging Science Subsystem (ISS) observaons over complete rotaonal phases show that these bright icy bodies have opposion surges comparable to those ofTNO binaries. This work is supported by NASA Planetary Astronomy and Cassini Data Analysis Programs.[1] Rabinowitz et al. 2009 BAAS 41, 1131. [2] Stansberry et al. 2010 Dynamical and Physical Properes of TNOs. [3] Mommert et al. 2010 Dynamical and PhysicalProperes of TNOs. [4] Stern 2009 Icarus 199, 571. [5] Dobrovolskis et al. 2010 Icarus, in press. [6] Verbiscer et al. 2007 Science 315, 815.

Session Number: 24Session Title: Solar System Origin, Planet and Satellite FormationSession Type: Poster24.01: Circumstellar and Circumbinary Disk Evoluon in a Binary SystemAuthor Block: Francesco Marzari 1 , A. F. Nelson 21 Univ. of Padova, Italy, 2 HPC-5, Los Alamos Naonal Laboratory.Presentaon Time: 10/4/2010 3:52 PM - 3:54 PMLocaon: Exhibit HallAbstract: We simulate the evoluon of the circumstellar and circumbinary disks in a system configured to appear similar to that observed for the GG Tau Abinary. We find that mass transfer onto the circumstellar disks is episodic with maximal transfer rates which change from orbit to orbit, but which occur followingeach apoapse passage. Accreon rates onto the stars themselves does not display such periodicies, so the disk masses vary somewhat over the binary orbit.Averaged over me, mass transfer into and out of the disks equilibrates at a disk mass of somewhat less than one Jupiter mass, for both the primary andsecondary. The transfer rate of material through the disks is rapid enough to effecvely replace the enre disk in less than 10000 yr. We discuss the implicaonsof our results on planet formaon in this and similar systems.This is Los Alamos Publicaon LA-UR 10-0481324.02: X−wind Transport Of Chondrules And CAIs Of The Solar SystemAuthor Block: Renyu Hu 11 M IT.Presentaon Time: 10/4/2010 3:54 PM - 3:56 PMLocaon: Exhibit HallAbstract: It has been suggested that chondrules and calcium−aluminum−rich inclusions (CAIs) were formed at the inner edge of the protoplanetary disk andthen entrained in magnetocentrifugal X−winds. We study trajectories of such solid bodies with the consideraon of the central star gravity, the protoplanetarydisk gravity, and the gas drag of the wind. The efficiency of the gas drag depends on a parameter η, which is the product of the solid body size and density. Wefind that the gravity of the protoplanetary disk has a non−negligible effect on the trajectories. If a solid body re−enters the flared disk, the re−entering radiusdepends on the stellar magnec dipole moment, η, and the disk's gravity. The disk's gravity can make the re−entering radius lower by up to 30%. We find a ηthreshold for any parcular configuraon of the X−wind, below which the solid bodies will be expelled from the planetary system. Only the solid bodies with a ηlarger than but very close to the threshold η can be launched to a re−entering radius larger than 1 AU. This size−sorng effect may explain why chondrules comewith a narrow range of sizes within each chondric class. In addion, our calculaons show that CAIs originally smaller than 0.2 cm must have been ejectedfrom the Solar system by X−winds. Therefore we propose the disaggregaon of CAIs at the accreon to the asteroids to explain the size distribuons of CAIs inchondrites.24.03: Planetesimal Formaon in the Dead Zone of Protoplanetary DisksAuthor Block: Xuening Bai 1 , J. M. Stone 11 Princeton University.Presentaon Time: 10/4/2010 3:56 PM - 3:58 PMLocaon: Exhibit HallAbstract: Planetesimals are building blocks of both terrestrial and giant planets, yet their formaon remains a mystery. The main difficulty comes from themeter-size barrier: meter-sized bodies suffer from rapid radial dri towards the central star due to the gas drag. Recently, it has been found that the inclusion ofback-reacon from solids to gas leads to a powerful drag instability: the streaming instability (SI). SI generates turbulence and is able to concentrate cenmeterto meter sized bodies into dense clumps, triggering gravitaonal collapse to form planetesimals directly, bypassing the meter barrier. We conduct local 2D and 3Dhybrid simulaons of parcles and gas in the midplane of protoplanetary disks (PPDs) using the Athena code. Parcles and gas are coupled aerodynamically,characterized by the dimensionless stopping me τ=Ωt s . Magnetorotaonal turbulence is neglected as appropriate for the dead zone of PPDs. Self-gravity isignored since we focus on the precursor of planetesimal formaon: parcle clumping. We have systemacally explored the parameter space relevant forplanetesimal formaon, including: 1) A wide distribuon of parcle sizes (τ); 2) The height-integrated solid to gas mass rao (Z); and 3) The strength of the diskradial pressure gradient (Π). The saturated state of our simulaons is characterized by parcle seling balanced by turbulent diffusion due to the SI, and theparcle dri velocies are well described by a mul-species NSH equilibrium, which generalizes the original Nakagawa-Sekiya-Hayashi soluon to includemulple parcle sizes. We find that favorable condions for planetesimal formaon via SI include: large parcles (τ>0.01), large solid abundance (Z>0.01), andsmall pressure gradient (Π

Presentaon Time: 10/4/2010 4:00 PM - 4:02 PMLocaon: Exhibit HallAbstract.Abstract: We performed 3D calculaons of the moon of a swarm of planetesimals in a protoplanetary disk that is perturbed by a Jupiter-mass planet.The interacons between the planet and the gaseous disk and the accreon of gas on the planet were modeled through a 3D hydrodynamics code. The trajectoryof each planetesimal, in the gravitaonal field of the planet and of a solar-mass star, was determined by means of a 4th order Runge-Kua algorithm that takesinto account gas drag forces. Thermodynamics condions that may apply to a protoplanetary disk towards the end of the planet's gas accreon epoch were used.The planetesimals were inially deployed on random Keplerian orbits about the star, between 1.1 and 1.5 planet's orbital radii. The gas dynamics around theplanet was resolved on a length-scale of 0.01 planet's Hill radii (Rh). Planetesimals within a few tenths of Rh from the planet and whose velocity relave to theplanet was smaller than the escape velocity were taken as accreted. Experiments were executed with a size distribuon of an equal number of 1, 10, and 100 kmradius planetesimals. The dynamics of the smallest size planetesimals appears to be more strongly affected by gas drag forces than it is that of planetesimals oflarger sizes. However, results suggest that the accreon rates on the planet are of the same order of magnitude, once the inial surface density of planetesimalsis corrected so that all size bins contain equal masses of solids. These rates, esmated at about 5 AU, are on the order of 1e-6 sigma Earth masses per year,where sigma is the solids' surface density of a given size bin, in grams per square cenmeters, exterior of the planet's orbit. Support from NASA Origins of SolarSystems Program grants NNX08AH82G and NNX07AI72G is gratefully acknowledged.24.06: The Formaon of Uranus and Neptune in Solid-Rich Feeding Zones: Connecng Chemistry and DynamicsAuthor Block: Sarah E. Robinson 1 , P. Bodenheimer 21 University of Texas at Ausn, 2 UCO/Lick Observatory.Presentaon Time: 10/4/2010 4:02 PM - 4:04 PMLocaon: Exhibit HallAbstract: The core accreon theory of planet formaon has at least two fundamental problems explaining the origins of Uranus and Neptune: (1) dynamicalmes in the trans-saturnian solar nebula are so long that core growth can take >15 Myr and (2) the onset of runaway gas accreon that begins when cores reach10 Earth masses necessitates a sudden gas accreon cutoff just as Uranus and Neptune’s cores reach crical mass. Both problems may be resolved by allowingthe ice giants to migrate outward aer their formaon in solid-rich feeding zones with planetesimal surface densies well above the minimum-mass solar nebula.We present new simulaons of the formaon of Uranus and Neptune in the solid-rich disk of Dodson-Robinson et al. (2009) using the inial semimajor axisdistribuon of the Nice model, with one ice giant forming at 12 AU and the other at 15 AU. The innermost ice giant reaches its present mass aer 3.8-4.0 Myr andthe outermost aer 5.3-6 Myr, a considerable me decrease from previous one-dimensional simulaons (e.g. Pollack et al. 1996). The core masses staysubcrical, eliminang the need for a sudden gas accreon cutoff. Our calculated carbon mass fracons of 22% are in excellent agreement with the ice giantinterior models of Podolak et al. (1995). Based on the requirement that the ice giant-forming planetesimals contain >10% mass fracons of methane ice, we canreject any Solar System formaon model that inially places Uranus and Neptune inside of Saturn’s orbit. We also demonstrate that a large populaon ofplanetesimals must be present in both ice giant feeding zones throughout the lifeme of the gaseous nebula. This research marks a substanal step forward inconnecng both the dynamical and chemical aspects of planet formaon.24.07: W ITHDRAW N: Coorbital Satellite Formaon Through DisruponAuthor Block: Décio Mourão 1 , O. C. Winter 11 UNESP, Brazil.Presentaon Time: 10/4/2010 4:04 PM - 4:06 PMLocaon: Exhibit HallAbstract: The satellite system of Saturn is the only one known to have coorbital satellites. In general they are small bodies librang around the lagrangianpoints of a larger satellite. Dione has Helene librang around L 4 and Polideuces around L 5 . Tethys has Calipso and Telesto around L 4 and L 5 , respecvely. There isalso the pair Janus-Epimetheus with similar masses in horseshoe orbits. In these intrincated satellite systems it is also well known that there are other meanmoon resonances between Enceladus and Dione and between Mimas and Tethys. In the present study we examine the necessary condions to form coorbitalsatellite systems generated from disrupon caused by impacts during the early age of Saturn's satellite system. We considered the following scenario: A parentsatellite suffers a light collision, which remove fragments from it, generang a cloud of smaller bodies that escape from its surface. Then, a small coorbitalsatellite might be the outcome from the dynamical evoluon of the cloud of fragments, where the mutual gravitaonal interacons and even collisions are takeninto account. In this work, we simulated sets of fragments with a wide range of different mass and velocity distribuon. The first results are given in terms of thevalues of these parameters in order to get temporary coorbital systems. Then, collision and/or strong interacon between fragments were considered to removeenergy from the system in order to get permanent coorbital systems. Finaly, we found sets of adequate condions in a space of inial condions and parameters.24.08: The Formaon Environment of the Galilean MoonsAuthor Block: Neal J. Turner 1 , M. H. Lee 2 , T. Sano 31 Jet Propulsion Laboratory, California Instute of Technology, 2 University of Hong Kong, China, 3 Osaka University, Japan.Presentaon Time: 10/4/2010 4:06 PM - 4:08 PMLocaon: Exhibit HallAbstract: The regular satellites of the gas giant planets were formed in circumplanetary disks of gas and dust, whose evoluon was governed by mass andangular momentum transport of uncertain origins. Turbulence driven by the magneto-rotaonal instability can provide the transport if the gas is sufficientlyionised to couple to the embedded magnec fields. We compute the ionisaon states of the minimum-mass and gas-starved models of the Jovian sub-nebula,including the key effects known from Solar nebula studies: ionisaon by cosmic rays and stellar X-rays, charge transfer to metal atoms, and recombinaon ongrains.The results show that magneto-rotaonal turbulence develops in a region whose size depends on the absorbing mass column, the grain surface area, the gasphasemetal abundance and the strength of the turbulent mixing. The turbulence is almost enrely absent from the minimum-mass sub-nebula model over a widerange in these parameters. In contrast, turbulence occurs in the gas-starved model in the surface layers and throughout the parts furthest from the planet,provided sub-micron grains are underabundant.This work was carried out in part at the Jet Propulsion Laboratory, California Instute of Technology with support from the NASA Outer Planets Research program,and at the University of Hong Kong under RGC grant HKU 7024/08P.24.09: Thermally-driven Escape From An Atmosphere: Transion From Jeans To Hydrodynamic EscapeAuthor Block: Robert E. Johnson 1 , A. Volkov 1 , O. J. Tucker 1 , J. T. Erwin 11 Univ. of Virginia.Presentaon Time: 10/4/2010 4:08 PM - 4:10 PMLocaon: Exhibit Hall

Abstract: The transion in the nature of thermally-induced atmospheric loss from escape on a molecule by molecules basis (Jeans escape), to an organizedoulow (hydrodynamic escape) is calculated using a direct simulaon Monte Carlo method. When the heang layer is well below the exobase in a 1D sphericallysymmetric atmosphere, this transion is shown to occur over a surprisingly narrow range of Jeans parameters near λ~ 2-3: λ= the gravitaonal energy of themolecules / kT. This crical Jeans parameter roughly corresponds to the upper limit for isentropic, supersonic oulow. For larger Jeans parameters, the escaperate never deviates significantly from the familiar Jeans rate evaluated at the nominal exobase, contrary to what has been suggested for Pluto and Titan. Scalingby the Jeans parameter, the results presented can be applied to thermal escape from solar and extrasolar planetary bodies.

Session Number: 28Session Title: Comets, including WISE Mission ResultsSession Type: Poster28.01: Survival of ice in Main Belt CometsAuthor Block: Dina Prialnik 1 , G. Sarid 2 , K. J. Meech 21 Tel Aviv Univ., Israel, 2 Instute for Astronomy.Presentaon Time: 10/4/2010 4:00 PM - 4:02 PMLocaon: Exhibit HallAbstract: The discovery of the new class of objects, known as Main Belt Comets (MBCs), raises a number of quesons regarding their structure, composionand origin. Whether MBCs were formed in their present locaon or captured from more distant regions during the early bombardment era is sll debated; eitherway, they have spent most of their lifemes in the main belt, which has been considered too hot for ice to survive for any length of me. The low conducvity ofporous cometary material suggests, however, that ice may be retained in the interior of main belt bodies, despite connual insolaon. Indeed, analycalesmates, as well as numerical computaons, indicate that this is possible. We invesgate the ice survival queson by means of detailed numerical modeling oflong-term evoluon for a range of inial parameters. We consider bodies of radii between 150m and 2.5km, composed of ice and dust, adopng two differentdensity values, and two heliocentric distances.The quesons that we address are: (a) To what extent and under what condions (related to structure and composion) may water ice be preserved in MBCs forthe age of the Solar System? and (b) How deep below the surface is the ice expected to be found? We find that small bodies (< 600m in radius) may completelylose the ice over a me corresponding to the age of the Solar System, especially if the density is low and they are relavely close to the Sun. By contrast, in largerbodies (a few km in size) that may have been captured or collisionally formed only 100 Myr ago, ice may be found at depths of only 10m. Such bodies could beeasily acvated by collisions to exhibit cometary acvity.28.02: Search for Acvity in Comet-Asteroid Transion Object 107P/Wilson-HarringtonAuthor Block: Alain Khayat 1 , K. Meech 1 , J. Pichova 1 , N. Schorghofer 1 , B. Yang 1 , S. Sonne 1 , T. Riesen 1 , J. Kleyna 1 , H. Kaluna 1 , J. Keane 11 Instute for Astronomy, University of Hawaii at Manoa.Presentaon Time: 10/4/2010 4:02 PM - 4:04 PMLocaon: Exhibit HallAbstract: Comet-asteroid transion object 107P/Wilson-Harrington was observed near its October 22, 2009 perihelion passage to search for acvity. No acvitywas detected. Consequently, we place limits on possible dust producon of 0.013 kg/s at 1.23 AU. Furthermore, the data was not sufficient to constrain a rotaonperiod; however, it is clear that the rotaon period is > 4hr. Our data is consistent with the observaons of others (6.1 hr). Phase funcon fing yielded a value ofthe phase coefficient beta= 0.0406 ± .0001 mag/deg, similar to C-type asteroids that have a linear phase curve at large phase angles. Thermal models for107P/Wilson-Harrington show that the average loss rate of exposed crystalline ice at zero latude is in the order of 0.3 meters/year. The derived high loss ratesuggests that 107P/Wilson-Harrington is deprived of surface ice. Our observaons and analysis confirm earlier findings that 107P/Wilson-Harrington is anexample of the very few such objects discovered so far. Such study we made is a crical next step in understanding the life of dormant comets, and a window intothe evoluonary end states of the lives of comets that become exnct. This work has been supported in part by AST-0807521 from the Naonal ScienceFoundaon.28.03: A New Model Of Non-gravitaonal Forces On CometsAuthor Block: Lucie Maquet 1 , F. Colas 1 , J. Crovisier 2 , L. Jorda 31 IM CCE-Observatoire De Paris, France, 2 LESIA-Observatoire de Paris, France, 3 LAM, France.Presentaon Time: 10/4/2010 4:04 PM - 4:06 PMLocaon: Exhibit HallAbstract: The gravitaonal orbit of a comet is affected by the sublimaon of water molecules by the nucleus when the comet approaches perihelion. Thisoutgassing triggers a non-gravitaonal force (NGF) which significantly modifies the orbit of the comet. The amplitude of the perturbaon depends on severalparameters which can be constrained by visible, infrared and radio observaons of the coma and nucleus of the comet. It depends also on the nucleus density,which can in turn be determined by modeling the effect of the NGF on the orbit of a comet. This method is the only method available so far to esmate thedensity of cometary nuclei from the ground. Up to now, the modeling of this effect is mostly based on an empirical model defined in the early 70's which uses asimplified isotropic outgassing model. Aempts have been made to use advanced anisotropic thermal models to calculate the NGF taking into account severalobservaonal constraint and to retrieve the nucleus density, but: (i) this approach is restricted to a handful of cometary nuclei which are sufficiently well-knownto allow this type of modeling, and (ii) the authors usually don't fit directly the astrometric measurements but rather « non-gravitaonal parameters » calculatedwith the above-menoned empirical model. We present a new model for non-gravitaonal forces with the aim of revising the problem of NGF calculaon andnucleus density determinaon. The method is based on the separaon of the surface of the nucleus in several strips located at different latudes. Thecontribuon of each strip to the overall NGF is fied from the astrometric measurements together with the density of the nucleus. This new method will be usedto interpret future astrometric measurements of these prisne objects with GAIA.28.04: The Deep Impact Coma of Comet 9P/Tempel 1 as a Time-of-Flight Experiment Movates DDSCAT Models for Porous Aggregate Grains withSilicate Crystal InclusionsAuthor Block: Diane H. Wooden 1 , S. S. Lindsay 2 , D. E. Harker 3 , M. S. Kelley 4 , C. E. Woodward 5 , D. T. Richard 6 , L. Kolokolova 4 , F. Moreno 71 NASA Ames Research Center, 2 New Mexico State University, 3 UCSD/CASS, 4 University of Maryland, 5 University of Minnesota, 6 San Jose State UniversityResearch Foundaon/NASA Ames, 7 Instuto de Astrofisica de Andalucia, Spain.Presentaon Time: 10/4/2010 4:06 PM - 4:08 PMLocaon: Exhibit HallAbstract.Abstract: Spitzer IRS spectra of short-period Eclipc Comets (ECs) have silicate features, and many have disnct crystalline silicate peaks. TheseSpitzer spectra, when fied with thermal models aer subtracon of the relavely strong contribuon of the nuclear flux to the IR spectrum (e.g., Harker et al.2007), demonstrate ECs have weaker silicate features than long-period Nearly-Isotropic Comets (NICs). There are excepons, however, as some NICs also haveweak features like most ECs. Grains with lower porosies (lower fracon of vacuum) can explain weaker silicate features (Kelley and Wooden 2009; Kolokolova etal. 2007). Alternavely, oming the smallest (submicron) solid grains can reduce the contrast of the silicate feature (Lisse et al. 2006). However, so far, onlymodels for solid submicron crystals fit the crystalline peaks in spectra of comets with weak silicate features. This presents a dilemma: how can the coma bedevoid of small grains except for the crystals? The Spitzer spectra of the Deep Impact event with EC 9P/Tempel 1 provides a data set to model larger porousgrains with crystal inclusions because the post-impact coma was a me-of-flight experiment: an impulsive release of grains were size-sorted in me by theirrespecve gas velocies so that the smaller grains departed the inner coma quicker than larger grains. A velocity law derived from fing small beam Gemini

spectra (Harker et al. 2007) indicates that at ~20 hour post-impact the (pre-impact subtracted) Spitzer IRS spectrum contained grains larger than 10-20 micronradii, moving at ~20 m/s, that produced a weak silicate feature with an 11.2 micron crystalline olivine peak. Furthermore, this feature looks like the silicatefeature from the nominal coma. We present some results of a computaonal effort to model discrete crystals and mixed-mineral porous aggregate grains withsilicate crystal inclusions using DDSCAT on the NAS Pleiades supercomputer.28.05: Gas And Dust Producon From A Comet With A Small Acve Area: Applicaon To The Rosea Target Comet 67p/churyumov-gerasimenkoAuthor Block: Michael R. Combi 1 , V. Tenishev 1 , M. Rubin 1 , N. Fougere 11 Univ. of Michigan.Presentaon Time: 10/4/2010 4:08 PM - 4:10 PMLocaon: Exhibit HallAbstract.Abstract: Comet 67P/Churyumov-Gerasimenko, the Rosea mission target comet, has a mean radius of 2 km; and it is evident that most of its acvity(i.e., gas and dust producon into the coma) originates from an area that is only ~4% of its enre surface. There is apparently a strong seasonal effect wherebythis area is predominantly illuminated by sun light by perihelion and thereaer. The dusty-gas coma structure for a comet with a dominant acve area deviatesstrongly from the typical models where gas and dust are produced more uniformly from the surface. Here we invesgate the dusty-gas environment around anucleus where the acvity is limited to 4% of the surface. We show the overall structure of the coma, the distribuon of gas, and the velocies and distribuon ofdust for a nominal dust parcle size distribuon for a relevant range of heliocentric distances. With such a limited acve area, larger dust parcles can beaccelerated to higher velocies because of the concentrated gas flux right near the surface, but the limited acve area also allows for some parcles to fall backto the surface when as the gas flow expands by much greater than the typical inverse square variaon. The physics of the dynamical condions vary greatly fromhaving moderately collisional (fluid) condions above the acve area near perihelion to being a transional flow and nearly free flow when at heliocentricdistances ~3 AU throughout most of the coma. [We acknowledge support from NASA Planetary Atmospheres grant NNX09AB59G.]28.06: Comet 67P/Churyumov-Gerasimenko’s Plasma Environment during Rosea’s Early Comet PhaseAuthor Block: Marn Rubin 1 , M. R. Combi 1 , T. I. Gombosi 1 , K. C. Hansen 1 , V. M. Tenishev 11 University of Michigan.Presentaon Time: 10/4/2010 4:10 PM - 4:12 PMLocaon: Exhibit HallAbstract: The Rosea spacecra is on its way to comet 67P/Churyumov-Gerasimenko to accompany it from roughly 3 AU all the way to perihelion at aheliocentric distance of 1.3 AU. During this journey the comet’s gas producon rate varies over several orders of magnitude and also the composion of thereleased material will likely change. Whereas the producon of H 2 O has been derived from observaons the relave abundance of CO as well as CO 2 is sllsubject of discussion, especially during Rosea’s early comet phase around 3 AU.The neutral gas is ionized by mostly solar photons and electron-impact and then picked-up by the solar wind. This mass loading slows down the solar wind asmomentum is transferred to the cometary ions and the bow shock appears where the solar wind transions from supersonic to subsonic speeds. In case of a highenough producon rate also a magnec cavity can form close to nucleus. Here the coupled cometary neutrals and ions flowing out from the nucleus prevent thepenetraon of solar wind parcles that carry the sun’s magnec field.With respect to the wide range of neutral gas producon rates ancipated in the early comet phase we will show results of our magentohydrodynamics(SWMF/BATSRUS) code modeling the plasma environment of the comet. For 2.7 and 3.0 AU we idenfied 8 different sets of relave and absolute gas produconrates injected spherically symmetric as well as in form of jets. We will show our model results thereof and discuss the expected plasma environment for Roseaduring the period of rendezvous and lander deployment.[This work has been supported by JPL subcontract 1266313 under NASA grant NMO710889 and NSF Planetary Astronomy grant AST0707283. We also acknowledgethe support from the ISSI comet-modeling group.]28.07: An Examinaon of Hydrogenaon of Cometary Parent MoleculesAuthor Block: Donna M. Pierce 11 Mississippi State Univ..Presentaon Time: 10/4/2010 4:12 PM - 4:14 PMLocaon: Exhibit HallAbstract: The hydrogenaon of CO and C 2 H 2 on icy grains may have contributed to the abundances of H 2 CO, CH 3 OH, and C 2 H 6 in comets. This suggests thatthe chemical composion of the ice was modified from its inial state prior to incorporaon into cometary nuclei. Here, we examine the relaonships betweenthese molecules and assess the conversion efficiencies of CO and C 2 H 2 . Potenal groupings of comets will also be discussed.28.08: Vectorial Modeling Of N H In Comet 2P/EnckeAuthor Block: Garre Dorman 1 , D. Pierce 1 , A. Cochran 21 Mississippi State University, 2 University of Texas, McDonald Observatory.Presentaon Time: 10/4/2010 4:14 PM - 4:16 PMLocaon: Exhibit HallAbstract.Abstract: Encke is an ideal comet for studying the relaonship of radicals to their photodissociave parent molecules due to its low dust content. On2003 October 22 - 24, we used the the 2.7 m telescope at the McDonald Observatory of the University of Texas to obtain spectra of several cometary radicalspecies. Using a version of the Vectorial Model that has been modified to simulate Encke's prominent sunward-facing fan, we examined the spacial distribuon ofNH in the coma. Potenal photochemical parents of NH were studied in order to understand its producon and spacial distribuon in the coma. Derivedproducon rates are compared to values in other comets to constrain the primary parent of NH in Encke.28.09: Fluorescence Excitaon Model And Mixing Raos Of Ethylene (C 2 H 4 ) In CometsAuthor Block: Hitomi Kobayashi 1 , H. Kawakita 11 Kyoto Sangyo University, Japan.Presentaon Time: 10/4/2010 4:16 PM - 4:18 PMLocaon: Exhibit HallAbstract: In the last decade, some kinds of organic volales in cometary comae have been observed by the high-dispersion spectroscopic observaons ofcomets in near-infrared region. One of interesng characters of cometary ices is the existence of abundant ethane (C 2 H 6 ) relave to methane (CH 4 ), even thoughethane could not be formed by gas phase reacons only. Formaon reacons of ethane in the early solar nebula (or in the pre-solar molecular cloud) are thoughtas the hydrogen addion reacons to acetylene on the cold grains (e.g., C 2 H 2 -> C 2 H 3 -> C 2 H 4 -> C 2 H 5 -> C 2 H 6 ). However, it is reported that ethane could be

formed by the dimerizaon of CH 3 in CH 4 -rich ice by irradiaon of energec protons (Hadson and Moore, 1997). So the existence of ethylene (C 2 H 4 ) is a key todisnguish these hypothesizes. The abundance of C 2 H 4 is clue to contribuon of C 2 H 6 formaon by hydrogen addion reacons.If we can confirm the existence of ethylene, conversion efficiency from acetylene to ethane and ethylene would provide clear view to the hydrogen addionreacons in the early solar nebula or in the pre-solar molecular cloud, because H atom can sck on cold grains under low temperature condions (< ~20 K) only.However, fluorescence excitaon model for ethylene in comets have never been proposed to date. In this work, we will present the fluorescence excitaon modelof ethylene and we will determine C 2 H 4 /H 2 O raos (or its upper limits) for the comets in our database.28.10: Fluorescence Excitaon Model of Ammonia in Low-Acvity CometsAuthor Block: Hideyo Kawakita 1 , H. Kobayashi 11 Kyoto Sangyo University, Japan.Presentaon Time: 10/4/2010 4:18 PM - 4:20 PMLocaon: Exhibit HallAbstract: Ammonia is one of the major N-bearing molecules in cometary ices. Ammonia can be observed by radio (inversion transions), far-infrared (rotaonaltransion) and near-infrared regions (vibraonal transions). In the near-infrared regions, not only ammonia but also water and other organic volales can beobserved as emission lines simultaneously by the high-dispersion spectroscopy. Therefore, it is easy to determine mixing raos of various organic volales fromthe near-infrared high-dispersion spectra of comets.The fluorescence efficiencies for the emission lines are necessary to determine the gas producon rate from the observaons, and there are a few studies for thefluorescence excitaon model of ammonia in comets. The populaon distribuon in the vibraonal ground state is assumed to follow the Boltzmann distribuonin these models. This assumpon is valid in the case of inner coma of producve comets (i.e., frequent inter-molecular collisions can maintain the Boltzmanndistribuon). In the low-acvity comets, however, the inter-molecular collisions are not so frequent enough to maintain the Boltzmann distribuon in thevibraonal ground state. In the case of ammonia, the populaon will favor the metastable states if the collision me scale is much longer than the decay mescales ~10 s for the non-metastable states.We developed the fluorescence excitaon model of cometary ammonia by involving collisional transions explicitly. Transions by the collision with water and bythe collision with electron are taken into account. We will apply our model to the observaons of Jupiter family comets.28.11: OP Rs Of Ammonia versus. 14N/15N Raos In CN In 15 CometsAuthor Block: Yoshiharu Shinnaka 1 , H. Kawakita 1 , H. Kobayashi 1 , E. Jehin 2 , J. Manfroid 2 , D. Hutsemékers 2 , C. Arpigny 21 Kyoto Sangyo University, Japan, 2 Instut d’Astrophysique et de Géophysique, Université de Liège, Belgium, Belgium.Presentaon Time: 10/4/2010 4:20 PM - 4:22 PMLocaon: Exhibit HallAbstract: The solar system was formed from interstellar maer 4.6 Gyrs ago and comets are considered as remnants of icy planetesimals formed in the earlysolar system. One of interesng primordial characters of cometary ice is an ortho-to-para abundance rao (OPR) of molecules such as H2O, NH3, etc. The OPRprobably indicates the molecular formaon temperatures in the solar nebula or in the pre-solar molecular cloud.We determined the OPRs of ammonia by using the high dispersion opcal spectra of NH2 in 15 comets: C/1995 O1 (Hale-Bopp), C/1999 S4 (LINEAR), C/2001 A2(LINEAR), C/2000 WM1 (LINEAR), 153P/Ikeya-Zhang, C/2002 V1 (NEAT), C/2002 X5 (Kudo-Fujikawa), C/2002 Y1 (Juels-Holvorcem), C/2001 Q4 (NEAT), C/2002 T7(LINEAR), C/2003 K4 (LINEAR), 8P/Tule, 88P/Howell, 9P/Tempel 1, and 73P-B and -C/Schwassmann-Wachmann 3. The observaons were mainly carried out bythe Ultraviolet and Visual Echelle Spectrograph (UVES) mounted on the Very Large Telescope (VLT) in Chile. Other telescopes/instruments were also used in somecases. The OPRs of ammonia are determined from OPRs of NH2 (0,9,0) ro-vibronic band around 600 nm. Although absorpon lines (by the telluric atmosphere)and cometary C2 emission lines blended affected to NH2 emission lines in this region, we removed them in our analysis. The determined OPRs of ammoniaclustered around ~30K but not in the cases of 73P-B and -C. This situaon is very similar to that of 14N/15N raos in CN (i.e., 73P-B and -C are quite peculiarrelave to other comets). We discuss about the relaonship between the OPRs of ammonia and 14N/15N raos in CN in these 15 comets. Our results indicate theformaon of materials at relavely higher temperatures for 73P-B and -C than other comets.28.12: Observaons of Water in Comet 81P/Wild 2 by Subaru Telescope / IRCSAuthor Block: Mio Hashimoto 1 , H. Kobayashi 2 , H. Kawakita 2 , Y. Shinnaka 21 Saga Pref. Space Science Museum, Japan, 2 Kyoto Sangyo Univ., Japan.Presentaon Time: 10/4/2010 4:22 PM - 4:24 PMLocaon: Exhibit HallAbstract.Abstract: Comet 81P/Wild 2 was the target of the STARDUST sample return mission by NASA, and the results of ground-based analysis of sampled dustgrains provided us the details of cometary dusts. However, it is lile known about gaseous species in the comet 81P/Wild 2. The most abundant gaseous speciesin the coma is H2O that controls physical processes in the coma. Water producon rate is one of important parameter to evaluate the acvity of the comet. Todetermine the water producon rate of comet 81P/Wild 2, we performed near-infrared high-dispersion spectroscopic observaons by Subaru telescope/IRCS. Ourobservaons were carried out on both January 31 and February 1, 2010. We concentrate on the data taken on February 1 because S/N rao of spectra taken onJanuary 31 was not so good. The brightness of the comet was about 10th magnitude at our observaons. We could detect the strong water emission lines; X(1,0,1) 202 --- X (1,0,0) 303 at 3526.5 cm-1 and X (1,0,1) 211 --- X (1,0,0) 312 at 3514.4 cm-1. We will present the water producon rate of comet 81P/Wild 2determined from those emission lines.28.13: Crystalline Silicate Grains Of Comet 17P/Holmes Ejected At Its Outburst Observed With Subaru/COMICSAuthor Block: Mitsuru Yamaguchi 1 , T. Ootsubo 2 , J. Watanabe 3 , M. Honda 4 , I. Sakon 5 , M. Ishiguro 6 , Y. Sarugaku 7 , Y. Shinnaka 1 , H. Kobayashi 1 , H. Kawakita 11 Kyoto Sangyo University, Japan, 2 Tohoku University, Japan, 3 NAOJ, Japan, 4 Kanagawa University, Japan, 5 University of Tokyo, Japan, 6 Seoul Naonal University,Korea, Republic of, 7 JAXA/ISAS, Japan.Presentaon Time: 10/4/2010 4:24 PM - 4:26 PMLocaon: Exhibit HallAbstract: Comets had formed from dust and icy materials in the solar nebula 4.6 Gyrs ago. The cometary materials are considered as the most prisne in thesolar system and both dust grains and icy materials in comets have been used to invesgate the formaon condions of the solar system. Furthermore, it isconsidered that the existence of crystalline silicate in comets indicates the radial mixing of materials in the early solar nebula.Crystalline silicate is formed in high temperature environment. Then, it is clue to understand the difference between thermal and dynamical evoluon of dust inproto-solar nebula.A large outburst of comet 17P/Holmes has occurred in late October 2007. Just aer the outburst began, we carried out low-dispersion spectroscopic observaonin mid-infrared region (8 -13 µm) with COMICS mounted on the 8.2-m Subaru Telescope on October 25th-28 th, 2007 UT, when the comet was at a heliocentricdistance of 2.44 -2.45 AU.

distance of 2.44 -2.45 AU.We detected an isolated dust cloud that moved toward the south-west direcon from the nucleus by imaging observaons in mid-infrared region. The 11.2 µmpeak of a crystalline silicate feature onto a broad amorphous silicate feature was detected both in the central condensaon of the nucleus and an isolated dustcloud. We will present the me variaon of the spectra at different posions in the coma of comet 17P/Holmes at the outburst.28.14: Survey for CO2/H2O and CO/H2O Rao of Cometary Ice by Japanese Infrared Satellite AKARIAuthor Block: Saki Hamada 1 , M. Yamaguchi 1 , T. Ootsubo 2 , H. Kobayashi 1 , H. Kawakita 1 , F. Usui 3 , AKARI MP-SOSOS team, AKARI/IRC team1 Kyoto Sangyo University, Japan, 2 Tohoku University, Japan, 3 JAXA/ISAS, Japan.Presentaon Time: 10/4/2010 4:26 PM - 4:28 PMLocaon: Exhibit HallAbstract: Cometary ices consist of H2O, CO2, CO and various molecular species such as NH3, CH4, and HCN. H2O is the most abundant species of cometaryice, and both CO2 and CO are also abundant. However, CO2 cannot be observed by ground-based observaons and it is lile known about the abundance of CO2in comets because CO2 is severely absorbed by CO2 in the telluric atmosphere.We carried out the near-infrared low-dispersion spectroscopic observaons by Japanese infrared satellite AKARI. We observed 13 comets by the InfraRed Camera(IRC) with grism, which can cover the wavelength range from 2.5 to 5µm where vibraonal fundamental bands of H2O, CO2 and CO (at 2.7, 4.3, and 4.7µm,respecvely) are recognized as emission in cometary spectra. We determined the mixing raos of CO2 and CO relave to H2O in 13 comets. We will discussabout the diversity of the mixing raos of CO2 and CO in comets and compare our results with previous studies.28.15: Forbidden Oxygen Lines in Comets C/2006 W3 Christensen and C/2007 Q3 Siding SpringAuthor Block: Adam McKay 1 , N. Chanover 1 , J. Morgenthaler 2 , A. Cochran 3 , W. Harris 4 , N. Dello Russo 51 New Mexico State University, 2 Planetary Science Instute, 3 University of Texas at Ausn, 4 University of California Davis, 5 Johns Hopkins University AppliedPhysics Laboratory.Presentaon Time: 10/4/2010 4:28 PM - 4:30 PMLocaon: Exhibit HallAbstract.Abstract: We present analysis of high spectral resoluon observaons of the forbidden oxygen lines at 5577, 6300 and 6364 angstroms in cometsC/2006 W3 Christensen and C/2007 Q3 Siding Spring, acquired at approximately 3 AU from the Sun. We obtained the data using the ARCES echelle spectrometer(R=31,500) mounted on the Apache Point Observatory 3.5 meter telescope. We observed C/2006 W3 on UT August 1 2009, while C/2007 Q3 was observed on UTMarch 28 2010. Most published observaons of these lines in other comets were obtained at small heliocentric distances (approx. 1 AU), wherephotodissociaon of water molecules is the dominant source of the atomic oxygen present in the coma. However, at larger heliocentric distances, watersublimaon drops off and molecules such as CO and CO2 may play a larger role, as suggested by the comparable producon rates of CO and OH in comet C/1995O1 Hale-Bopp at 3 AU. The relave role of H2O vs. CO/CO2 as a source of atomic oxygen can be examined by comparing the rao of the green line (5577) to thered doublet (6300 and 6364). For C/2006 W3, we detect all three lines, and therefore the line rao can be directly calculated. For C/2007 Q3 Siding Spring, wedetect only the 6300 line, and therefore we can only place an upper limit on the value of the rao. Since observing condions were photometric for C/2007 Q3,we are able to perform a flux calibraon of the 6300 line. We use this flux to calculate the producon rate of H2O, CO, and CO2 for cases where QH2O &gt;&gt;QCO2, QCO2 &gt;&gt; QH2O, and QH2O = QCO2, assuming the number density of atomic oxygen is described by a Haser Model. This work was supported by theNASA EPSCoR program through grant number NNX08AV85A.28.16: Unidenfied Spectral Lines between 4800 and 8100 Å in High-Resoluon Spectra of CometsAuthor Block: Chaekyung Sim 1 , S. Hwang 1 , S. Kim 11 School of Space Research, Kyung Hee University, Korea, Republic of.Presentaon Time: 10/4/2010 4:30 PM - 4:32 PMLocaon: Exhibit HallAbstract: Visible spectrum of Comet Machholz (C/2004Q2) was obtained in the wavelength range of 2800 ~ 8100 Å with a resoluon of ~30,000 using BOES(BOao Echelle Spectograph) at Bohyunsan Observatory on January 4, 2005. It was found that emission lines of Machholz spectra were mostly originate from C 2 ,NH 2 , CN, and H 2 O+. A list of unidenfied spectral lines was compared with high-resoluon visible spectra of other comets in literature: Swi-Tule, Brorsen-Metcalf, Ausn, and 122P/de Vico. We will present idenfied molecular lines, which are previously unknown; and these idenficaons will be useful informaonfor studying high-resoluon spectra of future comets.28.17: The Volale Composion of Comet C/2009 R1 (McNaught) as Revealed through Pure Rotaonal and Ro-vibraonal EmissionsAuthor Block: Stefanie N. Milam 1 , M. A. DiSan 1 , B. P. Bonev 2 , S. B. Charnley 11 NASA Goddard Space Flight Center, 2 Catholic University of America/Goddard Center for Astrobiology.Presentaon Time: 10/4/2010 4:32 PM - 4:34 PMLocaon: Exhibit HallAbstract.Abstract: We report pre-perihelion spectral observaons of C/2009 R1 with the SMT on UT 2010 May 25, 29, 31 and June 1, the KPNO 12-m telescopeon UT June 10 and 14, and IRTF-CSHELL on UT May 25 and June 22. Limited solar elongaon throughout this period (from 45 - 24 degrees) presented challenges -nevertheless we detected emissions from mulple parent volales (HCN, H2CO, CH3OH, CO, CH4, C2H6, H2O) plus two photo-dissociaon products (CS, OHprompt emission). Preliminary analysis indicates neither severely enriched nor severely depleted abundances. Our results will be presented and discussed. Wegratefully acknowledge support from the NSF Astronomy and Astrophyics Program, NASA Planetary Astronomy Program, NASA Planetary Atmospheres Program,and the NASA Astrobiology Program.28.18: Volale Composion and Cosmogonic Indicators of Comet C/2007 N3 (Lulin)Author Block: Erika L. Gibb 1 , B. P. Bonev 2 , E. Sudholt 1 , M. Dennis 1 , M. M. Mumma 3 , M. A. DiSan 3 , G. Villanueva 3 , K. Magee-Sauer 41 Univ. of Missouri - St. Louis, 2 Catholic University of America, 3 NASA Goddard Space Flight Center, 4 Rowan University.Presentaon Time: 10/4/2010 4:34 PM - 4:36 PMLocaon: Exhibit HallAbstract: We obtained high-resoluon (RP~25,000) near-infrared spectroscopic observaons of Comet C/2007 N3 (Lulin) on 31 January and 1 February 2009with the NIRSPEC instrument on Keck II in Hawaii. We report producon rates and rotaonal temperatures of H 2 O, C 2 H 6 , HCN, C 2 H 2 , CH 4 , NH 3 , H 2 CO, and CH 3 OH.We also report upper limits for deuterated species HDO and CH 3 D. While the rotaonal temperature reflects condions in the coma, the spin temperature isthought to be an indicator of the formaon temperature for a parcular molecule. We have determined spin temperatures for both water and CH 4 . We discussspin temperatures and upper limits of deuterated species in terms of formaon temperatures in the solar nebula.We gratefully acknowledge support from the NSF Planetary Astronomy Program, the NASA Planetary Astronomy Program, and the NASA Astrobiology Program.

28.19: Observaons Of Comet C/2007 (lulin) Before And During Its PerihelionAuthor Block: Gian-Paolo Tozzi 1 , J. R. Brucato 1 , P. Patriarchi 1 , J. Licandro 2 , E. Mazzoa Epifani 3 , C. Snodgrass 4 , J. Vincent 41 INAF Osservatorio Astrofisico di Arcetri, Italy, 2 IAC, Spain, 3 INAF, Italy, 4 M PS, Germany.Presentaon Time: 10/4/2010 4:36 PM - 4:38 PMLocaon: Exhibit HallAbstract.Abstract: Comet Lulin was observed in July 2008, when the comet was in-bound at 1.7 AU from the Sun. Analysis of the images showed that the comethad a very intense and anomalous enhancement of the column density of the solid components in the inner coma. This effect was before interpreted as due tothe presence of sublimang grains (Tozzi et al, 2004, AA, 424, 325; 2007, 476, 979) or, more recently, to a developing coma expanding very slowly (few meters persecond, Tozzi et al. 2010, submied). To disentangle the two phenomena the comet was re-observed in two epochs around its perihelion (Jan - Mar. 2009), whenit was at about 1.40 AU from the Sun and at about 0.4 AU from the Earth. In this case the enhancement in the inner coma had disappeared, showing only a widebut less intense enhancement at about 20000-30000 km of projected distance. A possible contaminaon of gas, that would produce a similar effect, has beenexcluded by spectra and observaons with narrow band filters centred in spectral regions without gas emission. In the presentaon the results of the analysiswith possible interpretaons will be given.28.20: A Study of Water in Comet C/2007 N3 (Lulin)Author Block: Emily Sudholt 1 , B. P. Bonev 2 , E. L. Gibb 1 , M. A. DiSan 3 , G. Villanueva 3 , M. J. Mumma 3 , K. Magee-Sauer 41 University of Missouri - St. Louis, 2 Catholic University of America, 3 NASA Goddard Space Flight Center, 4 Rowan University.Presentaon Time: 10/4/2010 4:38 PM - 4:40 PMLocaon: Exhibit HallAbstract: We conducted a sensive search for HDO and detected H 2 O and OH in the spectra of comet C/2007 N3 (Lulin) obtained by NIRSPEC at the Keck IItelescope atop Mauna Kea, Hawaii. OH prompt emission is a direct proxy of H 2 O producon and eliminates “inter-seng” calibraon uncertaines in evaluangthe HDO/H 2 O rao. We report an upper limit for HDO/H 2 O, and spaal profiles, rotaonal temperatures, and producon rates for H2O. The work ofundergraduate student E. Sudholt was supported over 12 months by NSF Grant AST- 0807939 (PI/Co-PI Bonev/Gibb) and by the Goddard Center for Astrobiology (PIMumma). Co-authors gratefully acknowledge support from the NSF Astronomy and Astrophysics Research Grants Program, and by the NASA’s PlanetaryAstronomy, Planetary Atmospheres, and Astrobiology Programs.28.21: Detecons of Ethane (C 2 H 6 ), Methane (CH 4 ), and Carbon Monoxide (CO) in the Coma of Comet C/2006 W3 (Christensen) at 3.25 AU from The SunAuthor Block: Boncho Bonev 1 , H. Böhnhardt 2 , M. J. Mumma 3 , M. A. DiSan 3 , G. L. Villanueva 1 , M. Lippi 2 , E. L. Gibb 41 The Catholic Univ. of America / Goddard Center for Astrobiology, 2 Max-Planck Instute for Solar System Research, Germany, 3 NASA Goddard Space FlightCenter / Goddard Center for Astrobiology, 4 Univ. of Missori - St. Louis / Goddard Center for Astrobiology.Presentaon Time: 10/4/2010 4:40 PM - 4:42 PMLocaon: Exhibit HallAbstract: We report high-resoluon spectroscopic observaons of comet C/2006 W3 (Christensen) using the Cryogenic Infrared Echelle Spectrograph at theVery Large Telescope Observatory atop Cerro Paranal, Chile. We detected the “hypervolales” C 2 H 6 , CH 4 , and CO in the coma observed at heliocentric distance of3.25 AU. We also detected CO at 4.03 AU from the Sun. This presentaon will report spaal profiles, rotaonal temperature, and producon rates of the threedetected species. We compare our results with the radio detecon of CO (Bockelee-Morvan et al. A&A, 518, L149) and other parent volales at 3.20 and 3.32 AUto achieve an overall measure of the volale composion of this comet. The apparent enrichment in the coma of “hypervolales” will be discussed in terms offraconaon of nave ices within the nucleus. We gratefully acknowledge support from the NSF Astronomy and Astrophysics Research Grants Program (PI/co-PIBonev/Gibb), by the NASA’s Planetary Astronomy (PI Mumma; PI DiSan), Planetary Atmospheres (PI DiSan; PI Villanueva), and Astrobiology (PI Mumma)Programs, and by the German-Isreal Foundaon for Scienfic Research and Development (PI Böhnhardt).28.22: The Molecular Composion of Comet C/2007 W1 (Boani): Evidence of a Peculiar Outgassing and Rich ChemistryAuthor Block: Geronimo Villanueva 1 , M. A. DiSan 1 , M. J. Mumma 1 , B. P. Bonev 2 , E. L. Gibb 3 , K. Magee-Sauer 4 , G. A. Blake 51 NASA's GSFC, 2 Catholic University of America, 3 University of Missouri, 4 Rowan University, 5 Caltech.Presentaon Time: 10/4/2010 4:42 PM - 4:44 PMLocaon: Exhibit HallAbstract.Abstract: We report observaons of comet C/2007 W1 (Boani) performed using the long-slit high-resoluon echelle grang spectrograph at Keck-2(NIRSPEC) on July 9 and 10 of 2008. We present results for 10 volale species (H2O, OH*, C2H6, CH3OH, H2CO, CH4, HCN, C2H2, NH3, CO), the ortho-para raosof H2O and CH4, and an upper-limit of the water D/H rao in comet Boani. We observe important differences in the spaal profiles of the detected species,with the majority of the polar volales showing very asymmetric profiles. We present emission profiles for all observed volales along the cometary coma anddiscuss different producon scenarios necessary to explain these. Ulmately, we compare all measured cosmogonic indicators and relate these to a possibleformaon path for this comet. We acknowledge support from the NASA Planetary Atmospheres, Planetary Astronomy, Astrobiology Programs, and the NSFAstronomy and Astrophysics Research Grants Program.28.23: Searching for Gas Emission through Visible Spectroscopy of Large Perihelia (>5AU) CometsAuthor Block: Sean Mossman 1 , L. M. Woodney 1 , Y. R. Fernandez 21 California State Univ. San Bernardino, 2 University of Central Florida.Presentaon Time: 10/4/2010 4:44 PM - 4:46 PMLocaon: Exhibit HallAbstract: We present spectroscopic observaons of several comets with perihelia beyond 5 AU. In recent years many large perihelia comets have beendiscovered with acve dust comae. The gas, which must be driving the dust producon, is rarely detected. These objects are not close enough to the sun forwater sublimaon to be responsible for coma producon, so sublimaon of other volales (CO, CO2) or phase changes in water-ice likely drive the acvity. Theyrepresent a class of comets less altered from their original states than those that regularly pass through the water sublimaon zone and therefore can be used toaddress quesons of cometary composion and disentangle evoluonary effects.We used the LRIS spectrometer (0.3 Å spectral resoluon) on the Keck 10 m telescope atop Mauna Kea, Hawaii in hopes of detecng fluorescence from some ofthe commonly observed visible gas species such as CN, C2 or CO+. Our targets were three Centaurs - 95P/Chiron, 29P/Schwassmann-Wachmann 1 and C/ 2001M10 (NEAT) - and one long-period comet - C/2003 O1 (LINEAR). We present upper limits of gas species producon rates and the gas-to-dust mass loss rao.28.24: Dynamics of Crystalline Silicates in the Coma of Comet 9P/Tempel and the Deep Impact EjectaAuthor Block: Michael S. Kelley 1 , D. H. Wooden 2 , S. S. Lindsay 3 , D. E. Harker 4 , C. E. Woodward 5

1 Univ. of Maryland, 2 NASA Ames, 3 New Mexico State Univ., 4 UCSD/CASS, 5 Univ. of Minnesota.Presentaon Time: 10/4/2010 4:46 PM - 4:48 PMLocaon: Exhibit HallAbstract: Mid-infrared spectra have revealed the presence of crystalline silicates in the dust of comet 9P/Tempel, both before and aer the Deep Impactcratering experiment (Wooden et al. 2010, 42nd DPS Meeng). The spectra of the Deep Impact ejecta reveal strong silicate emission features, includingresonances from Mg-rich crystalline silicates (forsterite and enstate), reminiscent of spectra of comet C/1995 O1 (Hale-Bopp). In constrast, spectra of theambient coma appears to be that of a typical eclipc comet: a weak 10 micron silicate plateau with subtle features aributable to forsterite. Wooden et al. (2010)examine the me evoluon of archival Spitzer Space Telescope spectra of the Deep Impact ejecta and find that crystalline silicates are present in the ejecta aslate as 40 hours post-impact. They also find that the spectra at these late epochs have the same spectral shapes as the ambient coma. Thus, the slower movingejecta and the ambient coma are both composed of large porous aggregates containing crystalline silicates. We examine the dynamics of dust ejected by DeepImpact and find that this slower moving ejecta is at least 10 microns in size. This result implies that the ambient coma of 9P/Tempel is dominated by grains withsizes of order 10 microns. If we generalize our results, we conclude that many eclipc comets may be dominated by large porous grains with high crystallinefracons, approximately 40% by mass, despite their weak silicate emission features.This research is supported by NASA's Planetary Atmospheres Program.28.25: Using Imaging of Mulple Outbursts to Invesgate the Behavior and Nucleus Properes of Comet 29P/Schwassmann-Wachmann 1Author Block: Yanga R. Fernandez 1 , N. H. Samarasinha 2 , B. E. A. Mueller 2 , L. M. Woodney 31 Univ. of Central Florida, 2 PSI, 3 Cal State U.-San Bernardino.Presentaon Time: 10/4/2010 4:48 PM - 4:50 PMLocaon: Exhibit HallAbstract.Abstract: We present an analysis of the dynamic dust coma of comet 29P/Schwassmann-Wachmann 1 (SW1), a comet with a long record of observedoutbursts. We have obtained R-band CCD imaging of SW1's dust coma in 2002, 2003, 2005, 2008, and 2010, and at every epoch, the comet was fortuitously inoutburst, showing dust jets, spirals, and/or shells. This gives us a significant and growing database of these events with which we can study properes of SW1'sdust and nucleus, and their me evoluon. As an outburst evolves, our data show that the near-nucleus dust brightness and dust morphology change on daily andweekly mescales. Moreover, not all outbursts have the same strength; in parcular our 2010 imaging shows evidence of a mini-outburst of shorter duraon andsmaller magnitude than the others. In this presentaon we will follow up earlier analyses of the dust coma [1,2], and we will present preliminary results frommodeling the dust seen in specific outbursts. We are using a Monte Carlo dust model [3] that reproduces the features seen in the coma and thereby constrainsproperes such as outburst ming, spin state, and source regions. References: [1] Ellis, C.E., et al. 2004, BAAS 36, 1146. [2] Fernandez, Y.R., et al. 2008, IAUC8991. [3] Samarasinha 2000, ApJ 529, L107.28.26: Visible-wavelength Observaons of Jupiter-family Comet Nuclei as Part of Seppcon.Author Block: Jana Pichova 1 , S. C. Lowry 2 , R. Laird 2 , M. F. A’Hearn 3 , J. M. Bauer 4 , H. Campins 5 , Y. Fernández 5 , A. Fitzsimmons 6 , O. Groussin 7 , H. Hsieh 6 , M.Kelley 3 , P. Lamy 7 , J. Licandro 8 , C. M. Lisse 9 , K. J. Meech 1 , W. T. Reach 10 , C. Snodgrass 11 , I. Toth 12 , H. A. Weaver 9 , P. Weaissman 41 Univ. of Hawaii, 2 Centre for Astrophysics and Planetary Sciences, University of Kent, United Kingdom, 3 Dept. of Astronomy, Univ. of Maryland, 4 NASA/JPL,5 Physics Dept., Univ. of Central Florida, 6 Astrophysics Research Centre, Queens Univ. Belfast, United Kingdom, 7 Laboratoire d’Astrophysique de Marseille, CNRS& Université de Provence, France, 8 Instuto de Astrosica de Canarias, Spain, 9 Johns Hopkins Univ. Applied Physics Lab., 10 SOFIA/USRANASA Ames ReseachCenter, 11 Max Planck Instute for Solar System Research, Germany, 12 Konkoly Obs., Hungary.Presentaon Time: 10/4/2010 4:50 PM - 4:52 PMLocaon: Exhibit HallAbstract: We present the latest analysis and results from SEPPCoN (Survey of Ensemble Physical Properes of Cometary Nuclei). This on-going survey involvesstudying 100 JFCs - about 25% of the known populaon - at both mid-infrared and visible wave-lengths to constrain the distribuons of sizes, shapes, spins, andalbedos of this populaon. Having earlier reported results from measuring thermal emissions of our sample nuclei [1,2,3,4], we report here progress on thevisible-wavelength observaons that we have obtained at many ground-based facilies in Chile, Spain, and the United States. To date we have aemptedobservaons of 91% of our sample of 100 JFCs, and at least 64 of those were successfully detected. In most cases the comets were at heliocentric distancesbetween 3.0 and 6.5 AU so as to decrease the odds of a comet having a coma. Of the 64 detected comets, 48 were apparently bare, having no extendedemission. Our datasets are further augmented by archival data and photometry from the NEAT program [5]. An important goal of SEPPCoN is to accumulate alarge comprehensive set of high quality physical data on cometary nuclei in order to make accurate stascal comparisons with other minor-body populaonssuch as Trojans, Centaurs, and Kuiper-belt objects. Informaon on the size, shape, spin-rate, albedo and color distribuons is crical for understanding theirorigins and evoluonary processes affecng them.This work was supported in part by grants from NASA (NNX09AB44G) and NSF (AST-0808004).[1] Fernandez, Y., et al. 2008, Asteroids Comets Mete-ors 2008, LPI Co. No. 1405, paper id. 8307.[2] Kelley, M., et al. 2008, Asteroids Comets Meteors 2008, LPI Co. No. 1405, paper id. 8272.[3] Groussin, O., et al. 2009, Icarus 199, 568.[4] Licandro, J., et al. 2009, A&A 507, 1667.[5] Bauer, J., et al. 2010, AAS Meeng 216, paper 409.01.28.27: Whither Cometary Dust?Author Block: Carey M. Lisse 11 Johns Hopkins Univ..Presentaon Time: 10/4/2010 4:52 PM - 4:54 PMLocaon: Exhibit HallAbstract: In this paper I will discuss recent findings that have important implicaons for our understanding of the formaon and evoluon of primive solarsystem dust, including:- Nesvorny et al. (2010), following up on their dynamical analyses of the zodiacal dust bands as sourced by the breakup of the Karin (5Mya) and Veritas (8Mya)asteroid families, argue that over 90% of the interplanetary dust cloud at 1 AU comes from JFC comets with near-circularized, low inclinaon orbits. This impliesthat the noted IPD collecons of anhydrous and hydrous dust parcles are likely to be from Oort cloud and JFC comets, respecvely, not from asteroids andcomets as thought in the past. Hydrous dust parcles from comets like 85P/Wild2 and 9P/Tempel 1 would be consistent with results from the STARDUST and DeepImpact experiments.- Esmates of the dust parcle size distribuons (PSDs) in the comae of 85P/Wild2 (Green et al. 2004, 2007) and 73P/SW-3 (Sitko et al. 2010, Vaubaillon & Reach2010) and in the trails of comets (Reach et al. 2007) have broken power law structure, with a plateau enhancement of parcles of 1 mm - 1 cm in size. This size is

also the size of most chondric inclusions, and the predicted size range of the “aggregaonal barrier”, where collisions between dust parcles becomedestrucve.- Studies of the albedo and polarizaon properes of cometary dust (Kolokolova et al. 2007) suggest there are 2 major groupings, one with low scaeringcapability and one with high. While these families could possibly have been explained by systemacs in the PSDs of the emied dust, independent work by Lisseet al. (2008) on the mineralogy of a number of highly dusty comets has shown evidence for one family of comets with highly crystalline dust and another withhighly amorphous dust.28.28: Dust And Gas Morphology Of Comets 81P/Wild 2, 10P/Tempel 2, And 103P/Hartley 2Author Block: Mahew M. Knight 1 , D. G. Schleicher 11 Lowell Observatory.Presentaon Time: 10/4/2010 4:54 PM - 4:56 PMLocaon: Exhibit HallAbstract: As part of the ongoing program to study comets at Lowell Observatory, we present our recent observaons of Jupiter Family Comets 81P/Wild 2,10P/Tempel 2, and 103P/Hartley 2. All comets were observed with the Hall 1.1-m telescope at Lowell Observatory using broadband and narrowband opcal filtersto isolate gas and dust coma morphology. These filters allow us to compare the spaal distribuon of various gas species and to infer properes of the nucleussuch as the pole orientaon, rotaon period, and the number and locaon of acve regions.Wild 2 reached perihelion in February 2010, its first return since the Stardust encounter in 2004. We observed it on 22 nights between October 2009 and June2010. Image enhancement reveals two dust jets whose seasonal acvies are consistent with those described by Farnham and Schleicher (2005; Icarus 173, 553-558). Addionally, we observed a CN jet that appears to be coincident with one of the dust jets. Tempel 2 has a favorable observing scenario in 2010, withviewing geometry significantly different than in the previous favorable apparions of 1988 and 1999, which should further constrain the pole soluon. We beganobserving Tempel 2 in March 2010, and observaons will connue into 2011, with the comet near opposion throughout the fall. Preliminary analysis reveals asingle CN jet that does not vary with rotaonal phase and a dust jet that is offset from the CN jet. These features are consistent with post-perihelion observaonsin 1999 that will be presented separately by Schwieterman et al. Hartley 2 passes within 0.12 AU of Earth in October 2010 and is the target of the EPOXIspacecra flyby in November 2010. Imaging commenced in July 2010 and we will present ongoing results at the meeng.This work was supported by the NASA Planetary Astronomy program.28.29: Analysis of 10P/Tempel 2’s Morphological Features and Pole OrientaonAuthor Block: Edward Schwieterman 1 , D. G. Schleicher 2 , M. M. Knight 2 , T. L. Farnham 31 University of Washington, 2 Lowell Observatory, 3 University of Maryland.Presentaon Time: 10/4/2010 4:56 PM - 4:58 PMLocaon: Exhibit HallAbstract: Using Lowell telescopes, primarily the 1.1-m Hall Telescope, we conducted an in-depth observing campaign of Comet 10P/Tempel 2 during its1999/2000 apparion and have begun a follow up observing campaign for the 2010 apparion. Thirty-one nights of broadband and narrowband images wereobtained for the 1999/2000 apparion over an 11-month interval. Our earlier invesgaon of broadband R photometry collected early in the 1999/2000 apparionyielded a precise rotaon period and confirmed a slight nucleus spin-down (Knight et al. 2010, submied to AJ).Using narrowband and broadband images collected late in the 1999/2000 apparion to invesgate coma morphology, we find a single CN fan and a single dustjet. Relavely benign image enhancements such as azimuthal-subtracon were used to aid in the quantave determinaon of the posion angles of these radialfeatures. There is an offset between the posion angles of the CN fan and the dust jet that is consistent within the uncertaines; during the interval of October1999 through January 2000 the measured offset between the CN and dust features ranges from 10 to 20 degrees. We are examining the possible cause of thisposion angle offset. No change in the posion angles of the CN fan or dust jet were seen associated with rotaonal phase, suggesng that both features arevery close to the comet’s pole. Our preliminary pole soluon is in general agreement with Sekanina’s pole soluon for 1925-1967 (1991; AJ 102, 350-358).Our inial observaons from May-July of 2010 (see poster by Knight et al.) also show a single CN fan and dust jet with a larger offset in posion angle, possiblydue to the change in viewing geometry. Addionally, we see evidence of a dust tail in the an-solar direcon.This project is supported by the NASA Planetary Astronomy Program.28.30: Modeling the Dynamics of Comet Hale-Bopp's Dust at Large Heliocentric DistancesAuthor Block: Emily A. Kramer 1 , Y. R. Fernandez 1 , M. S. Kelley 2 , L. M. Woodney 3 , C. M. Lisse 41 University of Central Florida, 2 University of Maryland, 3 California State University, 4 JHU APL.Presentaon Time: 10/4/2010 4:58 PM - 5:00 PMLocaon: Exhibit HallAbstract: Comet Hale-Bopp has provided an unprecedented opportunity to observe a bright comet over a wide range of heliocentric distances. We present hereSpitzer Space Telescope observaons of Hale-Bopp from 2005 and 2008 that show a disnct coma and tail, which is uncommon given its heliocentric distance --21.6 AU and 27.2 AU, respecvely. These 24 um images (obtained with MIPS, the Mulband Imaging Photometer for Spitzer) show thermal emission from thedust, and are being studied using dynamical models [1, 2] to explain the dust morphology and constrain the dust's properes. Preliminary work suggests that themoon of the dust cannot be solely due to the effects of gravity and radiaon pressure. We invesgate the role of other possible driving forces, including the socalledrocket force [3]. Our inial analysis also shows that: (1) there is no trail lying along the orbit plane, as Spitzer saw for many other comets [4]; (2) theposion angle of the tail changed by about 50º between 2005 and 2008; (3) the faintness and shape of the tail in 2008 compared to 2005 cannot solely be due tothe change in observing geometry. These points suggest that even though Hale-Bopp is far from the Sun its tail is made of relavely recently-released grains. Ourscience goals are to understand the comet's acvity mechanism, constrain the age of the dust, find the size of the grains, and compare properes of the dustseen now to those of the dust seen in the 1990s. We acknowledge support from the NSF, NASA and the Spitzer Science Center for this work. References: [1] Kelley,M.S., et al. 2008, Icarus 193, 572, [2] Lisse, C.M., et al. 1998, ApJ 496, 971, [3] Reach, W.T., et al. 2009, Icarus 203, 571, [4] Reach, W.T., et al. 2007, Icarus 191,298.28.31: Determinaon of the Rotaon Period of Comet 81P/Wild 2Author Block: Beatrice E. A. Mueller 1 , T. L. Farnham 2 , N. H. Samarasinha 1 , M. F. A'Hearn 21 Planetary Science Instute, 2 University of Maryland.Presentaon Time: 10/4/2010 5:00 PM - 5:02 PMLocaon: Exhibit HallAbstract: Unl now, the rotaon period of comet 81P/Wild 2 was unknown even though the comet was studied in situ by NASA's Stardust mission. We observedthe comet near perigee for several nights in March and April 2010 with HB narrowband filters (Farnham et al. 2000; Icarus 147, 180) using the KPNO 2.1mtelescope. A rotaon period of P=13.5 hours (with an upper limit for the error bars of 0.1 hours) was deduced for the nucleus of comet 81P/Wild 2 based on the

epeatability of the CN features in the coma. All other rotaon periods can be excluded due to our excellent rotaonal phase coverage over mulple cycles. Thisrotaon period is consistent with the CN photometry from the March and April data, as well as with the broadband R photometry of the comet taken by us in2008.We acknowledge support from a NASA Planetary Astronomy grant.28.32: Predicng The Rotaonal Phase Of 9P/Tempel 1 At The Stardust-N ExT Encounter.Author Block: Michael J. S. Belton 1 , S. Chesley 2 , K. J. Meech 3 , B. Carcich 4 , J. Veverka 41 Belton Space Explor. Iniaves, LLC, 2 Jet Propulsion Laboratory, 3 Instute for Astronomy, University of Hawaii, 4 Department of Astronomy, Cornell University.Presentaon Time: 10/4/2010 5:02 PM - 5:04 PMLocaon: Exhibit HallAbstract: The scienfic goals of the Stardust-NExT mission to comet 9P/Tempel 1 include imaging 25% of the area imaged by the Deep Impact mission at aresoluon of at least 80 m/pixel looking for changes to the surface, imaging, at the highest possible resoluon, of the arficial crater created during the DeepImpact encounter (349W, -26), and imaging coverage of a poron of the terrain not yet seen. Fulfilling these goals required detailed knowledge of the spin stateof 9P’s nucleus approximately one year ahead of the nominal me of encounter, Feb 14, 2011. Since the encounter occurs ~33 days aer perihelion passage itwas necessary to develop a model of the acceleraon of the comet's spin state through perihelion passage in order to make a predicon. Determinaon of thespin state to the required accuracy was achieved in January, 2010, and was accomplished using observaons taken from the Hubble Space Telescope and fromground-based observatories. This informaon was then used as the basis of trajectory correcon maneuver in Feb, 2010. We describe the independentdevelopment of two spin rate acceleraon models based on ~13 years of observaons of the rate and phase of spin of the comet’s nucleus through twoperihelion passages obtained with the Hubble and Spitzer Space Telescopes, many ground-based telescopes within the organizaon of a Internaonal World-Widecampaign (Meech et al., 2005), and the Deep Impact mission. We present a visualizaon of the encounter that shows the ancipated coverage of the surface of9P/Tempel 1 that should be aained and emphasizes the proporon of the surface previously seen with the Deep Impact cameras and the new terrain that will becovered.Meech, K.J, and 210 coauthors. 2005. Deep Impact: Observaons from a World-Wide Earth-based Campaign. Science 310, 265-269.28.33: HST And Ground-based Comet 9P/Tempel 1 Observing Campaign For The Stardust-N ExT EncounterAuthor Block: Karen Jean Meech 1 , H. A. Weaver 2 , M. F. A'Hearn 3 , M. J. S. Belton 4 , J. Pichova 1 , 9PTempel-1 Observing Campaign Group1 Inst. for Astronomy, 2 JHU/APL, 3 Univ. Maryland, 4 Belton Space Explr. Iniaves, LLC.Presentaon Time: 10/4/2010 5:04 PM - 5:06 PMLocaon: Exhibit HallAbstract: In order to meet Stardust-NExT mission requirements of imaging 25 percent of the previously imaged area to look for changes between perihelia andto image the Deep Impact crater, precise informaon about the rotaonal phase was needed 1 year before the 14 Feb. 2011 encounter. An internaonal observingcampaign during fall 2009 was undertaken to obtain me-resolved observaons to combine with rotaon light curve data since 1997. The approach ulized HSTobservaons from Sep. 12-14, 2009 using the WF3 camera to obtain data over a full rotaon so our team could idenfy therotaonal phase of the nucleus. Follow up observaons on 24 nights from mid November 2009 through early January 2010 from Mauna Kea, BOAO, Lowellobservatory, KPNO, the Himalayan Chandra telescope, Yunnan observatory, and the Purple Mountain Observatory were used to refine the precision of the period.The HST light curve exhibited uneven minima, differing in depth by 0.1 mag and this lined up perfectly with the previous HST observaons obtained in 2004,suggesng that there have been no large scale changes in albedo on the surface of comet Tempel 1 caused by the Deep Impact experiment. At 3.78 AU, the HSTobservaons were consistent with an inacve nucleus. None of the deep images of the nucleus during Nov-Jan showed any evidence of dust coma. Connuedobservaons of the comet unl it went into solar conjuncon in June 2010 allowed us to watch the onset of acvity. We will discuss the observing campaign, andthe results of the image analysis, for the onset of dust producon. This work was supported in part by the Stardust-NExT project through an award from CornellUniversity 51326-8653, and from the NASA through STScI HSt-GO-11998.01A.28.34: Bulk Density of Comet 9P/Tempel 1Author Block: Nalin H. Samarasinha 1 , P. J. Guerrez 2 , M. J. S. Belton 3 , T. Farnham 4 , B. E. A. Mueller 1 , S. R. Chesley 51 Planetary Science Instute, 2 IAA-CSIC, Spain, 3 Belton Space Exploraon Iniaves, 4 University of Maryland, 5 jet Propulsion Laboratory.Presentaon Time: 10/4/2010 5:06 PM - 5:08 PMLocaon: Exhibit HallAbstract: In the absence of rendezvous space missions to comets, the main technique to determine cometary bulk densies is by correlang the long-termorbital changes of the comet with the corresponding forces due to outgassing. However, there are significant uncertaines in these determinaons as theaccurate assessment of forces due to outgassing is challenging.Davidsson et al. (2007, Icarus, 187, 306-320) derived a bulk density of 200-700 kg m -3 for comet 9P/Tempel 1 based on the orbital non-gravitaonal forces.Richardson and colleagues (e.g., Richardson et al. 2007, Icarus, 190, 357-390) independently determined a density of 200-1000 kg m -3 for comet 9P/Tempel 1based on the analysis of the ejecta fallback caused by the impactor of the Deep Impact mission. While it is encouraging that the density determinaons based onwidely different techniques yield consistent results, the allowed density range is sll relavely large. We present numerical results based on simultaneousmodeling of both orbital and rotaonal changes in 9P/Tempel 1 to constrain the bulk density of this comet more accurately. This modeling incorporatesobservaonal data from the Deep Impact spacecra as well as from ground-based observaons.We thank NASA's Outer Planets Research Program.28.35: The Triggered Outburst aer the Deep Impact Collision with Comet Tempel 1 and the Composion of the CometAuthor Block: Sergei I. Ipatov 11 Catholic University of America.Presentaon Time: 10/4/2010 5:08 PM - 5:10 PMLocaon: Exhibit HallAbstract: Our studies of ejecon of material from Comet Tempel 1 tesfy in favor of that there was a triggered outburst aer the collision of the DI impactorwith the comet [1-2]. A considerable outburst began at about 10 s aer DI impact. The beginning of the increase of the outburst could be caused by excavaon ofa large cavity that contained dust and gas under pressure. The upper edge of the cavity excavated at me of ejecon te~10 s could be located a few metersunder the surface of Comet Tempel 1. The outburst decreased at ~60 s aer the impact. Besides the ‘fast’ outburst caused by ejecon from the cavies, therewas a ‘slow’ outburst ejecon, which was similar to the ejecon from a ‘fresh’ surface of a comet and could last 30-60 min or more. Analysis of observaons ofthe DI cloud and of outbursts from different comets tesfies in favor of that there can be large cavies with material under gas pressure below a considerablefracon of a comet’s surface. Internal gas pressure (e.g. due to crystallizaon of amorphous ice) and the material in the cavies can produce natural andtriggered outbursts and can cause spling of comets. Analysis of DI observaons that used different approaches showed that at 1

in characterisc velocity can be considered to be proporonal to te -0.75 , with 20-25 m/s at 100-115 s. The ‘fast’ outburst with velocies ~100 m/s probably couldconnue for at least several tens of seconds, and it could significantly increase the fracon of parcles ejected with velocies ~100 m/s compared with theexponenal decrease of velocity. The work was supported by NASA grant NNX08AG25G. [1] Ipatov S.I., A'Hearn M.F., 2010, IAU Symp. S263, 317-321. [2] IpatovS.I., A'Hearn M.F., 2010, submied to MNRAS, hp://arxiv.org/abs/0810.1294.28.36: Detecon Of Organic Compounds With COSIMA-rosea Instrument: Applicaon To PolyoxymethyleneAuthor Block: Lena Le Roy 1 , H. Con 2 , N. Fray 2 , C. Briois 3 , L. Thirkell 3 , G. Poulet 3 , M. Hilchenbach 41 LPC2E / LISA, France, 2 LISA, France, 3 LPC2E, France, 4 M PS, Germany.Presentaon Time: 10/4/2010 5:10 PM - 5:12 PMLocaon: Exhibit HallAbstract: The Rosea mission launched by ESA in March 2004 will reach the comet 67P/Churyumov-Gerasimenko in 2014 to perform the most exhausve studyever achieved on comets. A me-of-flight secondary ion mass spectrometer (TOF-SIMS), named COSIMA (COmetary Secondary Ion Mass Analyser), is onboard theRosea spacecra. It will focus on chemical analysis of solid cometary grains collected in situ. COSIMA is one of the most promising instrument in the payload ofRosea to idenfy the refractory organic molecules present on comet.Here, we focus on the detecon of a specific compound: the polyoxymethylene (POM: -(CH 2 -O) n -). Indeed POM could be at the origin of the distributed source offormaldehyde in several comets. Moreover it is produced during the irradiaon and/or thermal treatment of cometary ice analogs. It could also have played animportant role in the sugar synthesis on the primordial Earth: it is a very concentrated source of formaldehyde.We will discuss the extent to which COSIMA will be able to detect polyoxymethylene. The mass spectrum of POM has been measured using a ground analog ofCOSIMA, and we have calculated the lifeme of this polymer on cometary grains collected by COSIMA.

Session Number: 37Session Title: EducationSession Type: Poster37.02: Evolving the Technical Infrastructure of the Planetary Data System for the 21st CenturyAuthor Block: Reta F. Beebe 1 , D. Crichton 2 , S. Hughes 2 , E. Grayzeck 31 New Mexico State Univ., 2 Jet Propulsion Laboratory, 3 NASA Headquarters.Presentaon Time: 10/4/2010 4:12 PM - 4:14 PMLocaon: Exhibit HallAbstract: The Planetary Data System (PDS) was established in 1989 as a distributed system to assure scienfic oversight. Inially the PDS followed guidelinesrecommended by the Naonal Academies Commiee on Data Management and Computaon (CODMAC, 1982) and placed emphasis on archiving validateddatasets. But overme user demands, supported by increased compung capabilies and communicaon methods, have placed increasing demands on the PDS.The PDS must add addional services to beer enable scienfic analysis within distributed environments and to ensure that those services integrate with exisngsystems and data. To face these challenges the Planetary Data System (PDS) must modernize its architecture and technical implementaon. The PDS 2010 projectaddresses these challenges. As part of this project, the PDS has three fundamental project goals that include: (1) Providing more efficient client delivery of databy data providers to the PDS (2) Enabling a stable, long-term usable planetary science data archive (3) Enabling services for the data consumer to find, accessand use the data they require in contemporary data formats.In order to achieve these goals, the PDS 2010 project is upgrading both the technical infrastructure and the data standards to support increased efficiency in datadelivery as well as usability of the PDS. Efforts are underway to interface with missions as early as possible and to streamline the preparaon and delivery of datato the PDS. Likewise, the PDS is working to define and plan for data services that will help researchers to perform analysis in cost-constrained environments.This presentaon will cover the PDS 2010 project including the goals, data standards and technical implementaon plans that are underway within the PlanetaryData System. It will discuss the plans for moving from the current system, version PDS 3, to version PDS 4.37.10: Aer School Astronomy Clubs: Lessons Learned from Over 10 Years of CollaboraonAuthor Block: Louis Mayo 11 NASA's GSFC.Presentaon Time: 10/4/2010 4:28 PM - 4:30 PMLocaon: Exhibit HallAbstract.Abstract: Aer School Astronomy clubs are unique in focusing on children in the K-12 grades as opposed to the numerous Amateur Astronomy Clubswithin the US and abroad whose membership is largely adult focused. Over the last 12 years, we have idenfied over 100 clubs that were previously running inisolaon, provided them with science and educaon resources and a means to communicate, created an online community of aer School Astronomy Clubs, andfacilitated the development of new clubs. Over this me, our model for developing and running these clubs has changed as we gained experience with varioustarget populaons, educaonal sengs, and external partners and as best pracces have emerged regarding engagement, impact, pedagogy, and sustainability.This talk will highlight these experiences and pracces and discuss implicaons for future development of the Aer School Astronomy Club program.

Session Number: 48Session Title: Laboratory ResearchSession Type: Poster48.01: Atomic Carbon Chemistry in Photolyzed Triton-like IcesAuthor Block: Paul Johnson 1 , R. Hodyss 1 , H. R. Howard 1 , J. D. Goguen 1 , I. Kanik 11 JPL.Presentaon Time: 10/4/2010 4:22 PM - 4:24 PMLocaon: Exhibit HallAbstract: We report photochemical studies of thin cryogenic ice films composed of N 2 , CH 4 and CO in raos similar to those on the surfaces of Neptune’slargest satellite, Triton, and on Pluto. Experiments were performed using a hydrogen discharge lamp, which provides an intense source of ultraviolet light in orderto elucidate the solar induced photochemistry of these icy bodies. Characterizaon via infrared spectroscopy showed that C 2 H 6 and C 2 H 2 , and HCO are formed bythe dissociaon of CH 4 into H and CH 3 and the subsequent reacon of these radicals within the ice. Other radical species, such as C 2 , C - 2 , CN, a nd CNN a re obs e rve d i nthe vi s i bl e a nd UV re gi ons of the s pe ctrum. The s e s pe ci e s i mpl y a ri ch che mi s try ba s e d on re a cons of a tomi c ca rbon wi th the N 2 ma tri x. We di s cus s the i mpl i ca ons of the forma on of the s era di ca l s for the che mi ca l e vol uon of Tri ton a nd Pl uto. Ul ma te l y, thi s work s ugge s ts tha t C - 2 , CN, HCO, and CNN may be found in significant quanes on the surfaces of Triton and Pluto and that new observaons of these objects in theappropriate wavelength regions are warranted.48.02: Radiaon Synthesis Of Carbon Dioxide From Ice-coated C-13 FoilAuthor Block: Ujjwal Raut 1 , D. Fulvio 1 , M. J. Loeffler 2 , R. A. Baragiola 11 University of Virginia, 2 NASA GSFC.Presentaon Time: 10/4/2010 4:24 PM - 4:26 PMLocaon: Exhibit HallAbstract: We have studied the synthesis of 13 CO 2 from 100 keV proton irradiaon of ~ 100 nm thick amorphous water ice film on top of an amorphous 13 C foil(95% isotopic purity, ~ 50 nm thick) at 20 and 120 K using infrared spectroscopy and microbalance techniques. In contrast to previous work, we use pure carboninstead of hydrogenated carbon grains (Mennella et.al., 2004). We also spuer clean the carbon surface using 100 keV Ar + to remove any atmosphericcontaminants prior to deposion of the water ice layer.At 20K, the producon of 13 CO 2 increases linearly with fluence and saturates at a column density of ~ 1 × 10 15 CO 2 cm -2 . At 120K, the CO 2 column densityincreases linearly with fluence at a rate ~ 43% higher than at 20 K. Further, the rate of CO 2 producon doubles following a fluence of 7 × 10 15 H + cm -2 . Thesaturaon column density at 120 K is ~ 2.7 × 10 15 CO 2 cm -2 , nearly three mes larger than at 20 K. The profile of the ν 3 absorpon feature due asymmetric stretchof the C-O bond indicates that the CO 2 produced from radiaon is dispersed in the water ice, as opposed to being in aggregates at both temperatures.We will discuss the radiaon-induced chemical processes near the water ice - carbon interface that are involved in the synthesis of carbon dioxide. In parcular,the formaon and trapping of O 2 from radiolysis of water ice at high temperatures (Teolis et.al. 2009) could play an important role in the enhancement of CO 2producon at 120K. The formaon of CO 2 via radiolysis of the water ice-carbon interface can contribute to the solid CO 2 observed on the interstellar grains andon the surfaces of the Jovian satellites such as Ganymede and Callisto.48.03: Thermal Conducvies of Two Basalc Achondrite MeteoritesAuthor Block: Guy Consolmagno 1 , C. P. Opeil 2 , D. T. Bri 31 Vacan Obs., Holy See (Vacan City State), 2 Boston College, 3 University of Central Florida.Presentaon Time: 10/4/2010 4:26 PM - 4:28 PMLocaon: Exhibit HallAbstract.Abstract: In our ongoing survey of the physical properes of meteorites, we have measured the thermal conducvity for the basalc achondritemeteorites Frankfort, a howardite likely to be typical of material on the surface of asteroid 4 Vesta, and Los Angeles, a shergote believed to have originated onMars, at temperatures ranging from 300K to 5K. From 300K to 100K, the conducvity of Frankfort decreases gradually from 1.6 to 1.2 W/mK; that of Los Angelesdrops from 0.9 to 0.5 W/mK. At lower temperatures the thermal conducvity of both meteorites connues to drop, but more rapidly, to values below 0.1 W/mK at10K. We find that for both meteorites the conducvity is significantly lower than would be expected from averaging the laboratory conducvies of theirconstuent minerals. These results are similar to results from measurements of ordinary chondrites (Opeil et al 2010, Icarus 208, 449). The monotonic decreaseof conducvity with temperature over this range is different from the expected conducvity of pure minerals, which tend to vary as 1/T. This indicates that, incommon with the ordinary chondrites, the conducvity we measure is controlled by the presence of shock-induced microcracks within the meteorites, whichprovide a barrier to the transmission of thermal energy via phonons. Thus these measurements may accurately describe the conducvity of material at thesurfaces of their parent bodies. However results from surface samples may significantly underesmate the actual conducvity of material deeper in the parentbodies, depending on how characterisc the shock history of these meteorites reflects material sll in place inside these bodies.48.04: Low-Energy Impacts onto Lunar RegolithAuthor Block: Laura M. Seward 1 , J. Colwell 1 , M. Mellon 21 University of Central Florida, 2 University of Colorado at Boulder.Presentaon Time: 10/4/2010 4:28 PM - 4:30 PMLocaon: Exhibit HallAbstract.Abstract: We are conducng a program of laboratory experiments to study low velocity impacts of 1 to 5 m/s into regolith. We use direct measurementof ejecta mass and high resoluon video tracking of ejecta parcle trajectories to derive ejecta mass velocity distribuons. We wish to characterize andunderstand the collision parameters that control the outcome of low velocity impacts into regolith, including impact velocity, impactor mass, target sizedistribuon, regolith depth, and target relave density, and to experimentally determine the funconal dependencies of the outcomes of low velocity collisions(ejecta mass and ejecta velocies) on the controlling parameters of the collision. Our goal is to understand the physics of ejecta producon and regolithcompacon in low energy impacts and experimentally validate predicve models for dust flow and deposion. We will present results from our ongoing studyshowing the posive correlaon between impact energy and ejecta mass. Our results show that the ejecta mass fracon decreases as a funcon of esmatedejecta mass velocity. We will also discuss the effect of pressure, target mass density, target mass type, impactor type, and how these factors may affect ourresults.48.05: Rate Constant Values for Some Hydrocarbon and Nitrogenous Species Reacons at Low Pressure and TemperatureAuthor Block: Gregory P. Smith 1

1 SRI Internaonal.Presentaon Time: 10/4/2010 4:30 PM - 4:32 PMLocaon: Exhibit HallAbstract: Synthesis of larger molecules in Titan’s atmosphere and of astrobiological precursors depends upon reacons of hydrocarbon and nitrogen-containingradicals and molecules at low temperatures and pressures. Master equaon / transion state theory calculaons are used to provide rate coefficients formodeling this chemistry, oen using parameters determined from quantum chemistry computaons. Results are presented for the formaon of CH 3 CN, N 2 H 4 , andCH 3 NH 2 from radical recombinaon reacons. Predicons are given for H atom addion reacons with HCN, HCCCN, and other species, including the effects oftunneling. Two more complex chemical acvaon systems were also studied, C 2 H 3 + HCN → H + C 2 H 3 CN or C 2 H 4 CN , and NH 2 + CH 2 CN → HCN + CH 2 NH orNH 2 CH 2 CN. Potenal addion steps for the growth of alkene/nitrile polymers are also being explored.Research supported by NASA Outer Planets Research Program.48.06: High Resoluon Invesgaon of the Ethane Spectrum at 7 μAuthor Block: Linda R. Brown 1 , K. Sung 1 , C. Di Lauro 2 , F. Laanzi 2 , J. Vander Auwera 3 , A. W. Mantz 4 , M. A. H. Smith 51 Jet Propulsion Laboratory, 2 Universita di Napoli Federico II, Italy, 3 Universite Libre de Bruxelles, Belgium, 4 Conneccut College, 5 NASA Langley Research Center.Presentaon Time: 10/4/2010 4:32 PM - 4:34 PMLocaon: Exhibit HallAbstract: A new theorecal analysis of the ethane spectrum between 1330 and 1610 cm -1 has been undertaken in order to create the first line-by-line databaseof molecular parameters for this spectral region. For this, high resoluon spectra were obtained at room and cold (130 K) temperatures with two Bruker Fouriertransform spectrometers (at 0.002 cm -1 resoluon in Brussels and at 0.003 cm -1 resoluon in Pasadena). Over 5000 lines were assigned to five bands in theregion: v 6 , v 8 , v 4 +v 12 and 2v 4 +v 9 cold bands, and one hot band (v 4 +v 8 -v 4 ). This new study employed a much improved theorecal Hamiltonian to reproduce thevery complicated spectral structures resulng from numerous interacons between these vibraonal modes. This advancement has enabled us to provide aquantum mechanical predicon of line posions and intensies of C 2 H 6 at 7 micron long needed for remote sensing of outer planets and Titan. Two manuscriptsare in preparaon.Part of the research described in this paper was performed at the Jet Propulsion Laboratory, California Instute of Technology, Conneccut College, and NASALangley under contract with the Naonal Aeronaucs and Space Administraon, and with funding from FRS-FNRS in Belgium.48.07: Closed-cycle He-cooled Absorpon Cells Designed For A Bruker Ifs-125hr: First Results Between 79 - 297 KAuthor Block: Keeyoon Sung 1 , A. W. Mantz 2 , M. A. H. Smith 3 , L. R. Brown 1 , T. J. Crawford 1 , V. Malathy Devi 4 , D. Chris Benner 41 Jet Propulsion Laboratory, 2 Conneccut College, 3 NASA Langley Research Center, 4 The College of William and Mary.Presentaon Time: 10/4/2010 4:20 PM - 4:22 PMLocaon: Exhibit HallAbstract: Gas absorpon cells specifically designed to achieve stable temperatures down to 66K were developed at Conneccut College to fit inside the samplecompartment of an evacuated Bruker (IFS-125HR) Fourier Transform spectrometer (FTS) at the Jet Propulsion Laboratory. The temperature-controlled cooling by aclosed-cycle helium refrigerator achieved a temperature stability of ±0.01 K. Such temperature control is essenal to characterize the temperature dependence ofline shapes at the very low temperatures found in outer planets and their moons. In operaon, the effects of vibraons arising from the closed-cycle heliumrefrigerator upon the FTS spectra were minimized. Inial unwanted absorpon features from cryo-deposits on the cell windows were eliminated by adding aseparately-pumped vacuum shroud box around the coolable cell to isolate it from residual gases in the evacuated FTS chambers.Using this setup, high resoluon spectra of several methane isotopologues ( 12 CH 4 , 13 CH 4 and 12 CH 3 D) broadened by N 2 , were recorded in the 1230 to 1850 cm -1spectral region. Inial analysis of the R(2) manifold of the v 4 fundamental band of 13 CH 4 examined whether the N 2 -broadened half width coefficients follow asimple power-law temperature-dependence over the enre 80 - 296 K temperature range. The results from this work were published by Sung et al. [1].Low-temperature spectra of ethane [2-3] and carbon monoxide have also been recorded.This research is supported by NASA’s Planetary Atmospheres Program.[1] K. Sung et al., J. Mol. Spectrosc. (2010) doi:10.1016/j.jms.2010.05.004.[2] V. Malathy Devi et al., JQSRT (2010) submied.[3] L. R. Brown et al., adjacent poster.48.08: Measurements of Methane at 7.5 μm Broadened by Nitrogen at Low TemperaturesAuthor Block: Mary-Ann H. Smith 1 , A. W. Mantz 2 , K. Sung 3 , L. R. Brown 3 , T. J. Crawford 3 , V. Malathy Devi 4 , D. Chris Benner 41 NASA Langley Research Center, 2 Conneccut College, 3 Jet Propulsion Laboratory, 4 College of William and Mary.Presentaon Time: 10/4/2010 4:34 PM - 4:36 PMLocaon: Exhibit HallAbstract: Since the ν 4 band system of methane (CH 4 ) at 7.5 µm appears prominently in infrared spectra of Titan’s atmosphere, we are conducng laboratorystudies to examine the temperature-dependence of infrared transions of CH 4 broadened by N 2 in this spectral region. Spectra of methane-nitrogen mixtures attemperatures from 79 to 297 K were obtained at 0.006 cm -1 resoluon (resolving power = 2x10 5 ) using the Bruker IFS 125HR Fourier transform spectrometer at theJet Propulsion Laboratory with new temperature-controlled gas cells designed specifically to fit in the spectrometer’s sample compartment. Details of the cellsand spectrometer performance [1] are described in an adjacent poster by Sung et al. A mulspectrum nonlinear least squares technique [2] is used to fit selectedintervals of 9 or more spectra simultaneously to obtain the temperature dependences of line broadening, pressure-induced shi and line mixing parameters.Results for 13 CH 4 at 80 to 297 K are discussed relave to our previous high-resoluon studies of air- and self-broadened 12 CH 4 and 13 CH 4 [3-5] at terrestrialatmospheric temperatures (210 to 314 K).This research is supported by NASA’s Planetary Atmospheres Program.1. K. Sung et al., J. Mol. Spectrosc. (2010) doi:10.1016/j.jms.2010.05.004.2. D. Chris Benner et al., J. Quant. Spectrosc. Radiat. Transfer 53 (1995) 705-721.3. M. A. H. Smith et al., J. Quant. Spectrosc. Radiat. Transfer 110 (2009) 639-653.4. M. A. H. Smith et al., J. Quant. Spectrosc. Radiat. Transfer 111 (2010) 1152-1166.5. M. A. H. Smith et al., J. Quant. Spectrosc. Radiat. Transfer (2010) submied.48.09: Laboratory Measurements And Modeling Of Molecular Photoabsorpon Cross Secons In The Ultraviolet: N2, So2, S2, Co2Author Block: Glenn Stark 1 , P. L. Smith 2 , B. R. Lewis 3 , A. N. Heays 3 , D. Blackie 4 , J. Pickering 41 Wellesley College, 2 Harvard-Smithsonian Center for Astrophysics, 3 Australian Naonal University, Australia, 4 Imperial College, United Kingdom.

Presentaon Time: 10/4/2010 4:36 PM - 4:38 PMLocaon: Exhibit HallAbstract: Our research program comprises the measurement and modeling of ultraviolet molecular photoabsorpon cross secons with the highest praccalresoluon. Measurement and modeling efforts on molecular nitrogen, sulfur dioxide, diatomic sulfur, and carbon dioxide are in progress.N 2 : We measure line f-values and widths within the complex spectrum between 80 and 100 nm. Our measurements are incorporated into a theorecal model ofthe absorpon spectrum of N 2 which has established the mechanisms responsible for predissociaon and reproduces the observed features in all N 2 isotopomersas a funcon of temperature.SO 2 : We provide astronomers with high-resoluon cross secon data for the complex ultraviolet SO 2 absorpon spectrum. Using the Imperial College VUV Fouriertransform spectrometer, we have completed and published cross secons from 198 to 325 nm (295 K) and from 199 to 220 nm (160 K). We have completed workon further low-temperature measurements from 220 to 325 nm.S 2 : Interpretaons of atmospheric (Io, Jupiter) S 2 absorpon features are hindered by a complete lack of laboratory cross secons in the ultraviolet. We havebegun to quanfy the photoabsorpon spectrum of S 2 from 200 to 300 nm. We have designed an experimental apparatus to produce a stable column of S 2 vapor.Measurements of S 2 absorpon features at high resoluon will be complemented by coupled-channel calculaons of the relevant transions.CO 2 : The photodissociaon of CO 2 is a fundamental photochemical process in the atmospheres of Mars and Venus. Our research centers on the measurement ofhigh resoluon cross secons from 87 to 120 nm. We have completed measurements at 295 K and 195 K over the 106 to 120 nm region. We have recentlycompleted preliminary room temperature measurements in the 87 to 106 nm region.We acknowledge grant support from NASA (NNX08AE78G), STFC-PPARC, and ARC (DP0558962).48.10: High Resoluon Fluorescence Spectrometry: The N2 and N I EmissionsAuthor Block: C. Y. Robert Wu 1 , J. I. Lo 2 , Y. C. Lin 2 , H. S. Fung 3 , Y. Y. Lee 3 , T. S. Yih 2 , D. L. Judge 11 Univ. of Southern California, 2 Naonal Central University, Taiwan, 3 Naonal Synchrotron Radiaon Research Center, Taiwan.Presentaon Time: 10/4/2010 4:38 PM - 4:40 PMLocaon: Exhibit HallAbstract: Our goal is to invesgate the complicated interacons among the excited electronic states of N2. In addion to high resoluon absorpon crosssecon measurements we have studied the J-dependent predissociaon rates, cascade transions and their branching raos for several excited states of N2 atdifferent pressure and temperature condions. Dispersed fluorescence spectra (DFS) and fluorescence excitaon spectra (FES) produced through photoexcitaonof N2 using synchrotron radiaon in the extreme ultraviolet region have been obtained. An ultrahigh resoluon (0.0014 nm) spectrometer has been ulized toobtain a rotaonally resolved FES experiment in spectral region between 80 and 100 nm. In the DFS experiments we have employed a 0.5-m and a 0.2-mspectrometer coupled with a posion-sensive-array detector to study the fluorescence spectra. Furthermore, we have also measured the fluorescence crosssecons of several NI lines produced through photoexcitaon of N2 in the 70-80 nm region.We are currently carrying out the above N2 experiments at temperatures as low as 77 K so that the data can be applicable to the characterizaon of the N2emissions in the atmospheres of Titan and Pluto. Detailed results will be presented. This research is based on work supported by NSF grant AST-0906158.48.11: The Microwave Properes of Jovian Clouds: Laboratory Measurement of Aqueous Ammonia (N H4OH) Between 2-8.5 GHzAuthor Block: Danny Duong 1 , P. G. Steffes 11 Georgia Instute of Technology.Presentaon Time: 10/4/2010 4:40 PM - 4:42 PMLocaon: Exhibit HallAbstract: Laboratory measurements of the complex dielectric properes of aqueous ammonia, under condions characterisc of Jovian clouds, have beenmade in the 2-8.5 GHz range at temperatures ranging from 24-60 oC and concentraons of 0-8.5% ammonia (NH3) by volume. No previous laboratory experimentshave been made to characterize the microwave dielectric properes of aqueous ammonia. Previous models of Jovian microwave emission (de Pater et al., Icarus,2005) have assumed that for low concentraons of ammonia in soluon, the dielectric properes of aqueous ammonia are approximately equal to those of water;however, these measurements suggest that even at concentraons as low as 0.5% NH3 by volume, there is a marked difference in the complex dielectricproperes of aqueous ammonia. Assuming Raleigh scaering, these measurements are applied to a cloud aenuaon model to calculate the opacity of theJovian aqueous ammonia clouds. These measurements will improve our understanding of the data collected by the Juno microwave radiometer (MWR) bycharacterizing the absorpon properes of the aqueous ammonia present in the Jovian atmosphere.This work was supported by NASA Contract NNM06AA75C from the Marshall Space Flight Center supporng the Juno Mission Science Team, under Subcontract699054X from the South-west Research Instute.48.12: W ITHDRAW N: Laboratory Pressure Broadening Coefficients To Support SOIR/VEx And SOIR-N OMADAuthor Block: Rachel Drummond 1 , T. Földes 2 , J. Vander Auwera 2 , A. Mahieux 1 , S. Robert 1 , A. Vandaele 1 , V. Wilquet 11 Belgian Instute of Space Aeronomy, Belgium, 2 Université Libre de Bruxelles, Belgium.Presentaon Time: 10/4/2010 4:42 PM - 4:44 PMLocaon: Exhibit HallAbstract: Precise spectroscopic data to describe CO 2 pressure-broadened lineshapes of trace gases in the Venus and Mars atmospheres are rather scarce. Inan aempt to compensate for such a situaon, we recorded in the laboratory CO 2 broadened absorpon spectra of the 1-0 band of HCl near 2886 cm -1 and the ν 3band of CH 4 near 3019 cm -1 at several pressures between 150 and 700 Torr, using a high-resoluon Fourier transform spectrometer. CO 2 pressure broadeninghalf-width coefficients are extracted by least-squares fing of suitable molecular line profiles, including instrumental effects.Sensivity studies have been performed using the characteriscs of the SOIR instrument. This instrument is currently on board the Venus Express mission (ESA)and has been proposed as payload for the future ExoMars 2016 TGO mission (ESA/NASA).The SOIR instrument is designed to measure atmospheric transmission in the near-IR (2.2 - 4.3 µm) at high resoluon (0.12 cm -1 ) through solar occultaonobservaons. It therefore allows the derivaon of unique remote sensing informaon about the vercal structure and composion of the Venus mesosphere, withvery good spaal resoluon.At Venus, SOIR is able to provide HCl vercal profiles ranging typically from 80 to 105 km, at both morning and evening terminators, where the dynamics of theplanetary atmosphere are relavely unknown. At Mars, the high resoluon of the instrument will make it possible to observe CH 4 , if any.We show here how these two approaches, laboratory and space missions, are complimentary, as broadening coefficients measured in the laboratory allow us tosimulate perfectly HCl and CH 4 lines as seen by SOIR.48.13: Crical Evaluaon of the Photoabsorpon Cross Secon of CO 2 from 0.125 to 201.6 nm at Room Temperature

Author Block: David L. Huess 1 , J. Berkowitz 21 SRI Internaonal, 2 Argonne Naonal Laboratory.Presentaon Time: 10/4/2010 4:44 PM - 4:46 PMLocaon: Exhibit HallAbstract: Accurate ultraviolet photoabsorpon cross secons of polyatomic molecules are essenal tools for reliable modeling of the photochemistry ofplanetary atmospheres. Extensive experimental data already have been recorded and published, but they are of uneven spectral resoluon and coverage, and inmany cases, are unavailable in computer-readable forms needed for incorporaon in modeling calculaons. Furthermore, most laboratory invesgaons havebeen conducted at room temperature. Perhaps most serious is that there are relavely few published assessments or crical evaluaons of absolute calibraonand reliability, or which laboratory experiments should be most trusted.Here we report the results of crical evaluaon of the ultraviolet photoabsorpon cross secon of the carbon dioxide molecule, CO 2 , the principal component ofthe atmospheres of Venus and Mars, and an important component of comets. By careful comparison and selecon of data from published laboratoryinvesgaons we have assembled, documented, analyzed, recommended, and make available a data file of absorpon cross secons at 25,016 wavelengthsbetween 0.125 and 201.6 nm at room temperature.The data file will be submied to the Mainz spectroscopy archive and is currently available online at hp://www-mpl.sri.com/data/CO2uv300.html

Session Time: 10/5/2010 8:30 AM

Session Number: 14Session Title: Comets: Nucleus and Coma ModelingSession Type: Oral14.01: Thermal Inera and Surface Roughness of Comet 9P/Tempel 1Author Block: Bjorn Davidsson 1 , P. J. Guerrez 2 , H. Rickman 1 , J. Warell 11 Dept. of Physics and Astronomy, Uppsala University, Sweden, 2 Instuto de Astrofisica de Andalucia-CSIC, Spain.Presentaon Time: 10/5/2010 8:30 AM - 8:40 AMLocaon: Ballroom EAbstract: Near-infrared (NIR) thermal emission spectra of the resolved nucleus of Comet 9P/Tempel 1 was obtained by the NASA spacecra Deep Impact.Substanal efforts has been made [Groussin et al. (2007), Icarus 187, 16; Davidsson et al. (2009), Icarus 201, 335] to retrieve informaon regarding the surfaceproperes of the comet, e.g., its thermal inera, by aempng to reproduce the observed surface temperatures through thermophysical modeling. Consensus hasso far not been reached regarding the physical properes of the nucleus, although there is agreement that the presence of surface roughness is making theanalysis difficult. We report on results from new modeling which explicitly considers surface roughness(including associated phenomena such as shadowing and self heang), and 1D as well as 3D heat conducon. This modeling indicates that lateral heatconducon (which oen is ignored in the analysis of thermal emission from atmosphereless Solar System bodies) indeed is important for Comet 9P/Tempel 1.14.02: 3D Time-Dependent Model Of The Dusty-Gas Atmosphere Of Comet 67P/Churyumov-Gerasimenko: Recent Improvements.Author Block: Vladimir Zakharov 1 , A. V. Rodionov 2 , J. F. Crifo 31 LESIA, Observatoire De Paris, France, 2 TSNIIM ASH, Russian Federaon, 3 LATM OS, CNRS, France.Presentaon Time: 10/5/2010 8:40 AM - 8:50 AMLocaon: Ballroom EAbstract: Under support from the French Space Agency (CNES), a 3D+t dusty-gas model of Comet 67P/Churyumov-Gerasimenko is being developed, to compute,from the first 2014 Rosea orbital data, the aerodynamic forces exerted on the Rosea orbiter and on the descent lander. We report the recently developed dustdynamics part of the code.The mul-species (presently H 2 O and CO) gas code is opmized in terms of computaonal speed owing to the use of two complementary methods: (a) 3D+tDirect Simulaon Monte Carlo (DSMC) runs in the non-equilibrium regions adjacent to the surface and very distant from it, and (b) soluons of the Navier-Stokesequaons in-between. The model is used presently using Lamy et al. (Space Sci. Rev., 2007, 128, 23) coarse informaon on 67P nucleus shape and rotaon, and arange of possible gas producon rates Q for the early Rosea observaons at r h ~3 AU (Q~10 26 - 10 27 s -1 ).In the interim version, simplifying assumpons are made with respect to the physical processes of gas producon and with respect to the dust grain structure(grain sphericity).The dust code is based on the 3D+t Dust Monte-Carlo (DMC) approach of Crifo et al. ( Icarus, 2005, 176, 192) which allows for three forces: nucleus gravity,aerodynamic force, and solar radiaon pressure.The dynamics of grains of a large size range (submicron - millimeter) is described in detail, and three implicaons are discussed: (a) structure of the near-nucleusdust coma, (b) evoluon of the nucleus surface, and (3) dust impacts on the lander.14.03: Acvity on Internally Inhomogeneous Comet Nuclei Using a 3-D Numerical ModelAuthor Block: Eric Rosenberg 1 , D. Prialnik 21 Jet Propulsion Laboratory, 2 Tel-Aviv University, Israel.Presentaon Time: 10/5/2010 8:50 AM - 9:00 AMLocaon: Ballroom EAbstract: We present a fully 3-D thermal evoluon model for cometary nuclei. The model uses an implicit numerical scheme in spherical coordinates. Itincludes heat flow, crystallizaon of amorphous ice, surface and sub-surface sublimaon of volales, and gas drag on dust parcles. The model is applied withthe orbital and spin parameters of the Jupiter-family comet 67P/Churyumov-Gerasimenko. The calculaons are performed with inhomogeneous asymmetric inialconfiguraons.The inial composion is amorphous water ice and dust, in a "layered-pile" configuraon, where layers differing in ice/dust rao and thermal properes extendover a fracon of the surface area and about 10 meters in depth and may overlap. Four such layers are studied: a) Compact dust, b) Porous dust, c) Compact icerichwith dust, and d) Fluffy ice-rich with dust.We analyze the effect of individual layers, as well as the combined effect of many layers, randomly distributed. We found that internal inhomogeneies affectboth the surface temperature and the acvity paern of the comet. In parcular, they may lead to outbursts at large heliocentric distances and to acvity on thenight-side of the nucleus. The rates of ablaon, thickness of the dust mantle, and crystalline ice layer depth as funcons of longitude and latude are found to beaffected as well.14.04: Effects Of Non-uniform Surface Albedo On The Internal Structure Of Comets.Author Block: Aurélie Guilbert 11 ESS - UCLA.Presentaon Time: 10/5/2010 9:00 AM - 9:10 AMLocaon: Ballroom EAbstract: A key queson in cometary science remains whether the comet nuclei are internally heterogeneous or homogeneous in composion. A single cometcould equally well be an aggregate of cometesimals formed locally (leading to a globally homogeneous composion) or an aggregate of cometesimals formed indifferent regions of the protoplanetary disk (heterogeneous composion). Furthermore, various post-accreon processes can alter the primordial composion ofcomets. Their surfaces could be chemically altered by prolonged cosmic ray irradiaon while they are stored in the Kuiper belt and Oort cloud reservoirs. Theirinternal structure and composion could be locally modified by heat absorbed at the surface from the sun.We used a fast 3-dimensional model to explore the effects of non-uniform surface albedo on the internal thermal structure of a cometary nucleus moving onCentaur-like orbits. We find that albedo structures can result in lateral subsurface temperature variaons which then support composional inhomogeneies.14.05: Formaon and Dissociaon of Clathrate Hydrates in the Comet 67P/Churyumov GerasimenkoAuthor Block: Ulysse Marboeuf 1 , B. Schmi 1 , O. Mousis 2 , J. Pet 21 Laboratoire De Planétologie de Grenoble, France, 2 Observatoire de Besançon, France.Presentaon Time: 10/5/2010 9:10 AM - 9:20 AMLocaon: Ballroom E

Abstract.Abstract: Current interior models describing the thermodynamic evoluon of short-period comets consider water ice exisng only in the form ofamorphous or crystalline ice. However, a third structure of ice, i.e., clathrate, that has the capability of trapping efficiently other volales, can exist within thesebodies. Here we present a new model of cometary nucleus, which describes the formaon and dissociaon processes of clathrates within comets. We invesgatetheir formaon and evoluon condions within Comet 67P/Churyumov Gerasimenko, i.e. the target of the Rosea mission. We show that, provided that thekinecs of clathrates formaon is fast enough, a permanent layer of mulple guest clathrates can be formed in the subsurface of this comet. We show that theformaon of such a layer alters the thermal and physical evoluon of the comet and the outgasing profile of volales compared to models without formaon ofclathrates. These results allow us to predict different outgassing profiles of volales that could be measured by the Rosea mission and can be used to constrainthe structural type of ice exisng in the interior of Comet 67P/Churyumov Gerasimenko.14.06: Coma and Disk Modeling using Coupled Escape ProbabilityAuthor Block: Alan Gersch 1 , M. F. A'Hearn 11 Univ. of Maryland.Presentaon Time: 10/5/2010 9:20 AM - 9:30 AMLocaon: Ballroom EAbstract: In order to beer understand the innermost regions of cometary comae, such as those observed with high spaal resoluon in the Deep Impact andEPOXI missions, we have builta radiave transfer model for opcally thick molecular emission spectra.We use Coupled Escape Probability, a new accurate method of radiave transfer, which we have adapted to a non-symmetric spherical situaon.Our model can also be of use in other applicaons and/or geometries, such as, for example, in protoplanetary disks.Four species/molecules have been modeled thus far: CO, CO2, H2O and SiO.The first three are parcularly relevant for DI and other cometary spectra, and SiO is for use in PP disk studies.

Session Number: 15Session Title: Venus: Results from Venus Express and Ground Based ObservationsSession Type: Oral15.01: Results from Four Years of Venus ExpressAuthor Block: Hakan Svedhem 1 , D. Titov 2 , F. Taylor 31 ESA/ESTEC, Netherlands, 2 M PS, Germany, 3 Oxford University, United Kingdom.Presentaon Time: 10/5/2010 8:30 AM - 8:50 AMLocaon: Ballroom BCAbstract: Since arriving at Venus in April 2006 Venus Express has provided a wealth of informaon on a large variety of topics on the atmosphere, surface andplasma environment of the planet. The atmosphere in the southern hemisphere has been studied in detail by three instruments dedicated to atmosphericinvesgaons, from the near IR to the UV and addional informaon has been derived from radio science measurements. The structure and composion of theatmosphere has been mapped in three dimensions from 40 km to 140 km altude. Significant temporal and spaal variaons have been found, both incomposion, density and temperature. Imaging in the UV has revealed strong latudinal variaons and significant temporal changes in the global cloud topmorphology as well as idenficaon of various types of waves in the cloud layer. The cloud top altude varies from about 72 km in the low and middle latudes toabout 64 km in the polar region, marking vast polar depressions, likely a result of the Hadley-type meridional circulaon. A large amount of data on theatmospheric circulaon has been collected and results include maps of wind speeds at different altudes and movies of the dynamics of the southern polarvortex.A surface temperature map and an emissivity map of the full southern hemisphere have been constructed from IR images in the spectral windows. By correlangthese results and the Magellan radar images and gravity data, regions of young unweathered surfaces likely due to recent volcanism have been idenfied.The induced magnetosphere with its boundaries and the escape of planetary maer have been characterized by a magnetometer and an energec parcleinstrument, and escape rates of hydrogen, oxygen and helium have been determined.A decision to extend the mission unl end 2014 is expected at the end ofthis year.15.02: SO 2 Above The Clouds Of Venus As Measured By SPICAV-UV In NadirAuthor Block: Emmanuel Marcq 1 , J. Bertaux 1 , F. Montmessin 1 , D. Belyaev 1 , A. Fedorova 2 , A. Vandaele 3 , E. Neefs 31 LATM OS, France, 2 IKI, Russian Federaon, 3 BIRA-IASB, Belgium.Presentaon Time: 10/5/2010 8:50 AM - 9:00 AMLocaon: Ballroom BCAbstract: Using the SPICAV-UV spectrometer on-board Venus Express in nadir mode, we were able to derive spectral radiance factors in the middle atmosphereof Venus in the 170-320 nm range at a spectral resoluon R~200 during 2006 and 2007 in the northern hemisphere. By comparison with a radiave transfermodel, we could derive column abundance above the visible cloud top for SO 2 using its spectral absorpon bands near280 and 220 nm. SO 2 column densies show large temporal and spaal variaons on a horizontal scale of a few hundred kilometers.Typical SO 2 column densies at low latudes (up to 50°N) were found between 5 and 50 µm-atm, whereas in the northern polar region SO 2 content was usuallybelow 5 µm-atm. The observed latudinal variaons follow closely the cloud top altude derived by SPICAV-IR and are thought to be of dynamical origin. Also, asudden increase of SO 2 column density in the whole northern hemisphere has been observed in early 2007, possibly related to a convecve episode advecngsome deep SO 2 into the upper atmosphere. These results have been submied to Icarus journal for publicaon.15.03: First results of an Invesgaon of Sulfur Dioxide in the Ultraviolet from Pioneer Venus through Venus ExpressAuthor Block: Kevin McGouldrick 1 , K. Molaverdikhani 1 , L. W. Esposito 1 , C. K. Pankratz 11 University of Colorado.Presentaon Time: 10/5/2010 9:00 AM - 9:10 AMLocaon: Ballroom BCAbstract: The Laboratory for Atmospheric and Space Physics is carrying on a project to restore and preserve data products from several past missions forarchival and use by the scienfic community. This project includes the restoraon of data from Mariner 6/7, Pioneer Venus, Voyager 1/2, and Galileo. Here, wepresent inial results of this project that involve Pioneer Venus Orbiter Ultraviolet Spectrometer (PVO UVS) data. Using the Discrete Ordinate Method forRadiave Transfer (DISORT), we generate a suite of models for the three free parameters in the upper atmosphere of Venus in which we are interested: sulfurdioxide abundance at 40mb, scale height of sulfur dioxide, and the typical radius of the upper haze parcles (assumed to be composed of 84.5% sulfuric acid). Wecalculate best fits to our radiave transfer model results for mul-spectral images taken with PVO UVS, as well as the 'visible' channel (includes wavelengthsfrom 290nm to about 1000nm) of the mapping mode of the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS-M-Vis) on the Venus Express spacecra,currently orbing Venus.This work is funded though the NASA Planetary Mission Data Analysis Program, NNH08ZDA001N.15.04: Wind Measurements In Venus' Upper Mesosphere With The IRAM-Plateau De Bure InterferometerAuthor Block: Arielle Moullet 1 , R. Moreno 2 , E. Lellouch 2 , H. Sagawa 3 , M. Gurwell 11 Harvard-Smithsonian CfA, 2 LESIA-Observatoire de Paris, France, 3 Max-Planck-Instut for Solar System Research, Germany.Presentaon Time: 10/5/2010 9:10 AM - 9:20 AMLocaon: Ballroom BCAbstract: Venus' upper mesosphere (90-105 km altude) is a region of dynamic transion between the troposphere, exhibing retrograde zonal flow, and thethermosphere, driven by a subsolar-ansolar flow (SSAS). One possible method to measure the velocity field in the upper mesosphere is to map the Doppler-shiin the core of atmospheric lines in the mm/sub-mm range. Past observaons of CO lines have revealed dynamic paerns most oen interpreted as a combinaonof a SSAS flow and a retrograde zonal flow, with strong temporal variaons (Clancy et al., 2006).We present observaons of the CO(1-0) line at 115 GHz obtained at the IRAM-Plateau de Bure Interferometer, on June 12 and 13, 2009. The spaal resoluonachieved by the array (4-5") allowed a fine mapping of the line over Venus' disk (22"). The velocity fields obtained on both days display similar paerns, and areat odds with most previous observaons.On the day-hemisphere, the approaching wind observed is interpreted as a prograde zonal flow with an average velocity near the sub-solar point of 85 m/s. Onthe night-hemisphere, at mid-high latudes, the recessing wind observed could be idenfied again with a prograde zonal flow, with an average wind velocity of 60m/s in the Southern hemisphere, and of 110 m/s in the Northern hemisphere. Near the equator, a retrograde zonal wind is detected with velocies about 25 +/-8m/s near the an-solar point. The detecon of a prograde zonal wind, with similar values as those reported here, was so far only claimed once by Lellouch et al.(2007).

A full physical analysis of the CO lines profiles will be presented. The esmaons of the sounded level in the atmosphere will be used to provide an accurateinterpretaon of the observed velocity field, to be compared to the latest dynamical models and observaons.15.05: Wind Vercal Gradient Above the Venus Clouds on the Dayside : Search for Latudinal VariaonAuthor Block: Thomas Widemann 1 , Y. Liao 21 Paris Observatory, France, 2 Instute of Astronomy, Naonal Central University, Taiwan.Presentaon Time: 10/5/2010 9:20 AM - 9:30 AMLocaon: Ballroom BCAbstract: The wind regime near 80 km can only be measured in the Venus CO 2 absorpon features using the ground-based visible Doppler technique(Widemann et al., 2007). This region is of parcular interest between the stable, zonal retrograde circulaon at cloud top and the highly variable mesosphericwinds probed by 13 CO and 12 CO absorpon lines in the mm/submm range. Winds at cloud tops near 70 km are well constrained using space-borne or groundbasedvisible Doppler, and will be retrieved over longer connuous sequences using data from the UVI and LIR cameras on board VCO/Akatsuki.On observing runs in July, Sept. 2007 and Feb. 2009, the dayside of Venus was observed at R = 80000 using Canada-France-Hawaii’s ESPaDOnSspectropolarimeter. The instrument allows simultaneous acquision of the enre 0.35-1.05-micron range. It was operated at phase angle 107-110 deg at a spaalresoluon of 570-600 km on Venus, displaced over the dayside hemisphere across latudinal range +/- 55 deg. The ≈ 7k Fraunhofer lines scaered by upper cloudaerosols in co-moon with atmospheric circulaon measure cloud top winds, whereas a number of CO 2 absorpon features (in parcular near the strong 869.83nm bandhead) probe the zonal wind shear one scale height above cloud top, hence the cyclostrophic balance latudinal extent and the coupling with the lowerthermosphere. First analysis indicates evidence for a strong vercal shear with best-fit values of about 9 m/s/km, and a me variability of CO 2 Doppler windsnear 80 km of about 10 m/s/hour. Results over constant latudinal bands and comparison with thermal field measurements will be presented at the meeng.Widemann et al. 2008, Planet. and Space Sci., 56, 1320-1334Widemann et al. 2007, Planet. and Space Sci., 55, 1741-17515.06: Decadal Periodicies in a Venus Atmosphere General Circulaon ModelAuthor Block: Helen Parish 1 , G. Schubert 1 , C. Covey 2 , R. Walterscheid 3 , A. Grossman 4 , S. Lebonnois 51 University of California Los Angeles, 2 Lawrence Livermore Naonal Laboratory, 3 Aerospace Corporaon, 4 Rered from Lawrence Livermore Naonal Laboratory,5 Laboratoire de Meteorologie Dynamique, France.Presentaon Time: 10/5/2010 9:30 AM - 9:40 AMLocaon: Ballroom BCAbstract: We have modified a 3-dimensional Earth-based climate model, CAM (Community Atmosphere Model), to simulate the dynamics of Venus'atmosphere. We have removed Earth-related processes and introduced parameters appropriate for Venus. We use a simplified Newtonian cooling approximaonfor the radiaon scheme, without seasonal or diurnal cycles or topography. We use a high resoluon (1 degree in latude and longitude) to take account of smallscaledynamical processes that might be important on Venus. Rayleigh fricon is used to represent surface drag and to prevent upper boundary wave reflecon.The simulaons generate superrotaon at cloud heights with wind velocies comparable to those found in measurements. We find a significant decadaloscillaon in the zonal winds at cloud top heights and below. A vacillaon cycle is seen in the cloud top mid-latude zonal jets which wax and wane on anapproximate 10 year cycle. The decadal oscillaons we find may be excited by an instability near the surface, possibly a symmetric instability. Analyses ofangular momentum transport show that the jets are built up by poleward transport by a meridional circulaon while angular momentum is redistributed to lowerlatudes primarily by transient eddies. Observaons suggest that a cyclic variaon similar to that found in the model might occur in the real Venus atmosphere.Observaons by Mariner 10, Pioneer Venus, and Venus Express reveal variability in cloud top wind magnitudes and in the structure of Venus' cloud level midlatudejets with mescales of 5 to 10 years. Oscillaons in CO composion and in temperature above the cloud tops also exhibit a periodicity around 10 yearsand changes in the atmospheric SO 2 content over 40 years show a periodicity around 20 to 25 years. Venus' atmosphere must be observed over mul-year mescales and below the clouds if we are to understand its dynamics.15.07: Evidence For And Against 8-day Planetary Waves In Ground-based Cloud-tracking Observaons Of Venus' NightsideAuthor Block: Eliot F. Young 1 , M. A. Bullock 1 , S. Limaye 2 , J. Bailey 3 , C. C. C. Tsang 11 Southwest Research Inst., 2 University of Wisconsin, 3 University of New South Wales, Australia.Presentaon Time: 10/5/2010 9:40 AM - 9:50 AMLocaon: Ballroom BCAbstract: Several groups have esmated wind fields on Venus by tracking clouds that appear as silhouees on Venus’ nightside in CO2 windows at 1.74 or 2.3microns. In 2008, we presented 10 days of cloud-tracking results from July 2004 that suggested the presence of an 8-day wave manifested by velocity variaonsin clouds presumed to be at altudes of 48 - 55 km. A variety of waves are key predicons of recent Venus GCMs (e.g., Yamamoto and Takahashi 2006, Lebonnoiset al. 2010) and important areas of comparison between observaons and modeling efforts.Although we have measured equatorial zonal wind velocity variaons of 15 m/s for observaons separated by 24 hours, Hueso, Peralta and Sanchez-Lavega(2010) presented cloud-tracking results from VIRTIS-M image sequences in which velocies are mostly confined to 55 to 65 m/s in the 30°S - 10°S latude range.We now present cloud-tracking results from ground-based observaons obtained during July and September 2007. On some dates we are able to combineobservaons between the AAT and IRTF to increase the me baseline between images to roughly 4 hours and reduce the errors by about a factor of two. Akatsukiimage sequences should resolve the queson of zonal velocity variaons in the near future.---ReferencesHueso, Peralta and Sanchez-Lavega, 2010, “Temporal and spaal variability of Venus winds at cloud level from VIRTIS during the Venus Express mission.”Presented at the Venus Express Workshop in Aussois, June 2010.Lebonnois et al., 2010, “Superrotaon of Venus’ atmosphere analyzed with a full general circulaon model.” JGR 115, E06006.Yamamoto and Takahashi, 2006, “Superrotaon maintained by meridional circulaon and waves in a Venus-like AGCM.” J. Amtos Sci., 63, 3296.15.08: Venus Monitoring Camera Observaons and Results from Venus ExpressAuthor Block: Sanjay Limaye 1 , R. J. Krauss 1 , W. J. Markiewicz 2 , D. V. Titov 2 , I. Khatuntsev 3 , M. . Patsaeva 31 University of Wisconsin, 2 Max Planck Instute for Solar System Studies, Germany, 3 Space Research Instute of Russian Academy of Sciences, RussianFederaon.Presentaon Time: 10/5/2010 9:50 AM - 10:00 AMLocaon: Ballroom BCAbstract: The Venus Monitoring Camera (VMC) on ESA’s Venus Express mission has been systemacally imaging the planet in four filters since June 2006.

These images from the 24-hour eccentric, polar orbit show the dynamic behavior of the Venus cloud cover with rapid changes in relave brightness on global,regional and small scales and presence of planetary scale and small scale gravity waves (high Northern latudes). They have enabled esmates of the largescale circulaon of the cloud level flow from mulple, independent efforts for the southern hemisphere which is imaged rounely. The results are generallyconsistent and appear to show presence of planetary waves and solar thermal des. The precise vercal level of the measured cloud moons is not known buthas been esmated to be between ~ 70 km at low latudes and ~ 65 km in polar regions with a rise near the mid-latudes to about 73 km. Temporal or local solarme changes in the cloud top level appear possible but have not been invesgated. Thus some of the apparent temporal variability can be due to cloud levelchanges. The short term average zonal flow is observed to fluctuate between ~ 80 m/s - 100 m/s at low latudes while its meridional dependence shows either aweak increase with latude or near constant magnitude to mid-latudes and decreasing towards the pole, generally consistent with the profile expected for avortex circulaon. The mean meridional flow is poleward at most latudes, peaking in mid-latudes. Higher resoluon images with shorter me interval tend toshow slightly faster moons of clouds and thus the VMC large scale tracking results should be interpreted with cauon. Space me composites of the southernhemisphere images consistently show the presence of hemispheric vortex centered at the south pole.

Session Number: 16Session Title: Effusive EnceladusSession Type: Oral16.01: The Leading Side of Enceladus: New Views from Cassini ISSAuthor Block: Paul Helfenstein 1 , J. Veverka 1 , P. C. Thomas 1 , J. Perry 2 , T. Denk 3 , G. Neukum 3 , B. Giese 4 , T. Roatsch 4 , E. P. Turtle 5 , C. C. Porco 61 Cornell University, 2 University of Arizona, 3 Free University Berlin, Germany, 4 German Aerospace Center (DLR), Germany, 5 Johns Hopkins University (APL),6 Space Science Instute (CICLOPS).Presentaon Time: 10/5/2010 8:30 AM - 8:40 AMLocaon: Ballroom DAbstract: High-resoluon mosaics of the leading-hemisphere of Enceladus were acquired for the first me by Cassini's ISS Narrow Angle Camera (NAC) duringtwo close flybys, one on November 21, 2009 and another on May 18, 2010, respecvely. Addional imaging of the leading-hemisphere is planned for a close(2800 km) flyby on August 13, 2010 (orbit 136). Low resoluon imaging obtained earlier in the Cassini mission showed that the leading hemisphere is heavilymodified by tectonism, but the extent to which the tectonic styles on the leading hemisphere might be similar to those elsewhere on Enceladus was unclear. Thenew mosaics show that the leading side is subdivided into disnct geological provinces that exhibit different cratering histories and diverse tectonic styles. Thehighly tectonised terrains are bounded by a prominent broad annulus of grooved and striated terrains that ranges from about 60 km to over 140 km in width. Itsurrounds a complex arrangement of tectonic structures, including a conspicuous province near 30°N, 90°W of curvilinear ridges and approximately orthogonaltrendingridged-troughs. Among the most significant new findings is a region near 10°S, 60°W of terrain that is covered by a disnct paern of rounded, rope-likesub-parallel ridges. These ridges, in appearance and scale, are remarkably similar to ropy (funiscular) plains materials that previously have been found only in theSouth Polar Terrain region adjacent to acve ger stripes. We suggest that the paern of ropy ridges on the leading hemisphere arose from a similar style oftectonic deformaon that produced the South Polar funiscular plains - a terrain that is closely related to possible folding and tectonic spreading associated withthe ger stripes. These features may thus record an ancient episode of South Polar style tectonism and volcanism near the equator.16.02: Thrust Faulng as the Origin of Dorsa in the Trailing Hemisphere of EnceladusAuthor Block: Robert T. Pappalardo 1 , E. Crow-Willard 2 , M. Golombek 11 Jet Propulsion Laboratory, California Instute of Technology, 2 Occidental College.Presentaon Time: 10/5/2010 8:40 AM - 8:50 AMLocaon: Ballroom DAbstract: Several large ridges, or “dorsa,” located within a tectonically deformed region of the trailing hemisphere of Enceladus, have remained poorlyunderstood since they were imaged in Feb. 2005. In map view these ~2.5 km wide ridges can bifurcate in a branching manner, and in profile they appear to besomewhat trapezoidal or “boxy” in shape. Geological mapping of the trailing hemisphere’s Sarandib and Diyar Planiae (Crow-Willard and Pappalardo, 2009)suggests the dorsa cut across and deform older striated terrain, which consists of small-scale (200 m wide) ridges and troughs. A single high-resoluon (65m/pixel) Cassini image captures the western porons of the Cufa Dorsa, where ridges of the striated terrain are visible on the southern flanks. This relaonship isinconsistent with a previously suggested cryovolcanic origin, and there is no evidence of surrounding embayment. Instead, the relaonships suggest tectonicupli to form the dorsa. We propose that these ridges were formed by thrust faulng; in parcular, the Cufa Dorsa suggest formaon above south-dipping masterthrusts, as either fault-bend folds or more likely as fault-propagaon folds. The high-resoluon image reveals small (~300 m) irregular crenulaons atop theridges, and shadow roughness indicates significant roughness at sub-pixel scale. The crenulaons appear analogous to those atop wrinkle ridges on the Moonand Mars, and to the Yakima Ridges of eastern Washington state, which form via high-level back thrusts in layered materials above a relavely flat décollement.The Cufa Dorsa terminate to the west against a prominent trough, which may have served as a transcurrent fault that permied north-south contracon.Bifurcaon of the Cufa Dorsa is consistent with three-dimensional straining, if the dorsa resulted from mul-direconal contracon. Perhaps a thermal upli thatinialized trailing hemisphere tectonic deformaon subsequently cooled and collapsed to form the dorsa.16.03: Enceladus Plumes: Velocity Distribuon, Mass Flux, and Parcle Properes from ISS ImagesAuthor Block: Andrew P. Ingersoll 1 , C. C. Porco 2 , D. DiNino 2 , S. P. Ewald 1 , C. J. Mitchell 21 Caltech, 2 CICLOPS, Space Science Instute.Presentaon Time: 10/5/2010 8:50 AM - 9:00 AMLocaon: Ballroom DAbstract: The Imaging Science Subsystem (ISS) on Cassini has been observing the plumes of Enceladus intensively for the past several years over a broad rangeof phase angles (up to 178 degrees), image scales (down to 80 m per pixel) and wavelengths (from 338 nm to 918 nm). Cassini’s February 2010 Enceladus flybyhas returned the highest spaal resoluon yet, ten mes beer than that reported in Porco et al. (2006). From this one set of images, we have derived profiles ofbrightness and plume width vs. altude. From the former, we can get a beer esmate of the vercal velocity distribuon. From the laer, we can esmate thehorizontal spreading rate and interacon of parcles with the gas. The higher resoluon allows us to study individual jets close to the vent, revealing the slowmovingparcles that are falling back to the surface. Eventually, from the phase angle and filter coverage over the enre data set and the inclusion of VIMSspectral data we will be able to esmate parcle size, number density, and temporal variability. Comparing with UVIS observaons of the gas phase, we canesmate the solid-to-vapor rao. Together these data provide important constraints on condions below the surface. We will report on the progress made so farin the analysis of this extensive data set and implicaons for or against liquid water and what depth it might occur.16.04: Enceladus Heat Pump ModelAuthor Block: Dennis L. Matson 1 , T. V. Johnson 1 , J. I. Lunine 2 , J. C. Casllo-Rogez 11 Jet Propulsion Laboratory, California Instute of Technology, 2 Diparmento di Fisica, Università degli Studi di Roma "Tor Vergata", Italy.Presentaon Time: 10/5/2010 9:00 AM - 9:10 AMLocaon: Ballroom DAbstract.Abstract: Plume gas composion and the presence of dust grains rich in sodium salts [1,2] support a subsurface liquid as the source of the plumesobserved at the South pole of Enceladus. We suggest that seawater circulang from the ocean to the surface supplies water, gas, dust and heat to the plumes.Our model needs only a percent or two of gas dissolved in the ocean, a value that is very much consistent with available observaons ([1] suggest 10 percent ofvarious gas species in the plume). As seawater comes up, pressure is released and bubbles form. Bubbly seawater is less dense than ice. Expanding gas providesliing energy (cf. [6], [7]). The model delivers the materials that Postberg et al. [2] use for plume erupons. Popping bubbles throw a fine spray that contains salt.This aerosol exits with the plume gas [2]. Most significant is the south polar heat flow &gt;15 GW [4]. Water-borne oceanic heat is transferred to the surface ice.Less this heat, the water becomes colder, dissolves the bubble gases and becomes dense. It returns to the ocean via cracks in the ice. A large volume of ice isaccessible via cracks SO THAT chemical interacons, heat exchange and other processes are possible. [1] Waite Jr et al., Nature, 460, 487 (2009). [2] Postberg etal., Nature, 459, 1098 (2009). [4] Howe et al BAAS., 41, 1122 (2009). [6] Crawford, and Stevenson, Icarus, 73, 66 (1988). [7] Murchie, and Head, LPS XVII, 583

(1986). This work was conducted at the Jet Propulsion Laboratory, California Instute of Technology under NASA contract, and for JIL under "Incenvazione allamobilita' di studiosi straineri e italiani residen all'estero" of Italy.16.05: Modeling the Enceladus Plasma and Neutral Torus in Saturn’s Inner MagnetosphereAuthor Block: Yingdong Jia 1 , C. T. Russell 2 , K. K. Khurana 2 , T. I. Gombosi 31 Ucla, 2 UCLA, 3 University of Michigan.Presentaon Time: 10/5/2010 9:10 AM - 9:20 AMLocaon: Ballroom DAbstract: Saturn’s moon Enceladus, produces hundreds of kilograms of water vapor every second. These water molecules form a neutral torus which iscomparable to the Io torus in the Jovian system. These molecules become ionized producing a plasma disk in the inner magnetosphere of Saturn which exchangesmomentum with the “corotang” magnetospheric plasma. To balance the centripetal force of this plasma disk, Saturn’s magnec field is stretched in the radialdirecon and to accelerate the azimuthal speed to corotaonal values, the field is stretched in the azimuthal direcon. At Enceladus the massive pickup of newions from its plume slows down the corotang flow and breaks this force balance, causing plasma flows in the radial direcon. Such radial flows in the innermagnetosphere of Saturn are supported by Cassini observaons using various parcle and field instruments. In this study we develop a global model of the innermagnetosphere of Saturn in an aempt to reproduce such processes.16.06: Detecon of Enceladus Torus from Submillimeter Observaons with Herschel/HIFIAuthor Block: Emmanuel Lellouch 1 , P. Hartogh 2 , R. Moreno 1 , D. Bockelée-Morvan 1 , N. Biver 1 , C. Jarchow 2 , M. Rengel 3 , T. Cavalié 4 , F. Helmich 5 , HssO Team1 Obs. de Meudon, France, 2 Max Planck Instute, Germany, 3 Max Planck Instute, France, 4 Obs. de Bordeaux, France, 5 SRON, Netherlands.Presentaon Time: 10/5/2010 9:20 AM - 9:30 AMLocaon: Ballroom DAbstract: The presence of water vapor in the stratospheres of the Giant Planets and Titan has been established from their emission in rotaonal lineslongwards of 30 microns. Emission in the fundamental H2O line at 557 GHz has been spectrally resolved from heterodyne observaons with SWAS at Jupiter andSaturn and ODIN at Jupiter, showing emission line-widths of about 20 km/s, due to planetary rotaon. Inial observaons of Saturn with the HIFI instrument onHerschel, performed in June 2009, revealed an addional ~ 20 % deep, ~ 5 km/s broad absorpon superimposed to the emission, that was not seen in the SWASobservaon performed in 1999 (Bergin et al. 2000). This absorpon is certainly not due to water in Saturn itself, as the brightness temperature in the line corewould indicate implausibly cold temperatures (~95 K) in Saturn's upper atmosphere, and as the line-width is too narrow. Instead, we interpret it as water vaporabsorpon along the line-of-sight coming from the Enceladus H2O torus, the difference with the SWAS results being presumably related to the different viewinggeometries. We developed an excitaon model for water in Enceladus torus including excitaon by solar and Saturn's radiaon. Extended observaons performedin June 2010, and covering the H2O 557, 987, 1113 and 1670 GHz (including a 5-point map at this frequency) confirm this interpretaon, as does the fact that the1097 GHz H2O line does not show absorpon. An inial modelling of the data indicates line-of-sight water column densies of (1-3)x10 13 cm -2 . Theseobservaons provide a new method to study physical condions in the Enceladus torus.16.07: Are the Enceladus Plumes Variabie?Author Block: Howard T. Smith 1 , R. E. Johnson 2 , M. Perry 1 , D. G. Mitchell 1 , R. McNu 1 , D. Young 31 Johns Hopkins Applied Physics Lab, 2 University of Virginia, 3 Southwest Research Instute.Presentaon Time: 10/5/2010 9:30 AM - 9:40 AMLocaon: Ballroom DAbstract: Aer over 6 years of Cassini observaons, it has become evident that the plumes of the small icy Enceladus provide the primary source of heavyparcles in Saturn’s neutral parcle dominated magnetosphere. However, the mechanisms producing these plumes are sll being debated. Thus understandingthe plume characteriscs is essenal for insight into plume producon mechanisms as well as magnetospheric dynamics and interacons. We previouslyreported inial modeling and Cassini INMS data analysis research showing plume characteriscs as well as source rate esmates which indicated plumesvariability. Here we show addional evidence for at least an order of magnitude source rate variability as well as the impact of the neutral torus on apparentsource rate determinaons. We also examine the me scales on which the plume source rate appears to be variable from examinaons of mulple Enceladusencounters as well as the possible impact to parcle distribuon near Enceladus and throughout Saturn’s magnetosphere.16.08: The Composional Profile of the Enceladus' Ice PlumeAuthor Block: Frank Postberg 1 , J. Schmidt 2 , J. K. Hillier 3 , S. Kempf 1 , R. Srama 11 M PI for Nuclear Physics, Germany, 2 University of Potsdam, Germany, 3 IPSSR, The Open University, United Kingdom.Presentaon Time: 10/5/2010 9:40 AM - 9:50 AMLocaon: Ballroom DAbstract.Abstract: Data obtained by the Cassini spacecra during recent close flybys of Enceladus will be presented. Prior composional measurements of Ering grains with Cassini's Cosmic Dust Analyser (CDA) suggested salt-rich water as the dominant source of Enceladus' plume. Although the E ring dust populaonis dominated by ice parcles stemming from Enceladus it was unclear how representave the E ring parcles were of the original plume grain ensemble. During2008 and 2009 Cassini passed deep into the plumes on several occasions, allowing the CDA team to analyse the composions of freshly ejected plume parclesfor the first me. From this informaon a composional profile of the plume has been inferred, showing that close to Enceladus' surface its composion differssignificantly from that of the E ring. The observaons can only be reproduced with a dominant liquid water plume source.16.09: Modeling the Composion of the Enceladus Dust PlumeAuthor Block: Juergen Schmidt 1 , F. Postberg 2 , S. Kempf 21 University of Potsdam, Germany, 2 M PI, Germany.Presentaon Time: 10/5/2010 9:50 AM - 10:00 AMLocaon: Ballroom DAbstract.Abstract: Prior composional measurements of E ring grains with Cassini's Cosmic Dust Analyser (CDA) suggested salt-rich water as the dominantsource of Enceladus' dust plume (Postberg et al. 2009, Nature). Although the E ring dust populaon is dominated by ice parcles stemming from Enceladus, therelave abundance of various composional types of grains might be expected to differ from the original plume grain ensemble owing to dynamical filtering in theplume (size-dependent ejecon speeds). During 2008 and 2009 Cassini passed deep into the plumes on several occasions, allowing the CDA team to analyse thecomposions of freshly ejected plume parcles for the first me. Our modelling of the grain dynamics is consistent with the measured composional profile ofthe plume if the populaon of freshly ejected grains is dominated by parcularly sodium rich parcles (NaCl/H2O about 10**-3) which make only 5-10% of theensemble seen in the E ring.

Session Time: 10/5/2010 9:30 AM

Session Number: 17Session Title: Dust and Solar WindSession Type: Oral17.01: Electrostac Dust Launching MethodsAuthor Block: Chrisne Hartzell 1 , D. Scheeres 11 University of Colorado.Presentaon Time: 10/5/2010 9:30 AM - 9:40 AMLocaon: Ballroom EAbstract.Abstract: Electrostac dust loing has been proposed as an explanaon for lunar horizon glow observaons and regolith distribuon on asteroids.These hypotheses can only be numerically tested once a feasible parcle launching mechanism has been proposed and physically representave inial parclesstates are idenfied. We invesgate several mechanisms through which dust parcles could be separated from the surface of a planetary body. By evaluang thedynamical environment of the parcle prior to launching, we are able to constrain the physical environment required for launch and predict dust parcle sizes thatare most likely to be launched. We show that cohesion between dust parcles and the surface is the dominant force that must be overcome in order to launchsmall (less than 100 micron) parcles. Due to the strength of the cohesive force on small parcles, we find that 100 micron to 1mm parcles are most likely to belaunched from the lunar surface rather than tradionally considered sub-micron parcles. Addionally, we show that seismic shaking does not significantlyreduce the electric field strength required to launch parcles. The feasibility of parcle launching through micrometeoroid bombardment will also be discussed. C.Hartzell acknowledges support from NASA Headquarters under the NASA Earth and Space Science Fellowship Program: Grant NNX09AR51H. D. Scheeresacknowledges support from the NASA Discovery Data Analysis Program.17.02: Resonant Trapping and Subsequent Accreon of Interplanetary Dust Parcles Through Earth's Quasi-Satellite ResonanceAuthor Block: Stephen J. Kortenkamp 11 Planetary Science Instute.Presentaon Time: 10/5/2010 9:40 AM - 9:50 AMLocaon: Ballroom EAbstract: We used numerical integraon to study the orbital evoluon of IDPs decaying towards 1 AU under the influence of radiaon pressure, Poynng-Roberston light drag, solar wind drag, and perturbaons from the planets. The rao of radiaon pressure to solar gravity was β=0.005, corresponding to IDPdiameters of about 100 microns. In our inial simulaon 100% of the IDPs became temporarily trapped in mean-moon resonances just outside Earth's orbit.Eventually the parcles slipped out of these resonances and their orbits connued decaying. Subsequently, ~25% of the populaon became trapped in 1:1 coorbitalresonance with Earth. In addion to tradional horseshoe type co-orbitals, IDPs became trapped as so-called quasi-satellites. Quasi-satellite IDPs alwaysremain relavely near Earth (0.2-0.3 AU, or 20-30 Hill radii, R h ) and undergo two close-encounters with Earth each year. While resonant perturbaons from Earthhalt the decay in semi-major axis of quasi-satellite IDPs their eccentricies connue to decrease, forcing the IDPs onto more Earth-like orbits. This has dramacconsequences for the relave velocity and distance of closest approach between Earth and the IDPs. Aer ~10 4 years in the quasi-satellite resonance IDPs aretypically less than 10 R h from Earth and consistently coming within about 3 R. In the late stages of quasi-satellite evoluon IDPs escaping the resonance canhave deep close-encounters with Earth significantly below R h . Relave velocies between escaping quasi-satellite IDPs and Earth during these encounters are afew hundred m/s, well below the 2-4 km/s for non-resonant IDPs with similar inial orbits. This factor alone leads to about a 10-100 fold increase in Earth'sgravitaonal cross-secon for quasi-satellite IDPs compared to non-resonant IDPs. Because quasi-satellite resonant trapping varies directly with a planet’seccentricity, accreon of quasi-satellite IDPs will likely vary proporonally with Earth’s eccentricity on ~10 5 year me scales. [This work is supported by NASAgrant NNX10AJ61G.]17.03: Meteoroid Collisions in Interplanetary Space: Seeing the Invisible through their Effect on the Solar WindAuthor Block: Christopher T. Russell 1 , H. R. Lai. 1 , G. L. Delzanno 2 , J. G. Luhmann 3 , K. D. C. Simunac 4 , A. Opitz 51 UC, Los Angeles, 2 Los Alamos Naonal Laboratory, 3 UCBerkeley, 4 University of New Hampshire, 5 Centre d’Etude Spaale des Rayonnements, France.Presentaon Time: 10/5/2010 9:50 AM - 10:00 AMLocaon: Ballroom EAbstract: When meteoroids collide in space they usually do so at many tens of km relave velocity. This event should produce much possibly very fine dust.Few such events and only the most spectacular ones are ever recorded telescopically. However, the STEREO spacecra, and many spacecra before them, seetwo manifestaons of these collisions. First their electric antennas observe innumerable small pulses interpreted to be small plasma pulses due to an almostubiquitous flux of nanometer size dust parcles moving at the speed of the solar wind. This speed is possible because the smallest dust parcles are bothelectrically charged, and sufficiently small to be accelerated relavely rapidly by the electromagnec forces in the solar wind. Second, these same spacecraobserve pressure enhancements in the solar wind plasma and interplanetary magnec field that extend over 100s of thousands of km, that are capable oftransferring solar wind momentum to clouds of such parcles. One persistent source of such pressure enhancements is where the asteroid 2201 Oljato crossesVenus’ orbit plane, reinforcing our interpretaon of these events as due to collisions. Importantly and consistently, when mulspacecra measurements areavailable, these disturbances are clocked at the solar wind speed. We believe these macroscale disturbances consist of vast numbers of nanoscale charged dustproduced at one me and one locaon by a collision. The rate of detecon of such disturbances is consistent with the expected collision rate of meter-sizedobjects.

Session Time: 10/5/2010 10:30 AM

Session Number: 18Session Title: The Moon: New Observational ResultsSession Type: Oral18.01: Quesons And Implicaons Of Surficial OH/H2O On The MoonAuthor Block: Carle Pieters 1 , R. Green 2 , T. McCord 3 , R. Clark 4 , M3 Team1 Brown Univ., 2 JPL, 3 Bearfight Instute, 4 USGS.Presentaon Time: 10/5/2010 10:30 AM - 10:50 AMLocaon: Ballroom BCAbstract.Abstract: Three forms of OH/H2O on the Moon connue to be of great interest to planetary sciensts: interior or mantle volales, buried polar ice, andwidespread surficial deposits or coangs. The first deals with the original geochemical condions of this rocky body and the differenaon process. The seconddeals with the unique extremely cold polar environment that is difficult to access. The third (most paradigm shiing) deals with the recently observed OH/H2Othat occurs pervasively across the sunlit lunar surface (Clark; Sunshine et al., Pieters et al., Science, 326, 2009). Each of the three forms has sparked acvelaboratory and theorecal research in order to characterize and measure these properes in greater detail as well as to understand the physics and chemistryinvolved. A leading hypothesis for the surficial OH/H2O concerns interacon of silicate bodies with parcles of the solar wind. Understanding this thin butwidespread OH/H2O naturally has important implicaons for all airless bodies. Current data document that more than one species is involved on the Moon, anOH feature at 2800 nm as well as a stronger longer wavelength feature. The data hint at a composional and textural affinity, but are inadequate to documentthe crical me variaon distribuon and abundance.18.02: Water and More: An Overview of LCROSS Impact ResultsAuthor Block: Anthony Colaprete 11 NASA Ames Research Center.Presentaon Time: 10/5/2010 10:50 AM - 11:00 AMLocaon: Ballroom BCAbstract.Abstract: On October 9, 2009 at approximately 11:31:19 UTC the LRO/LCROSS Centaur impacted within about 100 meters of the planned target. Theimpact resulted in an ejecta cloud that was observed to expand to over 10 km across and to a height of more than 15 km above the surface. All instruments onthe LCROSS SC performed well and a wealth of data was collected. All porons of the impact, including the flash, ejecta curtain and resulng crater, whereobserved. From the data set the presence of water was confirmed as was the presence of several other compounds. In this presentaon an overview of theresults will be pre-sented.18.03: Evoluon Of The Dust And Water Ice Plume Components As Observed By The Lcross Visible Camera And Uv-visible SpectrometerAuthor Block: Jennifer Heldmann 1 , A. Colaprete 1 , D. Goldstein 2 , D. Summy 2 , W. Marshall 1 , K. Ennico 1 , M. Shirley 1 , D. Wooden 1 , P. Varghese 2 , L. Traon 21 NASA Ames Research Center, 2 University of Texas.Presentaon Time: 10/5/2010 11:00 AM - 11:10 AMLocaon: Ballroom BCAbstract.Abstract: LCROSS (Lunar Crater Observaon and Sensing Satellite) impacted the Cabeus Crater and created an impact plume that was observed by theLCROSS Shepherding Spacecra. Here we analyze data from the ultraviolet-visible spectrometer and visible context camera aboard the Spacecra. We then usethis data to constrain a numerical model to understand the physical evoluon of the plume. Constraining the modeling results with Spacecra observaons, weconclude that loed dust grains remained suspended above the lunar surface for the enre 250 seconds of observaon aer impact. The impact plume wascomposed of both a high angle and low angle plume component. Dust parcle sizes loed above the lunar surface were micron to sub-micron in size. Water iceparcles were also contained within the ejecta cloud and simultaneously photo-dissociated and sublimated aer reaching sunlight. Purity levels of the icesuggest a degree of comingling of ice and regolith grains within the permanently shadowed crater. This paper will present the observaonal data from theSpacecra observaons, detail the modeling efforts, and discuss our current understanding the impact plume evoluon.18.04: The LRO Diviner Lunar Radiometer Composional Invesgaon Aer One Year of MappingAuthor Block: Benjamin Greenhagen 1 , P. Lucey 2 , M. Wya 3 , T. Glotch 4 , C. Allen 5 , J. Arnold 4 , J. Bandfield 6 , N. Bowles 7 , K. Donaldson Hanna 8 , P. Hayne 9 , E. Song 6 ,I. Thomas 7 , D. Paige 91 JPL, 2 University of Hawaii, 3 Brown University, 4 Stony Brook University, 5 Johnson Space Center, 6 University of Washington, 7 University of Oxford, UnitedKingdom, 8 Brown Universy, 9 UCLA.Presentaon Time: 10/5/2010 11:10 AM - 11:20 AMLocaon: Ballroom BCAbstract.Abstract: During its first year of mapping (which ended on September 14, 2010), the LRO Diviner lunar radiometer has enabled new insights into lunarsurface composion. Diviner has three channels near 8 microns (7.81, 8.28, and 8.55) designed to characterize the Chrisansen feature (CF) of lunar soils. Todate, Diviner has placed important new constraints on lunar composional diversity including the idenficaon of areas with pure anorthite plagioclase feldspar,non-anorthite feldspar, and high silica contents. Addionally, Diviner data do not show strong evidence for kilometer scale extremely olivine-rich and feldsparpoorexposures or regional expressions of iron-poor, Mg-suite mafic materials. Diviner observaons of Apollo sites have been compared to returned soils. Divinermid-infrared data have been shown to be affected by soil maturity, which was not expected based on previous literature. Diviner data are also strongly dependenton latude and lunar local me, which is likely caused by anisothermality. This presentaon will summarize these and other efforts by the Diviner composionalinvesgaon team.18.05: The Ultraviolet Reflectance Of The Moon As Measured By LRO/LAMPAuthor Block: Amanda Hendrix 1 , K. D. Retherford 2 , G. R. Gladstone 2 , LRO/LAMP Team1 JPL, 2 SwRI.Presentaon Time: 10/5/2010 11:20 AM - 11:30 AMLocaon: Ballroom BCAbstract.Abstract: The Lunar Reconnaissance Orbiter (LRO) has been in orbit around the Moon since June, 2009. The Lyman Alpha Mapping Project (LAMP)instrument (Gladstone et al., 2010) is designed to idenfy and map exposed water frost in permanently shadowed polar regions and to characterize the lunaratmosphere and its variability. LAMP has also been making excellent quality measurements of the dayside lunar surface. In this study, we present inial results ofan analysis of the dayside observaons made to date. We are interested in studying the ultraviolet albedo of the Moon to invesgate the effects of spaceweathering and to look for diagnosc composional markers. We invesgate spectral variaons with terrain across the lunar surface and look into phase anglevariaons. We also compare with previous UV observaons of the Moon, from Apollo-17 UVS, Cassini UVIS, Hopkins Ultraviolet Telescope, and others.

18.06: The Surficial Nature of Lunar Swirls as Revealed by Mini-RF on LROAuthor Block: Catherine Neish 1 , D. Blewe 1 , D. B. Bussey 1 , S. Lawrence 2 , M. Mechtley 2 , B. Thomson 1 , M. Robinson 2 , Mini-RF Team1 Johns Hopkins University Applied Physics Laboratory, 2 Arizona State University.Presentaon Time: 10/5/2010 11:30 AM - 11:40 AMLocaon: Ballroom BCAbstract.Abstract: Lunar swirls are opcally bright, sinuous albedo features found on the Moon. Lunar swirls appear to overlay the lunar surface, apparentlyrepresenng diffuse brightening of unmodified terrains. Lunar swirls are associated with regions of anomalously high crustal magnec fields, but their exactformaon mechanism is unknown. The Mini-RF synthec aperture radar on LRO acquired a comprehensive set of radar images of these enigmac features,including the first radar observaons of swirls on the lunar farside. A few general remarks can be made about the nature of the lunar swirls from this data set.First, the average radar properes of lunar swirls are idencal to nearby non-swirl regions, in both total radar backscaer and circular polarizaon rao (CPR).This implies that average decimeter-scale roughness and composion within the high-albedo porons of the swirls do not differ appreciably from thesurroundings, and thus that the swirls are a very thin surface manifestaon (&lt; 10 cm) not observable with S-Band radar. Secondly, bright swirl material appearsto be stragraphically younger than an impact melt flow at Gerasimovich D newly discovered in Mini-RF images. This observaon indicates that the swirls arecapable of forming over mescales less than the age of the crater, perhaps less than 1 Ga. This data set also provides informaon about the origin of the lunarswirls. In at least one case, the presence of an enhanced crustal magnec field appears to be responsible for the preservaon of a high-albedo ejecta blanketaround an otherwise degraded crater, Descartes C. The degree of degradaon of Descartes C suggests it should not be opcally bright, yet it is. This suggeststhat the albedo is preserved due to its locaon within a magnec anomaly, and hence supports an origin hypothesis that invokes interacon between the solarwind and the magnec anomaly.18.07: Infrared Observaons of a Lunar Eclipse from Orbit: Constraints on Rock Abundance and Near Surface Thermal Properes from the Diviner LunarRadiometerAuthor Block: Paul Hayne 1 , D. A. Paige 1 , M. A. Siegler 1 , A. R. Vasavada 2 , B. T. Greenhagen 2 , R. C. Elphic 3 , J. L. Bandfield 41 UCLA, 2 NASA - Jet Propulsion Laboratory, California Instute of Technology, 3 NASA - Ames Research Center, 4 University of Washington.Presentaon Time: 10/5/2010 11:40 AM - 11:50 AMLocaon: Ballroom BCAbstract.Abstract: Lunar surface temperatures depend on the insolaon cycle and a variety of surface properes of interest for science and exploraon,including rock abundance and regolith density. Thermal waves generated by the 29-day lunar diurnal cycle affect the uppermost ~10-100 cm of regolith, such thatinfrared brightness temperatures depend on the bulk thermal inera of this layer. During a lunar eclipse, insolaon rapidly decreases and later increases to preeclipselevels on me scales of a few hours, generang a high-frequency thermal wave only affecng the upper few millimeters of regolith. Observaons ofsurface temperatures during this process could thus isolate the thermophysical properes of the very near surface. Moreover, high thermal inera materials suchas rocks and boulders will have a disnct thermal signature, since they cool much more slowly than the regolith. The Diviner Lunar Radiometer onboard the LunarReconnaissance Orbiter acquired the first thermal infrared measurements from orbit during a lunar eclipse, during the paral eclipses of December 31, 2009 andJune 26, 2010. We report on the near-surface lunar thermal properes derived from these observaons, which targeted several different terrain types, as well astwo north polar craters observed to have anomalous radar polarizaon signals (Spudis et al. 2010). To interpret the data, we employed a thermal model includinga simulated Earth passing in front of the Sun, the effects of local topography, and mulple orders of light scaering between surface elements (cf. Paige et al, thismeeng). We will present maps of esmated rock abundance and regolith thermal inera at several sites of interest, which will aid in understanding theirgeologic origins and evoluon.18.08: A New Look at Photometry of the MoonAuthor Block: Jay D. Goguen 1 , T. C. Stone 2 , H. H. Kieffer 3 , B. J. Bura 11 JPL, 2 USGS, 3 Celesal Reasonings.Presentaon Time: 10/5/2010 11:50 AM - 12:00 AMLocaon: Ballroom BCAbstract: We test 2 very different models for light scaering by the lunar regolith: 1) TRLA - a Topographically Rough surface layer comprised of Low Albedoparcles, and 2) RTE - a flat surface layer with the published size distribuon and opcal constants of Apollo soil parcles, Mie calculaon of the mean parclescaering matrix and rigorous soluon of the Radiave Transfer Equaon for all orders of scaering (Mishchenko et al 1999, JQRST 63, 409). For a typical lunarhighland locaon (-17.21, 20.01), ROLO photometry (Kieffer & Stone 2005, Astron. J. 129, 2887) shows a disnct difference between the radiances measuredbefore and aer full moon (BFM, AFM) at the same 47.5 ± 2.5 degree phase angle, corresponding to incidence angles of ~30 and ~70 degrees, respecvely. TheTRLA model requires rms slopes of 34.1 ± 2.6 degrees to reproduce this BFM/AFM radiance difference, similar to previously published results. Analysis of ApolloALSCC stereo images of in situ lunar regolith (Helfenstein and Shepard 1999, Icarus 141, 107) shows that such large rms slopes pertain to a sub-mm horizontaldistance scale. The RTE model also reproduces the same BFM/AFM radiance difference, but as a direct consequence of mulple scaering between parcleswithin the flat (zero topographic roughness) regolith layer. Approximately 80% of the radiance in the RTE model is contributed by photons scaered more thanonce. We conclude that topographic roughness of the regolith surface and mulple scaering between regolith parcles can have a nearly idencal effect on thisBFM/AFM difference in the lunar radiance. Roughness and mulple scaering are strongly correlated parameters in the sense that any approximaons regardingone of them will influence the value deduced for the other. A complete treatment of this work is published in Goguen et al 2010, Icarus 208, 548.

Session Number: 19Session Title: Planetary Rings I: Jovian and Saturnian RingsSession Type: Oral19.01: Vercal Ripples in the Jovian RingAuthor Block: Mark R. Showalter 1 , M. M. Hedman 2 , J. A. Burns 21 SETI Instute, 2 Cornell University.Presentaon Time: 10/5/2010 10:30 AM - 10:40 AMLocaon: Ballroom DAbstract.Abstract: Galileo spacecra images from 1996 revealed a paern of vercal "ripples" or corrugaons in the main Jovian ring. The paern appearedclearly in a set of three images, but was never reported again. Later ring images from Galileo in 2000-2001 and from New Horizons in 2007 were similar to the1996 data set in terms of viewing geometry, resoluon and sensivity, but they did not show any ripples with comparable wavelength and amplitude. We revisitthese data sets in light of the Cassini ISS result that corrugaons in Saturn's rings are a spiral paern that winds ghter due to differenal nodal regression. Amore detailed re-analysis of the 1996 images reveals that the Jovian paern is a superposion of two sinusoidal corrugaons. The stronger paern has awavelength of ~ 1700 km and a vercal amplitude of ~ 3 km. The weaker one has a wavelength of ~ 600 km and an amplitude of ~ 0.6 km. We now find thesesame corrugaons in Galileo images from 2000, at shorter wavelengths of ~ 700 km and ~ 500 km. The reduced wavelengths are consistent with the differenalnodal regression rate expected for Jupiter's gravity field; the wavenumber of corrugaons in the Jovian ring is predicted to increase linearly by 1/(4000 km) peryear. The wavelengths should be 200-300 km during the New Horizons flyby, too short to be detected in that data set. With two paerns now detected in Jupiter'sring and one in Saturn's, vercal corrugaons appear to be more common features of planetary rings than had been previously suspected. We invesgate thenature of the events that might iniate these features.19.02: Tilng at Tilted RingsAuthor Block: Joseph A. Burns 1 , M. M. Hedman 1 , M. R. Showalter 21 Cornell Univ., 2 SETI Instute.Presentaon Time: 10/5/2010 10:40 AM - 10:50 AMLocaon: Ballroom DAbstract: Saturn’s D (Hedman et al. 2007) and C (Hedman et al. 2010) rings display sinusoidal brightness variaons in which the radial wavelength increasessmoothly with distance from the planet. These structures likely represent 2-200m vercal corrugaons that arose due to differenal nodal regression (driven bySaturn’s higher-order gravity harmonics) of an inially flat, lted ring. Jupiter’s rings exhibit similar features (Showalter et al., this meeng). The spaal andtemporal behaviors of these paerns imply that the ring’s angular momentum vector shied by about 10 -7 radians relave to that of the planet in mid-1984; aerthat date, the once-flat ring subsequently wound up.We consider scenarios in which the inner parts of Saturn’s ring system were lted relave to the planet’s equator by the impact of external material moving atseveral tens of km/sec. In order for the angular momentum to be distributed across many thousand kilometers, the interplanetary projecle must first fragment(dally or collisionally) into many pieces. This permits a wide swath of ring to be eventually struck by smaller debris. Even though much of the ring is hit,planetary shadowing and gravitaonal focusing allow angular momentum to be emplaced non-uniformly in longitude, such that the net angular momentum has acomponent in the ring plane. To produce the necessary lt, the impactor must be >/~ 1 km in radius, the size of a small comet nucleus. We esmate that cometsthis big could pass close enough to Saturn for disrupon at ~2% of Jupiter’s impact rate. Accordingly, Saturn’s rings could potenally be lted every 500-10,000yrs.We have explored other possible scenarios for lng the rings (e.g., direct hits of large ring parcles, atmospheric break-up, and changes in Saturn’s massdistribuon that shi the planet’s inera tensor). Currently, they seem even less plausible.19.03: A Crack in the C Ring?Author Block: Philip D. Nicholson 1 , M. M. Hedman 1 , Cassini VIMS Team1 Cornell Univ..Presentaon Time: 10/5/2010 10:50 AM - 11:00 AMLocaon: Ballroom DAbstract: The most prominent wavelike feature in Saturn's C ring, at a radius of 77520 - 77600 km, was idenfied by Rosen & Lissauer (1988; Science 241, 690)in Voyager radio occultaon data as a vercal or bending wave driven at the Titan -1:0 nodal resonance. At such a resonance, the nodal regression rate of ringparcles approximately matches the negave of the satellite's mean moon. Unlike other bending waves, this wave propagates radially outwards due to itsnegave paern speed; its prominence in the Voyager profile was aributed to the very low elevaon angle of 6 degrees, which amplified the effect of subtlevercal corrugaons. However, the same wave appears in twenty stellar occultaon profiles of the C ring obtained with the Cassini VIMS instrument at elevaonangles as high as 62 degrees, casng some doubt on its idenficaon as a bending wave. Also troubling is an apparently empty gap in the inner part of theVoyager wave profile, which also appears in about one-half of the VIMS profiles. When these data are organized by their posion with respect to the predictedspiral paern, the gap is seen to extend over ~180 degrees in longitude, with varying width. A simple model which can account for these observaons consists ofa very narrow (< 1 km), connuous gap, one of whose edges is inclined with respect to the other by a few km. This is comparable to the amplitude of the bendingwave inferred by Rosen & Lissauer. The gap is located only 14 km exterior to the nominal locaon of the -1:0 resonance, suggesng that the vercal displacementof its edge is resonantly forced. We acknowledge helpful discussions with R.G. French of the Cassini RSS team, and support from the Cassini/Huygens project.19.04: The B1/B2 Boundary and the Ring Ionosphere/AtmosphereAuthor Block: Frank Crary 11 Southwest Research Instute.Presentaon Time: 10/5/2010 11:00 AM - 11:10 AMLocaon: Ballroom DAbstract: A sharp boundary in Saturn’s B ring is located at 99,000 km. At this distance, the opcal depth (measured by radio and ultraviolet occultaons), thedepth of the 3.6 micron water band (measured by the Cassini/VIMS instrument), and the abundance of small parcles (inferred from Cassini/VIMS spectra andradio occultaons) all increase. This boundary was also noted in Voyager occultaon data and aributed to a charged dust dynamics by Northrop and Hill (1982.)While this process does remove sub-micron parcles from the inner B ring, it does not result in a large-scale loss of ring material. The same principle, applied toions produced from the ring atmosphere, shows that ions trajectories are unstable and ions precipitate into Saturn’s atmosphere, if produced inside (2/3) 1/3 ofsynchronous orbit (i.e. 99,000 km.) This results in a net loss of water from the surface of ring parcles inside this distance. The esmated loss rate, 10-80microns per millions years, could deplete the ice abundance in the top few IR wavelengths of the ring parcles’ surface and account for the weaker water bandsobserver in VIMS spectra. In addion, the rapid loss of ions inside 99,000 km should result in lower plasma densies inside and outside this distance. Since dust

parcles charging depends on the local plasma condions, the surface charge of ring parcles would also differ in these two regions. A 2 V surface potenal,typical of charging by photoelectrons in a low density plasma, produces sufficient electrostac repulsion to prevent 65 micron ring parcles from colliding. Thismay be the case in the B1 region (i.e. inside 99,000 km.) A denser, colder plasma in the B2 region could cause parcles to charge to a much lower potenal. As aresult, the abundance of small parcles in the B1 and B2 regions would differ.19.05: The Temporal Variability of Spokes in Saturn's B RingAuthor Block: Colin Mitchell 1 , C. Porco 1 , L. Dones 2 , J. Spitale 11 CICLOPS/SSI, 2 SWRI.Presentaon Time: 10/5/2010 11:10 AM - 11:20 AMLocaon: Ballroom DAbstract: We report on the variability of the spoke acvity in Saturn's B ring as observed in Cassini ISS images. Two sets of observaons are analyzed. The firstconsists of 6 movies of the southern side of the rings prior to Saturn's northern vernal equinox on August 11, 2009 while the second consists of 13 movies of thenorthern side taken aer equinox. Both are of the illuminated side of the rings. First, we find photometric evidence that the parcles comprising the spokes areirregular in shape. Next, power spectral analysis of the northern-side spoke observaons produces a disnct peak at a period of 637 ± 9 minutes, very similar tothe Cassini-era period for the Saturn Kilometric Radiaon (SKR) arising from the planet's northern auroral zone (Gurne et al. 2009, GRL). Furthermore, histogramsof northern-side spoke acvity versus longitude in the coordinate system defined by the Cassini SKR indicates that the longitudinal sector in which spoke acvityreaches a maximum coincides with the northern SKR-acve sector at the me of our observaons, as was found during the Voyager era (Porco and Danielson1982; 1984).Though southern-side spoke observaons were too sparse to yield a period using spectral analysis, histograms of southern spoke acvity, created using an arrayof periods between 620 minutes and 660 minutes, indicate that southern-side spoke acvity may vary with two periods: one equal to that of the southern SKRsource (Kurth et al. 2008, JGR) and one equal to that of the northern SKR source. Interesngly, the northern SKR source was most acve during the me of oursouthern-side spoke observaons, perhaps explaining the presence of both periods in the variability of spokes on the southern side of the rings.19.06: Detecon of Free Unstable Modes and Massive Bodies in Saturn's Outer B RingAuthor Block: Joseph N. Spitale 1 , C. C. Porco 11 CICLOPS/Space Science Instute.Presentaon Time: 10/5/2010 11:20 AM - 11:30 AMLocaon: Ballroom DAbstract: Voyager images (Porco et al. 1984; Icarus 60) and Cassini occultaon data (Hedman et al. 2010; AJ 139) have previously shown that the behavior ofthe outer edge of Saturn's massive B ring is determined only in part by a stac response to the 2:1 inner Lindblad resonance. In Cassini images of this region, wefind, in addion to the expected wavenumber-2 forced distoron, evidence for unforced self-excited wavenumber-3, wavenumber-2, and wavenumber-1 normalmodes. These are the first observaons to suggest substanal wave amplificaon in Saturn's broad rings. Moreover, the presence of these free modes stronglyimplicates viscous overstability as their underlying cause (Borderies et al. 1985; Icarus 63) and, by inference, the cause for most if not all of the non-resonant, ≥100-m-class structures throughout the high-mass-density B ring and in other high-mass-density regions in Saturn's rings. Analysis of the inferred waves yields alower bound on the average surface mass density of 44 g cm -2 for the outer 250 km of the ring, though the true surface density could be as high as 100 g cm -2or higher. Interference between the forced and free wavenumber-2 modes yields a total wavenumber-2 paern that varies in amplitude and orientaon with acharacterisc period of 5.5 years. We also find localized disturbances, including 3.5-km-tall vercal structures, that provide circumstanal evidence forembedded massive bodies in the Mimas resonance zone. The presence of such bodies is supported by the direct discovery of a moonlet 0.3 km wide near thering's edge.19.07: Migraon Of Saturn's Small Satellites Embedded In Ring DivisionsAuthor Block: Julien Salmon 1 , S. Charnoz 11 CEA - Service D'Astrophysique - Université Paris Diderot, France.Presentaon Time: 10/5/2010 11:30 AM - 11:40 AMLocaon: Ballroom DAbstract: The migraon of a secondary body embedded in a disk orbing around a massive central body is a well-known problem in the study of protoplanetarydisks. Depending on the secondary’s properes, and the disk's surface density, the object will migrate differently (the so-called type I, II and III migraon). InSaturn's rings, the Encke and Keeler gaps shelter Pan and Daphnis. Although the formaon of Saturn's small satellites has been recently suggested to be theproduct of ring material accreon through the Roche limit (Charnoz et al. 2010), the origin of these very small bodies (~30km for Pan and ~9km for Daphnis)embedded in the rings is yet to be explained.The torque exerted by the rings onto these moonlets should cause them to migrate. The direcon of the migraon should however be very dependent on thedisk's surface density profile around the satellite, and also on the large scale structure of the disk. Determining how Pan and Daphnis migrate in the rings is animportant queson, as it might give us clues on the local density profile but also on the large-scale viscous evoluon of the A ring, that may depend crically onthe possible confinement of its inner edge, which is sll a maer of debate.We use a 1D numerical code including the disk's viscous evoluon, with a realisc viscosity model including the effects of the disk's self-gravity, and resonantinteracons between the disk and the satellites at Lindblad resonances. As expected, aer a short transion regime the moonlet starts to migrate with itsdivision, somewhat similarly to a type-II migraon. The migraon rate depends on the A ring density but is sensive also to the confinement state of the A ringinner edge. The magnitude and the detectability of this migraon will be quanfied.19.08: Classificaon of F Ring Features Observed in Cassini UVIS Occultaons

Author Block: Bonnie K. Meinke 1 , L. W. Esposito 1 , N. Albers 1 , M. Sremcevic 11 Univ. of Colorado, LASP.Presentaon Time: 10/5/2010 11:40 AM - 11:50 AMLocaon: Ballroom DAbstract: The Cassini Ultraviolet Imaging Spectrograph (UVIS) has observed 25 stascally significant F ring features in 91 occultaons since July 2004. Thiswork nearly doubles the number of features reported by Esposito et al. (2008). As the number of stascally significant features has grown, it has become usefulto classify them for the purposes of cataloging. We define three categories: Moonlet, Core, and Icicle, which classify the shapes of features seen to date in theoccultaon profiles of the F ring. Two features fall into the Moonlet class. Each is opaque in its occultaon, which makes them candidates for solid objects. Weclassify 17 of the significant observed features as Icicles, which parally block stellar signal for 22 m to just over 3.7 km along the radial expanse of theoccultaon. The density enhancements responsible for such signal aenuaons are likely due to transient clumping of material, evidence that aggregaons ofmaterial are ubiquitous in the F ring. Finally, the variety of core region shapes displays how even the general shape of the F ring is ever-changing. The core regionof the F ring usually has a smooth U-shape to it, but the core region takes the shape of Ws and Vs in some occultaon profiles.Our lengthy observing campaign reveals possible states and possible causes of the observed structure through these three feature classes. We discuss theconstraints on the dimensions of the physical objects responsible for the observed occultaon features. We explore how opacity and shape differences among theobserved features may be related to the porosies of aggregates in the F ring.This research was supported by the Cassini Project.19.09: Boom and Bust Cycles in Saturn’s RingsAuthor Block: Larry W. Esposito 1 , B. K. Meinke 1 , M. Sremcevic 1 , N. Albers 11 Univ. of Colorado.Presentaon Time: 10/5/2010 11:50 AM - 12:00 PMLocaon: Ballroom DAbstract: 7/16/10 12:23 PMUVIS occultaon data show clumping in Saturn’s F ring and at the B ring outer edge, indicang aggregaon and disaggregaon at these locaons perturbed byMimas and Prometheus. Timescales range from hours to months. The maximum clumping lags the moon by π in the forcing frame. This indicates a direct relaonbetween the moon and the ring clumping. We propose that the collecve behavior of the ring parcles resembles a predator-prey system: the aggregate meansize is the prey, which feeds the velocity dispersion; conversely, increasing dispersion breaks up the aggregates. For realisc values of the parameters thiscreates a limit cycle behavior, as for the ecology of foxes and hares or the boom-bust economic cycle. Solving for the long-term behavior of this forced systemgives a periodic response at the perturbing frequency, with a phase lag consistent with the UVIS occultaon measurements. We conclude that the agitaon by themoons at both these locaons in the F ring and at the B ring outer edge drives aggregaon and disaggregaon in the forcing frame.This agitaon of the ring material allows fortuitous formaon of solid objects from the temporary clumps, via stochasc processes like compacon, adhesion,sintering or reorganizaon that drives the denser parts of the aggregate to the center or ejects the lighter elements. These more persistent objects would thenorbit at the Kepler rate. Such processes can create the equinox objects seen at the B ring edge and in the F ring, explain the ragged nature of those ring regionsand allow for rare events to aggregate ring parcles into solid objects, recycling the ring material and extending the ring lifeme.7/16/10 12:23 PM7/16/10 12:23 PM

Session Number: 20Session Title: The Pluto SystemSession Type: Oral20.01: Results from the 2010 Feb 14 and July 4 Pluto OccultaonsAuthor Block: Leslie Young 1 , B. Sicardy 2 , T. Widemann 2 , M. J. Brucker 3 , M. W. Buie 1 , B. Fraser 4 , H. Van Heerden 5 , R. R. Howell 6 , K. Lonergan 7 , C. B. Olkin 1 , H. J.Reitsema 8 , A. Richter 9 , T. Sepersky 7 , L. H. Wasserman 10 , E. F. Young 11 Southwest Research Inst., 2 Observatoire de Paris, LESIA, France, 3 University of Nebraska, 4 Astronomical Society of Southern Africa, South Africa, 5 University ofthe Free State, South Africa, 6 University of Wyoming, 7 Wellesley College, 8 Reitsema Enterprises, 9 Aloe Ridge Hotel, South Africa, 10 Lowell Observatory.Presentaon Time: 10/5/2010 10:30 AM - 10:40 AMLocaon: Ballroom EAbstract.Abstract: The Portable High-speed Occultaon Telescope (PHOT) group observed two occultaons by Pluto in 2010. The first, of a I=9.3 magnituduestar on 2010 Feb 14, was organized by the Meudon occultaon group, with the PHOT group as collaborators. For this bright but low-elevaon event, we deployedto three sites in Europe: Obs. Haute Provence, France (0.8-m; L. Young, H. Reitsema), Leopold Figl, Austria (1.5-m; E. Young), and Apline Astrovillage, Lu,Switzerland (0.36-m; C. Olkin, L. Wasserman). We obtained a lightcurve at Lu under clear condions, which will be combined with two other lightcurves from theMeudon group, from Sisteron and Pic du Midi, France. We observed the second Pluto occultaon, of a I=13.2 star on 2010 July 4 UT, from four sites in South Africa:with our portable telescope near Upington (0.36-m; M. Buie, L. Wasserman), the Boyden telescope in Bloemfontein (1.5-m; L. Young, M. Brucker), the Innestelescope in Johannesburg (0.67-m; T. Sepersky, B. Fraser), and the telescope at Aloe Ridge north of Johannesburg (0.62-m; R. Howell, K. Lonergan, A. Richter).Upington was cloudy, Boyden had heavy scaered clouds, and Innes suffered from haze and telescope mechanical problems. A lightcurve was obtained from AloeRidge under clear condions. Data was also obtained by Karl-Ludwig Bath &amp; Thomas Sauer at Hakos, Namibia and by Berto Monard of ASSA near Pretoria,South Africa. The length of the Aloe Ridge chord suggests it is nearly central. These observaons give us four conguous years in which we observed one or morePluto occultaons, providing constraints on the seasonal evoluon of Pluto's atmosphere. Thanks are due to Marcelo Assafin and Jim Elliot for sharing prediconsprior to the July event. This work was supported, in part, by NASA PAST NNX08A062G.20.02: The 3/4 July 2010 Pluto Stellar-Occultaon ObservaonsAuthor Block: Jay M. Pasachoff 1 , J. L. Elliot 2 , S. P. Souza 3 , M. J. Person 2 , C. Zuluaga 2 , A. S. Bosh 2 , A. M. Zangari 2 , R. Jensen-Clem 2 , M. Lockhart 2 , A. A. S. Gulbis 4 ,P. Rojo 5 , M. Lu 3 , C. Malamut 6 , S. E. Levine 7 , K. M. Ivarsen 8 , D. E. Reichart 8 , A. P. LaCluyze 8 , M. C. Nysewander 8 , J. B. Haislip 8 , R. K. D. MacDonald 9 , C. D. Bailyn 9 , M.Emilio 10 , E. Jehin 11 , M. Gillon 11 , J. Manfroid 11 , V. Chantry 11 , P. Magain 11 , D. Hutsemekers 11 , D. Queloz 121 Williams College and Caltech, 2 M IT, 3 Williams College, 4 SALT, South Africa, and M IT, 5 U. Chile, Chile, 6 Williams College/Wesleyan/KNAC, 7 USNO/M IT/AAVSO,8 UNC, 9 Yale, 10 U. Ponta Grossa, Brazil, 11 U. Liège, Belgium, 12 Obs. Geneva, Switzerland.Presentaon Time: 10/5/2010 10:40 AM - 10:50 AMLocaon: Ballroom EAbstract: Connuing our monitoring of Pluto's atmospheric temperature and pressure, previously shown by us to be increasing (Elliot et al., Nature 424, 165,2003; Pasachoff et al., AJ 129, 1718, 2005) and subsequently found by us to be leveling off (Elliot et al., AJ 134, 1, 2007), we report on a stellar occultaon byPluto of UCAC2 mag=15.3, observed from South America and Africa on 4 July 2010 UT. Success was achieved with a 0.45 m at Cerro Calan using one of our POETS(Portable Occultaon, Eclipse, and Transit System; Souza et al. PASP 118, 1550, 2006), a 1.0 SMARTS (Small and Medium Aperture Research Telescope System) atCerro Tololo, four 0.6 m telescopes of PROMPT (Panchromac Roboc Opcal Monitoring and Polarimetry Telescopes) on Cerro Tololo, and TRAPPIST's(TRansing Planets and Planetesimals Small Telescope) 0.6-m telescope on La Silla in Chile; the 0.35 m telescope of U. Ponta Grossa, Brazil; and the 0.75-mATOM (Automac Telescope for Opcal Monitoring), Namibia, using POETS. Winds prevented opening the 6.5 m Magellan/Clay telescope on Las Campanas,Chile, with its own frame-transfer camera, and clouds obscured the 1.9 m telescope at Sutherland, South Africa, which had POETS. With shadow velocity 23.6km/s, it was a rapid event: maximum occultaon

Author Block: Angela M. Zalucha 1 , A. A. S. Gulbis 2 , X. Zhu 3 , D. F. Strobel 4 , J. L. Elliot 11 M IT, 2 Southern African Large Telescope and South African Astronomical Observatory, South Africa, 3 Applied Physics Laboratory, The Johns Hopkins University,4 The Johns Hopkins University.Presentaon Time: 10/5/2010 11:00 AM - 11:10 AMLocaon: Ballroom EAbstract.Abstract: We use the radiave-conducve model of Strobel et al. 1996 (Icarus 120, 266-289) to calculate a set of occultaon light curves for Pluto. Themodel has been improved to include the effects of moist convecon with respect to methane at low altudes, thus enabling a troposphere. We consider surfaceradius, surface pressure, and tropopause depth as model free parameters. The methane mixing rao and CO mixing rao are both held constant, as the modellight curves are least sensive to these parameters. The model light curves are compared with 2006 Siding Spring data (Elliot et al. 2007, Astron J. 134, 1-13),2002 UH 2.2m data (Elliot et al. 2003, Nature 424, 165-168), and 1988 KAO data (Elliot et al. 1989, Icarus 77, 148-170). In determining the best-fit model lightcurve, we find that the surface pressure and tropopause depth are highly correlated, such that higher surface pressure corresponds to higher tropopause depth.This relaonship is understandable from a physical standpoint, since extending the atmosphere downwards naturally produces a higher surface pressure. We alsofind that a lower surface radius and higher surface pressure are required to fit the data compared to model light curves in which the troposphere is excluded. Ouranalysis improves upon previous studies featuring tropopause depth in that we use a sophiscated radiave transfer model that requires the constraint of heatbalance, going beyond purely idealized temperature structures. This work was supported in part by NASA grants NNX08AE92G and NNX07AK73G. DFSacknowledges support from the New Horizons Mission through SWRI Contract No. 277043Q and NASA grant NNG05GO91G.20.05: Photometric Properes of the Pluto SystemAuthor Block: Marc W. Buie 1 , W. M. Grundy 2 , D. J. Tholen 3 , D. C. Stephens 41 Southwest Research Instute, 2 Lowell Observatory, 3 University of Hawaii, 4 Brigham Young University.Presentaon Time: 10/5/2010 11:10 AM - 11:20 AMLocaon: Ballroom EAbstract: We will present a summary of the current state of knowledge of the photometric properes of the surfaces of the four bodies in the Pluto system. Ourunderstanding of Pluto benefits from the longest running dataset and present-day photometry is especially valuable for tracking and characterizing the currentseasonal evoluon. In parcular, the surface of Pluto has recently been seen to have undergone a global-scale change in color. At the same me the phasecoefficient, a tracer for the state of surface texture, remains unchanged. The smaller bodes in the system are somewhat easier objects for study in that they arenot expected to exhibit seasonal variability. Charon is known to be composionally disnct from Pluto and the same is expected for Hydra and Nix. The phasecoefficient for Charon has now been shown to differ from Pluto both in degree and in character thus accentuang the differences in surface properes betweenthe two. Informaon about the newly discovered satellites, Hydra and Nix, is much more sparse but the expectaon is that they will more closely resembleCharon in surface properes.Our presentaon will include a summary of current properes with a special emphasis on seasonal evoluon on Pluto, phase coefficients, lightcurves, andcomparisons of surface composion enabled by filter photometry. Also included will be a discussion of future observaonal plans that will lead up to the NewHorizons flyby in 2015.This work has been supported by grants from NASA and STScI.20.06: Methane and Nitrogen Abundances on Eris and PlutoAuthor Block: Stephen C. Tegler 1 , D. M. Cornelison 1 , W. M. Grundy 2 , W. Romanishin 3 , M. Abernathy 1 , M. Bovyn 1 , J. Burt 1 , D. Evans 1 , C. Maleszewski 1 , Z.Thompson 1 , F. Vilas 41 Northern Arizona Univ., 2 Lowell Observatory, 3 University of Oklahoma, 4 M M T Observatory.Presentaon Time: 10/5/2010 11:20 AM - 11:30 AMLocaon: Ballroom EAbstract.Abstract: We present spectra of Eris from the MMT 6.5 meter telescope and Red Channel Spectrograph (5700 - 9800 angstroms; 5 angstroms per pixel)on Mt. Hopkins, AZ, and Pluto from the Steward Observatory 2.3 meter telescope and Boller and Chivens spectrograph (7100 - 9400 angstroms; 2 angstroms perpixel) on Ki Peak, AZ. In addion, we present laboratory transmission spectra of methane-nitrogen and methane-argon ice mixtures. By anchoring our analysiswith the methane-nitrogen phase diagram of Prokhvalov and Yantsevich (1983), and comparing methane bands in our Eris spectrum and methane bands in ourlaboratory spectra, we are able to make a quantave esmate of Eris' methane and nitrogen abundances. Our analysis suggests the surface ice consists ofabout 10% methane and about 90% nitrogen. By using the same analysis techniques on our Pluto spectrum, we find the an-Charon facing hemisphere of Plutohas a methane abundance of about 3% and a nitrogen abundance of about 97%. Such abundances are consistent with values reported in the literature. It appearsthat the bulk volale composion of Eris is similar to the bulk volale composion of Pluto. Both objects appear to be dominated by nitrogen ice. Our analysisalso suggests, unlike previous work reported in the literature, that the methane and nitrogen stoichiometry is constant with depth into the surface of Eris. Finally,we point out that our Eris spectrum is also consistent with an ice consisng of 40% methane and 60% argon. So, unl someone detects an absorpon aributableto nitrogen ice in the spectrum of Eris, it would be prudent to keep an open mind about the identy of ice components on Eris. We gratefully acknowledge supportfrom NASA Planetary Astronomy and NASA Planetary Geology and Geophysics. We thank Steward Observatory for the consistent allocaon of telescope me.20.07: Searching for CO in Pluto's AtmosphereAuthor Block: Jason C. Cook 1 , L. A. Young 21 NASA Ames, 2 Southwest Research Instute.Presentaon Time: 10/5/2010 11:30 AM - 11:40 AMLocaon: Ballroom EAbstract: Understanding the abundance of CO in Pluto's atmosphere is vital for three reasons: (i) the amount of CO helps us to understand the physics of mulcomponentvolale transfer, (ii) CO is expected to be an important cooling species in Pluto's atmosphere and (iii) the CO mole fracon is an unconstrainedparameter in all atmospheric models based on occultaon data. Since the first Pluto occultaon in 1988, occultaons have shown Pluto's atmosphere isundergoing changes consistent with an expanding atmosphere and a greater surface pressure (Elliot et al., 2003, 2007; Sicardy et al. 2003; Young et al 2008).Obtaining a baseline measurement of the CO mole fracon is vital before the arrival of New Horizons in 2015 to understand the changes in Pluto's atmosphere.Earlier aempts to detect CO have failed (Young et al., 2001, Bockelee-Morvan et al., 2001, Lellouch et al., 2010), and only produced upper limits. The ghtestconstraint on the CO/N2 mole fracon is < 5x10 -3 or < 1 cm-am (Lellouch et al., 2010). In spring 2010, we obtained high-resoluon (λ/Δλ ~ 54,000) spectra ofPluto at 2335-2345 nm using the Phoenix instrument on Gemini South. This spectral window covers the R(0)-R(5) lines of the 2-0 transion of CO as well as manyCH4 lines. The total integraon me of the data is 6.3 hours obtained under 0.8-1.0 aresecond seeing. The data will be discussed and the results presented.JCC would like to acknowledge that this research was supported by an appointment to the NASA Postdoctoral Program at the Ames Research Center, administeredby Oak Ridge Associated Universies through a contract with NASA.

20.08: Improved Masses of Nix and HydraAuthor Block: David J. Tholen 1 , M. W. Buie 2 , W. M. Grundy 31 Univ. of Hawaii, 2 Southwest Research Instute, 3 Lowell Observatory.Presentaon Time: 10/5/2010 11:40 AM - 11:50 AMLocaon: Ballroom EAbstract: New astrometry for the Pluto system has been extracted from HST/WFPC2 images taken during Cycle 15. By combining these results with theprediscovery astrometry extracted from the ACS/HRC images taken during Cycle 11, we have improved the orbit determinaons for the three satellites, Charon,Nix, and Hydra, as well as having improved the mass determinaons for all four bodies. Of parcular interest is the mass for Hydra, whose previousdeterminaon had a large enough uncertainty to allow for zero mass, even though the nominal GM value was 0.022 km 3 sec -2 . The new GM determinaon is0.028 km 3 sec -2 , with a one-sigma lower limit of about 0.008 and one-sigma upper limit of about 0.060 km 3 sec -2 , a considerable improvement on the previousresult. The new GM determinaon for Nix is 0.068 km 3 sec -2 , compared to the earlier value of 0.039 km 3 sec -2 . Both results imply somewhat larger satellites thanpreviously indicated and therefore lower albedos, making it more difficult to conclude that Nix and Hydra have surface properes similar to Charon. TheCharon/Pluto mass rao is 0.1163, and the system GM is 971.713 km 3 sec -2 , based on the adopted image scale that produces a semimajor axis of 19570 km forCharon's Plutocentric orbit. However, recent stellar occultaon results favor the image scale derived from the Cycle 2 observaons of Pluto and Charon, whichindicated a semimajor axis of 19636 km. Resolving this discrepancy remains an open issue. Further improvement in the mass and orbit determinaons can beexpected from new WFC3 images being taken during Cycle 17.20.09: Small Impact Craters on Triton: Evidence for a Turn-up in the Size-frequency Distribuon of Small (sub-km) KBOs, and Arguments Against aPlanetocentric OriginAuthor Block: William B. McKinnon 1 , K. N. Singer 11 Washington Univ..Presentaon Time: 10/5/2010 11:50 AM - 12:00 PMLocaon: Ballroom EAbstract: We report crater counts on the 10-frame, highest-resoluon (350-420 m/px) Voyager 2 Triton mosaic (kindly MTF-sharpened and photometricallycorrected by P.M. Schenk). Despite variable degrees of smear, crater counng on porons of these images is straighorward, and on the smoothest, presumablycryovolcanic plains, abundant craters are seen down to the resoluon limit (craters ~1 km in diameter). These counts complement those by Schenk & Zahnle(2007) on their 1.65 km/px global basemap. We find a fairly steep cumulave crater distribuon (-3.2 slope), which implies a differenal impactor index q ≈ 3.5.This is consistent with the classic Dohnanyi slope for a collisionally evolved populaon; more importantly, the transion from q = 2.8 (Schenk & Zahnle 2007) to3.5 (or higher on Cipango Planum, which while less cratered, offers the “cleanest” counng surface and the sharpest MTF), as crater diameters drop below 10 km(and thus impactor diameters drop below 1 km), may be a signature of the strength-gravity transion in terms of disrupon energy for KBOs (O’Brien & Greenberg2003). These craters cannot be secondaries, as they are larger than any plausible “crossover diameter” for Triton's young surface. But do Triton’s cratersrepresent the impacts of small KBOs? Schenk & Zahnle (and others) have argued for a prograde planetocentric origin, based mostly on the geographicconcentraon of Triton’s craters on its leading hemisphere. We argue that the trailing hemisphere cantaloupe terrain, a unique and topographically complexterrain of unknown composional and crater retenon properes, should be sparsely cratered. Conversely, their proposal for inner satellite sesquinaries wouldrequire, e.g., a fortuitous, >60-km-diameter impact crater on Proteus, which would launch ice blocks to speeds ≥1.6 km/s in order to reach Triton. Scaling fromPwyll secondaries on Europa (a best case analogy) indicates the ice blocks will not be big enough.

Session Time: 10/5/2010 1:30 PM

Session Number: 21Session Title: Mercury and the MoonSession Type: Oral21.01: MESSEN GER: Insights Regarding the Relaonship between Mercury’s Surface and Its Neutral and Ionized ExosphereAuthor Block: Ann L. Sprague 1 , R. J. Vervack 2 , R. M. Killen 3 , W. E. McClintock 4 , R. D. Starr 5 , D. Schriver 6 , P. Trávnícek 7 , T. M. Orlando 8 , J. L. McClain 8 , G. A.Grieves 8 , W. V. Boynton 9 , D. J. Lawrence 2 , MESSENGER Team1 Lunar and Planetary Laboratory, The University of Arizona, 2 Johns Hopkins University Applied Physics Laboratory, 3 Solar System Exploraon Division, NASAGoddard Space Flight Center, 4 Laboratory for Atmospheric and Space Physics, University of Colorado, 5 Physics Department, The Catholic University of America,6 Instute of Geophysics and Planetary Physics, UCLA, 7 Astronomical Instute, ASCR, Czech Republic, 8 School of Chemistry and Biochemistry, Georgia Instuteof Technology, 9 Department of Planetary Sciences, The University of Arizona.Presentaon Time: 10/5/2010 1:30 PM - 1:40 PMLocaon: Ballroom BCAbstract: Measurements by instruments on MESSENGER during the spacecra’s three Mercury flybys have led to discoveries of previously undetected neutral(Mg) and ionized (Ca+) species in Mercury’s neutral and ionized exosphere and mapped these and previously known constuents (Na, Ca) on the an-sunwardside of the planet and over the poles. Also, Neutron Spectrometer measurements have indicated neutron absorpon consistent with the presence of somecombinaon of Fe, Ti, Sm, and Gd. Another element with a high neutron cross secon is Mn. Manganese-bearing pyroxene has been inferred from modeling ofMercury Atmospheric and Surface Composion Spectrometer (MASCS) spectra of Mercury’s surface. The total neutron cross secon of Mn-bearing clinopyroxene,for example, (294.2 barns), is comparable to that of ilmenite (284.0 barns), and we suggest it as a possible neutron absorber at Mercury. Some ions and neutralscan be released directly from mineral surfaces by electron-smulated desorpon (ESD). Because cross secons of neutrals can be higher than photon-smulateddesorpon (PSD) cross secons and because acve electron precipitaon on both the day and night side of Mercury can produce ESD of ions, at least part of theionized exosphere is produced directly from surface materials by ESD. The process does not require photoionizaon of atoms or molecules. One inference is thatmodel assumpons for ion producon and magnetospheric- interacons may need to add ESD as another source. ESD experiments and simulaons of electronprecipitaon on Mercury provide support for this suggeson. More laboratory work is required to quanfy known, and to discover other, pathways to iondesorpon from Mercury’s surface. Searches for resonant fluorescent emissions from atoms, molecules and ions (e.g., Mn and S emission line triplets near 280and 162 nm, respecvely) in Mercury’s neutral and ionized exosphere during the orbital phase of the MESSENGER mission are planned.21.02: Mercury’s Neutral and Ionized Exosphere Observed with the Mercury Atmospheric and Surface Composion Spectrometer During the ThreeMESSEN GER FlybysAuthor Block: Ronald J. Vervack 1 , R. M. Killen 2 , W. E. McClintock 3 , A. L. Sprague 4 , M. H. Burger 2 , M. Benna 2 , N. Mouawad 5 , E. T. Bradley 6 , B. J. Anderson 1 , N. R.Izenberg 1 , M. C. Kochte 1 , M. R. Lankton 3 , S. C. Solomon 71 JHU/Applied Physics Lab, 2 NASA Goddard Space Flight Center, 3 University of Colorado/LASP, 4 University of Arizona/LPL, 5 University of Maryland, 6 Universityof Central Florida, 7 Carnegie Instuon of Washington.Presentaon Time: 10/5/2010 1:40 PM - 1:50 PMLocaon: Ballroom BCAbstract: The Mercury Atmospheric and Surface Composion Spectrometer (MASCS) on the MESSENGER spacecra observed Mercury’s exosphere during eachof the probe’s three Mercury flybys (M1 on 14 January 2008, M2 on 6 October 2008, and M3 on 29 September 2009). Two previously observed species, Na and Ca,were seen in unprecedented spaal resoluon, and two species - Mg and Ca + - were discovered in the exosphere by MASCS. A dawn/dusk asymmetry in the Caexosphere with a dawnside enhancement was found to be a persistent feature that was not previously known to exist. Surprisingly, a corresponding feature wasnot seen in Mg or the more volale species Na. A dawn/dusk asymmetry in Na cannot necessarily be ruled out because MASCS did not observe the dayside. Mostsurprising was the observaon of a region of intense concentraon of Ca + about 2-3 planetary radii an-sunward from the planet's center. This measurementprovides evidence for tailward magnetospheric convecon of photoions produced inside the magnetosphere. Observaons of neutral sodium, calcium, andmagnesium above the planet’s north and south poles revealed altude distribuons that are disnct for each species. Strong emission was seen above the polesin each of these species, but the altude distribuon was most unusual for Mg and is inconsistent with an exponenally decreasing density with altude. A twocomponentexosphere was clearly measured for Na, indicang that a combinaon of processes is at work in producing and maintaining the exosphere. Whereasthe Na distribuon is consistent with ground-based observaons, the differences in spaal distribuons for the chemically similar elements, Ca and Mg, areunexpected and remain unexplained.21.03: Mercury's Mg Exosphere Observed With the Mercury Atmospheric and Surface Composion Spectrometer During the Third MESSEN GER FlybyAuthor Block: Rosemary M. Killen 1 , M. H. Burger 1 , R. J. Vervack, Jr. 2 , A. L. Sprague 3 , M. Benna 1 , W. E. McClintock 4 , N. Mouawad 5 , S. C. Solomon 61 NASA Goddard Space Flight Center, 2 The Johns Hopkins University Applied Physics Laboratory, 3 Lunar and Planetary Laboratory, University of Arizona,4 Laboratory for Atmospheric and Space Physics, University of Colorado, 5 University of Maryland, 6 Department of Terrestrial Magnesm, Carnegie Instuon ofWashington.Presentaon Time: 10/5/2010 1:50 PM - 2:00 PMLocaon: Ballroom BCAbstract: Observaons made by the Ultraviolet and Visible Spectrometer (UVVS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging(MESSENGER) spacecra during the three flybys of the planet (M1 on 14 January 2008; M2 on 6 October 2008; M3 on 29 September, 2009) measured differingspaal distribuons for three exospheric species: sodium (Na), calcium (Ca), and magnesium (Mg). The M3 trajectory allowed the UVVS to obtain altude scansabove Mercury’s north and south poles, which was not possible during the earlier flybys because of poinng constraints. Near closest approach, a roll maneuveras MESSENGER entered Mercury’s shadow carried the UVVS field of view in an arc perpendicular to the Sun-Mercury line. During M3, these “fantail” observaonsbegan looking south and rolled through the dawn direcon to slightly duskward of north. Throughout M3 the UVVS scanned for emission lines from four species(vacuum wavelengths): Na at 589.2 and 589.8 nm, Mg at 285.3 nm, Ca at 422.8 nm, and Ca+ at 393.5 nm. The observed latudinal distribuon of each of thesespecies is markedly different in the ansunward region of the exosphere probed by the fantail observaons. The polar altude distribuons for the three specieswere also different from one another, but whereas the Na and Ca profiles were roughly symmetric between the north and south, the Mg emissions showedsignificant north-south variaons. We have run Monte Carlo simulaons of the Mg exosphere for condions that prevailed during M3 to establish the cause ofthese variaons.21.04: A Search For Metals In The Atmosphere Of Mercury With Keck/HIRESAuthor Block: Thomas A. Bida 1 , R. M. Killen 2 , T. H. Morgan 21 Lowell Observatory, 2 NASA Goddard Space Flight Center.

Presentaon Time: 10/5/2010 2:00 PM - 2:10 PMLocaon: Ballroom BCAbstract: We have observed the atmosphere of Mercury with the HIRES spectrograph at the Keck Observatory within the years 1997-2010. An important productof these observaons has been the discovery of Ca in the atmosphere (Bida, Killen, and Morgan, 2000), and the subsequent study of its local physical properesand source processes (Killen, Bida, and Morgan, 2005). Here, we report on 4-σ line detecons of the metals Al and Fe, and strict upper limits for Ca + , in Mercury’satmosphere as derived from recent Keck/HIRES data sets. A wide range of composional models, from refractory to volale-rich, predict significant mantleabundances for these metals. We present the spaal dependence of the Al, Fe, and Ca+ abundance upper limits, and discuss possible source processes for thesemetals. The Ca + upper limits from Keck/HIRES will be compared with the ion's measurements made with the MASCS instrument onboard MESSENGER (Vervack etal, 2010).21.05: Observaons of Mercury’s An-Sunward Emissions by the STEREO SpacecraAuthor Block: Carl Schmidt 1 , J. Baumgardner 1 , M. Mendillo 1 , C. Davis 2 , I. Musgrave 31 Boston University, 2 STFC Rutherford Appleton Labratory, United Kingdom, 3 University of Adelaide, Australia.Presentaon Time: 10/5/2010 2:10 PM - 2:20 PMLocaon: Ballroom BCAbstract.Abstract: Heliospheric Imagers HI-1 aboard both the STEREO-A (Ahead) and -B (Behind) spacecra occasionally record emissions extending ansunwardin a tail from Mercury. HI-1A measurements on 28 January 2009 show a sustained brightness of nearly 30 kilo-Rayleighs over more than 24 hours at adistance of 12 arcminutes from the planet. At this me, the line of sight from STEREO-A and the Sun-Mercury direcons differs by only 7 degrees, with the tailpointed toward the Ahead spacecra. Correcng for path length and projecon, this corresponds to a cross-tail brightness of 7 kiloRayleighs at a physicaldistance of nearly 430 planetary radii. A sodium tail has been observed from the ground at such distances, with a typical brightness between 100 and 200Rayleighs for similar orbital phases. The transmission of sodium D line wavelengths though the broadband filters in HI-1 is between 1 and 2 percent. It is unlikelythat the HI-1A recorded emissions in the kR range would be due to sodium at such distances. Thomson scaering of sunlight from nearby solar coronal electronsis seen simultaneously throughout the HI-1 field with short-term brightness variaons near Mercury. Whether the tail feature observed is due to solar windelectrons or scaering off dust parcles remains to be determined. The STEREO space-based observing capability provides new insights into long and short-termtemporal variability in the Hermean system and its potenal sources.21.06: Photometric Analysis of Mercury’s Surface from MESSEN GER observaons: Implicaons for Global Color ProperesAuthor Block: Deborah L. Domingue 1 , S. L. Murchie 2 , B. W. Denevi 3 , N. L. Chabot 2 , F. Vilas 41 Planetary Science Instute, 2 Johns Hopkins University/Applied Physics Laboratory, 3 Arizona State University, 4 M M TO.Presentaon Time: 10/5/2010 2:20 PM - 2:30 PMLocaon: Ballroom BCAbstract: The importance of correcng spectral observaons to common photometric condions prior to detailed composional analyses, such as mixturemodeling or comparison with analog materials, is evidenced in laboratory analyses of mineral and lunar samples. Our analysis of the photometric measurementsacquired by MESSENGER’s wide-angle mulspectral imager from all three flybys of Mercury provide both a method for correcng the global spectral image dataset to a common set of photometric condions and a descripon of Mercury’s regolith properes as compared to those of other airless rocky bodies. Thephotometric and spectral properes of Mercury as determined from the MESSENGER observaons are commensurate with corresponding Earth-basedobservaons. Modeling of the phase curves using Hapke’s equaons indicates that Mercury’s regolith is smoother (an average surface lt over size scalesranging from a few millimeters to kilometers) than the regoliths of the Moon and several asteroids, and exhibits a higher opposion amplitude yet with similarparcle scaering properes. The results from the photometric analyses also provide measures of the geometric and Bond albedo over the wavelength range 430nm to 1010 nm. In addion, a bolometric albedo of 0.081 is derived for this wavelength range. Our photometric modeling results provide correcons that makevisible improvements to the global color map of Mercury’s surface, thus enabling the comparison of broadband spectral properes across Mercury’s surface.This work was supported by the MESSENGER Project under NASA's Discovery Program.21.07: Solar Insolaon Driven Variaons of Mercury’s Lithospheric StrengthAuthor Block: Jean-pierre Williams 1 , J. Ruiz 2 , M. A. Rosenburg 3 , O. Aharonson 3 , R. J. Phillips 41 University of California Los Angeles, 2 Universidad Complutense de Madrid, Spain, 3 California Instute of Technology, 4 Southwest Research Instute.Presentaon Time: 10/5/2010 2:30 PM - 2:40 PMLocaon: Ballroom BCAbstract: Mercury’s coupled 3:2 spin-orbit resonance in conjuncon with its relavely high eccentricity of ~0.2 results in a surface variaon in annual averagesolar insolaon and thus equatorial hot and cold regions. This results in an asymmetric temperature distribuon in the lithosphere and a long wavelength lateralvariaon in lithosphere structure and strength that mirrors the insolaon paern. We employ a thermal evoluon model for Mercury generang strengthenvelopes of the lithosphere to demonstrate and quanfy the possible effects the insolaon paern has on Mercury’s lithosphere. We find the heterogeneity inlithosphere strength is substanal, increases with me, and is accentuated by the differenal ming of the mantle contribuon to the lithosphere strength. Forexample, by the end of late heavy bombardment (~4 Ga) we find a difference in brile-ducle transion depth of 6 km between the hot and cold equatorialthermal poles and 24 km between the hot equatorial pole and the latudes ±90°. We also find that a crust thicker than that of the Moon or Mars and dryrheologies for the crust and mantle are favorable when compared with esmates of brile-ducle transion depths derived from lobate scarps. Regions ofstronger and weaker compressive strength imply that the accommodaon of radial contracon of Mercury as its interior cooled, manifest as lobate scarps, maynot be isotropic, imparng a preferenal orientaon and distribuon to the lobate scarps. Although many of the parameters of the model are poorly constrainedfor Mercury, the overall lithospheric heterogeneity remains regardless of the choice of parameters. The latudinal surface temperature variaon experienced byMercury is not unlike that of the Earth’s Moon presently and thus one should expect an analogous latude dependence on lithospheric strength to have developedover me on the Moon as well. Funded by the NSF Astrophysics Research Grants program (AST-0709151).21.08: Support Of The Lunar Fossil Figure By The Elasc LithosphereAuthor Block: Isamu Matsuyama 11 UC Berkeley.Presentaon Time: 10/5/2010 2:40 PM - 2:50 PMLocaon: Ballroom BCAbstract: The figure of the Moon is triaxial, with three different principal moments of inera, as expected. However, the moment differences are significantlylarger than those predicted assuming hydrostac equilibrium. This has been explained as due to a fossil bulge that retains a figure for prior rotaonal and daldeformaon, at a me when the Moon was closer to Earth (Jeffeys, 1915; Lambeck & Pullan, 1980; Garrick-Bethell et al.,2006). Garrick-Bethell et al. (2006)illustrated that a fossil figure can enrely account for the moment differences if it is established at a me when the orbital eccentricity was high. They

approximate the Moon as a strengthless homogeneous body; however, a strengthless Moon cannot support a fossil figure over billions of years. We extend theanalysis of Garrick-Bethell et al. (2006) by taking into the presence of an elasc lithosphere capable of supporng a fossil figure.The fossil figure is established when the elasc lithosphere forms. For a 50 km thick elasc lithosphere, the moment differences can be explained by a lunar orbitwith an inial semimajor axis a=17.1 Earth radii and eccentricity e=0.49 if the Moon remains locked in synchronous rotaon. If the fossil figure is establishedduring a 3:2 spin-orbit resonance, a=18.1 Earth radii and e=0.16, or a=20.0 Earth radii and e=0.60. The inial semimajor axis decreases with decreasing elasclithospheric thickness, as expected. The inial orbital eccentricity is not sensive to the elasc lithospheric thickness. As Lambeck & Pullan (1980) noted, it isunlikely that the moment differences are due to a fossil figure alone. Therefore, we also consider the effect of including other contribuons to the momentdifferences.This work is supported by the Miller Instute for Basic Research.21.09: Precession of the Lunar CoreAuthor Block: Jennifer Meyer 1 , J. Wisdom 11 M IT.Presentaon Time: 10/5/2010 2:50 PM - 3:00 PMLocaon: Ballroom BCAbstract.Abstract: Goldreich (1967) showed that a lunar core of low viscosity would not precess with the mantle. We show that this is also the case for much oflunar history. But when the Moon was close to the Earth the Moon's core was forced to follow closely the precessing mantle, in that the rotaon axis of the coreremained nearly aligned with the symmetry axis of the mantle. The transion from locked to unlocked core precession occurred between 26.0 and 29.0 Earth radii.Implicaons for an early lunar dynamo will be discussed.21.10: Exploring the Lunar Interior with Tides, Gravity and OrientaonAuthor Block: James G. Williams 1 , D. H. Boggs 1 , H. Noda 21 JPL, 2 NAOJ, Japan.Presentaon Time: 10/5/2010 3:00 PM - 3:10 PMLocaon: Ballroom BCAbstract: Exploraon of the internal structure and properes of the Moon connues. Exisng informaon from gravity field, des and 3-dimensional orientaonincludes moments of inera, mean density, dal Love numbers, dal dissipaon, and fluid-core/solid-mantle interacons from dissipaon and oblateness.Tracking orbing spacecra gives gravity field and a Love number k 2 . Lunar laser ranging (LLR) determined des and orientaon give Love numbers k 2 and h 2 , fourdal dissipaon and two fluid-core/solid-mantle effects. Spacecra gravity and LLR combined give the moment of inera of the solid Moon, currently esmated tobe 0.3929 MR 2 . The detecons of the two core/mantle boundary effects require a fluid core. Love numbers are becoming accurate enough to constrain deepinterior models for fluid core and deepest mantle. Future possibilies include (LLR) determinaon of the fluid core moment and a (GRAIL and LLR) search for asolid inner core. Interior exploraons would be much expanded by a network of geophysical landers.21.11: Lunar Regolith Depths from LROC ImagesAuthor Block: Gwendolyn D. Bart 1 , R. Nickerson 1 , M. Lawder 11 University of Idaho.Presentaon Time: 10/5/2010 3:10 PM - 3:20 PMLocaon: Ballroom BCAbstract: Since the 1960's, most lunar photography and science covered the equatorial near side where the Apollo spacecra landed. As a result, ourunderstanding of lunar regolith depth was also limited to that region. Oberbeck and Quaide (JGR 1968) found regolith depths for the lunar near side: 3 m(Oceanus Procellarum), 16 m (Hipparchus), and 1-10 m at the Surveyor landing sites.The Lunar Reconnaissance Orbiter Camera recently released high resoluon images that sample regions all around the lunar globe. We examined a selecon ofthese images across the lunar globe and determined a regolith depth for each area. To do this, we measured the rao of the diameter of the flat floor to thediameter of the crater, and used it to calculate the regolith thickness using the method of Quaide and Oberbeck (JGR 1968). Analysis of the global distribuon oflunar regolith depths will provide new insights into the evoluon of the lunar surface and the frequency, distribuon, and effect of impacts.21.12: Hydrogen Isotope Similarity of the Earth and Moon Revealed by Water in Lunar Volcanic GlassesAuthor Block: Erik Hauri 1 , A. E. Saal 2 , M. C. Rutherford 2 , J. A. Van Orman 31 Carnegie Instuon for Science, 2 Brown University, 3 Case Western Reserve University.Presentaon Time: 10/5/2010 3:20 PM - 3:30 PMLocaon: Ballroom BCAbstract: Water is perhaps the most important molecule in the solar system, and understanding the origin and distribuon of water in planetary interiors hasimportant ramificaons for understanding the evoluon of planetary bodies. Here we report the first in-situ measurements of the isotopic composion ofhydrogen dissolved in volcanic glass samples recovered from the Moon by the Apollo 15 mission. We examined specific groups of lunar glasses contained in threesamples recovered by the Apollo 15 mission (15426,32; 15426,138 and 15427) with erupon ages of 3.35 to 3.65 Ga; H 2 O and D/H raos were measured by SIMS.Yellow-brown volcanic glasses contain the highest concentraons of H 2 O (up to 70 ppm) which is two mes higher than our previous measurements, while greenglasses contain smaller amounts of water (4 - 17 ppm H 2 O). Aer correcon for cosmogenic contribuons, our data exhibit a systemac negave correlaon ofδD (-200‰ to +2500‰) with water content. The systemac nature of the data correlaon, and the heterogeneous H 2 O concentraons and D/H data, indicatethat hydrogen isotopes were fraconated in these lunar magmas during kinec degassing during erupon. The average δD of the five highest-H 2 O glasses is+340‰ (+180‰/-240‰); this δD range overlaps the range of carbonaceous chondrites and terrestrial water. Furthermore, it is very likely that the original preerupveδD value of these lunar magmas was significantly lower, and that kinec D/H fraconaon has resulted in preferenal loss of H during magmacdegassing. As a result, within the uncertaines in our measurements and correcon for the effects of cosmic ray spallaon and degassing, we conclude thatjuvenile magmac water in the lunar interior has a D/H rao that is indisnguishable from terrestrial water. This study is the first to idenfy a planetary body witha hydrogen isotope composion that is the same as the Earth.

Session Number: 22Session Title: Planetary Rings II: Saturnian and Uranian RingsSession Type: Oral22.01: Spectroscopic Idenficaon of Clumps in the F RingAuthor Block: Mahew M. Hedman 1 , P. D. Nicholson 1 , M. R. Showalter 2 , Cassini VIMS Team1 Cornell University, 2 SETI Instute.Presentaon Time: 10/5/2010 1:30 PM - 1:40 PMLocaon: Ballroom DAbstract: Numerous compact, opcally-thick clumps in the F ring have been detected in both occultaon and imaging data returned by the Cassini spacecra(Esposito et al. 2008, Beurle et al. 2010). Such features are parcularly interesng because they may represent sites of acve parcle aggregaon. Stellaroccultaons observed with the Visual and Infrared Mapping Spectrometer (VIMS) reveal that some of these clumps have disncve infrared transmission spectra,which may provide new insights into their structure and dynamics..The transmission spectra of the dense main rings are featureless between 1 and 5 microns, consistent with the expected exncon by large (cenmeter-tometer-sized)parcles. However, dusty structures such as the F ring (and Encke Gap ringlets) show a reduced opcal depth at wavelengths around 2.9 microns.This opacity dip occurs where the real index of refracon of water ice nearly equals that of free space due to anomalous dispersion close to the fundamentalabsorpon band at 3.1 microns. Mie-scaering calculaons indicate that the dip arises due to a reducon in surface scaering from small (1-10 micron across)ice-rich parcles. However, several compact, opcally-thick features in the F ring exhibit much weaker opacity dips than other parts of the F ring with comparableopcal depths, and therefore probably contain a smaller fracon of 1-10 micron grains than the rest of the ring. We idenfy these spectrally-disnct regions withthe F-ring clumps seen by other Cassini instruments, and we suggest that their disncve parcle size distribuons are due to unusually low local velocitydispersions that enable small grains to sck to the surfaces of larger parcles. Furthermore, by using spectral decomposion techniques we are able to isolatethese clumps from the rest of the F ring in order to determine their radial extent and their spaal distribuon within the ring.22.02: The Disconnuous Core of Saturn's F-Ring and Orbit ModelAuthor Block: Essam A. Marouf 1 , K. Wong 1 , R. French 2 , N. Rappaport 3 , C. McGhee 21 San Jose State Univ., 2 Wellesley College, 3 Jet Propulsion Laboratory.Presentaon Time: 10/5/2010 1:40 PM - 1:50 PMLocaon: Ballroom DAbstract: Somewhat surprisingly, in 25 radio occultaons of the F-Ring during the Cassini Nominal Mission, it is detectable in only 11. In contrast, the F-Ringwas detectable in a single Voyager radio occultaon, suggesng me variability. Similar to Voyager, and with one excepon, an observed Cassini F-Ring profile isa single strand about 1 km wide and of peak opcal depth of few to several tenths. The profiles were reconstructed to remove diffracon effects (few 100 metersresoluon). To diffract the radio signals like 1-D structure, the strand must extend azimuthally for several km’s (several Fresnel scale). All 11 detecons are atboth 0.94 and 3.6 cm observaon wavelengths, with only 3 detecons at 13 cm. The detecons imply presence of parcle sizes of at least few cm’s, possiblyextending to few 10’s cm’s. The sensivity of the radio signals to these relavely large parcle sizes suggests that the observed 1 km wide strand idenfieslocaons where large fracon of the F-Ring mass likely resides, or the “core” of the F-Ring. This radio core can’t be azimuthally connuous given the absence ofdetecon on 14 other occultaons. In stellar occultaons conducted at much shorter wavelengths, the F-Ring core usually refers to a different broader feature10’s of km’s wide. Its nondetectability in the Cassini radio observaons implies parcles of smaller sizes (< 1 mm) likely populate this broad feature. We use theCassini radio observaons of the core to determine parameters of a freely precessing eccentric and inclined Keplerian ellipse model. Results are close to, butmeasurably different from, those reported based on fing the broader profiles observed in stellar occultaons (Bosh et al., Icarus 157, 57-75, 2002), with RMS fitresidual < 7 km compared with almost twice the value if the Bosh-model is directly applied to the radio observaons.22.03: Progresses in the Analysis of Density Waves in Saturn's RingsAuthor Block: Nicole Rappaport 1 , S. W. Asmar 1 , R. G. French 2 , E. A. Marouf 3 , C. A. McGhee 21 JPL, 2 Wellesley College, 3 San Jose State University.Presentaon Time: 10/5/2010 1:50 PM - 2:00 PMLocaon: Ballroom DAbstract: Table I. Objecves.OBJ. No. DESCRIPTIONABCVerify the nonlinear theory of density waves.Compute the non-linear torques exerted on the satellites.Idenfy damping modes.Rappaport et al. (2009) designed a procedure to analyze RSS ring opcal depth profiles. Recently we have designed an improved method. Two common conceptsof the two approaches are that they use the nonlinear theory of density waves and that they rely on a combinaon of mulple opcal depth profiles. The maindifferences are summarized in Table II.Table II. Methods.FIRST PROCEDURE1 • USE FEW LOW RESOLUTION RSS PROFILES.NEW METHOD•REQUIRES SEVERAL OR MANY LONG PROFILES.Advantages Disadvantages Advantages DisadvantagesWorks with 12 profiles, even badlydistributed.Opposite of A1.A1: Increase coherency of and confidence in the results.Meet obj. C.Requires combining data from differentinstruments.2 • •

2 DETERMINE THE PEAK LOCATIONS TO INFER INITIAL CONDITIONS. USE THE FIRST PROCEDURE TO GET THE INITIAL CONDITIONS.Advantages Disadvantages Advantages DisadvantagesCan be done by clicking on the profileplots.3 • CONSISTS OF TWO MAIN SUCCESSIVE STAGES.Time consuming.No confidence far from resonance.A2: Start with good inial condions. Requires pre-processing.•CONSISTS OF A SINGLE LEAST SQUARE FIT.Advantages Disadvantages Advantages DisadvantagesFuncons are determined separately. Opposite of A3.4 • MODELS THE REGIONS AROUND THE PEAKS.A3: Maximum accuracy since the five funcons areinter-related.•USES ALL THE POINTS.Requires many high resoluon data.Advantages Disadvantages Advantages DisadvantagesInial condions do not have to bevery good.5 • USES THE WKBJ APPROXIMATION.Throw away a lot of informaon, which leadsto approx.A4: Increased accuracy. None.•DOES NOTAdvantages Disadvantages Advantages DisadvantagesNone Opposite of A5. A5: Meet objecve B. None.22.04: Holes in Saturn's RingsAuthor Block: Kevin Baillie 1 , J. E. Colwell 1 , L. W. Esposito 21 University of Central Florida, 2 LASP - University of Colorado.Presentaon Time: 10/5/2010 2:00 PM - 2:10 PMLocaon: Ballroom DAbstract: Using UVIS stellar occultaon data, we analyzed isolated and unexpected high photon counts in different places. These "ghosts" are like holes in aringlet or plateau through which we directly observe the star: it is therefore characterized by an isolated peak in photon counts with a height equal to photoncounts in places without ring material.In order to detect ghosts, we focus on the plateaus in the Cassini Division and in the C ring and on the B ring. (The A ring contains so many clumps from selfgravitywakes that it consists almost enrelyof clumps and ghosts.) We have idenfied 45 ghosts in the C ring and 57 in the Cassini Division. We have also idenfied lower probability potenal ghosts (79 inthe C ring and 24 in the Cassini Division).We rule out cosmic rays as a cause of these high count rates by analyzing the frequency of high counng rates above the stellar signal. Applying this process toall our idenfied potenal cosmic rays allowed us to clearly idenfy 89 cosmic ray events out of 65443330 measured points. Therefore we derived a density of 1cosmic ray hit per 735318 points. Our detected potenal ghosts are very unlikely cosmic rays and rather due to some actual structure in the rings.We suggest that ghosts are the signatures of ephemeral structures in the rings that could be due to parcularly large clumps of material or small moonlets. Theusual S-shape around a "propeller" moonlet coincides with the presence of a hole around the clump: these moonlets are probably not massive enough to open fullgaps, but could produce azimuthally limited holes in the rings like those seen in the UVIS occultaon data.22.05: Rigid Aggregate Formaon (and Destrucon) as a Mechanism for Emergent Parcle Properes in Saturn’s Outer A RingAuthor Block: Randall P. Perrine 1 , D. C. Richardson 11 Univ. of Maryland.Presentaon Time: 10/5/2010 2:10 PM - 2:20 PMLocaon: Ballroom DAbstract: We connue our studies modeling rigid bonding within dense N-body systems in local coordinates, such as may occur in Saturn’s A and B rings.Laboratory experiments [1] suggest that such bonding is common if the parcles are coated in a layer of frost, and recent work [2, 3] shows that such “scky”parcles may account for unexplained dynamics within the dense rings.Our modified version of pkdgrav [4] includes the unique capability to model the creaon and destrucon of rigid bonds of arbitrary strength between collidingparcles in a non-ineral rotang frame. Parcles impacng below a user-defined speed threshold form a rigid bond that may subsequently break (withoutdeformaon), given sufficient impact speed or stress. While the strength of these frosty bonds remains uncertain, our work begins with plausible assumponsbased on currently available data. We present results from 3D simulaons of ring material (approximately a third of a square km in area) that explore theparameter space, including a range of merging and fragmentaon thresholds, bond strengths, ring surface densies, and parcle sizes. We show that areasonable range of these parameters is consistent with data for emergent parcle properes in the A ring, as seen by Voyager [5]. In matching to theseobservables, this range provides constraints on the bonding process potenally at work in the dense rings of Saturn.This work is supported primarily by a NASA Earth and Space Sciences Fellowship (NESSF).References: [1] Eg. Hatzes et al. (1991), Icarus 89, 113-121. [2] Tremaine (2003), Astron. J. 125, 894-901. [3] Porco et al. (2008), Astron. J. 136, 2172. [4] Perrine etal. (2010), Icarus, submied. [5] Zebker et al. (1985), Icarus 64, 531-548.22.06: Saturn’s Rings Thermal Opposion Effect with Decreasing Solar Elevaon as seen by Cassini CIRSAuthor Block: Estelle Deau 1 , L. Spilker 1 , R. Morishima 2 , S. Brooks 1 , C. Ferrari 3 , S. Pilorz 4 , N. Altobelli 51 Jet Propulsion Laboratory NASA, 2 LASP, University of Colorado, 3 AIM Paris-Saclay, Université Paris-Diderot CEA/Irfu CNRS/INSU, France, 4 SETI Instute,5 ESA/ESAC, Spain.Presentaon Time: 10/5/2010 2:20 PM - 2:30 PM

Locaon: Ballroom DAbstract: From 2004 to 2010, the Composite Infrared Spectrometer (CIRS) onboard Cassini spacecra took more than 50,000 spectra of the rings. By fing theFocal Plane 1 (FP1) spectra (16.67 - 1000 microns) with a blackbody model (Spilker et al. 2005, Planetary and Space Science 2006, vol. 54 pp1167-1176), we obtainthe effecve ring temperature T and the scale factor β, which includes the filling factor.We derived thermal phase curves, i.e. temperature as a funcon of phase angle, for 15 ring regions of 3000km across and for different ranges of solar elevaon(0°< |B'|< 25°).The thermal phase curves from almost zero to 50 degrees phase angle do not show any small surge (< 3°) contrary to that previously observed atopcal wavelengths, mainly due to lack of high data sampling at low phase angles. They are well fit by a linear funcon, for which we defined a slope and atemperature corresponding to the near-zero phase angle. At equinox, when the solar elevaon is zero, thermal phase curves are flat and temperatures are thecoldest ever reached during the prime and equinox missions.The trends of the temperature's decrease with phase angle for decreasing solar elevaon are different for the thickest ring (B ring) and the thinnest ring (C ring).In the B ring, the absolute slope of thermal phase curves increases with decreasing solar elevaon |B'| whereas the thermal phase curves of the C ring atdifferent |B'| seem almost parallel. We aribute these variaons to the shadowing effect that is a combinaon of the fracon of non-hidden parcles as seen bythe observer and by the Sun.Interesngly, the filling factor β from CIRS spectra decreases with decreasing solar elevaon. This implies that the shadowing effect could play a role in bothparameters β and T.22.07: Ring Equinox Temperature Variaons from Cassini CIRSAuthor Block: Linda J. Spilker 1 , C. Ferrari 2 , R. Morishima 3 , A. Flandes 4 , N. Altobelli 5 , C. Leyrat 6 , S. Pilorz 7 , S. Edgington 11 JPL, 2 AIM Paris-Saclay, Université Paris-Diderot CEA/Irfu CNRS/INSU, France, 3 LASP, Univ. of Colorado, 4 Instuto de Geosica, UNAM, Mexico, 5 ESA/ESAC,Spain, 6 Observatoire de Paris - LESIA, France, 7 SETI Instute.Presentaon Time: 10/5/2010 2:30 PM - 2:40 PMLocaon: Ballroom DAbstract: Cassini’s Composite infrared spectrometer (CIRS) retrieved the temperatures of Saturn’s main rings at equinox as the sun traversed from the south tonorth side of the rings. At equinox the solar input is very small and the primary heat sources for the rings are Saturn thermal and visible energy. The main ringscooled to their lowest temperatures measured to date. The ring temperatures at equinox were: C ring, 55-75 K; B ring, 45-60 K; Cassini Division, 45 - 58 K; and Aring, 43 - 52 K.The equinox geometry is unique because Saturn heang dominates, contrasted to earlier in the mission when the primary heat source is light from the sun.Equinox temperatures are almost idencal for similar geometries on the north and south sides of the main rings. Overall, the temperatures decrease withincreasing distance from the planet as expected but each ring displays a slightly different behavior. For the C ring the temperature varies slightly with the Saturnlocal me on the parcle while the temperature for the densest part of the B ring does not vary with changing geometry. Equinox results will be presented.This research was carried out at the Jet Propulsion Laboratory, California Instute of Technology, under contract with NASA and at CEA Saclay supported by theCNES and CEA. Copyright 2010 California Instute of Technology. Government sponsorship acknowledged.22.08: Scaering Properes of Saturn’s Rings from Cassini UVIS SpectraAuthor Block: Eric Todd Bradley 1 , J. E. Colwell 1 , L. W. Esposito 21 Univ. of Central Florida, 2 Univ. of Colorado.Presentaon Time: 10/5/2010 2:40 PM - 2:50 PMLocaon: Ballroom DAbstract: The Cassini Ultraviolet Imaging Spectrograph (UVIS) has acquired FUV spectra of the A, B, and C rings as well as the Cassini Division. The normalizedreflectance (I/F) in all four regions shows a characterisc water ice absorpon feature edge near 1650 Å. The spectral locaon and shape of the absorponfeature has been compared to both Hapke and Shkuratov reflectance models in order to retrieve the ring parcle scaering properes. One modeled parameter,the photon mean path length (L), is a measure of the amount of water ice that incident solar photons traverse before exing the ring parcles in the direcon ofthe detector. For larger path lengths the spectral locaon of the absorpon edge shis towards longer wavelengths. This shi is due to the spectral variaon ofthe absorpon coefficient, which for water ice decreases dramacally for wavelengths above 1600 Å. Typical values of L are less than 10 microns which impliesthat FUV photons only penetrate the outermost regolith grains covering the ring parcles. These small L values may be the result of scaering centers within aregolith ice grain consisng of cracks or contaminants and thus do not necessarily indicate the sizes of ice grains. Making use of the large number ofobservaons made by UVIS since 2004 the retrieved value of L shows a trend with phase angle. A possible explanaon for this effect is the relave importance ofmulple scaering at different phase angles. We will discuss these results as well as a comparison of the two models.22.09: The Fate if Circumplanetary Dust GrainsAuthor Block: Daniel Jontof-Huer 1 , D. P. Hamilton 11 University of Maryland.Presentaon Time: 10/5/2010 2:50 PM - 3:00 PMLocaon: Ballroom DAbstract: Charged dust grains in planetary ring systems experience both gravitaonal and electromagnec forces. Large grains orbit the planet along Keplerellipses, perturbed slightly by non-gravitaonal forces, while the smallest grains, controlled by Lorentz forces, spiral around planetary magnec field lines. Weexplore the stability of dust grain orbits between these regimes, covering a wide range of charge-to-mass raos and launch distances; first in an aligned dipolefield and then in more complicated magnec field geometries.With an aligned dipole, some negavely charged grains are unstable to vercal perturbaons via an instability first idenfied by Northrop and Hill (1982). TheNorthrop and Hill model ignores the effect of gyromoon which acts to parally stabilize the orbits of Kepler launched grains via the magnec mirroring process.We include this effect and derive new condions for instability. In addion, posively charged grains for which gravity and Lorentz forces are comparable haveorbits that are radially unstable to escape at high speed (if launched outside synchronous orbit), or to crash into the planet (if launched within synchronous orbit).We map the stability regions of the giant planets as a funcon of grain size and distance, and analycally derive many of the boundaries between stable andunstable trajectories.We also map the stability of grains orbing around the four giant planets, with the planetary magnec field accurately represented out to octupole components.In the non-axisymmetric fields of Jupiter, Uranus and Neptune, we find that negave grains outside synchronous orbit can sll escape, but the process is muchslower than for posive grains. We idenfy the cause of these escaping grains as destabilizing resonances driven by individual magnec field components.Similar resonances affect both posively and negavely charged grains inside synchronous orbit. Our theories are in good agreement with our numericalsimulaons.22.10: Constraining the Flux of Exogenous Dust Delivery onto Saturn Rings with CASSIN I-CDA

Author Block: Nicolas Altobelli 1 , S. Kempf 2 , V. Sterken 2 , G. Moragas 2 , R. Srama 2 , G. Schwehm 1 , E. Gruen 21 ESA, Spain, 2 M PIK, Germany.Presentaon Time: 10/5/2010 3:00 PM - 3:10 PMLocaon: Ballroom DAbstract: We present a progress report on the analysis of the CASSINI-CDA (Cosmic Dust Analyzer) data set to constrain the in-fall of exogenous dust into theSaturn’s system. Measuring the flux of parcles not gravitaonally bound to Saturn provides a crucial constraint on ring evoluon scenarii.The constant rain of dust parcles, probably rich in carbonaceous material, should darken the bright surface of icy ring parcles and the darkening rate can beenvisioned as a clock cking since the ring formaon.Dust parcles not gravitaonally bound to Saturn fall into two categories: parcles of interplanetary (IDPs) or interstellar (ISDs) origin. The later can in principlebe well characterized by their impact direcon, flux and size distribuon. In contrast, the IDP populaon at Saturn orbit is sll poorly characterized due to the lackof observaonal data. Contribuons from short period Jupiter family comet are expected as well as parcles generated by collisions in the Kuiper Belt andspiraling inwards the Solar system under Poynng-Robertson drag.22.11: Progress on Analysis of Keck AO Observaons of the Uranian Rings around the Time of the 2007 Ring Plane CrossingsAuthor Block: Imke de Pater 1 , D. Dunn 1 , H. Hammel 2 , M. Showalter 3 , S. Gibbard 4 , K. Mahews 5 , M. van Dam 6 , L. Sromovsky 7 , P. Fry 71 UC, Berkeley, 2 SSI, 3 SETI, 4 LLNL, 5 Caltech, 6 Flat Wavefronts, New Zealand, 7 U. Wisconsin-Madison.Presentaon Time: 10/5/2010 3:10 PM - 3:20 PMLocaon: Ballroom DAbstract: In 2007, the rings of Uranus appeared edge-on as seen from Earth for the first me since their 1977 discovery. Three ring plane crossings (RPXs)occurred from Earth’s perspecve over a ~9.5 months period: 3 May 2007, 16 August 2007, and 20 February 2008. The Sun crossed the ring plane on 7 December2007 (equinox). We observed at and near RPX using the Keck telescope equipped with the NIRC2 camera coupled to the adapve opcs system. This periodincludes the RPX on August 16, and observaons of the dark (unlit) face of the rings (May-August; December) and the lit side under small ring inclinaon angles(August-September). Together with observaons obtained in previous and later years, the data cover a wide range of viewing and emission geometries.As the rings are parally obscuring each other when the rings are close to being edge-on, we developed a model to analyze the observaons. The model wastested by Dunn, de Pater and Stam (2010, Icarus 208, 927-937) against observaons of the uranian rings that were taken in July 2004. Since then we made severalimprovements to the model to opmize it for low ring inclinaon angles. In this talk we compare Keck observaons with models under a wide range differentviewing and illuminaon angles.22.12: Applicaon Of A Stascal Accreon Model To Predict Undetected Moons Around Uranus In The Vicinity Of MabAuthor Block: Kark Kumar 1 , L. Benet 2 , C. H. Mena 3 , I. de Pater 4 , M. R. Showalter 51 Del University of Technology, Netherlands, 2 Universidad Nacional Autonoma de Mexico, Mexico, 3 Universidad Autonoma del Estado de Morelos, Mexico,4 University of California-Berkeley, 5 SETI Instute.Presentaon Time: 10/5/2010 3:20 PM - 3:30 PMLocaon: Ballroom DAbstract: In 2006, Showalter and Lissauer announced the discovery of the mu-ring around Uranus and a accompanying small moon Mab (Showalter andLissauer, 2006). They derived the orbital posion of Mab from both Voyager flyby (1986) and HST (2003-2006) data and showed that it is poorly understood. Theobserved posions were compared against an orbital model that includes gravitaonal flaening of Uranus. Although this model works well for nine otherUranian moons, for Mab the fing errors of the observed orbital moon are six mes larger. This indicates that we are currently overlooking an essenal part ofthe dynamics that determine the orbit of Mab. Known moons in the Uranian system do not perturb Mab sufficiently to account for the fing anomalies. Are thereundetected bodies in the Uranian system that affect Mab's orbit?In a previous study (Kumar et al., 2010), we applied a stascal accreon model (SAM) (Laskar, 2000) to determine the presence of undetected moons in thevicinity of Mab. We used a modified SAM, including different aggregaon criteria and employing conservaon of total angular momentum (Mena and Benet,2010). This model has been primarily used to simulate the evoluon of the solar system, in the secular limit.The results of our inial simulaons indicated that the environment around Mab is efficiently cleared such that only three to four large bodies remain when thesimulaons terminate (when the disc is collision-free). Observaonal constraints however imply that there must be more bodies in the neighbourhood of Mab.Hence, the suggeson is that the environment around Mab might not be collision-free.We revisit the previously obtained results and analyze configuraons of addional moons near Mab for systems that sll contain collision geometries. Based onthis new analysis, we indicate the likely configuraon of undetected bodies in the neighbourhood of Mab.

Session Number: 23Session Title: Centaurs and Trans-Neptunian Objects ISession Type: Oral23.01: Evoluon of the Known Centaurs Populaon - Dynamical and Thermal PathwaysAuthor Block: Gal Sarid 11 IfA/NAI, University of Hawaii.Presentaon Time: 10/5/2010 1:30 PM - 1:40 PMLocaon: Ballroom EAbstract: The structural and thermal evoluon of small Solar system bodies may be strongly dependent on their dynamical history and environment. Objects onplanet-crossing orbits are prone to gravitaonal perturbaons that de-stabilize their orbits. Such are the Centaurs, which are the transient populaon, betweenthe relavely stable trans-Neptunian objects (TNOs) and the short-lived Jupiter family Comets (JFCs). This may indicate that these objects experienceintermediate levels of internal processing, at different periods of their lives. Examining the evoluon of several these Centaur objects, both in orbital and physicalparameters, can help categorize the different states and origin and evoluon scenarios in the outer Solar system.Determining the dynamical evoluon of each object is achieved through stascal analysis of the results of mulple N-body integraons. This is achieved byusing many clones of specific objects, with known orbital elements. Stascs of large clone samples of specific objects yield valuable informaon about theircurrent states and future fates. Specifically, and with greater importance to thermal evoluon, we focus on the dynamical lifemes, survivability and mean orbitalelements. The laer are considered during the relavely stable and non-diffusive phase of orbital evoluon.Profiles of temperature, structure and composion are calculated ulizing our robust thermal evoluon code several specific objects, which represent slightlyvarying dynamical groups, and for different orbits of the same object, which represent specific orbital evoluon pathways. This has an influence on the internalstrafied structure, through an adapng thermal response of the nucleus.23.02: Size and Albedo of the Kuiper Belt Object 55636Author Block: James L. Elliot 1 , M. J. Person 1 , C. A. Zuluaga 1 , A. S. Bosh 1 , E. R. Adams 1 , T. C. Brothers 1 , A. A. S. Gulbis 2 , S. E. Levine 3 , M. Lockhart 1 , A. M. Zangari 1 ,B. A. Babcock 4 , K. DuPré 4 , J. M. Pasachoff 4 , S. P. Souza 4 , W. Rosing 5 , N. Secrest 61 M IT, 2 M IT & SALT, 3 USNOFS, AAVSO & M IT, 4 Williams College, 5 Las Cumbres Observatory, 6 U. of Hawaii.Presentaon Time: 10/5/2010 1:40 PM - 1:50 PMLocaon: Ballroom EAbstract: Due to the small sizes and great distances of Kuiper belt objects (KBOs), it is difficult to determine their diameters. We report mul-chordobservaons of a KBO stellar occultaon, which occurred on 2009 October 9 (Elliot, J. L., et al. 2010, Nature, 465, 897). We set up a network of 21 telescopes at18 staons, spanning a distance of 5920 km perpendicular to the predicted shadow path for the 2009 October 9 stellar occultaon by the KBO 55636. Of thesestaons, seven could not observe due to weather, nine reported non-detecons, and two observed an occultaon, both in Hawai'i: the 2.0-m Faulkes Northtelescope at Haleakala and a 0.36-m portable telescope at the Visitor Informaon Staon at the Onizuka Center for Internaonal Astronomy on Mauna Kea(located at the Mauna Kea Mid Level). We find that 55636 (2002 TX300), which is a member of the water-ice rich Haumea KBO collisional family (Brown, M. E., etal. 2007, Nature, 446, 294), has a mean radius of 143 ± 5 km (for a circular soluon). Allowing for possible ellipcal shapes we find a geometric albedo of 0.88+0.15/-0.06 in the V photometric band. This firmly establishes that 55636 is smaller than previously thought and like its parent body, Haumea, is among the mosthighly reflecve objects in the Solar System. Dynamical calculaons by two groups indicate that the collision that created 55636 occurred at least 1 Gyr ago(Ragozzine, D., & Brown, M. E. 2007, AJ, 134, 2160; Schlichng, H. E., & Sari, R. 2009, ApJ, 700, 1242), which implies either that 55636 has an acve resurfacingmechanism, or that fresh water ice in the outer solar system can persist for Gyr mescales. This work was supported, in part by NASA Grants NNX10AB27G (MIT),NNX08AO50G (Williams College), and NNH08AI17I (USNO-FS).23.03: Properes of the Large KBOs: Results from the Palomar Distant Solar System SurveyAuthor Block: Megan E. Schwamb 1 , M. E. Brown 2 , D. L. Rabinowitz 11 Yale Univeristy, 2 Caltech.Presentaon Time: 10/5/2010 1:50 PM - 2:00 PMLocaon: Ballroom EAbstract: We present the results of a wide-field survey using the 1.2-m Samuel Oschin Telescope located at Palomar Observatory. This survey was designed tofind the most distant members of the Kuiper belt and beyond. We searched ~12,000 square degrees within ± 30° of the eclipc down to a mean limingmagnitude of 21.3 in R. Although designed to probe the Sedna region, our survey probes the orbital properes of the hot classical, scaered disk, detached, andresonant populaons. A total number of 52 KBOs and Centaurs have been detected, 25 of which were discovered in this survey. We report our observed latudedistribuon and implicaons for the Pluno populaon parcularly the Kozai Plunos. Our survey also probes the bright end of the dynamically hot (i>5°) KBO sizedistribuon. We will discuss the brightness distribuon of the excited (i > 5°) Kuiper belt for the largest and brightest objects and compare to previous resultsfrom pencil-beam surveys constraining the faint end of the observed luminosity funcon.23.04: The Formaon Of Large Kuiper Belt Objects: Many Chips Off Of Many BlocksAuthor Block: Michael E. Brown 11 Caltech.Presentaon Time: 10/5/2010 2:00 PM - 2:10 PMLocaon: Ballroom EAbstract.Abstract: The large Kuiper belt objects exhibit one of the largest composional variaons of any class of objects in the solar system. These bodiesrange in composion from nearly pure ice to nearly pure rock, with a loose trend of increasing rock fracon with increasing size. This composional variability isunexpected: generic accreon and mixing models would suggest that these objects formed from essenally the same mixtures of primordial materials and thustheir composions should be nearly uniform and reflect a primordial ice-rock rao. Many of the large KBOs have apparent signatures of giant impacts, and thesegiant impacts have been suggested to play a role in removing ice form these bodies. However, the expected velocies of impacts that were common in the earlysolar system are too low to allow more than modest mass removal in any single event. We propose, instead, that removal of ice from large KBOs occurred as theobjects accreted from a series moderate-sized differenated bodies. Each impact between ~like-sized objects removes ~10% of the total mass of the system. In adifferenated body, this mass could be exclusively water ice. We will present simulaons showing how this process leads to a correlaon between size anddensity and how the densies of many of the known large KBOs fit within this paradigm. A few of the most extreme densies sll cannot be explained simply inthis context, but we discuss possible soluons.23.05: Transneptunian Binaries: Stascs of Orbital Properes

Author Block: William M. Grundy 1 , K. S. Noll 2 , M. W. Buie 3 , S. D. Benecchi 4 , H. G. Roe 1 , S. B. Porter 1 , F. Nimmo 5 , J. A. Stansberry 6 , D. C. Stephens 7 , H. F. Levison 31 Lowell Obs., 2 STScI, 3 SwRI, 4 PSI, 5 UCSC, 6 Univ. Arizona, 7 BYU.Presentaon Time: 10/5/2010 2:10 PM - 2:20 PMLocaon: Ballroom EAbstract: We present new mutual orbits of transneptunian binary systems (TNBs) from Hubble Space Telescope and Keck 2 laser guide star adapve opcsobservaons. Combining our new orbit soluons with previously published orbits yields a growing sample of mutual orbits for which the period P, semimajor axisa, and eccentricity e are known (23 and counng).The observed distribuon of orbital properes reveals several interesng characteriscs. The most loosely-bound TNB systems only occupy dynamically coldheliocentric orbits, implying a link between the mechanism that excited the heliocentric orbits and the stripping of loose binaries (although it remains possiblethat differences already existed before the excitaon of the heliocentric orbits). The existence of a number of TNBs with near-circular mutual orbits suggests thatsmall transneptunian bodies could be highly dissipave, in order for them to have become dally circularized within 4.5 Gyr. Many TNB systems undergo Kozaioscillaons of their eccentricies and inclinaons. The amplitudes of these oscillaons can be quite large for some of the more highly inclined systems. However,we see no evidence for any paucity of highly inclined systems, as might be expected if the highest amplitude eccentricity oscillaons resulted in stripping ofsatellites or parcularly rapid dal dissipaon and coalescence.Of our binary mutual orbits, sky-plane orientaon ambiguies are now resolved for 8, of which 6 are prograde and 2 are retrograde, consistent with a randomdistribuon of orbital orientaons, but not with models predicng a strong preference for retrograde orbits, as would be expected if dynamical fricon from a seaof small bodies gradually ghtened transiently captured binaries. Likewise, the existence of 2 retrograde orbits seems inconsistent with the uniformly progradeorbits expected if TNBs accreted via the streaming instability mechanism.23.06: Wide Trans-Neptunian Binaries as Dynamical TracersAuthor Block: Alex Parker 1 , J. Kavelaars 21 University of Victoria, Canada, 2 Herzberg Instute of Astrophysics, Canada.Presentaon Time: 10/5/2010 2:20 PM - 2:30 PMLocaon: Ballroom EAbstract: Ultra-wide, near-equal mass Trans-Neptunian binaries (TNBs) are difficult to create, very sensive to perturbaon, and represent 5-10% of all TNBs.Accurate mutual orbits and masses, derived from a long astrometric monitoring campaign, are presented for seven ultra-wide binaries in the Cold Classical KuiperBelt, six of which have non-degenerate pole soluons. We use the properes of these binaries to constrain the dynamical history and collisional environment ofthe Kuiper Belt. Due to the ease by which dal impulses can disrupt these systems, we find that a binary-bearing component of the Cold Classical Kuiper Belt wasnever subjected to a period of Neptune close encounters, and may have been formed in-situ. Addionally, we use the suscepbility of these systems to disruponby collision to determine an upper limit on the populaon of small (R>1km) objects in the current Kuiper Belt.Alex H. Parker is supported by the NSF-GRFP award DGE-0836694.23.07: The Common and Unique Composion of the Cold Classical Kuiper Belt ObjectsAuthor Block: Wesley Fraser 1 , M. E. Brown 11 California Instute of Technology.Presentaon Time: 10/5/2010 2:30 PM - 2:40 PMLocaon: Ballroom EAbstract: The surfaces of Kuiper belt objects exhibit an enigmac physical diversity; with the excepon of the largest methane-bearing objects, and thosemembers of the Haumea family, the cause of the broad range of albedos and reflectance spectra exhibited by these objects remains all but unexplained. Trends inphysical colour with other properes such as dynamical class suggest that different formaon histories resulted in different spectral classes of object. Thepossibility of using the surface properes of Kuiper belt objects to constrain their genesis is a tantalizing prospect that requires a more indepth understanding ofthe causes behind the diversity of these objects.We have executed a large spectro-photometric survey of 120 Kuiper belt objects using WFC3 on HST. This survey was designed to detect spectral features knownto exist on large objects, but on objects up to 3 magnitudes fainter than can be observed by ground-based observaons. This uniform sample of high-qualityobservaons has allowed us to idenfy many new properes and physical characteriscs of these confusing objects. A new trend in the opcal and near infraredcolours of cold classical objects has been revealed which is unique to this populaon alone. We find that a simple spectral absorbance model in which water-icecontent and grain-size are the only free parameters can fully account for not only the observaons from this project, but also other physical properes such asalbedo and colour previously observed for this populaon. This simple yet successful model demonstrates that these objects exhibit virtually the same surfacecomposion and have a thermal history common to all members. As this model cannot account for the range of colours and albedos observed in other Kuiper beltpopulaons, we conclude that the cold classical populaon has a different genesis than that of the rest of the Kuiper belt.23.08: Possible Evidence of a Collisional Break in the Color Distribuon of Resonant Kuiper Belt ObjectsAuthor Block: Ruth Murray-Clay 1 , H. E. Schlichng 2 , S. D. Benecchi 3 , K. S. Noll 41 Harvard-Smithsonian CfA, 2 CITA, Canada, 3 PSI/DTM, 4 STScI.Presentaon Time: 10/5/2010 2:40 PM - 2:50 PMLocaon: Ballroom EAbstract.Abstract: The power-law size distribuon of classical Kuiper belt objects exhibits a break at diameters of approximately 90km. Whether this breakreflects the primordial process of planetesimal formaon or ongoing collisional evoluon of KBOs remains a subject of debate, with implicaons for both of thehistory of the outer solar system and the physical properes of planetesimals. While many measurements of the opcal colors of KBOs have been obtained, fewdata are available for objects below the break in the size distribuon. Because KBOs in 3:2 resonance with Neptune range closer to the Sun than classical objects,more color informaon is available for small bodies in this dynamical class. Here, we demonstrate that KBOs in 3:2 resonance have colors that differ strongly withsize, and argue that this color dependence may show that the break in the size distribuon was generated by collisions.23.09: (90377) Sedna: Heterogeneous Surface ComposionAuthor Block: Crisna M. Dalle Ore 1 , M. Barucci 2 , A. Alvarez-Candal 3 , C. de Bergh 4 , F. Merlin 5 , C. Dumas 3 , D. P. Cruikshank 61 SETI Instute / NASA Ames Research Ctr., 2 LESIA, Observatoire de Paris, France, France, 3 ESO, Chile, 4 LESIA, Observatoire de Paris, France, 5 University ofMaryland, 6 NASA Ames Research Ctr..Presentaon Time: 10/5/2010 2:50 PM - 3:00 PMLocaon: Ballroom EAbstract: The peculiar TNO (90377) Sedna is one of the most remote solar system objects accessible to invesgaons (current heliocentric distance ~88AU).This dwarf planet is one of the reddest objects following the taxonomic group RR.

To beer constrain its surface composion and to invesgate the possible heterogeneity of the surface of Sedna, several observaons have been carried out atESO-VLT with the powerful spectrometer SINFONI, which observes the H and K bands simultaneously. Even if Sedna, given its faintness, was at the limit ofobservaons, the new analyzed spectra (obtained in 2005, 2007, and 2008) show a different behavior, parcularly in the K band. Spectral modeling using theShkuratov radiave transfer method has been performed using the various sets of data, including visible and Spitzer data, for a large wavelength range 0.4-4.5microns, and the albedo value (0.21) esmated by Stansberry et al. (2008). We find that the surface of Sedna is not completely homogeneous. The visible andnear-IR spectra can be modeled with organic materials (triton and tan tholin), serpenne, and H2O ice in fairly significant amounts, and CH4, N2 and C2H6 invarying trace amounts. One of the spectra, showing a different signature in the K-band, observed as part of the October 2005 group of data, is best modeled withCH3OH in place of CH4, with reduced amounts of serpenne and with the addion of olivine.The composional surface heterogeneity can give clues to the origin and past history of this peculiar distant object.23.10: A Southern Sky and Galacc Plane Survey for Bright Kuiper Belt ObjectsAuthor Block: Sco S. Sheppard 1 , A. Udalski 2 , C. Trujillo 3 , OGLE Team, M. Kubiak 2 , G. Pietrzynski 2 , R. Poleski 2 , I. Soszynski 2 , M. Szymanski 2 , K. Ulaczyk 21 Carnegie Inst. of Washington, 2 Warsaw University Observatory, Poland, 3 Gemini Observatory.Presentaon Time: 10/5/2010 3:00 PM - 3:10 PMLocaon: Ballroom EAbstract.Abstract: The OGLE Carnegie Kuiper belt Survey (OCKS) is one of the first Southern sky surveys for bright outer solar system objects. Starng in 2009we have covered a few thousand square degrees South of Declinaon -25 degrees where Northern KBO surveys cannot efficiently observe. The surveyed areaincludes almost all of the Southern sky within about 30 degrees of the eclipc. Our survey obtains a liming magnitude of about 21.5 in the R-band during opmalobserving condions using the 1.3 meter Warsaw telescope at Las Campanas observatory in Chile. We have also covered the area near the eclipc within theline-of-sight of the galacc plane for the first me using opmal image subtracon techniques in order to find moving objects with the high stellar densitybackground removed. To date our survey has discovered tens of bright Trans-Neptunian objects including several of the most Southern outer Solar System objectsever detected as well as some of the intrinsically brightest Solar System objects discovered in several years (2010 EK139 with H=3.8 and 2010 KZ39 with H=3.9).23.11: The 2010, February 19 stellar occultaon by VarunaAuthor Block: Bruno Sicardy 1 , F. Colas 1 , L. Maquet 1 , F. Vachier 1 , A. Doressoundiram 1 , F. Roques 1 , T. Widemann 1 , J. Orz 2 , M. Assafin 3 , F. Braga-Ribas 4 , J. I. B.Camargo 3 , R. Vieira-Marns 3 , A. Andrei 3 , D. da Silva Neto 3 , R. Behrend 5 , F. Hund 6 , M. Hauser 7 , S. Wagner 7 , A. Slotegraaf 8 , D. Willasch 8 , M. de Jesus Costa 9 , P.Melo Sousa 10 , E. Fausno 11 , A. Prazeres 11 , S. Machado 12 , J. Dias do Nascimento 13 , E. Souza Barreto 14 , A. Amorim 15 , P. da Rocha Poppe 16 , M. Geraldete Pereira 16 ,C. Jacques 17 , B. Loureiro Giacchini 17 , A. Collucci 18 , W. Ferreira da Costa 19 , V. Marns de Morais 201 Obs. de Paris, France, 2 Inst. Astrof. Andalucia-CSIC, Spain, 3 Obs. Valongo & Obs. Nacional, Brazil, 4 Obs. Valongo, Obs. Nacional & LESIA Obs. Paris, France,5 Obs. de Geneve, Switzerland, 6 Hakos farm, Namibia, 7 Landessternwarte, Koenigstuhl 12, Germany, 8 Stellenbosch Flying Field, South Africa, 9 OBAFIS-UEM A,Brazil, 10 SAM A, Brazil, 11 AAP-SAR, Brazil, 12 Quixada, Brazil, 13 Natal, Brazil, 14 Obs. Genival Leite, Brazil, 15 Florianopolis, Brazil, 16 Obs. Antares, Brazil,17 CEAM IG-REA, Brazil, 18 Vespasiano, Brazil, 19 Brasilia, Brazil, 20 Est. Astronomica PieGise, Brazil.Presentaon Time: 10/5/2010 3:10 PM - 3:20 PMLocaon: Ballroom EAbstract: On 2010, February 19, Varuna occulted UCAC2 star 41014042, as seen from regions in southern Africa and north-eastern Brazil.No occultaon was observed neither from the staon deployed in South Africa, nor from three other staons in Namibia. Out of twelve staons deployed in Brazil,seven had clouds or instrument malfuncons. Three were negave, one possibly posive (visual) is sll being analyzed, and one is definitely posive from SaoLuis (CCD). This makes Varuna the most remote solar system object observed to date through a stellar occultaon, with a geocentric distance of 6.4 billions km.The Sao Luis occultaon has a duraon of 52.5 +/- 0.5 sec, corresponding to a chord length of 1003 +/- 9 km projected in the plane of the sky. No atmosphericsignature is apparent in the light curve. Since the closest observaon to Sao Luis is negave at a transversal distance of 225 km (Quixada, CCD), a significantlyelongated shape is required for Varuna.We will discuss our results in view of current independent esmaons of Varuna's diameter combining IR thermal and visible data, with a typical value of ~1050km +/- ~200 km (Lellouch et al. 2002, Stansberry et al., 2008). We will also discuss the fact that the occultaon occurred near Varuna's maximum brightness alongits 6.4 hr rotaonal (0.4-mag amplitude) light curve. Thus Varuna was observed at maximum apparent surface area, which also corresponds to maximum apparentoblateness for an ellipsoidal shape.Lellouch et al, Astron. Astrophys. 391, 1133-1139 (2002).Stansberry et al., in The Solar System beyond Neptune (eds Barucci, M. A.,Boehnhardt, H., Cruikshank, D. P. & Morbidelli, A.) 161-179 (Univ. Arizona Press, 2008).This work is parally supported by french ANR 08-BLAN-0177 "Beyond Neptune".23.12: Hubble Space Telescope Observaons of Haumea during a Predicted Mutual EventAuthor Block: Darin Ragozzine 1 , M. E. Brown 21 Smithsonian Astrophysical Observatory, 2 California Instute of Technology.Presentaon Time: 10/5/2010 3:20 PM - 3:30 PMLocaon: Ballroom EAbstract.Abstract: The dwarf planet Haumea is one of the most interesng objects in the solar system with a highly ellipcal shape, two moons, and as theprogenitor or the only known collisional family in the Kuiper belt. Despite being one of the most well-observed objects beyond Neptune, some of Haumea's basicproperes (e.g., density) are poorly known or based on model assumpons. Through a fortuitous alignment of the inner satellite, Namaka, we can significantlyimprove our understanding of this important body with a detailed characterizaon of a Haumea-Namaka mutual event. Similarly to the informaon-rich Pluto-Charon mutual events, the Haumea-Namaka mutual events promise to reveal an accurate size, shape, albedo, density, and spin pole orientaon of Haumea, alongwith a measurement of the size, albedo, and density of the inner satellite Namaka, and improved orbits of both Namaka and Hi'iaka (through measuringperturbaons on Namaka's orbit). Although enrely fulfilling these goals requires observing several mutual events, the single well-characterized mutual event weaempted to observe will provide valuable first steps in this direcon and will provide crucial ming informaon required for intrepretaon of other events, pastand future. So far, ground based observaons have been limited by systemac errors (such as the unknown but significant light curve of Hi'iaka). We haveobtained Hubble Space Telescope observaons of Haumea during the June 28, 2010 mutual event, predicted to be a nearly central transit of Haumea by Namakaand a grazing shadow-transit. We have confirmed that HST has successfully observed Haumea and its satellites in 270 ~45-second exopsures spanning 10 orbits(~15 hours). We will present photometric and astrometric analyses of these data and discuss their implicaons for Haumea. This work is based on NASA/ESAHubble Space Telescope program 12243 and is supported by NASA with grants from the Space Telescope Science Instute.

Session Time: 10/5/2010 3:30 PM

Session Number: 10Session Title: Venus: Results from Venus Express and Ground Based ObservationsSession Type: Poster10.01: The Odd-nitrogen Chemistry Of The Near- and Post-terminator Thermosphere Of VenusAuthor Block: Jane Fox 11 Wright State University.Presentaon Time: 10/5/2010 3:40 PM - 3:42 PMLocaon: Exhibit HallAbstract.Abstract: We invesgate the odd nitrogen chemistry of the near- and post-terminator thermosphere of Venus by numerical modeling of the densityprofiles of N, NO, and NO+ (along with the 13 other ions, and 7 other neutral species) in our Venus thermosphere/ionosphere model. Odd nitrogen is produced onthe dayside by N2 photo- and electron-impact dissociaon, and ion-molecule reacons. Odd nitrogen species are interconverted rapidly. Atomic nitrogen (andatomic oxygen) are transported to the nightside from the dayside. In a 1-D model, we mimic the day-to-night transport of N by introducing a flux of N at the top ofthe model (as others have done, including Gerard et al., 2008). The VTGCM of S. Bougher (e.g., Stewart et al., 1980; Gerard et al., 1981) has also been used tomodel horizontal and downward transport of N and O atoms to produce the nitric oxide nightglow. Our model is constrained by the limb profiles of the nightglowemissions of the nitric oxide gamma and delta bands, as measured by the SPICAM on VEX, by the surface brightnesses of these emissions measured by thePioneer Venus Orbiter Ultraviolet Spectrometer, and by comparison of the N density profile to those of the VTS3 and VIRA models. We find that we cannotreproduce a maximum in the density profiles of N without a finite value for the rate coefficient for the reacon N + CO2= NO + CO. Measurements to date haveonly yielded upper limits for this rate coefficient. We use our model calculaons to esmate the value (or range) of the rate coefficient.10.02: The Structure of the Venus Neutral Atmosphere as seen by the Radio Science Experiment VeRa on Venus ExpressAuthor Block: Silvia Tellmann 1 , B. Haeusler 2 , M. Paetzold 1 , M. K. Bird 3 , G. L. Tyler 4 , T. Andert 2 , S. Remus 51 Rheinisches Instut fuer Umwelorschung, Abteilung Planetenforschung, Germany, 2 Instut fuer Raumfahrechnik, Universitaet der Bundeswehr Muenchen,Germany, 3 Argelander-Instut fuer Astronomie, Universitaet Bonn, Germany, 4 Department of Electrical Engineering, Stanford University, 5 ESAC, ESA, Spain.Presentaon Time: 10/5/2010 3:42 PM - 3:44 PMLocaon: Exhibit HallAbstract.Abstract: The Venus Express Radio Science Experiment VeRa performs regular radio-sounding measurements as part of the ESA Venus Express (VEX)mission since 2006. The first nine occultaon seasons yielded more than 350 observaons. The polar orbit of Venus Express provides us with the opportunity tostudy the troposphere and mesosphere in the altude range of 40 to 90 km over a pole-to-pole range of latudes, and a wide range of local mes. We derivevercal profiles of temperature and pressure from retrieved profiles of neutral number density, and use these to invesgate the thermal structure as a funcon oflatudinal and temporal variability. The Venus mesosphere is highly variable as the result of atmospheric waves and turbulence. Profiles of atmospheric stacstability are latude dependent and nearly adiabac within the middle cloud region. Abrupt changes in the stac stability occur on and near the boundaries of themiddle cloud layer, the vercal distribuon of which shows a disnct latudinal dependence. We plan further study of the correlaons of wave acvity with thestac stability.10.03: The Synthec Spectrum of Venus in the 8-micron RegionAuthor Block: Therese Encrenaz 11 Obs. de Paris, France.Presentaon Time: 10/5/2010 3:44 PM - 3:46 PMLocaon: Exhibit HallAbstract: The thermal emission of Venus in the 1220-1380 cm-1 range, observable from the ground, probes the upper atmosphere, above the H2SO4 clouds.Depending upon the altude of the upper clouds, the brighness temperature of the connuum, as measured by the Venera probes, is expected to range betweenabout 220 and 240 K. A calculaon of the synthec spectrum of Venus at high resoluon (R > 50000) shows that transions of CO2, HDO and SO2 are expected tobe detectable. Mapping the disk of Venus from the ground in the 8-micron region, both on the night side and on the day side, at the me of quadrature, shouldgive informaon upon the variaons of SO2 as a funcon of latude which are presently a maer of debate. In addion, day-night variaons of H2O could also bestudied through the use of HDO transions, and a global esmate of the D/H rao above the clouds could be inferred.Such observaons could be performed using the TEXES high-resoluon imaging spectrometer at IRTF and, in the future, with the EXES instrument aboard theSOFIA spacecra. This program will fully complement the VIRTIS/VEx observaons which probe HDO and SO2 in the lower atmosphere of Venus in the 2-4 micronregion.10.04: Photochemical Distribuon of Venusian Sulfur and Halogen SpeciesAuthor Block: C. D. Parkinson 1 , F. Mills 2 , A. Brecht 1 , S. W. Bougher 1 , Y. L. Yung 31 Univ. of Michigan, 2 Australian Naonal University, Australia, 3 California Instute of Technology.Presentaon Time: 10/5/2010 3:46 PM - 3:48 PMLocaon: Exhibit HallAbstract: The photochemistry of Venus’ atmosphere from the cloudtops to 110 km has been modeled using an updated/expanded chemical scheme, with theview to improving our understanding of the vercal distribuons of sulfur and halogen species. We mainly follow Yung and DeMore (1982), Mills (1998), Perniceet al. (2004), and Krasnopolsky (2009) in our choice of chemical reacons, chemical rate constants, and boundary condions for several key species. We examinetwo models, with HCl mixing raos of 10-7 and 4 x 10-7, respecvely. The former corresponds to Venus Express observaons made at high northern latudes andthe laer to the mid- to low-latude value Young (1972) determined based on infrared measurements by Connes et al (1967). Both models agree sasfactorilywith stratospheric observaons of key species such as CO, O2 and SO2, but we hope to beer quanfy the implicaons of the different HCl mixing raosobserved. Addionally, we perform sensivity tests where water is set to ~31 ppm at 40 km, but vary the SO2 mixing rao at the lower boundary about a nominalvalue of ~25 ppm. We also consider a range of eddy diffusion profiles and other sensivity studies. For most cases, K = Ko (n(z)/n_ref)-a, where Ko is the eddydiffusion coefficient at some reference altude, n is the number density, z is altude, and a is the variable parameter (

Cosmica, Italy.Presentaon Time: 10/5/2010 3:48 PM - 3:50 PMLocaon: Exhibit HallAbstract: Near-infrared spectra from the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on Venus Express have been used to invesgate thevercal structure and global distribuon of cloud properes on Venus. The spectral range covered by VIRTIS is sensive on the nightside to absorpon by thelower and middle cloud layers, which are back-lit by radiaon from the lower atmosphere and surface. The cloud model used to interpret the spectra is based onprevious work by Pollack (1993) and others, and assumes a composion for the cloud parcles of sulfuric acid and water, with acid concentraon as a freeparameter to be determined. Other retrieved parameters are the average size of the parcles and the altude of the cloud base in the model. The sensivity tothese variables across the measured spectral range (1.5 to 2.6 µm) is invesgated, and radiances at suitable pairs of wavelengths are used in model branch plotsto recover each variable independently.Spaal variaon of sulfuric acid concentraon in the cloud parcles has been esmated for the first me. This is then used in the determinaon of other cloudproperes and gaseous abundances. Key findings include increased acid concentraon and decreased cloud base altude in regions of opcally thick cloud, apeak in cloud base altude at -50°, and an increased average parcle size near the pole. These results are being used to develop beer models of the structureand variability of the clouds, which are needed to understand the chemistry, meteorology and radiave energy balance on Venus.This research is supported by the Science and Technology Facilies Council (UK) the Centre Naonale d'Etudes Spaales (France), the Agenzia Spaziale Italianaand ESA.10.06: Meteoroid Collisions in Interplanetary Space: Stascal Properes of Isolated Pressure Pulses in the Solar Wind Plasma Known as InterplanetaryField EnhancementsAuthor Block: Hairong Lai 1 , C. T. Russell 1 , G. L. Delzanno 2 , J. G. Luhmann 3 , K. D. C. Simunac 4 , A. Opitz 5 , A. Weggmann 61 University of California, Los Angeles, 2 Los Alamos Naonal Laboratory, 3 UCBerkeley, 4 University of New Hampshire, 5 Centre d’Etude Spaale desRayonnements, France, 6 University of Cologne, Germany.Presentaon Time: 10/5/2010 3:50 PM - 3:52 PMLocaon: Exhibit HallAbstract: Interplanetary Field Enhancements (IFEs) appear as smoothly varying cusp-shaped enhancements in the interplanetary magnec field which lastminutes to many hours. They were discovered almost 30 years ago in the Pioneer Venus magnec field records and aributed to dust released by asteroids andcomets because the locaon of some of the IFEs occurred where the comet 2201 Oljato crossed the Venus orbital plane and because the IFEs recurred at eachOljato apparion. We use Helios and STEREO data to examine the properes of IFEs such as their spaal distribuon in eclipc longitude and radial distance,their size distribuon and plasma properes. We find that at 1 AU, the spaal distribuon is greater at discrete longitudes. We also find that more than half of IFEevents consist of cool low-beta plasma. In these events, the increase in magnec pressure during an IFE can be compensated by a decrease in the plasmapressure, suggesng that the center of the disturbance is a “cold” region, possibly where the dust has displaced the solar wind ions. We interpret these featuresas regions of dusty plasma produced by meteoroid collisions.10.07: Solar Cycle Effects of Importance for Current Planet-Solar Wind Interacon StudiesAuthor Block: Janet Luhmann 1 , C. O. Lee 1 , T. McEnulty 1 , D. Ulusen 1 , L. K. Jian 2 , H. Y. Wei 2 , Y. J. Ma 2 , C. T. Russell 2 , K. C. Hansen 3 , T. L. Zhang 4 , E. Dubinin 5 , S.Barabash 61 UC, Berkeley, 2 UCLA, 3 University of Michigan, 4 IWF, Austria, 5 M PS, Germany, 6 IRF, Sweden.Presentaon Time: 10/5/2010 3:52 PM - 3:54 PMLocaon: Exhibit HallAbstract.Abstract: We consider condions on the Sun and in interplanetary space during the recent solar cycle minimum, and their potenal effects on what hasbeen observed on Venus and Mars Express and Cassini. In parcular we consider how solar wind parameters, in combinaon with low solar EUV fluxes, may haveaffected our overall interpretaons of what is concluded from studies ranging from the Venus and Mars ion escape rates and processes to the number of mesTitan flybys occur outside Saturn's magnetopause. This poster thus serves as a reminder of the influences of the solar cycle, and the ming and duraon ofplanetary missions, on both what is observed and what we conclude from the observaons.

Session Number: 25Session Title: Enceladus PostersSession Type: Poster25.01: Using Cassini UVIS Data to Constrain Enceladus’ Libraon StateAuthor Block: Terry Hurford 1 , P. Helfenstein 2 , C. Hansen 31 NASA GSFC, 2 CRSR, Cornell University, 3 JPL.Presentaon Time: 10/5/2010 3:50 PM - 3:52 PMLocaon: Exhibit HallAbstract: Given the non-spherical shape of Enceladus, the satellite may experience gravitaonal torques that will cause it to physically librate as it orbitsSaturn. Physical libraon would produce a diurnal oscillaon in the longitude of Enceladus’ dal bulge, which could have a profound effect on the diurnal stressesexperienced by the surface of the satellite. Although Cassini ISS has placed an observaonal upper limit on Enceladus’ libraon amplitude, small amplitudelibraons may have geologically significant consequences. For example, a physical libraon will affect heat producon along the ger stripes as produced by dalshear heang and a previous study has explored possible libraon states that provided beer matches to Cassini CIRS observaons of heat along the gerstripes.Cassini UVIS stellar occultaons provided measurements of the column density of the Enceladus plume at two different points in Enceladus’ orbit and findcomparable column density values. This column density may be a reflecon of the amount of the ger stripe ris in tension and able to vent volales and aphysical libraon will also affect the fracon of ger stripe in tension at different points in the orbit. We have modeled the expected fracon of ger stripes intension under different libraon condions. Without libraon the amount of ger stripe ris in tension at both points in the orbit would not be comparable andtherefore may not allow comparable amounts of volales to escape. However, we idenfy libraon condions that do allow comparable amounts of the gerstripes to be in tension at each point in the orbit, which might lead to comparable column densies. The libraons idenfied coincide with possible libraonsstates idenfied in the earlier study, which used Cassini CIRS observaons.25.02: Detecon of OI630nm Emission in the Enceladus TorusAuthor Block: Shoichi Okano 1 , K. Kodama 1 , M. Kagitani 1 , Y. Kasaba 11 Tohoku Univ Japan, Japan.Presentaon Time: 10/5/2010 3:52 PM - 3:54 PMLocaon: Exhibit HallAbstract: Cassini observaons have revealed the presence of acve plumes of water from the south pole of Enceladus and atomic oxygen emissionsconcentrated in the orbit of Enceladus. If ground-based observaon of oxygen emission at 630nm in the Enceladus torus becomes possible, though it is difficultbecause of absorpon by telluric atmosphere, it will be useful to monitor the long-term variability of Saturn’s inner magnetosphere.We report the first detecon of OI 630nm emission in the Enceladus torus from the ground. Observaon was made at Mt. Haleakala from December 10, 2009through January 21, 2010 using an Echell spectrograph with resoluon of 37,000, coupled to a 40cm Schmidt-Cassegrain telescope. In observaon, spectrographslit (500” by 5.1” corresponding to 28.6R S by 0.29R S ) was placed at a distance of 4Rs in the eastern side of Saturn perpendicularly to the Saturn’s equatorialplane. The plate scale was 1.82”/pixel. Exposure me for each spectral image was 40 minutes and 30 spectral images were co-added to increase signal-to-noiserao.Observed Peak intensity of the OI630nm emission was 4±2 Rayleighs and the half-width in the north-south direcon was 1.7R S .The detecon of OI630nm emission in the Enceladus torus was made possible with the use of our own facility at Mt. Haleakala by remote operaon from Japanthrough internet. This means connuous observaons will allow us to provide meaningful results even the telescope is not a large one. A new telescopededicated to planetary observaon is desired. To meet this demand, a project to construct a new telescope at Haleakala is in progress. The new telescope will bean off-axis Gregorian type with a diameter of 1.8m. Details of the project and the telescope will be given at the presentaon.25.03: Global Geological Mapping of EnceladusAuthor Block: Emma Crow-Willard 1 , R. T. Pappalardo 21 Occidental College, 2 Jet Propulsion Lab.Presentaon Time: 10/5/2010 3:54 PM - 3:56 PMLocaon: Exhibit HallAbstract: Global geological mapping of Enceladus highlights 3 disnct tectonized regions, which we term trailing hemisphere terrain (THT), leading hemisphereterrain (LHT), and south polar terrain (SPT). All three terrains are framed by curvilinear terrain units, and all have comparable areal extent with the south polarterrain being the smallest. In its central region, the THT contains a unit consisng of smooth materials and long shallow troughs, which is nearly idencal tomaterials of the SPT just northward of the “ger stripes” and with similar orientaon of SPT troughs. This suggests that these shallow troughs may have formedin a similar manner to the SPT fractures. In contrast to the SPT, the THT contains a ridged unit of large dorsa, cross-cung a striated plains unit, all within theTHT’s frame of curvilinear terrain. The LHT contains a disorganized network of troughs similar to parts of the SPT. The LHT also has units with polygons of subparalleltroughs suggesng shearing. Heavily cratered terrain reaches around the saturnian and an-saturnian sides of the satellite, abung the south polarterrain. We recognize a total of 13 different geological units within the three tectonized regions and the cratered terrain of Enceladus. Differences in the localterrains might be explained by combinaons of local diapiric upli, collapse, and satellite reorientaon to form the tectonized terrains, ed to episodic localizedheat flow related to dal stresses.25.04: Small Crater Populaons on Enceladus and HyperionAuthor Block: Edward B. Bierhaus 1 , L. Dones 2 , K. Zahnle 31 Lockheed Marn, 2 Southwest Research Instute, 3 NASA Ames.Presentaon Time: 10/5/2010 3:56 PM - 3:58 PMLocaon: Exhibit HallAbstract: We will present our latest crater measurements for Enceladus and Hyperion, along with interpretaons and constraints on deriving an impactorpopulaon from the crater data.Connuing measurements of small crater populaons on Enceladus young terrains and Hyperion demonstrate a shallow (> -3) differenal slope for the cratersize-frequency distribuons (SFDs).We focus our measurements on these objects because they should be largely free of secondary craters, which add noise to the primary crater signal. (Enceladusyoung terrains because they are insufficiently old to accumulate a significant populaon of secondaries, and Hyperion because its low surface gravity is too lowto retain ejecta of sufficient velocity that would form secondaries.) Given the measured SFDs are in fact free of non-primary crater contaminaon, the currentimpactor flux through the saturnian system should express an equivalent SFD.

Measurements on young Enceladus terrains reveal crater density variaons from zero craters (within a large area around the south pole) to lightly cratered.Heavily cratered terrains on Enceladus (at equatorial and northern latudes) demonstrate steeper slopes, implying either changes in impactor flux SFD with me,or the addion of non-primary sources (e.g. secondaries) to the crater populaons. Our measurements are consistent with those of Kirchoff and Schenk (2009)[Icarus, v. 202], who found variaons in crater SFD as a funcon of locaon and terrain type.25.05: Hybrid Simulaon of the Gas/Parcle Plume of EnceladusAuthor Block: Seng Keat Yeoh 1 , T. A. Chapman 1 , D. B. Goldstein 1 , P. L. Varghese 1 , L. M. Traon 11 University of Texas at Ausn.Presentaon Time: 10/5/2010 3:58 PM - 4:00 PMLocaon: Exhibit HallAbstract.Abstract: Cassini first detected a water vapor plume near the warm, ice-covered south pole of Enceladus in 2005. Since then, more flybys have beenmade over the moon and have yielded spectacular images, details on the plume structure and composion, as well as the possible locaons of the contribungsources. Observaons suggest that the plume is composed of gas with ny entrained ice parcles. Based on the images and data from Cassini, we construct ahybrid model of the gas/parcle plume. The model divides the plume into two regimes. The direct simulaon Monte Carlo (DSMC) method is used in the regionnear the vent where the plume is relavely dense and collisional. This model incorporates ice grains into the gas flow. The parcle mass loading is assumed to below, thus the coupling is only one-direconal. The gas flow affects the parcle moon but not the other way. A range of possible vent condions is parametricallyexamined. The output of the DSMC model is fed into a computaonally less-expensive free-molecular model that simulates the far-field, where collisions arenegligible and the assumpon of non-collisional dynamics is adequate. The free-molecular model ulizes several pre-defined point sources on the surface ofEnceladus to produce a three-dimensional plume model, and includes the effects of a sublimaon atmosphere, a spuered atmosphere and background E-ringgas. The E3 and E5 flybys are simulated in the plume and the ideal results are convolved with a simulated instrument response funcon to account for adsorponand desorpon rates of the INMS instrument. The outcome can be directly compared to the in-situ measurements from Cassini. Stellar occultaon measurementsduring the flybys are also modeled. Simulaon results may be used to constrain the physical condions at the plume sources, such as temperature, velocity, ventgeometry and plume generaon mechanism.25.06: Thermochemical Constraints of the Old Faithful Model for Radiaon-Driven Cryovolcanism on EnceladusAuthor Block: Paul Cooper 1 , C. J. Franzel 1 , J. F. Cooper 21 George Mason University, 2 NASA Goddard Space Flight Center.Presentaon Time: 10/5/2010 4:00 PM - 4:02 PMLocaon: Exhibit HallAbstract: We have used a combinaon of thermochemical data, plume composion, and the esmated surface power flux to constrain the Old Faithful modelfor radiaon-driven cryovolcanism on Enceladus (1). This model proposes episodic cryovolcanic acvity brought about by the chemical reacon betweenreductants that are primordially present within Enceladus’s ice, and oxidants produced by energec parcles impacng the icy surface. Assuming no limit onaccumulaon of oxidants in the ice crust in the billions of years since formaon and subsequent magnetospheric irradiaon of Enceladus, this new work extends(1) by examining limits on acvity from reductant abundances. Our calculaons show that an almost negligible amount of methane or ammonia, compared withthe mass of Enceladus, would potenally be needed to account for the surface power flux of the gas plume over 10 million years of acvity, consistent withgeologic models for episodic overturn of the ice crust and heat flow (2). Liming the permanently ejected fluid mass during this me by the volume of thetopographical depression in the SPT of Enceladus, we have constrained the number rao of reductant-to-water. Results are in support of our model. In addion,using the measured abundances of CO 2 and N 2 (products of CH 4 and NH 3 oxidaon) in the plume, we have further constrained the amounts of CH 4 and NH 3 thatcould be present and these are also in line with our predicons. These calculaons fully support the Old Faithful model (1).1)Cooper, J. F., Cooper, P. D. Siler, E. C., Sturner, S. J., Rymer, A. M., “Old Faithful Model for Radiolyc Gas-Driven Cryovolcanism at Enceladus”, Planet. Space Sci.,57, 1607-1620,2009.2)O’Neill, C., F. Nimmo, “The Role of Episodic Overturn in Generang theSurface Geology and Heat Flow on Enceladus, Nature Geosci., 3, 88-91. 2010.25.07: Tidal Love Numbers and Tidal Heang of a Rotang BodyAuthor Block: Howard Houben 11 Bay Area Environmental Research Instute.Presentaon Time: 10/5/2010 4:02 PM - 4:04 PMLocaon: Exhibit HallAbstract.Abstract: Many studies of dal dissipaon in solar system objects make use of Love numbers (non-dimensional measures of the height of the dalbulge and the associated induced gravitaonal quadrupole moment) based on Kelvin's soluon for the deformaon of a homogeneous incompressible body. Thissoluon ignores (assumes negligible) the ineral terms in the equaons of moon. When the oscillatory dal me dependence is included, analyc soluons canbe obtained which, surprisingly, do not asymptote to Kelvin's soluon in the long-period limit. When the Coriolis terms are also included, a system of threecoupled second-order paral differenal equaons (for the three velocity components, or suitable substutes) results. Free surface boundary condions must besasfied. When the object is not homogeneous, the Poisson equaon for the gravitaonal potenal must also be solved. There appear to be no analyc soluonsfor this system, but numerical soluons are straighorward, and the results can be tabulated in terms of non-dimensionalized values of the rigidity, viscosity,forcing frequency, and rotaon frequency. This rotang system couples modes with different latude structures. The resulng dal torque is more complicatedthan usually assumed. In addion to the global net dal torque that exchanges rotaonal and orbital angular momentum (and thus leads to the tradional dalheang and orbital evoluon), local differenal torques act on the body. Depending on the body's long-term viscoelasc properes, considerable addionalheang (which does not affect the orbital evoluon and therefore does not figure in the calculaon of the body's dal dissipaon factor) may occur, parcularly ina layered, inhomogeneous object.25.08: The Extent Of Enceladus’ Mass-loading Region: Ion Cyclotron Wave Observaons And Parcle SimulaonsAuthor Block: Hanying Wei 1 , C. Russell 1 , M. Cowee 2 , J. Leisner 3 , Y. Jia 1 , M. Dougherty 41 Univ. of California Los Angeles, 2 Los Alamos Naonal Lab, 3 University of Iowa, 4 Imperial College, United Kingdom.Presentaon Time: 10/5/2010 4:04 PM - 4:06 PMLocaon: Exhibit HallAbstract: Cassini observaons have revealed that Enceladus, the Saturnian moon at 3.95 Saturn radii, is the mass-loading source for the neutral cloud in theinner magnetosphere. Enceladus‘ southern plume releases hundreds of kilograms of water-group neutrals per second. To understand the spaal scale of

Enceladus‘ mass-loading region and the me scale of the process, we use ion cyclotron wave observaons and a Monte Carlo parcle tracing simulaon toinvesgate this process. The ion cyclotron waves generated by the water group pickup ions are observed at all longitudinal separaons from Enceladus at themoon’s orbital distance, but are enhanced between forty degrees upstream and over a hundred degrees downstream. The waves extend radially from slightlyinsider Enceladus‘ orbit to outside of Dione’s, but this longitundinal asymmetry is only observed near the former distance. The development of such a large massloadingregion can be studied by using a parcle-tracing model, which assumes the neutral gas produced from Enceladus is first ionized, accelerated by thecorotaonal electric field and then dris away from the source region. Later they are neutralized by charge exchange and are transported across fieldlines as fastneutrals, which have a chance of escaping the Saturnian system without being re-ionized. This model was first developed to study the mass loading at Io. Byadapng it to Enceladus, we can examine the extent of the Enceladus‘ mass-loading region and the me scale of the process. Just like Io in the Jovianmagnetosphere, Enceladus plays an important role in the Saturninan magnetospheric dynamics. Studying the Enceladus mass-loading temporal and spaal scaleshelps us to understand the influence of the moon on the inner magnetosphere, and allows us to infer the behavior of the analogous processes in the Jovianmagnetosphere where we have many fewer observaons.

Session Number: 29Session Title: Mercury PostersSession Type: Poster29.01: Calcium In Mercury’s Exosphere: Modeling Messenger DataAuthor Block: Mahew H. Burger 1 , R. M. Killen 2 , R. J. Vervack, Jr. 3 , W. E. McClintock 41 NASA/GSFC and UM BC/GEST, 2 NASA/GSFC, 3 Johns Hopkins University Applied Physics Laboratory, 4 University of Colorado/LASP.Presentaon Time: 10/5/2010 4:00 PM - 4:02 PMLocaon: Exhibit HallAbstract: Although neutral calcium in Mercury’s exosphere was discovered by ground-based observaons, the Mercury Atmospheric and Surface ComposionSpectrometer (MASCS) on MESSENGER has made the first high-spaal-resoluon measurements of Ca in the tail region an-sunward of Mercury and over bothpoles. We use a Monte Carlo model of the exosphere to track the trajectories of Ca atoms and molecules (e.g., CaO) ejected from the surface unl they arephoto-ionized or dissociated, escape from the system, or sck to the surface. This model allows us to understand the exospheric source processes and theinteracons among neutrals, solar radiaon, Mercury’s magnetosphere, and the planetary surface. The MASCS data have suggested a stable, high-energy sourceof Ca that is enhanced in the dawn-side equatorial region. Although the origin of the asymmetry in the producon flux is uncertain, high-energy calcium atomscan be supplied through a two-step process. In the first step, CaO may be ejected from the surface by impact vaporizaon, spuering, or some other process. Thismolecule quickly photo-dissociates (within a few minutes), producing atomic Ca with ~2 eV excess energy, equivalent to a speed of 3 km/s. This speed is lessthan Mercury’s escape velocity (4.3 km/s), but radiaon pressure can push Ca produced near the terminator into the tail. Simulaons of possible source processesprovide insight into these scenarios. A beer understanding of the calcium source mechanism will be possible once MESSENGER enters orbit about Mercury andMASCS measures the global distribuon of exospheric calcium.29.02: The Evoluon Of Mercury’S Exosphere Through Four Years Of Observaon With ThemisAuthor Block: Alain Doressoundiram 1 , F. Leblanc 21 Observatoire de Paris, France, 2 LATM OS/IPSL, France.Presentaon Time: 10/5/2010 4:02 PM - 4:04 PMLocaon: Exhibit HallAbstract: Almost twenty years of ground based observaons have highlighted several features of Mercury’s exosphere which will further explore by twoforthcoming space missions to Mercury, MESSENGER to be inserted in 2011 and Bepi-Colombo to be inserted in 2020. Long and short term evoluons of theexosphere, local and global spaal distribuons, its sources and sinks and its coupling with both surface and magnetosphere are among the characteriscs ofMercury’s exosphere that begin to be more clearly understood. Actually, ground based observaons provide a view of Mercury’s exosphere that will be only poorlyseen by these two space missions. As an example, the global annual cycle of Mercury’s exosphere, its energec characteriscs and its large scale structure willbe poorly or not at all observed by these space missions. In this presentaon, we will summarize these points and will describe our most recent observaonsusing THEMIS Solar Telescope.29.03: Effect Of Pressure Coupling On The Rotaon Of MercuryAuthor Block: Benoit Noyelles 1 , J. Dufey 1 , A. Lemaitre 1 , ROMEO Team1 University of Namur, Belgium.Presentaon Time: 10/5/2010 4:04 PM - 4:06 PMLocaon: Exhibit HallAbstract.Abstract: We present an adaptaon of the Poincare model of core-mantle interacon (Poincare 1910, Touma &amp; Wisdom 2001) to Mercury, inwhich the planet is seen as composed of a rigid mantle and an ellipcal liquid core. Thanks to a Hamiltonian formulaon, we perform extensively both ananalycal (Lie transforms) and a numerical analysis of this 4-degree of freedom problem. This allows us to highlight a long-term behavior of the obliquity, theconsequences of the proximity of a resonance between the spin frequency of Mercury and the free core nutaon, and also the influence of the polar flaening ofthe core.29.04: Modificaon of Mercury’s Bulk Mantle Composion by Reaccumulaon of Condensed Ejecta from a Formave Giant ImpactAuthor Block: Sean Wahl 1 , D. J. Stevenson 2 , L. Elkins-Tanton 11 M IT, 2 Caltech.Presentaon Time: 10/5/2010 4:06 PM - 4:08 PMLocaon: Exhibit HallAbstract: Difficules encountered in reproducing Mercury’s composional aributes through modeling of formaonal processes have bolstered support for thehypothesis that one or more giant impacts stripped away a significant proporon of proto-Mercury’s silicate mantle. Previous invesgaons demonstratesufficient removal of mantle material to account for the planet’s unusually high mean density, but do not consider the effects of mulple silicate and oxidephases. In this study we extend the present theory by invesgang the consequences of a more realisc chemical model on the evoluon of the ejected material.We suggest that the majority of condensaon within the expanding vapor plume can be modeled as an equilibrium process following homogeneous nucleaon ofrefractory phases leading to larger parcle sizes than previously esmated. We use a thermodynamic model focused on major element composion of ejectedmaterial to analyze the effect of differenal condensaon on the expansion and final state of ejecta. For ejecta of sufficiently high specific entropy, our simplifiedchemical models indicate that energy released during condensaon of MgO-rich phases buffers the temperature, delaying or prevenng onset of FeOcondensaon. If sufficient spaal separaon between condensates and vapor arises or if significant amounts of uncondensed FeO vapor remain uncondensed,reaccumulated ejecta would be enriched in MgO and refractory phases. This is compable with an FeO depleon of Mercury’s surface relave to other terrestrialbodies as spectroscopic data suggest (McClintock, Science, 2008). Despite conflicts in the data and the necessity for further relang it to bulk mantlecomposion, we describe potenal tests of our model. Concentraon of incompable elements in the crust formed by a magma ocean would intensify FeO loss.The proposed process leads to a greater depleon in FeO and a lesser depleon in refractory, incompable elements (Al2O3, CaO, TiO2), than models assuminguniform removal of material from a differenated proto-Mercury.

Session Number: 38Session Title: Moon PostersSession Type: Poster38.01: Lyman Alpha Mapping Project (LAMP) Brightness MapsAuthor Block: Kurt D. Retherford 1 , G. Gladstone 1 , S. Stern 1 , A. F. Egan 1 , P. F. Miles 1 , J. W. Parker 1 , T. K. Greathouse 1 , M. W. Davis 1 , D. C. Slater 1 , D. E. Kaufmann 1 ,M. H. Versteeg 1 , P. D. Feldman 2 , D. M. Hurley 3 , W. R. Pryor 4 , A. R. Hendrix 51 Southwest Research Inst., 2 The Johns Hopkins University, 3 JHU Applied Physics Laboratory, 4 Central Arizona College, 5 Jet Propulsion Laboratory.Presentaon Time: 10/5/2010 4:10 PM - 4:12 PMLocaon: Exhibit HallAbstract.Abstract: The Lyman Alpha Mapping Project (LAMP) is an ultraviolet (UV) spectrograph on the Lunar Reconnaissance Orbiter (LRO) that is designed tomap the lunar albedo at far-UV wavelengths. LAMP primarily measures interplanetary Hydrogen Lyman-alpha sky-glow and far-UV starlight reflected from thenight-side lunar surface, including permanently shadowed regions (PSRs) near the poles. Dayside observaons are also obtained. Brightness maps sorted bywavelength (including the Lyman-alpha wavelength of 121.6 nm) are reported for the polar regions, with a few regions of interest reported in more detail. LAMP'sspectral range of 58 nm to 196 nm includes a water ice spectral feature near 160 nm, which provides a diagnosc tool for detecng water on the lunar surfacethat is complementary to recent discoveries using infrared and radio frequency techniques. Progress towards producing far-UV albedo maps and searching forwater ice signatures will be reported. We'll discuss how LAMP data may address quesons regarding how water is formed on the moon, transported through thelunar atmosphere, and deposited in the PSRs.38.02: The Extended Lunar Sodium Tail: Analysis of Brightest Ten NightsAuthor Block: Majd Mayyasi-Maa 1 , S. Smith 1 , J. Baumgardner 1 , C. Marnis 1 , M. Mendillo 11 Boston University.Presentaon Time: 10/5/2010 4:12 PM - 4:14 PMLocaon: Exhibit HallAbstract: The extended lunar sodium tail that forms at every new moon has been monitored connuously since April 2006 using an all-sky camera at theEl-Leoncito Observatory in Argenna. The 10 brightest observaons to date of the extended tail’s sodium imprint are analyzed and compared withmeteor, solar photon and solar wind acvity in search of correlaons to possible sources of variability in surface-spuering mechanisms.38.03: Lunar Sodium Exosphere Measured By Selene (kaguya)Author Block: Masato Kagitani 1 , M. Taguchi 2 , A. Yamazaki 3 , I. Yoshikawa 4 , G. Murakami 4 , K. Yoshioka 2 , S. Kameda 5 , S. Okano 11 Planetary Plasma and Atmospheric Research Center, Tohoku University, Japan, 2 Rikkyo University, Japan, 3 Instute of Space and Astronaucal Science, Japan,4 Department of Earth and Planetary Science, The University of Tokyo, Japan, 5 Planetary Exploraon Research Center, Chiba Instute of Technology, Japan.Presentaon Time: 10/5/2010 4:14 PM - 4:16 PMLocaon: Exhibit HallAbstract: The Moon is known to have a surface-bounded exosphere, that is, a collision-free tenuous atmosphere. Although many ground-based observaonshave been conducted under different condions of source candidates, connuous observaons from the ground covering the whole lunar phase have beendifficult because of strong reflected sunlight and geometrical constraints. Observaons from a lunar orbiter, however, would be free of the constraints of groundbasedobservaons. The present study presents the results of connuous observaons of the sodium exosphere from the same lunar polar orbiter over a period ofsix months.Observaons of the lunar sodium exosphere were conducted from December 2008 through June 2009 using the UPI-TVIS (UPI: upper atmosphere and plasmaimager; TVIS: telescope for visible light) instrument onboard the Japanese lunar orbiter SELENE (Kaguya). Variaons in line-of-sight integrated intensity measuredon the night-side hemisphere of the Moon could be described as a spherical symmetric distribuon of the sodium exosphere with a temperature of 2400 to 6000K. The average surface density in February is well above that in the other months, namely, by 30%. As for variaon depending on lunar-phase angle, the sodiumdensity gradually decreased by about 20% from the first to the last quarters during each lunar cycle, although any clear indicaon of changes in sodium densitycaused by the Moon’s passages through the Earth’s magnetotail could not be seen. One of the possible explanaons for such a density decay in a half lunar cycleis an inhomogeneous source distribuon of photon-smulated desorpon (PSD) on the lunar surface. If a sodium-rich region exists on the surface around λ = 90 ±90 degrees, increased release of sodium atoms by PSD will explain the observed result.38.04: A Concept for Small, Remotely Operated, Coronagraph located at Small Observatory Designed for Frequent, Low-cost Remote Observaons ofthe Lunar ExosphereAuthor Block: Thomas H. Morgan 1 , C. Playmate 2 , R. M. Killen 1 , A. E. Poer 21 NASA Goddard Space Flight Center, 2 Naonal Solar Observatory.Presentaon Time: 10/5/2010 4:16 PM - 4:18 PMLocaon: Exhibit HallAbstract: The sodium in the lunar exosphere serves as a marker species for studying the lunar exosphere because the element possesses two strong resonancetransions from the ground state whose wavelengths fall in the visible spectrum near 590 nm. Emissions at these wavelengths are thus, observable from Earth.Observaons have shown that the exosphere responds in a complex way to the external processes (impact vaporizaon, spuering, and photon smulateddesorpon) that weather the lunar regolith to produce the sodium. Unraveling the sodium producon allows us to study the processes that weather the regolith.Obtaining the extensive me sequence of observaons required to unravel the sources of sodium using convenonal observatories is impraccal, and tooexpensive. Effecvely imaging the lunar sodium exosphere close to the Moon requires an off-axis rejecon of scaered light that can only be obtained with acoronagraph.We present here a concept for a small, rugged coronagraph sited at an observatory dedicated to remote roboc observing (the Winer Observatory in SonoitaArizona) that can obtain the quality and quanty of lunar sodium observaons needed to answer these quesons. The design uses Commercial Off the ShelfTechnology (COTS). If this facility is operaonal by 2013, the observaons will be concurrent with the Lunar Atmosphere and Dust Environment Explorer (LADEE)mission.

Session Number: 40Session Title: Centaurs and Trans-Neptunian Objects, including WISE Mission ResultsSession Type: Poster40.01: Out Of Plane S-type Orbits In The Pluto-charon Binary SystemAuthor Block: Silvia M. Giulia-Winter 1 , E. Vieira Neto 1 , O. Winter 11 UNESP, Brazil.Presentaon Time: 10/5/2010 4:30 PM - 4:32 PMLocaon: Exhibit HallAbstract: Previous work (Giulia Winter et al, 2010) found several stable regions for parcles in S-type orbits around Pluto or Charon, whose families ofperiodic orbits have been idenfied through the analysis of the Poincaré surface of secons. In this work we present the results concerning parcles in orbitsaround Pluto and Charon taking into account different values of eccentricity and inclinaon. We numerically simulated a sample of parcles located between theorbits of these two massive bodies with eccentricity varying from 0 to 0.99 and the inclinaon ranging between 0 and 180deg. As a result we found that the sizeof the stable regions for those parcles around Pluto decrease while the inial inclinaon (I) of the parcles increases up to 110deg. For I = 100deg only a smallstable region at 0.5d, where d=19570km, and 0.2 < e < 0.3 is found. There is no stable region for parcles with inial inclinaon equals to 110deg. Aer I =120deg, the stable region starts increasing unl reaches its maximum for I = 180deg. No stable region was found for those parcles in orbits around Charon for80deg < I < 110deg. We will present the orbits of the parcles located in these stable regions.40.02: Hybrid Fluid Model with Analyc/DSMC Thermal Escape in Pluto’s AtmosphereAuthor Block: Jusn Erwin 1 , O. Tucker 1 , R. E. Johnson 11 University of Virginia.Presentaon Time: 10/5/2010 4:32 PM - 4:34 PMLocaon: Exhibit HallAbstract: Atmospheric escape from small bodies in the outer solar system is a highly acve research problem, and is of parcular interest with ongoing andfuture exploraon missions. This requires modeling such atmospheres in both the low and high Knudsen number regimes (dense and tenuous, respecully), withparcular aenon to the transion region between the two regimes. In many atmospheres of interest, non-thermal processes in the upper atmosphere driveescape. However, Pluto is an instance where heang in the lower atmosphere appears to drive the escape from the upper atmosphere.There is no efficient method to model both regimes together due to vastly different length scales involved. Models like Slow Hydrodynamic Escape (SHE) use thein viscid fluid equaon and apply them to the full atmosphere, and then fit the escape parameters to match an upper boundary condion at infinity or fit tomeasurement data. In place of an upper boundary condion, we require the escape parameters to agree with Jeans theory. From recent Direct-Simulated Monte-Carlo (DSMC) models, we believe that escape rates do not deviate significant from Jeans escape for atmospheres with moderate Jeans parameter.When compared to SHE our soluons differ, yet with a sufficient heang rate the escape rates are comparable. Our model predicts a higher exobase altude andtemperature. We show that the affect of enhancement in actual escape rate (relave to Jeans escape) is lessened on the final escape rate in our model. Wefurther use to model the upper atmosphere, and we are able to find a soluon in both regimes that are consistent in escape rate and match profiles in a transionregion.AKN OW LEDGEMEN TSThis report is funded in part by NASA.40.03: Dust Parcles In Pluto System: The Solar Radiaon Pressure EffectsAuthor Block: Pryscilla Maria Pires Dos Santos 1 , S. Giulia Winter 1 , R. Sfair 11 Unesp, Brazil.Presentaon Time: 10/5/2010 4:34 PM - 4:36 PMLocaon: Exhibit HallAbstract: Stable regions, favorable regions to find new satellites, were found around the two large bodies Pluto and Charon, coorbital to Nix and Hydra and alsoin a small region between the orbits of these two small satellites (Giulia Winter et al., 2010 and Pires dos Santos et al., 2010). The discovery of the smallsatellites Nix and Hydra, located in the external region of the Pluto-Charon binary system, increased the possibility of rings in this system. If this ring werecomposed of dust parcles the effects of non-gravitaonal forces, such as the solar radiaon pressure, has also to be taken into account. In this work weanalyzed the effects of the solar radiaon pressure on a sample of micrometer-sized dust grains in circular orbits around Pluto, assuming spherical dust grainsand neglecng the planetary shadow and the light reflected from the planet. As result we verified that the Poynng-Robertson component of the solar radiaonforce is responsible for the decreasing in the semimajor axis of the parcles leading them to a collision with the planet on a mescale between 1.47 x 10 6years (pa rcl e s of 1 mi crome te r-s i ze d i n ra di us ) a nd 1.47 x 107 ye a rs (pa rcl e s of 10 mi crome te r-s i ze d i n ra di us ), a ccordi ng to the va l ue e s ma te d by Burns e t a l . (1979); whi l e the ra di a onpre s s ure compone nt ca us e s a n i ncre a s e i n the e cce ntri ci ty of the pa rcl e s , l e a di ng pa rcl e s s ma l l e r tha n 10 mi crome te r-s i ze d i n ra di us to col l i de wi th the pl a ne t i n l e s s tha n 10 ye a rs . Forthos e pa rcl e s cl os e r to the pl a ne t, l oca te d a t 20 me s Pl uto's ra di us , the e ffe ct of ra di a on pre s s ure i s we a ke r. We a l s o a na l yze d the col l i s i ons be twe e n the s e dus t pa rcl e s a nd the fourma s s i ve bodi e s Pl uto-Cha ron-Ni x a nd Hydra .40.04: Dynamical Parameters Determinaon In Mulple SystemsAuthor Block: Laurène Beauvalet 1 , V. Lainey 1 , J. Arlot 11 IM CCE, France.Presentaon Time: 10/5/2010 4:36 PM - 4:38 PMLocaon: Exhibit HallAbstract.Abstract: Many Kuiper Belt Object and asteroids have now been discovered to be part of more complex dynamical systems consisng of a primary andits satellites. In this case, the primary's moon is not strictly keplerian around the Sun since the influence of its companions disturbs its trajectory. We present amodel which will allow for a global soluon when fing the orbital parameters to astrometric observaons. The goal of this work is to be able to constrain themasses and other dynamical parameters in this kind of system. The mulple system which has been studied for the longest me and would then make a perfectcandidate is Pluto's one, with its binary Pluto/Charon and its smaller satellites. Our model has been tested on simulated observaons of Pluto's system in orderto determine the parameters which can be properly determined.40.05: A Photometric And Astrometric Study Of The Trans-neptunian Object OrcusAuthor Block: Jose L. Orz 1 , A. Cikota 2 , S. Cikota 2 , D. Hestroffer 3 , A. Thirouin 1 , N. Morales 1 , R. Duffard 1 , R. Gil-Huon 4 , P. Santos-Sanz 1 , I. de la Cueva 51 Instuto de Astrofisica de Andalucia-CSIC, Spain, 2 Physik-Instut, Universitat Zurich, Switzerland, 3 IM CCE/Observatoire de Paris, CNRS, France, 4 ComplejoAstronomico El Leoncito (CASLEO-CONICET) and San Juan Naonal University, Argenna, 5 Astroimagen, Spain.

Presentaon Time: 10/5/2010 4:38 PM - 4:40 PMLocaon: Exhibit HallAbstract: We obtained high precision relave astrometry and photometry of Orcus’ system with respect to background stars. The Right Ascension residuals ofan orbital fit to the astrometric data revealed a period of 9.7 ± 0.3 days, which is what one would expect to be induced by the known Orcus companion (Vanth).The residuals also are correlated with the theorecal posions of the satellite relave to the primary. The oscillaon in the residuals is due to the photocentermoon of the combined Orcus plus satellite system around the barycenter along an orbital revoluon of the satellite. We show here that detecng some binariesthrough a carefully devised astrometric technique might be feasible with telescopes of moderate size. We have also analyzed the system’s mid-term photometryin order to determine whether the rotaon could be dally locked to the satellite’s orbital period. We found that a photometric variability of 9.7 ± 0.3 days is clearin our data, nearly coincident with the orbital period of the satellite. We believe this variability might be induced by the satellite’s rotaon. In our photometrythere is also a slight hint for an addional very small variability in the 10 hr range that was already reported in the literature. Such short-term variability wouldindicate that the primary is not dally locked and therefore the system would not have reached a double synchronous state. From angular momentumconsideraons we suspect that Orcus satellite might have formed from a rotaonal fission. This requires that the mass of the satellite would be around 0.09mes that of the primary, close to the value that one derives by using an albedo of 0.12 for the satellite and assuming equal densies for both the primary andsecondary.40.06: Composion of Ices on the Surfaces of KBOs 136108 Haumea and 136472 MakemakeAuthor Block: Daine Wright 1 , J. Emery 1 , D. Cruikshank 2 , C. Dalle Ore 2 , Y. Fernandez 3 , J. Stansberry 4 , D. Trilling 51 University of Tennessee, 2 NASA Ames Research Center, 3 University of Central Florida, 4 University of Arizona, 5 Northern Arizona University.Presentaon Time: 10/5/2010 4:40 PM - 4:42 PMLocaon: Exhibit HallAbstract: 136108 Haumea and 136472 Makemake are two of the largest known objects in the Kuiper Belt. They have orbits typical for classical Kuiper BeltObjects (KBOs), with semi-major axes of 43 and 46 AU respecvely. We know from visible and near-infrared (0.4 to 2.5 μm) spectroscopy that the surface ofHaumea is primarily comprised of water (H2O) ice (Pinilla-Alonso et al 2009) and Makemake’s of methane (CH4) ice (Brown et al 2007, Licandro et al 2006).Increasing the wavelength range of data further constrains the composion of other materials on their surfaces. We report measurements of reflectances ofHaumea and Makemake at four infrared wavelengths, 3.6, 4.5, 5.8, and 8.0 μm, using the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. Theselonger wavelength albedos are added to exisng data to extend the KBOs' known spectra to a broader range. Composional spectral modeling is used to searchthese data for absorpon by other materials, including volales. Both Haumea and Makemake are detected at 3.6 and 4.5 μm. Makemake is also detected at 5.8μm. Upper limits for the wavelengths at which the objects were not detected provide useful constraints as well. We find the following results so far: Haumea hasan albedo that is higher at 3.6 than 4.5 μm, which is consistent with a mixture of amorphous water ice, crystalline water ice, and a small amount of graphite, orother carbon. Makemake's albedo is lower at 3.6 μm than 4.5 μm, consistent with methane ice. Makemake has a more complex spectrum, requiring the presenceof ethane and tholin or other organic ice; although addion of these materials improve the model fits, we do not claim to have idenfied them. Work connues toimprove the model fits of spectra from Haumea, Makemake and other KBOs.40.07: Colors of Outer Solar System Objects Measured with VATTAuthor Block: William Romanishin 1 , S. C. Tegler 2 , G. J. Consolmagno 31 Univ. of Oklahoma, 2 Northern Arizona University, 3 Vacan Observatory.Presentaon Time: 10/5/2010 4:42 PM - 4:44 PMLocaon: Exhibit HallAbstract: Over the past 7 years, we have measured opcal B-V and V-R colors for about 40 minor outer solar system objects using the 1.8-m Vacan AdvancedTechnology Telescope (VATT) located on Mt. Graham in southeast Arizona. We will present these colors and use them to update the discussion of colors of minorbodies in the outer solar system.We gratefully acknowledge funding from the NASA Planetary Astronomy Program to Northern Arizona University and the U. of Oklahoma which helped support thiswork.40.08: The Effect of Planetary Encounters on the Inclinaon Distribuon of the CentaursAuthor Block: Kathryn Volk 1 , R. Malhotra 11 University of Arizona.Presentaon Time: 10/5/2010 4:44 PM - 4:46 PMLocaon: Exhibit HallAbstract.Abstract: The Centaurs are a populaon of small bodies whose orbits cross those of the outer planets. They represent a dynamically short-livedtransion populaon in-between the trans-Neptunian region and the Jupiter family short-period comets. Centaurs suffer many close encounters with the outerplanets during their evoluon from the trans-Neptunian region to their current orbits. Here we examine how these close encounters affect the orbital inclinaonsof hypothecal Centaurs as they evolve, in order to determine the extent to which the Centaurs' orbits retain memory of their original inclinaons in the trans-Neptunian region. Using these results, we show how the inclinaon distribuon of the Centaurs depends on the inclinaon distribuon of their source populaon.We also explore the full range of inclinaons that can be produced by close encounters to assess the possibility of very high inclinaon or even retrogradeCentaurs being produced by a trans-Neptunian source.40.09: Formaon Of The Haumea System: Checking Alternave Scenarios By N-body Based Numerical Simulaons.Author Block: Audrey Thirouin 1 , A. C. Baga 2 , J. Orz 1 , R. Duffard 1 , P. Benavidez 2 , D. Richardson 31 Instuto De Astrosica De Andalucía (IAA-CSIC), Spain, 2 Universidad de Alicante, Spain, 3 University of Maryland.Presentaon Time: 10/5/2010 4:46 PM - 4:48 PMLocaon: Exhibit HallAbstract: Haumea is one of the most studied and probably one of the most interesng Trans-Neptunian Objects (TNOs) and a fast spinning dwarf planet(Rabinowitz et al., 2006; Thirouin et al. 2010) that has at least two satellites and whose orbital elements are related to a group/family of bodies.A catastrophic collision at high relave velocity (around 3 km/s) between two bodies in the 1000-1500 km size range and a mass rao 0.2 has been suggested forthe formaon of the 'family' and the presence of satellites (Brown et al. 2007). Leinhardt et al. (2010) proposed another mechanism in which two 1300 km sizebodies undergo a grazing collision with reacculumaon of part of the mass and dispersion of the rest, partly into satellites. The likelihood of both scenarios issmall when tested against collisional and dynamical evoluon model predicons of collisional probabilies. Furthermore, these mechanisms have trouble inexplaining the velocity dispersion of the family members and the fast spin of Haumea.Schlichng and Sari (2009) proposed that a former collision at lowspeed formed a proto-satellite that should lately undergo a final impact finally leading to the current observed system.

In this work, we propose alternave mechanisms for the formaon of the Haumea system ant test them by means of N-body numerical simulaons (PKDGRAVcode. Richardson, 1994).40.10: The Origin Of 2004 XR190 Orbit From The Primordial Scaered DiskAuthor Block: Rodney S. Gomes 11 Observatório Nacional, Brazil.Presentaon Time: 10/5/2010 4:48 PM - 4:50 PMLocaon: Exhibit HallAbstract: The trans Neptunian Object 2004 XR190 (Buffy) is located beyond the classical Kuiper belt and has a high inclinaon at 46.7° and a comparavely loweccentricity at 0.106. The origin of this unusual orbit has been credited to the perturbaons of a putave passing star, a rogue planet or resonance dynamics. It isa fact that scaered objects can be trapped in mean moon resonances with Neptune which, associated with Kozai resonances, produces large amplitudecoupled oscillaons of the inclinaon and eccentricity of a trapped object. This suggests a possible mechanism to produce 2004 XR190 orbit. The problem ishowever that Buffy is not currently in any mean moon resonance with Neptune. Here I show evidence that 2004 XR190 was a scaered object in the past thatunderwent an episode of a 3:8 period commensurability with Neptune and eventually escaped this resonance while Neptune was migrang. I show that 2004XR190 eccentricity and inclinaon are well in accord with what would be expected if this unusual TNO did experience this resonance trapping/escapemechanism. Other important MMR resonances with Neptune that could also produce Buffy-like orbits are compared.40.11: The Canada France Eclipc Plane Survey: CFEP S-L7 Data ReleaseAuthor Block: Bre Gladman 1 , CFEPS team1 Univ. of Brish Columbia, Canada.Presentaon Time: 10/5/2010 4:50 PM - 4:52 PMLocaon: Exhibit HallAbstract: Starng March 2003, the Canada-France-Hawaii telescope began a large-scale, fully-characterized, eclipc plane survey for Kuiper Belt Objects. Thediscovery phase ended July 2005 having searched and characterized 320 square degrees. The crical long-term follow-up campaign, aimed at determining theorbits of almost all the detected objects, ran unl 2009. Our dedicated effort resulted in 85% of our sample being tracked over 3 or more opposions, yielding 169objects for which all discovery, follow-up circumstances, and biases are known and can be accurately modeled.We find that the so-called 'main' classical belt shows a complex dynamical structure even in the limited region of 40-47 AU. At least three sub-components arerequired to model the populaon, not just a 'hot' and 'cold' component separated by an inclinaon cut. We retain a 'hot' component (which we are able to extendthroughout the Kuiper Belt, out to at least 70 AU), but find that the lower-inclinaon populaon cannot be represented by a single simple structure in a/e space.We separate it into a 'srred' component which extends from 42.5 to 44.4 AU, and a very confined 'kernel' component, which may be a dynamical family.Our model reproduces the orbital-element and magnitude distribuons of the Kuiper Belt. At 95% confidence level the 'cold' inclinaon sub-populaons (srredplus kernel) have a steeper size distribuon in the H=7-8 range than the hot component. We also find that the inner and outer classical belts lack a coldcomponent (raising intriguing cosmogonic quesons), the resonances are well populated and have very hot inclinaon distribuons (except those for whicherosion might explain an absence of low-i TNOs), and the leading/trailing asymmetry for the transneptunian 2:1 resonance is not supported by CFEPS.40.12: The Edgeworth-Kuiper Debris DiskAuthor Block: Chrisan Vitense 1 , A. V. Krivov 1 , T. Loehne 11 Astrophysikalisches Instut und Universitaetssternwarte, Germany.Presentaon Time: 10/5/2010 4:52 PM - 4:54 PMLocaon: Exhibit HallAbstract: The Edgeworth-Kuiper belt with its presumed dusty debris is a natural reference for extrsolar debris disks. We employ a new algorithm to eliminatethe inclinaon and the distance selecon effects in the known TNO populaons to derive expected parameters of the "true" EKB. Its esmated mass is M EKB =0.12M e a rth , which is by a factor of ~15 larger than the mass of the EKB objects detected so far. About a half of the total EKB mass is in classical and resonant objectsand another half is in scaered ones. Treang the debiased populaons of EKB objects as dust parent bodies, we then "generate" their dust disk with ourcollisional code. Apart from accurate handling of collisions and direct radiaon pressure, we include the Poynng-Robertson (P-R) drag, which cannot be ignoredfor the EKB dust disk. Outside the classical EKB, the radial profile of the opcal depth approximately follows tau~r -2 which is roughly intermediate between theslope predicted analycally for collision-dominated (r -1.5 ) and transport-dominated (r -2.5 ) disks. The cross secon-dominang grain size sll lies just above theblowout size (~ 1...2µm), as it would without the P-R transport. However, if the EKB were by one order of magnitude less massive, the opcal depth profile wouldfall off as tau~r -3 , and the cross secon-dominang grain size would shi from ~1...2µm to ~100µm. These properes are seen if dust is assumed to be generatedonly by known TNOs. If the solar system were observed from outside, the thermal emission flux from the EKB dust would be about two orders of magnitude lowerthan for solar-type stars with the brightest known infrared excesses. Herschel and other new-generaon facilies should reveal extrasolar debris disks nearly astenuous as the EKB disk. The Herschel/PACS instrument should be able to detect disks at a ~1...2M EKB level.40.13: Detecon Biases for Resonant Kuiper Belt ObjectsAuthor Block: Samantha Lawler 1 , B. Gladman 1 , J. Pet 2 , J. Kavelaars 3 , R. Jones 4 , J. Parker 51 University of Brish Columbia, Canada, 2 Observatoire de Besancon, France, 3 Herzberg Instute of Astrophysics, Canada, 4 University of Washington, 5 SouthwestResearch Instute.Presentaon Time: 10/5/2010 4:54 PM - 4:56 PMLocaon: Exhibit HallAbstract.Abstract: Using the Canada-France Eclipc Plane Survey (CFEPS) we have performed detailed modeling of Trans-Neptunian Objects (TNOs) in meanmoonresonances with Neptune, producing absolute populaon esmates for ten resonances. Because CFEPS is well-characterized, we are able to de-bias thesurvey to study the internal structure of the most populated resonances, especially the 3:2. To de-bias, we must account for the survey's poinngs: TNOs willcome to perihelion at specific eclipc posions which depend on the resonant angle and the libraon amplitude distribuon. For the pluno Kozai subcomponent,the biases are more complicated, because pericenter will occur at high eclipc latudes. This results in eclipc surveys being inherently biased against detecngKozai resonators. We discuss constraints we can place on the inherent pluno Kozai fracon. For the 3:2 and 5:2 resonances, we are able to constrain the powerlawH-magnitude distribuon as well as the eccentricity, inclinaon, and libraon amplitude distribuons. The n:3, n:4, and 2:1 resonances have fewer detecons,and we provide populaon esmates and constrain the inclinaon distribuons. For poorly-sampled resonances (the 3:1 and 5:1), we give only rough populaonesmates. These are the first absolute populaon esmates for most of these resonances. In parcular, we find the populaons of H &lt; 9 objects in the 3:2 and5:2 resonances to be roughly equal. Although somewhat model-dependent, we find that the populaon of the 2:1 resonance is a factor of 4 smaller than that ofthe 3:2 resonance. If resonant TNOs were emplaced during migraon late in the giant planet formaon process, these populaon raos may give clues about the

state of the Kuiper Belt at the me of planet migraon and about the migraon rate. Our nominal 3:2/2:1/5:2 populaon raos of 4/1/4 are not produced inpublished models of resonant TNO producon.40.14: Excited TN Os in the HST ArchiveAuthor Block: Cesar Fuentes 1 , D. Trilling 1 , M. Holman 21 NAU, 2 CfA.Presentaon Time: 10/5/2010 4:56 PM - 4:58 PMLocaon: Exhibit HallAbstract.Abstract: The Hubble Space Telescope has observed numerous targets all over the sky over the years. The resoluon, sensivity and observaoncadence of the WFC channel on the ACS camera allows an extensive search for trans-neptunian objects on the HST archive. This project was arbitrarily divided ineclipc bands. The first band (0-5 deg) is already published (Fuentes et al., 2010) We present the results of the second part (5-20 deg). Unlike most surveys thatsample a combinaon of dynamically "hot" and "cold" objects, this one focuses mostly on "hot" objects. In this talk we present the results of this survey, and putit in the context of other surveys in the literature. Possible extensions of this project will also be presented.40.15: Trojan Asteroids and the Early Evoluon of the Solar SystemAuthor Block: Patryk S. Lykawka 1 , J. Horner 2 , B. Jones 3 , T. Mukai 41 Kinki University, Japan, 2 University of New South Wales, Australia, 3 The Open University, United Kingdom, 4 Kobe University, Japan.Presentaon Time: 10/5/2010 4:58 PM - 5:00 PMLocaon: Exhibit HallAbstract: Trojan asteroids can be used to constrain Trojan formaon mechanisms, giant planet formaon/migraon and the orbital structure in the asteroid andKuiper belts. We performed numerical simulaons totaling a few million massless objects under the gravitaonal influence of the four giant planets. Firstly, welooked at the dynamics of primordial (local) Neptune Trojans placed at the L4/L5 Lagrange points in compact planetary systems prior to planet migraon, over10Myr. We also invesgated the evoluon of local Neptune Trojans and captured Trojans from a planetesimal disk for all giant planets during planet migraon.The orbits were integrated for several Myr, aer which the giant planets acquired their current orbits. The orbits of representave final populaons were alsointegrated over Gyr. Overall, the great majority of plausible pre-migraon planetary systems resulted in severe levels of depleon of the Neptunian Trojan cloudsprior to planet migraon. In parcular, substanal Trojan losses occurred when Uranus and Neptune were placed near their mutual 2:3 or 3:4 MMR and within 18AU. Neptune Trojan populaons were obtained at the end of the migrang scenarios, composed of remaining local and captured Trojan asteroids. In addion toNeptune, the other three giant planets were also able to capture and retain a significant populaon of Trojan objects from the disk aer planet migraon. Finally,the distribuons of these objects and their resonant properes were obtained aer Gyr. In general, captured Trojans yielded a wide range of eccentricies andinclinaons, while local Trojans survived with colder orbital condions. However, the bulk of captured objects decay over Gyr, providing an important source ofnew objects on unstable orbits (the Centaurs). Our results suggest the bulk of observed Jovian and Neptunian Trojan populaons were captured from theprimordial planetesimal disk during planet migraon, but their high-i component (>20°) remain unexplained so far.40.16: Layered Model for Radiaon-Induced Chemical Evoluon of Icy Surface Composion on Kuiper Belt and Oort Cloud BodiesAuthor Block: John F. Cooper 1 , M. E. Hill 2 , J. D. Richardson 3 , S. J. Sturner 41 NASA GSFC, 2 Applied Physics Laboratory Johns Hopkins University, 3 Massachuses Instute of Technology, 4 CRESST, NASA GSFC.Presentaon Time: 10/5/2010 5:00 PM - 5:02 PMLocaon: Exhibit HallAbstract.Abstract: The diversity of albedos and surface colors on observed Kuiper Belt and Inner Oort Cloud objects remains to be explained in terms ofcompeon between primordial intrinsic versus exogenic drivers of surface and near-surface evoluon. Earlier models have aempted without success toaribute this diversity to the relaons between surface radiolysis from cosmic ray irradiaon and gardening by meteoric impacts. A more flexible approachconsiders the different depth-dependent radiaon profiles produced by low-energy plasma, suprathermal, and maximally penetrang charged parcles of theheliospheric and local interstellar radiaon environments. Generally red objects of the dynamically cold (low inclinaon, circular orbit) Classical Kuiper Belt mightbe accounted for from erosive effects of plasma ions and reddening effects of high energy cosmic ray ions, while suprathermal keV-MeV ions could alternavelyproduce more color neutral surfaces. The deepest layer of more prisne ice can be brought to the surface from meter to kilometer depths by larger impact eventsand potenally by cryovolcanic acvity. The bright surfaces of some larger objects, e.g. Eris, suggest ongoing resurfacing acvity. Interacons of surfaceirradiaon, resultant chemical oxidaon, and near-surface cryogenic fluid reservoirs have been proposed to account for Enceladus cryovolcanism (Cooper et al.,Plan. Sp. Sci., 2009) and may have further applicaons to other icy irradiated bodies. The diversity of causave processes must be understood to account forobservaonally apparent diversies of the object surfaces.40.17: Infrared Spectra and Opcal Constants of Pure C2H6, CH3OH and Mixtures in H2O from Laboratory MeasurementsAuthor Block: Rachel M.E. Mastrapa 1 , A. S. Curry 2 , J. A. Myszka 3 , S. A. Sandford 41 SETI Instute/NASA Ames Research Center, 2 Cal Poly Pomona, 3 Villanova University, 4 NASA Ames Research Center.Presentaon Time: 10/5/2010 5:02 PM - 5:04 PMLocaon: Exhibit HallAbstract: Recent observaons of TNOs include possible detecons of C2H6 (ethane) and CH3OH (methanol) from absorpons in their infrared spectra. Ourmeasurements of pure materials and mixtures have demonstrated that absorpons can shi in locaon and change in shape and strength when materials aremixed and compared to end member spectra. We will concentrate of the changes in the absorpons in the region from 2 to 2.5 μm, since these are the mostcommonly used regions for ground based observing. Since there are mulple stable phases of CH3OH and C2H6 at the temperature range seen on TNOs, we willthe possibility of detecng different phases of these ices.

Session Number: 49Session Title: Future Missions and InstrumentsSession Type: Poster49.01: Studying Methane in the Mars Atmosphere Using SOIR-N OMADAuthor Block: Ann Carine Vandaele 1 , R. J. Drummond 1 , F. Daerden 1 , E. Neefs 1 , J. Lopez-Moreno 2 , G. Bellucci 3 , M. Patel 41 IASB, Belgium, 2 Instuto de Astrofisica de Andalucia, Spain, 3 IFSI-INAF, Italy, 4 Open University, United Kingdom.Presentaon Time: 10/5/2010 4:40 PM - 4:42 PMLocaon: Exhibit HallAbstract: SOIR-NOMAD is a spectrometer suite capable of solar-occultaon, limb and nadir observaons in the UV-Visible-IR wavelengths (0.2-0.65 and 2.3-4.2micron). It builds on the heritage of SOIR from Venus Express and UVIS from the ExoMars lander (both ESA missions). The wide spectral range allows detecon ofmany trace species, such as CH4, CO2, CO, H2O, NO2 N2O, O3, C2H2, C2H4, C2H6, H2CO, HCN, OCS, SO2, HCl, HO2, H2S and isotopologues including those ofCH4 and H2O. Methane will be constrained to sub parts per billions in occultaon and mapped at parts per billion levels (column fracon) in nadir; allowingidenficaon of source regions. This instrument suite will also characterize dust and ice aerosols and clouds.We will present each of the channels of the SOIR-NOMAD instrument, their characteriscs and capabilies, including detecon limits for species important to thedeeper understanding of the Maran atmosphere. We will present simulaons of spectra that could be measured at Mars as well as showing the predictedcoverage from the expected TGO orbit.49.02: N IRS-3: A Near-Infrared Spectrometer For The Hayabusa-2 MissionAuthor Block: Kohei Kitazato 1 , M. Abe 2 , Y. Takagi 3 , T. Matsunaga 4 , M. Ohtake 2 , N. Takato 5 , T. Hiroi 61 University of Aizu, Japan, 2 Japan Aerospace Exploraon Agency, Japan, 3 Aichi Toho University, Japan, 4 Naonal Instute for Environmental Studies, Japan,5 Naonal Astronomical Observatory of Japan, Japan, 6 Brown University.Presentaon Time: 10/5/2010 4:42 PM - 4:44 PMLocaon: Exhibit HallAbstract.Abstract: The NIRS-3, a near-infrared spectrometer that will benefit the heritage of NIRS on Hayabusa, has been proposed to characterize themineralogical composion of asteroid surfaces in Hayabusa-2. The Hayabusa-2 mission aims to return samples of a C-class asteroid, on which hydrated mineralsare oen present and provide spectral features to determine composions. Parcularly diagnosc absorpon features due to hydrated minerals appear in the 3-micron region. Thus the NIRS-3 focuses on 3-micron observaons of the target asteroid, which will provide informaon for the selecon and characterizaon ofsampling sites and informaon concerning the composion and thermal evoluon of the asteroid. We present the instrument design and expected performance ofNIRS-3.49.03: The Boundary Layer RadiometerAuthor Block: Ranah Irshad 1 , N. E. Bowles 1 , S. B. Calcu 1 , J. Hurley 11 University of Oxford, United Kingdom.Presentaon Time: 10/5/2010 4:44 PM - 4:46 PMLocaon: Exhibit HallAbstract: The Boundary Layer Radiometer is a small, low mass (

Locaon: Exhibit HallAbstract: The Large Synopc Survey Telescope (LSST) will survey >30,000 square degrees to a typical liming magnitude of r~24.7 (per image) with a rapidobservaonal cadence, observing each field twice per night, approximately 4-5 mes each month. LSST will be a survey telescope with powerful potenal fordetecng and characterizing small moving objects. Near the eclipc, LSST is expected to detect approximately 4000 moving objects per 9.6 square degree field ofview; automated soware will provide the means to link these individual detecons into orbits. The result will be catalogs of hundreds of thousands of NEOs andJupiter Trojans, millions of asteroids, tens of thousands of TNOs, as well as thousands of other objects such as comets and irregular satellites of the majorplanets. These catalogs will be publicly available, with both final orbits as well as the underlying mul-color observaons, highly accurate in astrometry (~50mas) and photometry (~0.01-0.02 mag).By providing an order of magnitude larger datasets, LSST will generate new insights into links between different populaons of moving objects, such as therelaonship between Main Belt asteroids and NEOs, and allow for much stronger tests of solar system evoluon. High accuracy mul-color photometry andlightcurves could be used to derive physical properes of a significant fracon of the objects detected. Derivaon of proper elements, parcularly with theaddion of precise color informaon, would allow idenficaon of collisional families across many populaons.LSST has established science collaboraons in various areas of astronomy to facilitate communicaon between the project and users in the community, includinga Solar System Science Collaboraon. These collaboraons provide the opportunity for users to familiarize themselves with LSST-style data products before firstlight, as well as give feedback to LSST. An open call to join this science collaboraon will be issued this fall.49.06: Effecve Scenarios for Exploring Asteroid SurfacesAuthor Block: Pamela E. Clark 1 , C. Clark 2 , C. Weisbin 31 NASA's GSFC, 2 architect, 3 NASA's JPL.Presentaon Time: 10/5/2010 4:50 PM - 4:52 PMLocaon: Exhibit HallAbstract: In response to the proposal that asteroids be the next targets for exploraon, we aempt to develop scenarios for exploring previously mappedasteroid 433 Eros, harnessing our recent experience gained planning such acvity for return to the lunar surface. The challenges faced in planning Apollo led tothe development of a baseline methodology for extraterrestrial field science. What ‘lessons learned’ can be applied for asteroids? Effecve reconnaissance(advanced mapping at 1 km/s. Composional measurements by the Cassini Cosmic Dust Analyzer of ice grains emied from Enceladus probed the deep interior of thissatellite (Postberg et al., Nature, 459, 1098, 2009). New instrumentaon has been developed that meet or exceeded the capabilies in sensivity and massresoluon of all previous dust analyzers. The deployment of such dust analyzers on the Jupiter Europa Orbiter (JEO) and the Jupiter Ganymede Orbiter (JGO)

missions will provide unprecedented informaon on the surface composions of these satellites and their potenal acvity.49.09: Evaluaon of Thermocouple Temperature Sensors in a Simulated Mars EnvironmentAuthor Block: Hanna Sykulska-Lawrence 1 , J. Mansell 1 , N. Bowles 1 , S. Calcu 1 , J. Temple 11 Oxford University, United Kingdom.Presentaon Time: 10/5/2010 4:56 PM - 4:58 PMLocaon: Exhibit HallAbstract: The Maran environment is meteorologically extremely dry, dusty, cold (with a large diurnal temperature change), is irradiated by UV and is probablyhighly chemically oxidising. Detailed measurements of the near-surface atmospheric temperature profile coupled with other meteorological data allow thedynamics of the Maran atmospheric boundary layer to be invesgated. This is of parcular importance given the atmosphere’s tendency to turbulent mixingobserved by previous experiments, on e.g. Mars Pathfinder within a few metres of the surface.We examine thermocouple sensors for the Mars environment by evaluang the sensor designed for the AEP instrument, a meteorology package previouslyselected for the ExoMars geophysics lander. The design of the sensor contains three thin wire thermocouples for redundancy in a configuraon based on thoseflown on the Viking, Mar Pathfinder and Phoenix landers. Thin-wire thermocouples offer the best type of temperature sensor for in-situ atmospheric temperaturemeasurements as they have a fast response me, are less sensive to radiave heat coupling and do not have problems with self-heang. The sensor describedin this presentaon is accurate to < 0.25K.The work presented will describe the sensor itself and provide results of detailed calibraon tests in an isothermal Mars environmental chamber (simulang thetemperatures, pressure and atmospheric composion expected near the surface) tesng the instruments accuracy, and response in relaon to the thermalcapacity of the wire. Further to this, numerical models used to invesgate the difficules in correctly measuring the temperature of the atmosphere will bedescribed. These models consider effects such as radiave heang from direct sunlight or radiaon reflected from the surface, shielding from flowing air. Havingstudied the behaviour of this sensor and different types of design of thermocouple weld, including re-examining the Viking sensors, if appropriate, designimprovements are suggested.49.10: Interstellar Dust InstrumentaonAuthor Block: Zoltan Sternovsky 1 , E. Gruen 1 , M. Horanyi 1 , K. Drake 1 , A. Collee 1 , S. Kempf 2 , R. Srama 2 , F. Postberg 2 , H. Krueger 3 , S. Auer 41 LASP, Univ. of Colorado, 2 M PI-K, Germany, 3 M PI-S, Germany, 4 A&M Associates.Presentaon Time: 10/5/2010 4:58 PM - 5:00 PMLocaon: Exhibit HallAbstract.Abstract: Interstellar grains traversing the inner planetary system have been idenfied by the Ulysses dust detector. Space dust detectors on othermissions confirmed this finding. Analysis of the Stardust collectors is under way to search for and analyze such exoc grains. Interstellar dust parcles can bedetected and analyzed in the near-Earth space environment. New instrumentaon has been developed to determine the origin of dust parcles and theirelemental composion. A Dust Telescope is a combinaon of a Dust Trajectory Sensor (DTS, Rev. Sci. Instrum. 79, 084501, 2008) together with a high massresoluon mass analyzer for the chemical composion of dust parcles in space. Dust parcles' trajectories are determined by the measurement of inducedelectric signals when a charged grain flies through a posion sensive electrode system. A modern DTS can measure dust parcles as small as 0.2 micron inradius and dust speeds up to 100 km/s. Large area chemical analyzers of 0.1 m2 sensive area have been tested at a dust accelerator and it was demonstratedthat they have sufficient mass resoluon to resolve ions with atomic mass number up to &gt;100 (Earth, Moon and Planets, DOI: 10.1007/s11038-005-9040-z,2005; Rev. Sci. Instrum. 78, 014501, 2007). The advanced Dust Telescope is capable of idenfying interstellar and interplanetary grains, and measuring theirmass, velocity vector, charge, elemental and isotopic composions. An Acve Dust Collector combines a DTS with an aerogel or other dust collector materials,e.g. like the ones used on the Stardust mission. The combinaon of a DTS with a dust collector provides not only individual trajectories of the collected parclesbut also their impact me and posion on the collector which proves essenal in finding collected sub-micron sized grains on the collector.49.11: A Review of Technology Development for N ASA's Planetary Science Division MissionsAuthor Block: Patricia Beauchamp 1 , J. T. Clarke 2 , R. Lorenz 3 , T. Kremic 4 , P. Hughes 5 , B. Perry 6 , J. Singleton 71 Jet Propulsion Laboratory - Caltech, 2 Boston University, 3 Applied Physics Lab, 4 NASA Glenn Res. Ctr., 5 Nasa Goddard Sp. Flt Ctr., 6 NASA Langley, 7 Air ForceResearch Lab.Presentaon Time: 10/5/2010 5:00 PM - 5:02 PMLocaon: Exhibit HallAbstract: NASA has made tremendous progress in addressing crical quesons about our solar system but oen the knowledge gained raises new and morechallenging quesons. Future roboc space missions need to be endowed with more capable instruments, spacecra subsystems and ground support on order tobe able to answer the new and more difficult quesons that lay before us. Developing future instrument, spacecra subsystem, or ground support technologiesfor roboc planetary missions is a complicated and challenging endeavor. Recognizing this, the Planetary Science Division (PSD) in NASA’s Science MissionDirectorate has chartered a panel to review its current technology development programs and provide recommendaons on process and policy improvements thatwill enable beer ulizaon of technology. This paper discusses the work and findings of that panel, known as the Planetary Science Technology Review (PSTR)panel. The paper discusses the technology development challenges faced by the PSD as well as panel findings and observaons about the current programs andprocesses employed. The paper also discusses the potenal recommendaons that may be considered by the Planetary Science Division in future technologydevelopment efforts.49.12: Solar System Observaons with the James Webb Space TelescopeAuthor Block: Heidi B. Hammel 1 , J. Lunine 2 , G. Sonneborn 3 , G. Rieke 4 , M. Rieke 4 , J. Stansberry 4 , E. Schaller 5 , G. Orton 6 , J. Isaacs 71 Space Science Instute, 2 U. Rome Tor Vergata, Italy, 3 NASA's GSFC, 4 U. Arizona, 5 LPL, U. Arizona, 6 JPL, 7 STScI.Presentaon Time: 10/5/2010 5:02 PM - 5:04 PMLocaon: Exhibit HallAbstract.Abstract: The James Webb Space Telescope is a large infrared space telescope currently scheduled for launch in 2014. Webb will reside in a ellipcalorbit about the semi-stable second Lagrange point (L2). Its 6.5-meter primary mirror is designed to work primarily in the infrared, with some capability in thevisible (i.e., from 0.6 to 27 microns). Webb has four science instruments: the Near InfraRed Camera (NIRCam), the Near InfraRed Spectrograph (NIRSpec), the Mid-InfraRed Instrument (MIRI), and the Fine Guidance Sensor Tunable Filter Camera (FGS-TFI). One of Webb's science themes is "Planetary Systems and the Originsof Life" which includes observaons of Solar System objects; the telescope will be able to track moving targets with rates up to 0.030 arcseconds per second. Itscombinaon of broad wavelength range, high sensivity, and near-diffracon limited imaging around 2 microns make it a superb facility for a variety of SolarSystem programs. In this poster, we present an overview of Webb's scienfic capabilies and their relevance to current topics in planetary science.49.13: An AOTF-LDTOF Spectrometer Suite for In Situ Organic Detecon and Characterizaon

Author Block: Nancy J. Chanover 1 , D. Glenar 1 , D. Voelz 1 , X. Xiao 1 , R. Tawalbeh 1 , P. Boston 2 , W. Brinckerhoff 3 , P. Mahaffy 3 , S. Gey 31 New Mexico State Univ., 2 New Mexico Inst. of Mining and Tech., 3 NASA's Goddard Space Flight Ctr..Presentaon Time: 10/5/2010 5:04 PM - 5:06 PMLocaon: Exhibit HallAbstract: On future surface missions to Mars, small bodies, and outer solar system satellites, increasingly robust sample screening and selecon may beessenal for achieving the maximum scienfic benefit within limited payload resources. One approach to defining a sequence of analysis steps for a variety ofmissions is the idenficaon of key organic funconal groups by a spectroscopic prescreening tool, followed by organic compound analysis with massspectrometric methods.We discuss the development of a miniature near-infrared point spectrometer, operang in the 1.7-4 micron region, based on acousto-opc tunable filter (AOTF)technology. This instrument may be used to screen and corroborate analyses of samples containing organic biomarkers or mineralogical signatures suggesve ofextant or exnct organic material collected in situ from planetary surfaces. The AOTF point spectrometer will be paired with a laser desorpon me-of-flight(LDTOF) mass spectrometer and will prescreen samples for evidence of volale or refractory organics before the laser desorpon step and subsequent massspectrometer measurement. AOTF systems provide great flexibility, being very compact, electronically programmable, with low power requirements. The LDTOFmass spectrometer provides pulsed-laser desorpon and analysis of refractory organic compounds up to > 5,000 Da on a spaal scale of 10-30 mm, determinedby the laser spot size at the target.We describe the prototype AOTF point spectrometer instrument and present laboratory analysis of geological samples of known astrobiological importance. Aninial mineral and rock sample suite of planetary relevance was used in the laboratory for baseline tesng. To this, we added a complement of astrobiologicallyrelevant biosignatures from a variety of well characterized geomicrobial study sites.This work is supported by NASA's ASTID and EPSCoR programs through grant numbers NNX08AY44G and NNX08AV85A, respecvely.49.14: A New Instrument for the IRTF: the MIT Opcal Rapid Imaging System (MORIS)Author Block: Amanda A. S. Gulbis 1 , J. L. Elliot 2 , F. E. Rojas 2 , S. J. Bus 3 , J. T. Rayner 3 , W. E. Stahlberger 3 , A. T. Tokunaga 3 , E. R. Adams 2 , M. J. Person 21 SALT/M IT, South Africa, 2 M IT, 3 Univ. of Hawaii.Presentaon Time: 10/5/2010 5:06 PM - 5:08 PMLocaon: Exhibit HallAbstract: NASA’s 3-m Infrared Telescope Facility (IRTF) on Mauna Kea, HI plays a leading role in obtaining planetary science observaons. However, there hasbeen no capability for high-speed, visible imaging from this telescope. Here we present a new IRTF instrument, MORIS, the MIT Opcal Rapid Imaging System.MORIS is based on POETS (Portable Occultaon Eclipse and Transit Systems; Souza et al., 2006, PASP, 118, 1550). Its primary component is an Andor iXon camera,a 512x512 array of 16-micron pixels with high quantum efficiency, low read noise, low dark current, and full-frame readout rates of between 3.5 Hz (6 e~/pixelread noise) and 35 Hz (49 e~/pixel read noise at electron-mulplying gain=1). User-selectable binning and subframing can increase the cadence to a few hundredHz. An electron-mulplying mode can be employed for photon counng, effecvely reducing the read noise to sub-electron levels at the expense of dynamicrange. Data cubes, or individual frames, can be triggered to nanosecond accuracy using a GPS.MORIS is mounted on the side-facing widow of SpeX (Rayner et al. 2003, PASP, 115, 362), allowing simultaneous near-infrared and visible observaons. Themounng box contains 3:1 reducing opcs to produce a 60 arcsec x 60 arcsec field of view at f/12.7. It hosts a ten-slot filter wheel, with Sloan g×, r×, i×, and z×,VR, Johnson V, and long-pass red filters.We describe the instrument design, components, and measured characteriscs. We report results from the first science observaons, a 24 June 2008 stellaroccultaon by Pluto. We also discuss a recent overhaul of the opcal path, performed in order to eliminate scaered light.This work is supported in part by NASA Planetary Major Equipment grant NNX07AK95G. We are indebted to the University of Hawai’i Instute for Astronomymachine shop, in parcular Randy Chung, for fabricang instrument components.49.15: The Deep Impact eXtended Invesgaon: Sights on Comet 103P/Hartley 2Author Block: Lori M. Feaga 1 , DIXI Science Team1 Univ. of Maryland.Presentaon Time: 10/5/2010 5:08 PM - 5:10 PMLocaon: Exhibit HallAbstract: NASA’s EPOXI mission has repurposed the healthy Deep Impact spacecra to flyby a smaller, more acve comet, 103P/Hartley 2, in order toinvesgate the observed diversity among comets. The Deep Impact eXtended Invesgaon (DIXI) began its approach observaons of Hartley 2 in September andwill flyby Hartley 2 on November 4, 2010. Since Hartley 2 has a much smaller nucleus and larger acve fracon than the nuclei of any of the comets visited thusfar, it may become possible to discern some of the paerns that lead to the dramac differences among comets, including differences in surface morphology andchemical heterogeneies found in comae. In addion, we will be able to study whether an acve comet has more surface dust. Hence, the observing sequence isopmized for outburst monitoring and high spaal resoluon images and spectra of the coma, nucleus and their interface. EPOXI is funded by the NASA DiscoveryProgram.49.16: Titan AVIATR - Aerial Vehicle for In Situ and Airborne Titan ReconnaissanceAuthor Block: Simon A. Kaenhorn 1 , J. W. Barnes 1 , C. P. McKay 2 , L. Lemke 2 , R. A. Beyer 3 , J. Radebaugh 4 , M. Adamkovics 5 , D. H. Atkinson 1 , D. M. Burr 6 , T.Colaprete 2 , R. Foch 7 , S. Le Mouélic 8 , J. Merrison 9 , J. Mitchell 10 , S. Rodriguez 11 , E. Schaller 121 Univ. of Idaho, 2 NASA Ames Research Center, 3 SETI Instute, 4 Brigham Young Univ., 5 Univ. of California Berkeley, 6 Univ. of Tennessee, 7 Naval ResearchLaboratory, 8 Université de Nantes, France, 9 Aarhus Universitat, Denmark, 10 Univ. of California Los Angeles, 11 Université Paris Diderot, France, 12 Univ. of Arizona.Presentaon Time: 10/5/2010 5:10 PM - 5:12 PMLocaon: Exhibit HallAbstract: Titan AVIATR - Aerial Vehicle for In Situ and Airborne Titan Reconnaissance - is a small (120 kg), nuclear-powered Titan airplane in the Discovery/NewFroners class based on the concept of Lemke (2008 IPPW). The scienfic goals of the mission are designed around the unique flexibility offered by an airborneplaorm: to explore Titan’s diversity of surface landforms, processes, and composions, as well as to study and measure the atmospheric circulaon, aerosols,and humidity. AVIATR would address and surpass many of the science goals of hot-air balloons in Titan flagship studies.The strawman instrument payload is narrowly focused on the stated scienfic objecves. The opcal remote sensing suite comprises three instruments - an offnadirhigh-resoluon 2-micron camera, a horizon-looking 5-micron imager, and a 1-6 micron pushbroom near-infrared spectrometer. The in situ instrumentsinclude atmospheric structure, a methane humidity sensor, and a raindrop detector. An airplane has operaonal advantages over a balloon. Its piloted natureallows a go-to capability to image locaons of interest in real me, thereby allowing for directed exploraon of many features of primary geologic interest:Titan’s sand dunes, mountains, craters, channels, and lakes. Subsequent imaging can capture changes in these features during the primary mission. AVIATR canfly predesigned routes, building up large context mosaics of areas of interest before swooping down to low altude to acquire high-resoluon images at 30-cmspaal sampling, similar to that of HiRISE at Mars. The elevaon flexibility of the airplane allows us to acquire atmospheric profiles as a funcon of altude at

any desired locaon. Although limited by the direct-to-Earth downlink bandwidth, the total scienfic data return from AVIATR will be >40 mes that returned fromHuygens. To maximize the science per bit, novel data storage and downlink techniques will be employed, including lossy compression, downloading thumbnails,and on-board image evaluaon.49.17: The Primive Material Explorer (PriME) MissionAuthor Block: Anita L. Cochran 1 , H. A. Weaver 2 , PriME Science and Engineering Teams1 McDonald Observatory, 2 Johns Hopkins University Applied Physics Lab.Presentaon Time: 10/5/2010 5:12 PM - 5:14 PMLocaon: Exhibit HallAbstract: The Primive Material Explorer (PriM E) Mission is a proposed Discovery mission that will rendezvous with comet 46P/Wirtanen in 2021 in order to 1)clarify the roles played by comets in the formaon and evoluon of the Solar System and the origin of life; 2) ascertain the bulk physical properes, the surfacegeology, and the sources of acvity in a fresh comet nucleus; and 3) invesgate the composional diversity of primive material in the Solar System. PriM Eteams an experienced group of comet sciensts (led by PI Anita Cochran and by DPI Harold Weaver) with university and industrial partners.The PriM E payload accomplishes the mission objecves with only three instruments. MASPEX (MAss Spectrometer for Planetary EXploraon) has higher massresoluon and is more sensive than any mass spectrometer ever flown. MASPEX will measure D/H in H 2 O, noble gases, isotopes of many species, and complexmolecular compounds to test solar nebula models and the role comets played in delivering water and other biologically important materials throughout the SolarSystem. The VIS (Visible Imaging System), consisng of a Narrow Angle Camera (NAC) and Wide-Angle Camera (WAC), will constrain the condions under whichthe building blocks of the outer Solar System were assembled by measuring key physical properes of the nucleus of 46P/Wirtanen. Using the radio antenna andclose flybys of the nucleus, PriM E will determine the mass of the nucleus to an accuracy of ~1% and the bulk density and average porosity of the nucleus tobeer than ~5%. All spacecra subsystems have significant planetary flight heritage. The spacecra is a high-heritage derivave of the Kepler and Deep Impactspacecras, compable with the three launch vehicle families specified in the Discovery Announcement of Opportunity.49.18: Comet Odyssey: Comet Surface Sample ReturnAuthor Block: Paul R. Weissman 1 , J. Bradley 2 , W. D. Smythe 1 , J. R. Brophy 1 , M. E. Lisano 1 , M. L. Syvertson 1 , L. A. Cangahuala 1 , J. Liu 1 , G. L. Carlisle 11 Jet Propulsion Laboratory, 2 Lawrence Livermore Naonal Laboratory.Presentaon Time: 10/5/2010 5:14 PM - 5:16 PMLocaon: Exhibit HallAbstract: Comet Odyssey is a proposed New Froners mission that would return the first samples from the surface of a cometary nucleus. Stardustdemonstrated the tremendous power of analysis of returned samples in terrestrial laboratories versus what can be accomplished in situ with roboc missions. ButStardust collected only ~1 milligram of coma dust, and the 6.1 km/s flyby speed heated samples up to 2000 K. Comet Odyssey would collect two independent 800cc samples directly from the surface in a far more benign manner, preserving the primive composion. Given a minimum surface density of 0.2 g/cm 3 , this wouldreturn two 160 g surface samples to Earth. Comet Odyssey employs solar-electric propulsion to rendezvous with the target comet. Aer ~180 days ofreconnaissance and site selecon, the spacecra performs a “touch-and-go” maneuver with surface contact lasng ~3 seconds. A brush-wheel sampler on aremote arm collects up to 800 cc of sample. A duplicate second arm and sampler collects the second sample. The samples are placed in a return capsule andmaintained at colder than -70 C during the return flight and at colder than -30 C during re-entry and for up to six hours aer landing. The enre capsule is thenrefrigerated and transported to the Astromaterials Curatorial Facility at NASA/JSC for inial inspecon and sample analysis by the Comet Odyssey team. CometOdyssey’s planned target was comet 9P/Tempel 1, with launch in December 2017 and comet arrival in June 2022. Aer a stay of ~300 days at the comet, thespacecra departs and arrives at Earth in May 2027. Comet Odyssey is a forerunner to a flagship Cryogenic Comet Sample Return mission that would returnsamples from deep below the nucleus surface, including volale ices. This work was supported by internal funds from the Jet Propulsion Laboratory.49.19: Whipple: Exploring the Solar System Beyond NeptuneAuthor Block: Charles Alcock 1 , Whipple Science Team1 Harvard-Smithsonian, CfA.Presentaon Time: 10/5/2010 5:16 PM - 5:18 PMLocaon: Exhibit HallAbstract: Whipple is a Discovery-class mission that will explore the outer Solar System by searching for the occultaons of bright (R

simulaons show how Whipple will measure size distribuons as a funcon of (three dimensional) posion for these populaons.49.21: Exploring Saturn With Shallow ProbesAuthor Block: David H. Atkinson 1 , T. R. Spilker 2 , K. Reh 2 , S. K. Atreya 3 , T. S. Balint 2 , R. Beebe 4 , A. Colaprete 5 , P. Mahaffy 61 Univ. of Idaho, 2 Jet Propulsion Laboratory, 3 Univ. of Michigan, 4 New Mexico State University, 5 NASA Ames Research Center, 6 Goddard Space Flight Center.Presentaon Time: 10/5/2010 5:20 PM - 5:22 PMLocaon: Exhibit HallAbstract: Entry probe missions to the outer planets are essenal to constrain models of solar system formaon and the origin and evoluon of atmospheres, toprovide a basis for comparave studies of the gas and ice giants, and to provide a valuable link to extrasolar planetary systems. It is within the deep, well-mixedatmospheres and interiors of the giant planets that material from the epoch of solar system formaon can be found, providing clues to the local chemical andphysical condions exisng at the me and locaon at which each planet formed. The giant planets therefore offer a laboratory for studying the atmosphericchemistries, dynamics, and interiors of all the planets, including Earth.A shallow entry probe mission to Saturn carrying a Neutral Mass Spectrometer, Atmospheric Structure Instrument, and ultrastable oscillator can provide thecomposion, structure, and dynamics of Saturn’s upper troposphere. The key measurement for a Saturn probe mission is the composion of the well-mixedatmosphere below the cloud layers, including the heavy elements C, N, O, and S, the noble gases He, Ne, Ar, Kr, Xe and their isotopes, isotope raos 15N/14N,13C/12C and D/H, and disequilibrium species such as PH3, AsH3, GeH4 as tracers of internal processes. A precise determinaon of the helium abundance isrequired for the formaon models. Moreover, helium sedimentaon could provide significant indigenous energy at Saturn, thus a measurement of the Heabundance in Saturn's atmosphere and its comparison with the value at Jupiter determined by the Galileo Probe is important for understanding the process ofinternal heat generaon in the gas giant planets. All of above species can be accessed and measured by entry probes at pressures less than 10 bars at Saturn,with the excepon of oxygen whose gradient with depth can be determined from H2O.

Session Number: 50Session Title: Planetary RingsSession Type: Poster50.01: Sharp Edges in Saturn’s Rings: Radial Structure and Longitudinal VariabilityAuthor Block: Joshua E. Colwell 1 , R. G. Jerousek 1 , L. W. Esposito 21 University of Central Florida, 2 University of Colorado.Presentaon Time: 10/5/2010 4:20 PM - 4:22 PMLocaon: Exhibit HallAbstract: The Cassini Ultraviolet Imaging Spectrograph has observed more than 100 occultaons of stars by Saturn’s rings with a typical ring plane radialresoluon of

Locaon: Exhibit HallAbstract: The accurate descripon of the thermal behavior of the main rings of Saturn relies on the different energy sources accounted in models (e.g. directand reflected solar energy, thermal contribuon from Saturn and the inter-parcle energy exchange), but the observed temperature strongly depends on theobservaon geometry (e.g. solar elevaon, B’, spacecra elevaon, B, phase φ and local hour angles, Ψ). The observaon geometry defines what fracon of theparcles that compose the rings is illuminated and what fracon is under shadows in our field of view, which yields to apparent colder or warmer parcles. Thisvariaon can be described with the so-called shadowing funcon.In order to study the C ring temperature behavior we use ray tracing, which can accurately and virtually reproduce a good number of opcal effects with a highdegree of realism, to simulate a layer of irregularly-shaped rough parcles that mimics the opcally thin C ring -τ=0.08-. A virtual observer is set to simulate thespacecra moon to account for the different elevaons wrt the ring plane as well as local hour angle posions. For these different geometries we analyze theshadow behavior on the simulated ring parcles surfaces and obtain sets of numerical shadowing funcons that account variaons in B', B, φ and Ψ.50.06: Mapping Ring Parcle Cooling across Saturn's Rings with Cassini CIRSAuthor Block: Shawn M. Brooks 1 , L. J. Spilker 2 , S. G. Edgington 2 , S. H. Pilorz 3 , E. Deau 21 JPL, 2 Jet Propulsion Laboratory/California Instute of Technology, 3 SETI.Presentaon Time: 10/5/2010 4:30 PM - 4:32 PMLocaon: Exhibit HallAbstract: Previous studies have shown that the rings' thermal inera, a measure of their response to changes in the thermal environment, varies from ring toring. Thermal inera can provide insight into the physical structure of Saturn's ring parcles and their regoliths. Low thermal inera and quick temperatureresponses are suggesve of ring parcles that have more porous or fluffy regoliths or that are riddled with cracks. Solid, coherent parcles can be expected tohave higher thermal ineras (Ferrari et al. 2005).Cassini's Composite Infrared Spectrometer has recorded millions of spectra of Saturn's rings since its arrival at Saturn in 2004 (personal communicaon, M.Segura). CIRS records far infrared radiaon between 10 and 600 cm -1 (16.7 and 1000 µm) at focal plane 1 (FP1), which has a field of view of 3.9 mrad. Thermalemission from Saturn’s rings peaks in this wavelength range. FP1 spectra can be used to infer ring temperatures. By tracking how ring temperatures vary, we candetermine the thermal inera of the rings.In this work we focus on CIRS observaons of the shadowed poron of Saturn's rings. The thermal budget of the rings is dominated by the solar radiaonabsorbed by its constuent parcles. When ring parcles enter Saturn's shadow this source of energy is abruptly cut off. As a result, ring parcles cool as theytraverse Saturn's shadow. From these shadow observaons we can create cooling curves at specific locaons across the rings. We will show that the rings'cooling curves and thus their thermal inera vary not only from ring to ring, but by locaon within the individual rings.This research was carried out at the Jet Propulsion Laboratory, California Instute of Technology, under contract with NASA. Copyright 2010 California Instute ofTechnology. Government sponsorship acknowledged.50.07: Oxygen Ions from Over the Main Rings into the Inner MagnetosphereAuthor Block: Meredith Elrod 1 , R. E. Johnson 1 , W. L. Tseng 1 , R. J. Wilson 2 , R. L. Tokar 31 University of Virginia, 2 Laboratory for Atmospheric and Space Sciences, 3 Los Alamos Naonal Laboratory.Presentaon Time: 10/5/2010 4:32 PM - 4:34 PMLocaon: Exhibit HallAbstract: The discovery of a stable oxygen atmosphere over Saturn’s main rings was one of the first major surprises of the Cassini mission. The primary sourceof neutral oxygen for this ring atmosphere was suggested to be due to solar UV photons that produce O 2 by decomposion of H 2 O ice parcles in the main rings.This process, as well as charged parcles radiaon, can also produce O 2 from ice grains in the tenuous F and G rings. The oxygen ring atmosphere is very thin tothe point of being nearly collisionless primarily interacng with the ring parcles. That is O 2 is adsorbed and desorbed from the rings causing changes in thetrajectories so that the O 2 produced from the opcally thick B and A rings diffuses onto the C and D rings and out to the inner magnetosphere. In addion, thescaering of O 2 by its ionized products O+ 2 and O + , allows for a redistribuon of O 2 from the rings throughout the magnetosphere. Predominately through photoionizaonO 2 neutrals from the ice grains become a source for O+ 2 ions over the rings and in the inner magnetosphere. Once formed the O+ 2 ions follow the fieldlines. The ions also interact with the icy ring parcles effecvely liming the ion density. As a result the ion density is greater over the Cassini Division and thearea between the F and G ring where the opcal depth due to the ice grain is less. The purpose of this study is to re-examine the ion data from the CassiniPlasma Spectrometer (CAPS) from the Saturn Orbit Inseron (SOI) in 2004 as well as compare it with other data from 2007 where Cassini passed within 3.5 Rsnear the equator.50.08: Dust Producon By Hypothecal Satellites In The Secondary Ring-moon System Of UranusAuthor Block: Rafael Sfair 1 , S. M. Giulia Winter 11 UNESP - Campus de Guarangueta, Brazil.Presentaon Time: 10/5/2010 4:34 PM - 4:36 PMLocaon: Exhibit HallAbstract: The populaon of the ν and μ rings of Uranus is mostly composed by micrometric parcles (de Pater et al, 2006), which can be strongly disturbed bythe solar radiaon pressure (SRP). Sfair & Giulia Winter (2009) showed that the combinaon of the SRP with the planetary oblateness and the gravitaonalperturbaon of the closest satellites results in a series of close encounters and somemes collisions with the small nearby satellites. When a collision occurs theprobably result is the deposion of parcles onto the surface of these satellites. Since this mechanism tends to cause a depleon of material of the rings, weinvesgate addional sources for these dust parcles. Following the method presented in Krivov et al. (2002) and adopng a rough esmave of the flux ofinterplanetary meteoroids at Uranus' orbit, we calculated the amount of ejecta produced by hypervelocity impacts. If we assume that these collisions areeffecve in order to create more debris than the mass of the impactor, due to the small cross secon of the satellites, the producon rate is only about few gramsper second. We also invesgated if a supplementary amount of material can be generated by collisions of interplanetary projecles with a populaon of meterto-kilometerbodies embedded within the rings, since these bodies may provide an addion of effecve cross secon area to the impactors. As a preliminaryanalysis we analyzed a sample of hypothecal satellites located at the peak of the brightness profile of each ring. We restricted ourselves to satellites smallerthan the observaonal threshold of 5 km. Although a sample of moonlets smaller than 5 km can survive at the ν ring without cause any perturbaon in theeccentricity larger than 1E-3 of the nearby satellites, those moonlets at the μ ring disturb the orbit of Mab.

Session Time: 10/6/2010 8:30 AM

Session Number: 31Session Title: Jovian Planets: JupiterSession Type: Oral31.01: Long-term Evoluon of the Aerosol Debris Cloud Produced by the 2009 Impact of an Object with JupiterAuthor Block: Agusn Sanchez-Lavega 1 , G. S. Orton 2 , R. Hueso 1 , S. Pérez-Hoyos 1 , L. N. Fletcher 3 , E. Garcia-Melendo 4 , J. M. Gomez 4 , I. de Pater 5 , M. Wong 5 , H.B. Hammel 6 , P. Yanamandra-Fisher 2 , M. Simon-Miller 7 , N. Barrado-Izagirre 8 , F. Marchis 9 , O. Moussis 10 , J. L. Orz 11 , J. Garcia 12 , M. Cecconi 13 , J. T. Clarke 14 , K.Noll 15 , S. Pedraz 16 , A. Wesley 17 , N. McConnel 5 , P. Kalas 5 , J. Graham 5 , L. McKenzie 18 , V. Reddy 19 , W. Golisch 20 , D. Griep 20 , P. Sears 20 , Internaonal Outer PLanetWatch (IOPW)1 ETS Ingenieros UPV-EHU, Spain, 2 Jet Propulsion Laboratory, 3 U. Oxford, United Kingdom, 4 F. Esteve Duran, Spain, 5 U. California, 6 Space Science Instute,7 NASA Goddard Space Center, 8 EUITI UPV-EHU, Spain, 9 SETI Instute, 10 O. Besancon, France, 11 Instuto Astrosica Andalucía, Spain, 12 Instuto AstrosicaCanarias, Spain, 13 Fundación Galileo Galilei. INAF, Spain, 14 U. Boston, 15 Space Telescope Science Instute, 16 Calar Alto Obs., Spain, 17 Acquerra PTy. Ltd.,Australia, 18 U. Colorado, 19 U. North Dakota, 20 Instute for Astronomy.Presentaon Time: 10/6/2010 8:30 AM - 8:40 AMLocaon: Ballroom BCAbstract: We report the evoluon of the cloud of aerosols produced in the atmosphere of Jupiter by the impact of an object in 19 July 2009 (Sánchez-Lavega etal., Astrophys. J. Le, Vol. 715, L155. 2010). This study is based on images obtained with a baery of ground-based telescopes and the Hubble Space Telescope inthe visible and in the deep near infrared absorpon bands at 2.1-2.3 microns from the impact date to 31 December 2009. The impact cloud expanded zonally from~ 5000 km (July 19) to 225,000 km (about 180 deg in longitude by 29 October) and it was meridionally localized within a latude band from -53.5 deg to -61.5 deg.During the first two months it showed a heterogeneous structure with embedded spots of a size of 500 - 1000 km. The cloud was mainly dispersed in longitude bythe dominant zonal winds and their meridional shear and, during the inial stages, by the acon of local moons perhaps originated by the thermal perturbaonproduced at the impact site. The tracking of individual spots within the impact cloud showed that the winds increase their eastward velocity with altude abovethe tropopause by 5-10 m/s. We found evidence of discrete localized meridional moons in the equatorward direcon with speeds of 1 - 2 m/s. Measurements ofthe cloud reflecvity evoluon during the whole period showed that it followed an exponenal decrease with a characterisc me of 15 days, shorter than the 45- 200 days sedimentaon me for the small aerosol parcles in the stratosphere. A radiave transfer model of the cloud opcal depth coupled to an adveconmodel of the cloud dispersion by the wind shears, reproduces this behavior. Acknowledgements: ASL, RH, SPH, NBI are supported by the Spanish MICIIN AYA2009-10701 with FEDER and Grupos Gobierno Vasco IT-464-07.31.02: First Earth-based Detecon of a Superbolide on JupiterAuthor Block: Ricardo Hueso 1 , A. Wesley 2 , C. Go 3 , S. Perez-Hoyos 1 , M. H. Wong 4 , L. N. Fletcher 5 , A. Sanchez-Lavega 1 , M. B. E. Boslough 6 , I. de Pater 4 , G. S.Orton 7 , A. A. Simon-Miller 8 , S. G. Djorgovski 9 , M. L. Edwards 10 , H. B. Hammel 11 , J. T. Clarke 12 , K. S. Noll 13 , P. A. Yanamandra-Fisher 71 Universidad del Pais Vasco, Spain, 2 Acquerra Pty. Ltd, Australia, 3 University of San Carlos, Philippines, 4 University of California, Berkeley, 5 University of Oxford,United Kingdom, 6 Sandia Naonal Laboratories, 7 JPL-Caltech, 8 Goddard Space Flight Center, 9 Caltech, 10 Gemini Observatory, Chile, 11 Space Science Instute,12 Boston University, 13 Space Telescope Science Instute.Presentaon Time: 10/6/2010 8:40 AM - 8:50 AMLocaon: Ballroom BCAbstract: On June 3, 2010 a bolide in Jupiter’s atmosphere was observed from the Earth for the first me. The flash was detected by amateur astronomers A.Wesley and C. Go observing in two wavelength ranges. We present an analysis of the light curve of those observaons that allow esmang the size of the objectto be significantly smaller than the SL9 and the July 2009 Jupiter impact. Observaons obtained a few days later by large telescopes including HST, VLT, Keck andGemini showed no signature of the impact in Jupiter atmosphere confirming the small size of the impact body. A nearly connuous observaon campaign basedon several small telescopes by amateurs astronomers might allow an empirical determinaon of the flux of meteoroids in Jupiter with implicaons for thepopulaons of small bodies in the outer solar system and may allow a beer quanficaon of the threat of impacng bodies to Earth.Acknowledgements: RH, ASL and SPH are supported by the Spanish MICIIN AYA2009-10701 with FEDER and Grupos Gobierno Vasco IT-464-07. LNF is supported bya Glasstone Science Fellowship at the University of Oxford.31.03: Jupiter Impacts in the Thermal-Infrared: Comparing Atmospheric Responses in 1994, 2009 and 2010Author Block: Leigh N. Fletcher 1 , G. S. Orton 2 , I. de Pater 3 , O. Mousis 4 , M. Edwards 5 , C. M. Lisse 6 , A. Sánchez-Lavega 7 , R. Hueso 7 , S. Pérez-Hoyos 7 , P. G. J.Irwin 1 , N. A. Teanby 81 University of Oxford, United Kingdom, 2 JPL/California Instute of Technology, 3 UC Berkeley, 4 Observatoire de Besancon, France, 5 Gemini South Observatory,Chile, 6 Johns Hopkins University, 7 Universidad del País Vasco, Spain, 8 University of Brisol, United Kingdom.Presentaon Time: 10/6/2010 8:50 AM - 9:00 AMLocaon: Ballroom BCAbstract: Rising plumes and high temperature shocks resulng from collisions of primive bodies with Jupiter produce dramac perturbaons to theatmospheric structure and chemistry. Spectroscopy of Jupiter’s 7-25 µm spectrum, from NASA/IRTF, VLT and Gemini, demonstrates that these atmosphericperturbaons differ substanally between impacts and can reveal the nature of the impactor. VLT/VISIR spectroscopy of the July 2009 impact site revealedelevated abundances of ethane (and possibly acetylene), the products of shock-induced chemistry in a reducing environment (i.e., an absence of water,suggesng an asteroidal origin in 2009). This is counter to observaons of the 1994 Shoemaker-Levy 9 (SL9) collisions, where no increase in hydrocarbons wasobserved, due to the formaon of CO in a water-rich environment (consistent with a cometary origin). VLT and Gemini imaging demonstrated no excess thermalenergy in the upper stratosphere following the 2009 and June 2010 impact events, and yet SL9 le traces of high-altude heang at mulple impact sites. The2010 event was considerably smaller in scale, generang a shock wave too small to penetrate the ammonia cloud depths to lo NH 3 into the lower stratosphere,as was observed for the SL9 and 2009 impacts. Nor did the 2010 impact generate high-altude parculate debris, which was clearly evident in the SL9 and 2009impact sites. Finally, minearological differences between the 1994 and 2009 debris have been revealed by Gemini spectroscopy, indicang the presence ofsilicates in both cases, but also silicas in the 2009 collision.We present results for the fate of stratospheric ammonia, hydrocarbons and parculates from the 2009 impact, plus the non-detecon of thermal signatures ofthe 2010 event by Gemini and VLT. These are compared to SL9 results to describe the different origins of Jupiter impactors and the differences in the atmosphericresponse.* Fletcher is supported by a Glasstone Science Fellowship.31.04: Scaering Properes of Jovian Tropospheric Cloud Parcles from Cassini/ISS: Mie Scaering Phase Funcon and Parcle Size in the SouthTropical Zone

Author Block: Takao M. Sato 1 , T. Satoh 2 , Y. Kasaba 11 Tohoku University, Japan, 2 JAXA/ISAS, Japan.Presentaon Time: 10/6/2010 9:00 AM - 9:10 AMLocaon: Ballroom BCAbstract: It is essenal to know scaering properes (e.g., scaering phase funcon) of clouds for determinaon of vercal cloud structure. However, wecannot derive those from ground-based and Earth-orbit observaons because of the limitaon of solar phase angle as viewed from the Earth. Then, most previousstudies have used the scaering phase funcon deduced from the Pioneer 10/IPP data (blue: 440 nm, red: 640nm) [Tomasko et al., 1978].There are two shortcomings in the Pioneer scaering phase funcon. One is that we have to use this scaering phase funcon at red as a substute for analysesof imaging photometry using CH 4 bands (center: 727 and 890 nm), although clouds should have wavelength dependency. The other is that the red pass band ofIPP was so broad (595-720 nm) that this scaering phase funcon in red just show wavelength-averaged scaering properes of clouds.To provide a new reference scaering phase funcon with wavelength dependency, we have analyzed the Cassini/ISS data in BL1 (451 nm), CB1 (619 nm), CB2(750 nm), and CB3 (938 nm) over wide solar phase angles (3-141 degrees) during its Jovian flyby in 2000-2001.A simple cloud model which consists of a thin stratospheric haze, a semi-infinite cloud, and an intervening Rayleigh gas layers is adopted. Applying Mie theory toscaering by clouds, we deduce the scaering phase funcon of cloud and effecve parcle size in the South Tropical Zone. When we use the nominal value ofreflecve index for ammonia ice (Martonchik et al., 1984), we cannot obtain reasonable fit to the observed limb-darkening profiles. This would imply that weshould consider possible effects on the impurity and/or the nonsphericiy of clouds.In this presentaon, we will show detail model descripon and these results. Finally, we discuss scaering properes of clouds through comparison with previousworks.31.05: Mapping water in Jupiter with Herschel/HIFIAuthor Block: Thibault Cavalié 1 , P. Hartogh 2 , E. Lellouch 3 , R. Moreno 3 , C. Jarchow 2 , F. Billebaud 1 , G. Orton 4 , M. Rengel 2 , H. Sagawa 5 , L. Lara 6 , A. Gonzalez 2 ,HssO Team1 Laboratoire D'Astrophysique De Bordeaux, France, 2 Max Planck Instute für Sonnensystemforschung, Germany, 3 Observatoire de Paris-Meudon, France, 4 JetPropulsion Laboratory/Caltech, 5 Naonal Instute of Informaon and Communicaons Technology, Japan, 6 Instuto de Astrofisica de Andalucia CSIC, Spain.Presentaon Time: 10/6/2010 9:10 AM - 9:20 AMLocaon: Ballroom BCAbstract: A major discovery of ISO was the detecon of water in the upper atmospheres of the four giant planets and Titan (Feuchtgruber et al, 1997; Cousteniset al, 1998), implying the existence of external sources of water. This oxygen supply, which manifests itself also through the presence of CO 2 and CO in theseatmospheres, may have several sources: (i) a permanent flux from interplanetary dust parcles produced from asteroid collisions and from comet acvity (Pratheret al,1978), (ii) local sources from planetary environments (rings, satellites) (Strobel and Yung, 1979; Prangé et al, 2006), (iii) cometary ‘‘Shoemaker-Levy 9 (SL9)type’’ impacts (Lellouch et al, 1995). Disentangling the various sources at Jupiter is a key objecve of the Herschel Space Observatory key program HssO (Hartoghet al, 2009).Herschel/HIFI observed H 2 O in Jupiter at 1669 GHz in a 5x5 point map on July 7, 2010. From this observaon, we will present and discuss the search for latudinalvariability of H 2 O in Jupiter.Acknowledgement: Research by T. Cavalié was supported by the Fondaon des Amis des Sciences.References:Coustenis et al, A&A 336,L85-L89.Feuchtgruber et al, 1997. Nature 389, 159-162.Hartogh et al, 2009. Planet. Space Sci. 57, 1596-1606.Lellouch et al, 1995. Nature 373, 592-595.Prangé et al, 2006. Icarus 180, 379-392.Prather, 1978. ApJ 223, 1072-1081.Strobel & Yung, 1979. Icarus 37, 256-263.31.06: Evidence For N H4SH As The Primary 3-micron Absorber In Jupiter's Clouds.Author Block: Lawrence A. Sromovsky 1 , P. M. Fry 11 Univ. of Wisconsin-Madison.Presentaon Time: 10/6/2010 9:20 AM - 9:30 AMLocaon: Ballroom BCAbstract: A prominent characterisc of Jovian near-IR spectra is the widely distributed presence of a strong absorpon at 2.9-3.1 microns, first noced in a 3-micron spectrum obtained by the Infrared Space Observatory (ISO) in 1996. While Brooke et al. (1998, Icarus 136, 1-13) were able to fit the ISO spectrum usingammonia ice as the sole source of parculate absorpon, Irwin et al. (2001, Icarus 149, 397-415) noted that their best-fit cloud model implied a strong absorponat 2 microns that was not observed in Galileo NIMS spectra. Subsequent significant revisions in ammonia gas absorpon models (Bowles et al. 2008, Icarus 196,612-614) also raised quesons about the Brooke et al. results because ammonia gas absorpon overlaps regions of ammonia ice absorpon. Our reanalysis,based on improved ammonia absorpon models, finds that the ISO spectrum can be fit much beer with NH4SH as the sole 3-micron absorber than with NH3. Buteven beer fits result from cloud models that include both NH3 ice and NH4SH, with the laer substance providing most of the absorpon. The component due toNH3 is very possibly in the form of a coang on either large (r~15 microns) parcles in a deeper layer at ~550 mb or on small (r~0.3 micron) photochemical hazeparcles in a higher layer near 370 mb. Neither opon conflicts with the lack of significant NH3 absorpon features at thermal wavelengths. VIMS spectral fits(Sromovsky and Fry 2010, Icarus in press, doi:10.1016/j.icarus.2010.06.039) are also compable with NH4SH as the primary 3-micron absorber, and also benefitfrom the inclusion of a layer of small (r~0.3 micron) composite parcles, with NH3 as a minor fracon, either as coang or core.This work was supported by NASA Outer Planets Research Program, the Cassini Data Analysis program, and the Jupiter Data Analysis Program.31.07: Jovian Chromophore Characteriscs from Mulspectral HST ImagesAuthor Block: Paul D. Strycker 1 , N. J. Chanover 1 , A. A. Simon-Miller 2 , D. Banfield 3 , P. J. Gierasch 31 New Mexico State Univ., 2 NASA Goddard Space Flight Center, 3 Cornell Univ..Presentaon Time: 10/6/2010 9:30 AM - 9:40 AMLocaon: Ballroom BCAbstract.Abstract: Characterizing the chromophores responsible for coloring the Jovian atmosphere remains a challenging problem. In this study, we usedradiave transfer models to derive spectral shapes of chromophore parcles at seven wavelengths in the visible regime from HST WFPC2 data. The observaonswe selected are from 15 May, 28 June, and 08 July 2008, covering a passage of Oval BA and the Great Red Spot, and include nine filters: F255W, F343N, F375N,

F390N, F410M, F437N, F469N, F502N, and F673N. We employed a forward-modeling approach using an adding-doubling radiave transfer code developed toanalyze Galileo SSI data (Simon-Miller et al. 2001, Icarus 154, 459). We adopted a model atmosphere with three aerosol layers: a stratospheric haze, uppertropospheric haze, and tropospheric cloud. We parametrized each aerosol layer by a base pressure, opcal depth, parcle radius, and parcle color (a singlescaering albedo at each wavelength). For filters F375N-F673N, we assumed the chromophore (non-white) component resides solely in the upper tropospherichaze. We present derived parcle colors for Jovian locaons with a large variaon in observed color and a discussion of the number of independent chromophoresnecessary to produce the variaons in derived parcle color. This work was supported by NASA's Planetary Atmospheres Program through grant numberNNX08AF53A. This work is based on observaons made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Instute, which isoperated by the Associaon of Universies for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observaons are associated with program#GO/DD11498.31.08: Spherical Harmonic Analysis of Jupiter's Cloud Features and Kinec Energy from CassiniAuthor Block: David S. Choi 1 , A. P. Showman 11 Univ. of Arizona.Presentaon Time: 10/6/2010 9:40 AM - 9:50 AMLocaon: Ballroom BCAbstract.Abstract: Recent power spectrum analysis of Jupiter's cloud features and atmospheric kinec energy from a common Cassini imaging data setrevealed suggesve evidence for an inverse energy cascade. We now report preliminary results from a re-analysis of our data ulizing spherical harmonics.Similar to our previous analysis, the typical power spectrum of Jupiter's cloud paerns and the kinec energy of the atmosphere at the altude of the ammoniacloud deck are broadly similar but contain some important differences. Power spectra of Jupiter's cloud paerns imaged with certain imaging filters resembletheorecal spectra of two-dimensional turbulence, with power-law slopes near -5/3 and -3 at low and high wavenumbers, respecvely. The slopes of the kinecenergy power spectrum are also near -5/3 at low wavenumbers. At high wavenumbers, the spectral slopes appear to be relavely flaer than the theorecalpredicon of -3, but the inferred slopes are sensive to data analysis methods and may not represent the true spectral slope. In addion, the image mosaic andkinec energy power spectra differ with respect to the locaon of the transion in slopes. The transion in slope is near planetary wavenumber 70 for the kinecenergy spectra, but is typically above 200 for the image mosaic spectra. We interpret the results overall as evidence suggesng the presence of an inverseenergy cascade within Jupiter's atmosphere. Our results also show the importance of calculang spectral slopes from full 2D velocity maps rather than 1D zonalmean velocity profiles, as the spectral slopes obtained from 1D data sets differ greatly from those obtained from full 2D data sets. Furthermore, the differencebetween the image and kinec energy spectra suggests cauon in the interpretaon of power spectrum results solely from image mosaics and its significance forthe underlying dynamics.31.09: First Clear Detecon Of Jupiter Global OscillaonsAuthor Block: Patrick Gaulme 1 , F. Schmider 2 , J. Gay 21 Instut d'Astrophysique Spaale, France, 2 Observatoire de la Côte d'Azur, France.Presentaon Time: 10/6/2010 9:50 AM - 10:00 AMLocaon: Ballroom BCAbstract: The knowledge of the inner structure of Jupiter, in parcular the central region, would bring unique constraints on the Solar system formaonscenario. Nowadays, the inner structure of Jupiter is poorly constrained and seismology, which consists in idenfying planetary acousc eigen modes, is the onlyway to invesgate the core region. Seismology of Jupiter has been considered since the very beginning of seismology of the Sun, because of their common fluidnature, leading to similar oscillaons and same techniques to search them for. From 1980 and 1990's experiments, emerged the need for a specificinstrumentaon, able to combine high spectral resoluon and spaal resoluon. The SYMPA instrument is a Fourier tachometer developed at Observatoire de laCôte d'Azur (Schmider et al. 2007, A&A 474, 1073 and Gaulme et al. 2008, A&A 490, 859). Two instruments were built and simultaneously used during 2observaon runs in 2004 and 2005 at San Pedro Marr and Teide observatories. In this presentaon, we show a new analysis of the 2005 data set, where wedetect several oscillaon modes of Jupiter. In parcular, we measure an excess power in the frequency range [800, 2000] µHz and a mean frequency spacingbetween the modes of about 155+/-1 µHz, which corresponds with the theorecal expectaons from Gudkova et al. 1999 (PSS 47, 1211).

Session Number: 32Session Title: Galilean Satellites ISession Type: Oral32.01: DSMC Simulaons of Irregular Source Geometries for Io's Pele PlumeAuthor Block: William McDoniel 1 , D. B. Goldstein 1 , P. L. Varghese 1 , L. M. Traon 1 , D. A. Buchta 2 , J. Freund 2 , S. W. Kieffer 21 The University of Texas at Ausn, 2 University of Illinois at Urbana-Champaign.Presentaon Time: 10/6/2010 8:30 AM - 8:40 AMLocaon: Ballroom DAbstract: Volcanic plumes on Io represent a complex rarefied flow into a near-vacuum in the presence of gravity. A 3D rarefied gas dynamics method (DSMC) isused to invesgate the gas dynamics of such plumes, with a focus on the effects of source geometry on far-field deposion paerns. These deposion paerns,such as the deposion ring's shape and orientaon, as well as the presence and shape of ash deposits around the vent, are linked to the shape of the vent fromwhich the plume material arises.We will present three-dimensional simulaons for a variety of possible vent geometries for Pele based on observaons of the volcano's caldera. One is a curvedline source corresponding to a Galileo IR image of a parcularly hot region in the volcano’s caldera and the other is a large area source corresponding to theenre lava lake at the center of the plume. The curvature of the former is seen to be sufficient to produce the features seen in observaons of Pele's deposionpaern, but the parcular orientaon of the source is found to be such that it cannot match the orientaon of these features on Io's surface. The laer correctsthe error in orientaon while losing some of the structure, suggesng that the actual source may correspond well with part of the shore of the lava lake.In addion, we are collaborang with a group at the University of Illinois at Urbana-Champaign to develop a hybrid method to link the connuum flow beneathIo's surface and very close to the vent to the more rarefied flow in the large volcanic plumes.This work was funded by NASA-PATM grant NNX08AE72G.32.02: Morphology and Temperatures at PeleAuthor Block: Robert R. Howell 1 , R. M. C. Lopes 21 Univ. of Wyoming, 2 JPL.Presentaon Time: 10/6/2010 8:40 AM - 8:50 AMLocaon: Ballroom DAbstract.Abstract: The Pele region of Io has been the site of vigorous volcanic acvity from the me of the first Voyager I observaons in 1979 up through thefinal Galileo ones in 2001. There is high temperature thermal emission from what is thought to be a rapidly overturning lava lake, and also the source of a largesulfur-rich plume. We present a new analysis of Voyager I visible wavelength images, and Galileo Solid State Imager (SSI) and Near Infrared MappingSpectrometer (NIMS) thermal emission observaons which beer define the morphology of the region and the intensity of the emission. The observaons showremarkably correlaons between the locaons of the emission and the features seen in the Voyager images, which provide insight into erupon mechanisms andconstrain the longevity of the acvity. We also analyze an addional wavelength channel of NIMS data (1.87 micron) which paradoxically, because of reducedsensivity, allows us to esmate temperatures at the peak locaons of emission. Measurements of erupon temperatures on Io are crucial because they provideour best clues to the composion of the magma. High color temperatures indicave of ultramafic composion have been reported for the Pillan hot spot andpossibly for Pele, although recent work has called into queson the requirement for magma temperatures above those expected for ordinary basalts. Our newanalysis of the Pele emission near the peak of the hot spot shows color temperatures near the upper end of the basalt range during the I27 and I32 encounters.We also analyze those temperatures in terms of lava cooling models to determine the required magma temperatures.32.03: Io’s Acve Volcanoes from New Horizons MVIC and LORRI DataAuthor Block: Julie A. Rathbun 1 , K. B. McMillian 1 , L. W. Kamp 2 , R. M. Lopes 2 , J. R. Spencer 31 Univ. of Redlands, 2 JPL, 3 SWRI.Presentaon Time: 10/6/2010 8:50 AM - 9:00 AMLocaon: Ballroom DAbstract: Io was a major target of New Horizons as it flew by the Jupiter system in February 2007. The Long-Range Reconnaissance Imager (LORRI), a highresoluon panchromac camera, obtained 190 images of Io at wavelengths from 400-900 nm. The Mulcolor Visible Imaging Camera (MVIC), a near-infraredimager, obtained 17 color nighme and eclipse images of Io. We have examined these images to determine which volcanoes were acve. Furthermore, bycombining data from mulple instruments, we will determine the erupon temperatures for several of the volcanoes. The total brightness of a volcano, along withits variaon with wavelength and its temporal variability, yields insight into the erupon process of the volcano. Furthermore, the spaal distribuon of volcanoesand its variaon over me can yield insights into the dal heang process. Io’s volcanoes were not studied extensively between the end of the Galileo missionand the New Horizons mission, so these new data will expand the me-frame over which we have data.32.04: Impact of Plasma Chemistry on Io’s AtmosphereAuthor Block: Chris H. Moore 1 , H. Deng 2 , D. B. Goldstein 1 , D. Levin 2 , P. L. Varghese 1 , L. M. Traon 1 , A. C. Walker 1 , B. D. Stewart 11 The University of Texas Ausn, 2 Pennsylvania State University.Presentaon Time: 10/6/2010 9:00 AM - 9:10 AMLocaon: Ballroom DAbstract: We present results of an invesgaon of the jovian plasma torus’ interacon with Io’s sublimaon atmosphere using the direct simulaon MonteCarlo (DSMC) method which is appropriate for solving rarefied flows such as Io’s atmosphere. Accurate simulaon of Io’s atmosphere is crical for modeling thesupply of material to the torus and understanding the morphology and intensity of the electron excited aurora on Io. The plasma sweeps past Io at 57 km/s andthe resultant energec collisions with Io’s neutral atmosphere create an inflated, mixed atmosphere of SO 2 and its daughter products. In the present work, theplasma interacon is modeled by a flux of ions and electrons which flow around and through Io’s atmosphere along pre-computed perturbed magnec field lines.Since the Debye length is everywhere much less than the size of the DSMC computaonal cells (which scale with the neutral mean free path), we assume theplasma is quasi-neutral. A two me-step method is used in which the neutrals move and then are staonary while the ions and electrons move with a muchsmaller me-step. Ions can undergo non-reacve collisions and charge exchange collisions with the neutral species. Fast neutrals produced via charge exchangehave sufficient energy to dissociate the neutral molecular species; these interacon cross secons have been computed using MD/QCT simulaons. The electroninteracons with the neutral species are funcons of the collision energy and are based on measured reacon cross secons (elasc, excitaon, ionizaon, anddissociaon). The effect of the plasma on the circumplanetary winds, the escape rate of neutrals from Io, and the composion and structure of Io’s atmosphere isinvesgated and compared with previous connuum simulaons by Smyth and Wong. Future work will invesgate the resultant auroral emissions and theirimplicaons on volcanic acvity and the upstream electron temperature.

32.05: Effect of Orbital Phase on the Structure of Io's AtmosphereAuthor Block: William H. Smyth 1 , M. L. Marconi 21 Atmos. & Envir. Research, Inc., 2 Prisma Basic Research.Presentaon Time: 10/6/2010 9:10 AM - 9:20 AMLocaon: Ballroom DAbstract: Io possesses a highly non-uniform collisional atmosphere that is created by sublimaon of surface SO 2 frost and volcanoes and is both intenselyheated and excoriated by its high-velocity (~60 km/s) interacons with the Io plasma torus. The plasma moon parallel to the more-or-less north-south alignedmagnec field lines intersects an almost radial and hence thinner neutral column density near the pole but an almost tangenal and much thicker neutral columndensity near the equator. The plasma moon perpendicular to the magnec field lines always impinges on the trailing satellite hemisphere while the Io plasmawake is above the leading hemisphere. The hemisphere of the thicker dayside sublimaon atmosphere, however, moves about Io as the satellite moves in its orbitabout Jupiter. Mulple volcanoes scaered throughout Io's surface represent substanal addional sources of atmosphere. Io's resulng atmosphere is thereforeinherently three-dimensional in nature. To invesgate the changing nature of Io's atmospheric structure, composion, and dynamics with orbital phase, we havedeveloped a three-dimensional mul-species hydrodynamic model with sublimaon and volcanic sources. The model includes the relevant photo, gas-phase, andelectron-impact chemistry and the changing locaon of plasma-ion heang in the day and night atmosphere as Io moves about Jupiter. The interacon of theplasma torus with the atmosphere involves various processes, and the current model includes electron impact ionizaon/dissociaon of neutrals and ion-neutralelasc collisions. Select model calculaons for the composion and structure of the atmosphere for different orbital phases of Io will be compared. This researchhas been supported by the NASA Planetary Atmospheres Program.32.06: Strike-slip Moon as a Natural Consequence of Europan Tidal StressAuthor Block: Alyssa R. Rhoden 1 , M. Manga 1 , T. A. Hurford 21 UC - Berkeley, 2 NASA GSFC.Presentaon Time: 10/6/2010 9:20 AM - 9:30 AMLocaon: Ballroom DAbstract: We have idenfied an unexpected property of Europa’s eccentricity-driven dal stress field that can generate net shear stress along faults and maythus elucidate the mechanics of strike-slip fault formaon. Europa’s eccentricity raises a me-varying dal bulge that differs in magnitude and direcon from theprimary dal bulge throughout an orbit, leading to dal stress. The magnitude of the eccentricity bulge is at a maximum at pericenter and minimum at apocenter,while the maximum deviaon between the direcons of the eccentricity and primary bulges occurs at 1/4 and 3/4 of an orbit; the bulges are aligned at pericenterand apocenter. Hence, the direcon of moon of the eccentricity bulge is westward across the surface from 1/4 of the way through the orbit unl 3/4, duringwhich me the magnitude of the bulge is always less than average. The direcon of moon is then in the opposite direcon, eastward across the surface, from3/4 unl 1/4, while the magnitude of the dal bulge is always greater than average. The result is that the deformaon caused by the moon of the bulge relaveto a given locaon on Europa occurs with larger magnitude in one direcon. Therefore, the stresses induced by the deformaon are not equal and opposite. Aninteresng consequence is that, when decomposed along a fault, the stresses will not necessarily cancel out over one orbit. Depending on the azimuth of thefault, and its latude and longitude, the fault can experience net posive or negave shear stress perhaps leading to slip. We discuss implicaons of thisphenomenon on models of strike-slip formaon on Europa and compare predicons based on these models with observed fault paerns.32.07: Geophysical Implicaons Of The Long-wavelength Topography Of Rhea And EuropaAuthor Block: Francis Nimmo 1 , B. G. Bills 2 , P. C. Thomas 3 , S. W. Asmar 21 U C Santa Cruz, 2 Jet Propulsion Laboratory, 3 Cornell University.Presentaon Time: 10/6/2010 9:30 AM - 9:40 AMLocaon: Ballroom DAbstract: We use limb profiles to invesgate the long-wavelength topography and topographic variance spectra of Rhea and Europa. One-dimensional variancespectra for Rhea show a break in slope at a wavelength of 300 km and may be a signature of an elasc lithosphere having a thickness Te15 km. The impliedheat flux is 10 mW/m2, much higher than can be explained by long-lived radionuclides. A similar break in slope is seen for Europa limb profiles, but occurs at60 km wavelength, implying a lower elasc thickness of about 4 km. We use the 1D spectral behaviour to constrain our soluon for the long-wavelength globaltopography of Rhea. The degree-three topography is large enough, if uncompensated, to contaminate esmates of the degree-two gravity using exisng flybydata. Current models of Rhea internal structures which rely on these degree-two esmates may thus be inaccurate, illustrang the need to acquire further Rheagravity data32.08: Heat Flow Signatures on Europa: Thermal Model ResultsAuthor Block: David A. Paige 1 , P. O. Hayne 1 , K. A. Benne 1 , B. T. Greenhagen 21 UCLA, 2 JPL.Presentaon Time: 10/6/2010 9:40 AM - 9:50 AMLocaon: Ballroom DAbstract: Measuring Europa’s heat flow will place important constraints on its interior structure and history. We have developed a ray-tracing thermal model forthe moon that can calculate surface temperatures that are in good agreement with LRO Diviner Lunar Radiometer measurements. The model includes the effectsof mulply scaered solar and infrared radiaon, one-dimensional heat conducon, and the radiave effects of earthshine at solar and infrared wavelengths. Wehave adapted the lunar model to quanfy the potenal effects of global-scale and local-scale heat flow on surface temperatures on Europa. The results show theextent to which mul-spectral measurements of thermal emission from the surface of Europa can differenate between thermal signatures due to heat flow, andthose due to variaons in diurnal and seasonal insolaon, radiaon from Jupiter, and local variaons in topography, thermal inera and surface roughness.

32.09: Youthful Geologic Terrains with Anomalous Surface Chemistry on EuropaAuthor Block: James H. Shirley 1 , J. B. Dalton III 1 , L. M. Prockter 2 , L. W. Kamp 11 Caltech-JPL, 2 JHU-APL.Presentaon Time: 10/6/2010 9:50 AM - 10:00 AMLocaon: Ballroom DAbstract: Geologic mapping of Europa’s Argadnel Regio has idenfied more than a dozen disncve geologic terrains. We have assembled and registeredspacecra imaging, geologic mapping, and spectroscopic mapping datasets for part of this region. We have obtained linear mixture modeling composionalsoluons for more than 40 non-overlapping exposures of ridged plains, low albedo plains, chaos, dark spots, and crater ejecta (Dalton et al., LPSC XL #2511, 2009;Shirley et al., 2010, Icarus, in press). This work has uncovered a well-defined spaal gradient of sulfuric acid hydrate abundance, with concentraons of thismaterial increasing in the direcon of Europa’s trailing-side apex. Surprisingly, the gradient appears to be independent of the nature of the underlying terrain(Shirley et al., LPSC XLI, 2010). This suggests that the H 2 SO 4 hydrate abundance may be closely linked with magnetospheric bombardment processes, whichsupply both sulfur ions and energy for driving the chemical reacons of the sulfur cycle (Carlson et al., Science 286, 97, 1999; Dalton et al., this meeng).Stragraphic relaonships indicate that the low albedo plains are among the youngest geologic terrains within our study area. Composional soluons for fourconguous non-overlapping exposures of low albedo plains materials exhibit abundances of the H 2 SO 4 hydrate that are lower than those of their immediateneighbors by up to 33%. We suggest that these parcular exposures may not have been exposed to the surface radiaon environment long enough to reachradiolyc chemical equilibrium; if so, this would suggest that these deposits may have been emplaced quite recently. We will touch on implicaons for chemicalmodels of Europa’s subsurface fluids, for observing strategies for future missions to Europa, and for astrobiological invesgaons. This work was supported byNASA’s Outer Planets Research Program, and was performed at the California Instute of Technology-Jet Propulsion Laboratory under contract with NASA.

Session Number: 33Session Title: Centaurs and Trans-Neptunian Objects IISession Type: Oral33.01: Dwarf planets observaons with Herschel Space ObservatoryAuthor Block: Pablo Santos-Sanz 1 , E. Lellouch 1 , S. Fornasier 1 , C. Kiss 2 , T. G. Müller 3 , P. Lacerda 4 , TNOs are Cool Team1 Observatoire De Paris-Meudon (CNRS), LESIA, France, 2 Konkoly Observatory of the Hungarian Academy of Sciences, Hungary, 3 Max-Planck-Instut fürextraterrestrische Physik, Germany, 4 Astrophysics Research Centre, Physics Building, Queen’s University, United Kingdom.Presentaon Time: 10/6/2010 8:30 AM - 8:40 AMLocaon: Ballroom EAbstract: We present results of the observaons of dwarf planets Haumea and Makemake performed with Herschel Space Observatory within the "TNOs areCool" key program.Haumea was observed on December 23 and 25, 2009, and June 20- 21, 2010 with the PACS photometer at 100 and 160 microns. Assigning a rotaonal phase foreach one of these observaonal dates (rotaonal period= 3.915341 h), we obtain a clear thermal lightcurve at 100 microns, and only a marginal one at 160microns. This thermal lightcurve is correlated with the visible lightcurve which confirms that the laer is due to shape effects. An inial data reducon using theDec. 2009 data suggested a very large and difficult to explain amplitude for the thermal lightcurve of almost a factor of 2 (Lellouch et al. 2010). With the newJune 2010 data rather indicates a more modest amplitude with a factor around 1.5, closer to the 30 % amplitude obtained for the visible lightcurve. The effect ofthe dark and red spot present in the opcal lightcurve is sll unclear. The albedo and effecve diameter derived from the thermal fits are consistent with theprevious analysis of the thermal lightcurve.Makemake was observed on November 30, 2009, and June 2-3, 2010 with PACS at 70, 100 and 160 microns obtaining a very nice detecon. This object was alsoobserved with SPIRE at 250, 350 and 500 microns on November 29, 2009, and December 1st, 2009 (Lim et al. 2010). We will present and discuss the obtainedfluxes and the albedo and diameter resultant for the radiometric fits.33.02: EVLA Observaons of the Largest TN OsAuthor Block: Bryan J. Butler 1 , M. A. Gurwell 2 , A. Moullet 21 NRAO, 2 CfA.Presentaon Time: 10/6/2010 8:40 AM - 8:50 AMLocaon: Ballroom EAbstract: Despite the importance of understanding TNOs in the context of solar system formaon and evoluon, the physical properes of these bodies arerelavely poorly known. Though masses are known for at least those with satellites, their radii are poorly constrained, making esmates of such a fundamentalquanty as density highly uncertain. Lile is also known about the surface temperatures of these bodies; equilibrium with solar radiaon is usually assumed.Long wavelength thermal emission observaons are a powerful way to constrain such quanes more accurately. They addionally sample below the surface (toroughly 10 wavelengths), yielding informaon about thermal and structure characteriscs to that depth. Unfortunately, long wavelength emission is weak and hasonly been done successfully at millimeter wavelengths for a few of the largest TNOs.The EVLA is the next generaon cenmeter wavelength telescope, building on the tremendous success of the VLA. The main improvement is an eventual factor of10 beer sensivity. Observaons at a wavelength of 1 cm of the TNOs 2002 TC302, Makemake, Quaoar, and Eris, along with the Pluto system and Triton havebeen approved for the EVLA, and we will present all data taken on these bodies (the Pluto system will not be observed unl spring 2011, when Pluto and Charoncan be resolved from each other). This is part of a longer term program to measure the microwave emission spectrum of these bodies from roughly 0.5 mm to 5cm using both the EVLA and ALMA.33.03: Subarcsecond Scale Imaging of the Pluto-Charon System at 1.1 and 1.4 mmAuthor Block: Mark A. Gurwell 1 , B. J. Butler 2 , A. Moullet 11 Harvard-Smithsonian Center For Astrophysics, 2 NRAO.Presentaon Time: 10/6/2010 8:50 AM - 9:00 AMLocaon: Ballroom EAbstract: Determining the surface temperatures of Pluto and Charon places strong constraints on the types of ices stable on their surfaces. This in turn yieldsinformaon on the composion of these bodies, and constrains models of solar system formaon. Prior to 2005, no direct measurements of the separatedthermal flux densies (and therefore surface temperatures) of Pluto and Charon had been obtained. Their close proximity (maximum separaon under 0.9") makespaally resolving the pair at thermal wavelengths a challenge. However, models of composion and thermal properes for the surfaces of each depend onaccurate thermal measurements and call for high resoluon imaging, now achievable at millimeter/submillimeter wavelengths.To beer constrain the temperatures of Pluto and Charon, we used the Submillimeter Array (SMA) to image the system at 1.4 mm (21 May 2005) and are currentlyobtaining data at 1.1 mm (late July 2010). With baselines at the SMA up to 509 m in length, these observaons achieve 0.5" and 0.4" resoluon, respecvely, andthus allow us to separate the pair, and independently measure the thermal brightness of each object.The 2005 observaons were the first observaons ever that separated the pair at a true thermal wavelength, finding the brightness temperature of Pluto to be39±4 K while Charon was 48±12 K. At the meeng will present an improved analysis of this data.We will also present new results from our current campaign at 1.1 mm; we currently have data from July 9 and July 19, 2010, with more data expected. While thedata obtained to date have not been fully analyzed, a qualitave analysis from imaging the July 19 data set shows the intensity rao of Pluto to Charon to beabout 0.75; e.g. Pluto has a significantly lower brightness temperature than Charon, as we previously saw at 1.4 mm.

Session Time: 10/6/2010 9:00 AM

Session Number: 34Session Title: Mars: Surface Spectroscopy and MorphologySession Type: Oral34.01: Detecon Of Hydrated Silicates In Craters Of The Northern Plains Of MarsAuthor Block: Francois Poulet 1 , J. Carter 2 , J. Bibring 2 , S. Murchie 31 Universite de Paris IX, France, 2 Universite Paris Sud/CNRS, France, 3 JHU/APL.Presentaon Time: 10/6/2010 9:00 AM - 9:10 AMLocaon: Ballroom EAbstract: Data acquired by the OMEGA and CRISM spectrometers onboard Mars Express and Mars Reconnaissance Orbiter have confirmed that the surface ofthe ancient, Noachian-aged southern highlands of Mars is mostly unaltered, preserving old crustal material but also revealing thousands of small outcrops ofvarious hydrated minerals, mostly phyllosilicates. These altered minerals record an early era during which Mars likely harboured environmental condions thatsustained surface liquid water. By contrast, the younger northern hemisphere lowlands are covered by material over hundreds of meters thick, likely volcanic anddetrital in origin, and overlying the ancient crust whose composion is nearly unknown. An efficient way to access this buried crust is to study material ejected byimpactors large enough to have penetrated the thick cover, in craters tens of kilometres in diameter. Using CRISM, OMEGA and imaging instruments, we studiedover ninety northern plain craters and discovered at least nine sites exhibing outcrops of various hydrated minerals. These minerals are found in central peaks,rims and ejecta, and are dominated by prehnite, chlorites and iron/magnesium/aluminium rich smectes. Craters with occurrences of hydrated minerals are foundat wide ranges of latude and longitude, and have diameter larger than fieen kilometres. Phyllosilicates and unaltered olivine outcrops deposits are foundclosely juxtaposed, randomly within the crater floors. What’s more, the hydrated metamorphic mineral prehnite is found in several craters both in central uplisand crater ejecta. This leads us to favour an excavaon scenario rather than an impact hydrothermal one. The phyllosilicates likely record alteraon process thataffected the northern crust prior to its being covered by kilometers-thick volcanic and detrital deposits. The similaries between their composion and those ofthe hydrated minerals in the southern highlands craters are an important indicaon that the Maran crust was altered on a global scale during the Noachianperiod.34.02: Diverse Aqueous Condions on Mars from New Orbital Detecons of Carbonate and SulfateAuthor Block: James J. Wray 1 , S. W. Squyres 11 Cornell Univ..Presentaon Time: 10/6/2010 9:10 AM - 9:20 AMLocaon: Ballroom EAbstract: Diverse aqueous environments on ancient Mars have been a key inference from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM)on NASA's Mars Reconnaissance Orbiter, which has idenfied many alteraon minerals in a range of sengs [e.g., 1-4]. Here we report two new mineralsdetected using CRISM.In the southern highlands northwest of the Hellas basin, a mid-sized crater exposes carbonate in its central upli. Spectral absorpons at 1, 2.33, and 2.53microns are most consistent with Fe-carbonate, disnct from the Mg-carbonates idenfied from orbit by [5]. Fe-carbonate is associated with Mg-phyllosilicate infractured materials formerly buried kilometers beneath the surface, and--like the Mg/Fe-carbonate found by the Spirit rover [6]--suggests a reducing, neutral-toalkalinealteraon environment.One of the largest phyllosilicate exposures on Mars occurs in the Mawrth Vallis region [e.g., 7]. We idenfy bassanite (Ca-sulfate hemihydrate) in layersunderlying the phyllosilicate-bearing beds [8], a stragraphy disnct from that predicted by global models of maran aqueous history [9]. Bassanite could haveformed via acid-sulfate alteraon of Ca-carbonate, through dehydraon of gypsum, or under hydrothermal condions [10].These detecons expand the known mineralogic diversity of Mars and the range of environments to explore for past habitability.[1] Mustard, J. F. et al. (2008) Nature 454, 305-309.[2] Murchie, S. L. et al. (2009) J. Geophys. Res. 114, E00D06.[3] Ehlmann, B. L. et al. (2009) J. Geophys. Res. 114, E00D08.[4] Wray, J. J. et al. (2009) Geology 37, 1043-1046.[5] Ehlmann, B. L. et al. (2008) Science 322, 1828-1832.[6] Morris, R. V. et al. Science, in press, doi:10.1126/science.1189667.[7] Poulet, F. et al. (2005) Nature 438, 623-627.[8] Wray, J. J. et al. Icarus, in press, doi:10.1016/j.icarus.2010.06.001.[9] Bibring, J.-P. et al. (2006) Science 312, 400-404.[10] Vaniman, D. T. et al. (2009) LPSC 40, 1654.34.03: Reconstrucon of Eolian Bedforms and Paleocurrents from Cross-Bedded Strata at Victoria Crater, Meridiani Planum, MarsAuthor Block: Alexander Hayes 1 , J. P. Grotzinger 1 , L. A. Edgar 1 , S. W. Squyres 2 , W. A. Waers 2 , J. Sohl-Dickstein 31 California Instute of Technology, 2 Cornell University, 3 University of California.Presentaon Time: 10/6/2010 9:20 AM - 9:30 AMLocaon: Ballroom EAbstract: Outcrop exposures imaged by the Opportunity rover at Victoria Crater, a ~750 m diameter crater in Meridiani Planum, are used to study cross-beddedstrata with geometries and scales similar to eolian deposits found on Earth. Preserved cross-bedded stragraphy is rich in geologic informaon, providing insightinto deposional environments and sediment transport direcons. High-Resoluon images of the cross-bedded strata observed at Victoria Crater are used toreconstruct sedimentary bedforms on Mars in order to infer formaon process and describe the deposional environment. The stragraphy at Victoria Craterincludes the best examples of meter-scale cross-bedding observed on Mars to-date. The Cape St. Mary promontory is characterized by meter-scale trough-stylecross bedding, suggesng sinuous-crested dunes with scour pits migrang perpendicular to the outcrop face. Cape St. Vincent, which strikes 110away fromCape St. Mary, shows tabular-planar straficaon indicave of climbing bedforms with meter to decameter-scale dune heights.The findings at Cape St. Mary and Cape St. Vincent are combined with other outcrop faces to produce an eolian deposion model for straficaon exposed atVictoria Crater. Promontories located between Cape St. Mary and Cape St. Vincent contain superposed stragraphic units with northward and southward dippingbeds separated by outcrop-scale erosional contacts. Any deposional model used to explain the bedding must conform to reversing N-S, S-N, and NW-SEpaleobedform migraon direcons. In addion to strafied outcrop, a bright band is observed to overprint bedding and lie on an equipotenal parallel to the pre-

impact surface. Super-resoluon images show that the band transects and cross-cuts exisng bedding, suggesng a diagenec origin. Meter-scale cross beddingat Victoria Crater is similar to terrestrial eolian deposits and is interpreted as a dry dune field, comparable to Jurassic-age eolian deposits in the western US.34.04: Impact-Induced Overland Fluid Flow and Channelized Erosion at Lyot Crater, MarsAuthor Block: Tanya Harrison 1 , M. C. Malin 1 , K. S. Edge 1 , D. E. Shean 1 , M. R. Kennedy 1 , L. J. Lipkaman 1 , B. A. Cantor 1 , L. V. Posiolova 11 Malin Space Science Systems.Presentaon Time: 10/6/2010 9:30 AM - 9:40 AMLocaon: Ballroom EAbstract: Lyot Crater is the youngest impact basin > 200 km in diameter on Mars. Although published hydrological models suggest that impact-relatedgroundwater release might have occurred at Lyot, no geomorphic evidence for such acvity has been previously idenfied. Here, we use images acquiredpredominantly from the Mars Reconnaissance Orbiter Context Camera (CTX) and Mars Odyssey Thermal Emission Imaging Spectrometer (THEMIS) to documentan extensive channeled scabland roughly radial to the north, west, and east of Lyot. The channels are first visible at the margins of the basin’s primary ejectablanket and cover an area of ~300,000 km 2 . The scabland consists of channels displaying braided reaches and areas of scour without well-defined channels.Individual channel widths range from ~0.1-1 km, while some collecons of channels and areas of scour span > 30 km. Channel depths are typically on the order ofmeters. The channels follow the local topography and slope; similar features are not observed to the south in Deuteronilus Mensae. This is consistent with theobserved distribuon of ejecta and secondaries, which extend predominantly to the north. The geomorphic configuraon suggests that the channel-forming fluid --most likely water from the Lyot target substrate-- appears to have come from dewatering of the ejecta blanket shortly aer the impact occurred. The only otherplace on Mars where dewatering channels have been reported is the 140 km-diameter Hale Crater in the southern hemisphere. This may suggest that olderimpacts of similar/greater magnitude resulted in water release, but evidence for this acvity is no longer visible. The channels at Lyot and Hale are preservedlikely due to their relave youth.34.05: Maran Floor Pit and Summit Pit Craters: Can One Formaon Mechanism Explain Both?Author Block: Nadine G. Barlow 11 Northern Arizona Univ..Presentaon Time: 10/6/2010 9:40 AM - 9:50 AMLocaon: Ballroom EAbstract: Many Maran impact craters display central pits either directly on the floor (“floor pits”) or atop a central peak (“summit pits”). Several central pitformaon models have been proposed, including central peak collapse in weak target material, excavaon into subsurface weak layers, precursor to central domeformaon, coalescence of smaller pits formed by impact melt interacng with target volales, vaporizaon of target volales, and drainage of impact-producedmelt into subsurface fractures. This study ulizes THEMIS IR and VIS imagery to chart the distribuon and characterize the morphologies/morphometries ofMaran floor and summit pit craters. We have completed our survey of the northern hemisphere and the 0-30°S 180-315°E region, where we have classified 745floor and 506 summit pit craters. Floor and summit pit craters display similar latude ( 11years of daily global imaging and coverage of > 60% of Mars at ≤ 6 m/pixel (with the remaining < 40% largely outside of volcanic regions), we have found no suchevidence, although one lava field in Aeolis (5°N, 220°W) stands out as possibly the site of the most recent volcanism. Authors of impact crater size-frequencystudies suggest some volcanic landforms on Mars are as young as tens to hundreds of Ma. This interpreted youth has implicaons for understanding the internalgeophysical state of Mars and has encouraged those seeking sources for trace gases (methane) in the atmosphere and those seeking “warm havens for life”(Jakosky 1996, New Scienst 150, 38-42). We targeted thousands of Mars Global Surveyor (MGS) MOC and Mars Reconnaissance Orbiter (MRO) CTX (and HiRISE)images to examine volcanic regions; we also studied every MGS MOC and MRO MARCI wide angle image. For evidence of acve volcanism, we sought eruponplumes, new vents, new tephra deposits, and new volcanogenic flows not observed in earlier images. For recent volcanism, we sought volcanogenic flows withzero or few superposed impact craters and minimal regolith development or superposed eolian sediment. Targets included all volcanic landforms idenfied inresearch papers as “recent” as well as areas speculated to have exhibited erupve plumes. An independent search for endogenic heat sources, a key MarsOdyssey THEMIS objecve, has also not produced a posive result (Christensen et al. 2005, P24A-01, Eos, Trans. Am. Geophys. Union 86/52).

Session Time: 10/6/2010 1:30 PM

Session Number: 35Session Title: Planetary Highlights from Astrophysics MissionsSession Type: PlenarySession Description: Masursky Award presented to Alan Tokunaga (Univ. of Hawaii), 1:30 - 1:40pm35.01: Two Easy Pieces, On a Theme Of Disks: Saturn's Rings, and Planetesimal FormaonAuthor Block: Jeffrey N. Cuzzi 11 Ames Research Center, NASA.Presentaon Time: 10/6/2010 1:40 PM - 2:20 PMLocaon: Plenary BallroomAbstract.Abstract: Subject to change, it's my intent for this talk to highlight progress and outstanding problems in two fascinang, topically different,methodologically related research areas (reality may limit me to only one). New understanding of Saturn's rings has flowered under their close scruny byCassini; the rings have come alive before our eyes. I'll review highlights of what we have learned about the rings to date, and note the big open quesons in needof more aenon. Many ring sciensts go on to study the physics of accreon in protoplanetary parcle disks, where much ring physics is readily applicable;however, in the early stages of protoplanetary accreon, nebula gas plays a key role, unlike in the rings case. A number of new theorecal and observaonalinsights have emerged in the last decade, spurred partly by new observaons and theorecal models of accreon disks and exoplanets. Some of these modelshave significant and novel implicaons for meteorics - which is oen disconnected from astrophysics, but which provides powerful and unique ground truthabout the nature of our own protoplanetary system. Recent progress will be reviewed, emphasizing the "terra incognita" of the primary accreon of planetesimalswe observe today as asteroids (the parent bodies of primive meteories), comets, and KBOs. Some of the problems and promises of current scenarios will bedescribed.35.02: W ISE Solar System ScienceAuthor Block: Amanda K. Mainzer 1 , E. L. Wright 2 , J. M. Bauer 1 , R. Cutri 3 , J. Dailey 3 , T. Grav 4 , J. Masiero 1 , R. S. McMillan 5 , D. Tholen 6 , R. Walker 71 JPL, 2 UCLA, 3 Infrared Processing and Analysis Center, Caltech, 4 Johns Hopkins University, 5 University of Arizona, 6 University of Hawaii, 7 M IRA.Presentaon Time: 10/6/2010 2:20 PM - 2:55 PMLocaon: Plenary BallroomAbstract: In early January, 2010, the Wide-field Infrared Survey Explorer (WISE) began imaging the enre sky with sensivies in the mid-IR hundreds of mesgreater than previous surveys. WISE consists of a 40 cm cryogenically-cooled telescope taking simultaneous images at 3.4, 4.6, 12 and 22 microns. WISE hasrecently completed its first full survey of the sky and is expected to connue flight operaons through November. Although WISE itself is an astrophysics mission,NASA’s Planetary Science Mission Directorate has funded an enhancement to the WISE project, called “NEOWISE”, that is dedicated to serving the individualexposures and extracted source lists, providing an interface for small bodies based on orbital elements, and discovering new moving objects. The WISEbandpasses sample the flux from most inner-Solar System bodies near the peak of their thermal emission, making the survey extremely efficient at detecng anddiscovering solar system objects. Infrared observaons are sensive to the low albedo objects that are preferenally missed by opcal surveys. By the me thecryogen is depleted, NEOWISE will observe ~700 Near-Earth Objects (NEOs), ~200,000 Main Belt Asteroids, ~200 comets, and ~1500 Trojan asteroids. TheNEOWISE dataset represents a treasure trove of new informaon on small bodies in our Solar System that will leave a legacy for decades to come. We willpresent preliminary results of the NEOWISE survey from the first six months of flight operaons and will offer an introducon to the community on how to accessthe data when they become available next year.This research was funded in part by the NASA (ROSES) NEOO program. This work makes use of data products from the Wide-field Infrared Survey Explorer, whichis a joint project of UCLA and JPL/Caltech, funded by NASA.35.03: Herschel Mission Part I: First Results Of The Hsso Key ProgramAuthor Block: Paul Hartogh 11 Max Planck Instute for Solar System Research, Germany.Presentaon Time: 10/6/2010 2:55 PM - 3:15 PMLocaon: Plenary BallroomAbstract: The Herschel guaranteed me key program "Water and related chemistry in the solar system" also known as HssO aims at determining thedistribuon, the evoluon and the origin of water in Mars, the Outer Planets and comets, using the three Herschel instruments HIFI, PACS and SPIRE. It addressesthe broad topic of water and its isotopologues in planetary and cometary atmospheres. The nature of cometary acvity and the thermodynamics of cometarycomae is subject of invesgaons by studying water excitaon in a sample of comets. To date C/2006 W3 (Christensen), C/2008 Q3 (Garradd), 81P/Wild 2,29P/Schwassmann-Wachmann 1 and 10P/Tempel 2 were observed. A brief overview on the results will be given. Mars has been observed a couple of mesbetween Ls = 340° and Ls = 114°. Spectral scans between 0.45 and 5.26 THz as well as dedicated line observaons of water and carbon monoxide and itsisotopes, hydrogen chloride, hydrogen peroxide and molecular oxygen have been performed and some results will be presented. Idenfying the external source(s)of water in the stratospheres of the Outer Planets and Titan by detecng its vercal profiles and for Jupiter and Saturn by mapping observaons as well as thedetecon of new molecules, determining higher accuracies on known molecules and an unexpected detecon in the Saturn system will be other important topicsof this talk.35.04: Planetary Results from the Herschel Mission Part II: TN O's are Cool!Author Block: Emmanuel Lellouch 1 , T. Müller 2 , TNOs are Cool Team1 Obs. de Meudon, France, 2 Max Planck Instute, Germany.Presentaon Time: 10/6/2010 3:15 PM - 3:30 PMLocaon: Plenary BallroomAbstract.Abstract: We report on the first results of a photometric program of transneptunian objects in the thermal range, conducted on the Herschel satellite,launched in 2009. This program includes photometric measurements on about 140 TNOs or Centaurs at wavelengths ranging from 70 to 500 micron, using thePACS and SPIRE instruments of Herschel. The goals are (i) to obtain albedo and size measurements on a large sample of objects, with the aim of searching forcorrelaons between these and other physical and orbital parameters (ii) to perform more detailed studies of thermophysical and surface properes on a smallersample (20 objects) (iii) to infer densies for a set of binary systems (iv) to search for thermal lightcurves on a few objects showing well-marked opcallightcurves. The early results of the program will be presented.

Session Time: 10/6/2010 3:30 PM

Session Number: 11Session Title: Jovian Planets: The Cool Part of the Solar SystemSession Type: Poster11.01: Longitudinal Variaons in Jupiter's WindsAuthor Block: Amy A. Simon-Miller 1 , P. J. Gierasch 2 , G. Tierney 21 NASA's GSFC, 2 Cornell University.Presentaon Time: 10/6/2010 3:40 PM - 3:42 PMLocaon: Exhibit HallAbstract.Abstract: Long-term studies of Jupiter's zonal wind field revealed temporal variaons on the order of 20 to 40 m/s at many latudes, greater than thetypical data uncertaines of 1 to 10 m/s. No definive periodicies were evident, however, though some latudinally-confined signals did appear at periodsrelevant to the Quasi-Quadrennial Oscillaon (Simon-Miller &amp; Gierasch, Icarus, in press). As the QQO appears, from vercal temperature profiles, topropagate downward, it is unclear why a signal is not more obvious, unless other processes dominate over possibly weaker forcing from the QQO. An addionalcomplicaon is that zonal wind profiles represent an average over some parcular set of longitudes for an image pair and most data sets do not offer global windcoverage. Even avoiding known features, such as the large ancyclonic vorces especially prevalent in the south, there can be disnct variaons in longitude. Wepresent results on the full wind field from Voyager and Cassini data, showing apparent longitudinal variaons of up to 60 m/s or more. These are parcularlyobvious near disrupons such as the South Equatorial Disturbance, even when the feature itself is not clearly visible. These two dates represent very differentstates of the planet for comparison: Voyagers 1 &amp; 2 flew by Jupiter shortly aer a global upheaval, while many regions were in a disturbed state, while theCassini view is typical of a more quiescent period present during much of the 1990s and early 2000s.11.02: Seasonal and Temporal Changes on Jupiter and Saturn: A Review of Ground-based ObservaonsAuthor Block: Padma A. Yanamandra-Fisher 1 , G. S. Orton 1 , B. M. Fisher 1 , L. N. Fletcher 2 , A. S. Miller 31 Jet Propulsion Laboratory/California Instute of Technology, 2 Oxford University, United Kingdom, 3 NASA/Goddard Space Flight Center.Presentaon Time: 10/6/2010 3:42 PM - 3:44 PMLocaon: Exhibit HallAbstract: We report on the seasonal and temporal changes observed on Jupiter and Saturn, based on near- and mid-infrared data acquired from severalobservatories (NASA/InfraRed Telescope Facility, NAOJ/Subaru, ESO/Very Large Telescope) and provide compelling raonale for a coordinated network of largetelescopes for connued ground-based observaons. Jupiter has been experiencing an era of atmospheric global upheaval since 2005, the observed atmosphericchanges being manifestaons of changes in local meteorology and latent physical parameters of the system, and occur on various mescales and latudes. Thediscrete storms in Jupiter's atmosphere have undergone significant changes over the past decade. The merger of the three white ovals into Oval BA and itssubsequent color change in 2006 appear to be correlated to periodic interacons with the Great Red Spot (GRS). Subsequent episodes of GRS-Oval BAinteracons in 2006 and 2008 and the upcoming interacon in 2010 provide snapshots of changes in the local meteorology. We idenfy relaonships betweenlatent physical variables of the spaally and temporally changing systems in terms of cloud opacies, aerosol distribuon and thermal fields. Ground-based nearandmid-infrared observaons of Saturn from 1995 - 2009, covering half a Saturnian year, provide a rich data set to model seasonal changes in Saturn'satmosphere from autumnal equinox (1995) to vernal equinox (2009). Since 1995, as Saturn's south pole received increasing solar insolaon, its albedo exhibits anincrease in reflecvity at mid-latudes in the southern hemisphere, decreasing towards the equator, an-correlated with the thermal field. Similar to equatorialoscillaons of temperatures on Earth and Jupiter, Saturn displays stratospheric temperature oscillaons, with a period of half a Saturnian year, suggesng theinfluence of seasonal forcing. We ancipate development of similar phenomena in the next few years, as Saturn approaches northern solsce.11.03: Mid-IR Atmospheric Tracers of Jupiter's Storm Oval BAAuthor Block: Mahew J. Shannon 1 , G. Orton 2 , L. Fletcher 31 University of Victoria, Canada, 2 Jet Propulsion Laboratory, 3 University of Oxford, United Kingdom.Presentaon Time: 10/6/2010 3:44 PM - 3:46 PMLocaon: Exhibit HallAbstract.Abstract: The 2005-2006 reddening of a major ancyclonic storm, known as Oval BA, in Jupiter's turbulent atmosphere may well be a paradigm for theformaon of red-colored vorces on the giant planets, including Jupiters Great Red Spot. Mid-infrared observaons can be effecvely used to determine physicaland chemical properes of the atmosphere, and we present the results of mid-infrared thermal imaging observaons, collected from NASAs Infrared TelescopeFacility (IRTF) in Hawaii, ESOs Very Large Telescope (VLT) in Chile and the NAOJ Subaru Telescope in Hawaii between spring of 2005 and summer of 2006. Theseaddress the role of atmospheric tracers, including cloud opacity, the ammonia gas content, and the variaon of the fracon of para- to ortho-hydrogen from localthermal equilibrium in assessing the rate of upwelling. These properes were retrieved with the Oxford-developed code, Nemesis, with the purpose of providingconstraints on dynamical models in an effort to idenfy the mechanism for the color change. The most obvious change is that the temperature gradient from theinner to the outer part of Oval BA increased over the me of the color change, indicang a strengthening of the intensity of the vortex.11.04: New Measurements Of Jupiter’s Equatorial Region In Visible WavelengthsAuthor Block: Jose Rojas 1 , J. Arregi 1 , E. García-Melendo 2 , N. Barrado-Izagirre 1 , R. Hueso 1 , J. M. Gómez-Forrellad 2 , S. Pérez-Hoyos 1 , J. F. Sanz-Requena 3 , A.Sánchez-Lavega 11 Universidad Del Pais Vasco, Spain, 2 Fundació Privada Observatori Esteve Duran, Spain, 3 Universidad Europea Miguel de Cervantes, Spain.Presentaon Time: 10/6/2010 3:46 PM - 3:48 PMLocaon: Exhibit HallAbstract: We have studied the equatorial region of Jupiter, between ~15ºS and ~15ºN, on Cassini ISS images obtained during the Jupiter flyby at the end of2000 and on HST images acquired in May and July 2008. We have found significant longitudinal variaons in the intensity of the 6ºN eastward jet, up to 60 m s -1in Cassini and HST observaons. In the HST case we found that these longitudinal variaons are associated to different cloud morphology.Photometric and radiave transfer analysis of the cloud features used as tracers in HST images shows that there is only a small height difference, no larger than~ 0.5 - 1 scale heights at most, between the slow (~ 100 m s -1 ) and fast (~ 150 m s -1 ) moving features. This suggests that speed variability at 6ºN is notdominated by vercal wind shears and we propose that Rossby wave acvity is the responsible for the zonal variability. Aer removing this variability we foundthat Jupiter’s equatorial jet is actually symmetric relave to the equator with two peaks of ~ 140 - 150 m s -1 located at latudes 6ºN and 6ºS and at a similarpressure level.We also studied a large, long-lived feature called the White Spot (WS) located at 6ºS that turns to form and desapear. The internal flow field in the White Spotindicates that it is a weakly rotang quasi-equatorial ancyclone relave to the ambient meridionally sheared flow.Acknowledgements: This work was supported by the Spanish MICIIN AYA2009-10701 with FEDER and Grupos Gobierno Vasco IT-464-07.

11.05: High-Resoluon Simulaons of the Great Red Spot Vorcity and Temperature FieldsAuthor Block: Raul Morales-Juberias 1 , T. E. Dowling 21 New Mexico Instute of Mining & Technology, 2 Univ. of Louisville.Presentaon Time: 10/6/2010 3:48 PM - 3:50 PMLocaon: Exhibit HallAbstract: The Great Red Spot (GRS) is the largest and longest-lived vortex on Jupiter; it is a centuries-old ancyclone with a current semi-major axis of a ~9,000 km. High-resoluon observaons taken with spacecra and ground-based observatories have revealed many fine details in its vorcity and temperaturestructure (Choi et al. 2007, Fletcher et al. 2010). We have performed numerical simulaons of the GRS using the EPIC model to explore the space of parametersfor atmospheric condions that would best reproduce the observed details of both the vorcity and temperature fields. When we take the model to sufficientlyhigh resoluon, the correlaons between model vorcity and observed cloud morphology are nearly indisnguishable, with the excepon of the obviouslyconvecve acvity in the northwest quadrant adjacent and exterior to the GRS. The observed north-south lt in the temperature field is sensive to the vercalstructure of the GRS with respect to that of the zonal winds. We also explore how the merger of smaller vorces into the GRS affects its vorcity and temperaturefields. Computaonal resources were provided by the New Mexico Compung Applicaons Center and New Mexico Instute of Mining and Technology.This workwas supported by PATM grant numbers NNX08AE91G and NNX08AE64G.11.06: Development of Jovian Impactor PlumesAuthor Block: Csaba J. Palotai 1 , D. G. Korycansky 2 , J. Harrington 1 , T. Gabriel 11 Univ. Of Central Florida, 2 Univ. Of California, Santa Cruz.Presentaon Time: 10/6/2010 3:50 PM - 3:52 PMLocaon: Exhibit HallAbstract: We have simulated the entry of cometary nuclei into Jupiter (Korycansky et al. 2006 ApJ 646. 642-652) and now extend our 3D hydrodynamic modelsto plume formaon and blowout. We invesgate the physics that control plume behavior, including why and where plumes "pinch off", separang from thedescending cometary remains, and what determines how much cometary material is in a plume. We also examine the effects of impactor size, composion,velocity, and impact angle, and the corresponding changes in visible and infrared observaons, with applicaon to the Shoemaker-Levy 9, 2009, and 2010 Jovianimpacts.We adapted the ZEUS-MP/2 hydrodynamic model (Hayes et al. 2006 ApJ.SS. 165. 188-228), using a grid aligned and moving with the impactor and containing alted Jovian atmosphere. The grid is large enough to contain both the impact and blowout phases to avoid the need for ad hoc inial condions. We presentdetails on the ejecon mechanism, velocity and mass distribuon within the plume, and the shock waves generated by the expanding plume.This work was supported by Naonal Science Foundaon Grants AST-0813194 and AST-0964078 and NASA Science Mission Directorate Grant NNG04GQ35G.11.07: Vercal Cloud Structure Of The 2009 Jupiter Impact Based On HST/W FC3 ObservaonsAuthor Block: Sanago Perez-Hoyos 1 , J. F. Sanz-Requena 2 , A. Sanchez-Lavega 1 , M. Wong 3 , R. Hueso 1 , H. B. Hammel 4 , G. S. Orton 5 , L. N. Fletcher 6 , I. de Pater 7 ,A. A. Simon-Miller 8 , J. T. Clarke 9 , K. Noll 3 , P. A. Yanamandra-Fisher 51 Universidad del Pais Vasco, Spain, 2 Universidad Europea Miguel de Cervantes, Spain, 3 Space Telescope Science Instute, 4 Space Science Instute, 5 JetPropulsion Laboratory - CALTECH, 6 University of Oxford, United Kingdom, 7 University of California, 8 Goddard Space Flight Center, 9 Boston University.Presentaon Time: 10/6/2010 3:52 PM - 3:54 PMLocaon: Exhibit HallAbstract: The impact of a body of unknown origin with Jupiter in July 2009 (Sánchez-Lavega et al., Astrophys. J. Le, Vol. 715, L155. 2010) produced an intenseperturbaon of the planet’s atmosphere at the visible levels. The perturbaon was caused by dense aerosol material; this strongly absorbing material expandedsteadily as it was advected by the local winds. This phenomenon was observed at high spaal resoluon by the Hubble Space Telescope in July, August,September and November 2009 with recently installed Wide Field Camera 3. In this work, we present radiave transfer modeling of the observed reflecvity in thenear UV (200nm) to near IR (950nm) range. The geometrical and spectral variaons of reflecvity elucidate the main parcle properes (opcal thickness, size,imaginary refracve index) and their temporal evoluon. The aerosol parcles that formed during the impact have a mean radius of about 1 micron and arelocated high in the atmosphere (above 10 mbar), in good agreement ith ground-based observaons in deep methane absorpon bands in the near infrared. Thedensity of this parcle layer decreases with me unl it approaches that of the pre-impact atmosphere. These results are also discussed in terms of what weknow from other impacts in Jupiter (1994's SL9 event and 2010's bolide). Acknowledgements: SPH, ASL and RH are supported by the Spanish MICIIN AYA2009-10701 with FEDER and Grupos Gobierno Vasco IT-464-07.11.08: Modificaon of Jupiter's Stratosphere Three Weeks Aer the 2009 ImpactAuthor Block: Kelly Elizabeth Fast 1 , T. Kosuk 1 , T. A. Livengood 2 , T. Hewagama 3 , J. Annen 11 NASA/GSFC, 2 Naonal Center for Earth and Space Science Educaon, 3 University of Maryland.Presentaon Time: 10/6/2010 3:54 PM - 3:56 PMLocaon: Exhibit HallAbstract: Infrared spectroscopy sensive to thermal emission from Jupiter’s stratosphere reveals effects persisng 3½ weeks aer the impact of a body in lateJuly 2009. Measurements obtained at 11.7 µm on 2009 August 11 UT at the impact latude of 56°S (planetocentric), using the Goddard Heterodyne Instrument forPlanetary Winds and Composion (HIPWAC) mounted on the NASA Infrared Telescope Facility, reveal an interval of reduced thermal connuum emission thatextends ~60°-80° towards planetary East of the impact site, esmated to be at 305° longitude (System III). Retrieved stratospheric ethane mole fracon in thenear vicinity of the impact site is enhanced by up to ~60% relave to quiescent regions at this latude. Thermal connuum emission at the impact site, andsomewhat west of it, is significantly enhanced in the same spectra that retrieve enhanced ethane mole fracon. Assuming that the enhanced connuumbrightness near the impact site results from thermalized aerosol debris, then connuum emission by a haze layer can be approximated by an opaque surfaceinserted at the 45-60 mbar pressure level in the stratosphere in an unperturbed thermal profile, seng a lower limit on the altude of the top of the ejecta cloudat this me. The reduced connuum brightness east of the impact site can be modeled by an opaque surface near the cold tropopause, consistent with a loweraltude of ejecta/impactor-formed opacity or significantly lesser column density of opaque haze material. The physical extent of the observed region of reducedconnuum implies a minimum average velocity of 21 m s -1 transporng material prograde (East) from the impact. Spectra acquired further East, with quiescentcharacteriscs, imply an average zonal velocity of less than 63 m s -1 . This work was supported by the NASA Planetary Astronomy Program.11.09: Locaon, Structure, And Moon Of Jupiter's Dusk Magnetospheric Boundary From ~1625 To 2550 R JAuthor Block: Robert Ebert 1 , D. J. McComas 2 , F. Bagenal 3 , H. A. Ellio 41 University of Texas at San Antonio/Southwest Research Instute, 2 Southwest Research Instute/University of Texas at San Antonio, 3 University of Colorado,4 Southwest Research Instute.

Presentaon Time: 10/6/2010 3:56 PM - 3:58 PMLocaon: Exhibit HallAbstract: We report on plasma observaons along Jupiter’s dusk magnetospheric flank from ~1625 to 2550 R J using measurements from the Solar Wind AroundPluto instrument onboard New Horizons (NH). NH made sixteen magnetopause crossings between 1654 and 2400 R J that were idenfied by transions betweenmagnetotail/boundary layer and magnetosheath plasma. These transions were either sharp, with the magnetopause clearly separang two disnct plasmaregimes, or comparavely gradual, where it was difficult to disnguish between different plasma populaons. The magnetosheath distribuons had high counts,were relavely wide in energy/charge (E/Q) and steadily decreased in speed. Flow speeds in the sheath were always higher (lower) when NH entered (exited)this region. A boundary layer was observed inside of the magnetopause at several crossings. The boundary layer plasma was composed of light ions and thecounts and mean E/Q of these distribuons were generally lower than magnetosheath values indicang a lower density and speed. Some of the NHmagnetopause crossing locaons fell within tail cross-secon esmates from model results/observaons closer to the planet, though more than half wereoutside of the largest tail radius esmate. Esmates of angular displacement of the tail boundary compared favorably with a stascal study of near Jupiter solarwind flow cone angle distribuons. We propose that the outward crossings resulted from dawnward deflecon and contracon of the tail from forward shocks andcompression regions in the near Jupiter solar wind, the inward crossings from the duskward deflecon and expansion of the tail from the passage of reverseshocks and rarefacon regions. We thank NASA for funding this project through the New Horizons program along with the members of the New Horizons andSWAP teams for making this work possible.11.10: Prospects for Observing Waves in Jupiter's Thermosphere using H3+ EmissionAuthor Block: Daniel Barrow 1 , K. Matcheva 1 , P. Drossart 21 University of Florida, 2 LESIA/Observatoire de Paris, France.Presentaon Time: 10/6/2010 3:58 PM - 4:00 PMLocaon: Exhibit HallAbstract.Abstract: A variety of heang mechanisms have been proposed to explain the high temperatures in Jupiter's upper atmosphere. Gravity wavestransport energy and momentum to the upper atmosphere that can significantly alter the temperature and wind structure at these altudes. Currently there islile informaon about the spectrum of the present gravity waves, their amplitudes, frequency of occurrence, and direcon of propagaon. Without observaonalconstraints the effect of waves on the upper atmosphere cannot be correctly assessed. We propose to use variaons in the H3+ emission in Jupiter's ionosphereas a measure of wave acvity. We have constructed a two dimensional model of the Jovian ionosphere in which we use a gravity wave model to propagate wavesand a radiave transfer model to examine the potenally observable parameters the waves. We find that the gravity waves strongly affect the lower ionosphereand can induce observable variaons in the H3+ emission. We explore the wave parameter space to study the magnitude of the effect for different direcons ofwave propagaon, magnec field orientaon, and locaon on the planet.11.11: Aerosol Heang in the Stratosphere of JupiterAuthor Block: Xi Zhang 1 , R. A. West 2 , D. Banfield 3 , Y. L. Yung 11 Caltech, 2 JPL, 3 Cornell University.Presentaon Time: 10/6/2010 4:00 PM - 4:02 PMLocaon: Exhibit HallAbstract.Abstract: This work is composed of two parts. First, latudinal and vercal distribuons of Jovian stratospheric aerosols are retrieved based on theCassini ISS (Imaging Science Subsystem) images in the strong methane absorpon band at 890 nm and previous work by Banfield et al. (Icarus, 134, 11, 1998).Second, heang rates due to stratospheric aerosol layers are calculated by a mulple scaering model in the visible wavelengths. Our model used the methane k-distribuon parameters from Karkoschka and Tomasko (Icarus, 205, 674, 2010) and H2-H2 connuum absorpon coefficients from Borysow et al. (A&amp;A, 390,779, 2002). Two types of aerosol are disnguished. Haze at low and middle latude is opcally thin and can be treated as Mie parcles. And the high latudeaerosols with large opcal depth are modeled as aggregated parcles using the mul-sphere method (Mackowski and Mishchenko, J. Opt. Soc. Amer. A., 13, 2266,1996). The effect of the aerosol heang rates on the radiave balance of stratosphere of Jupiter is studied.11.12: Unidenfied Lines In The High-resoluon 3-micron Spectra of Jupiter And TitanAuthor Block: Mi-Rim Sohn 1 , S. Kim 11 School of space research, Kyung Hee University, Korea, Republic of.Presentaon Time: 10/6/2010 4:02 PM - 4:04 PMLocaon: Exhibit HallAbstract: We introduce unidenfied lines detected in the high-resoluon spectra of Jupiter and Titan which were reported by Seo et al. (2009), Kim et al. (2005)and Kim et al. (2010). We have reanalyzed the high-resoluon spectra of Titan and Jupiter in the 2.87 - 3.4 micron range in order to find appropriate molecularbands which are responsible for those unidenfied lines. We used the theorecal and laboratory IR databases for molecular ro-vibraonal spectra available inliterature. We present a preliminary result for the idenficaon and suggest low-temperature laboratory observaons, which might help the idenficaons.References :Seo, H. et al. 2009, Icarus 199, 449-457Kim, S.J. et al. 2005, Icarus 173, 522-532Kim, S.J. et al. 2010, Icarus 208, 837-84911.13: High Resoluon Lyman-α Mapping of the Jovian Upper Atmopshere and CoronaAuthor Block: Loi Ben-Jaffel 1 , G. Ballester 2 , J. T. Clarke 3 , F. Vincent 41 IAP-UPM C-CNRS, France, 2 LPL-Univ. Arizona, 3 Boston Univ., 4 Univ. California.Presentaon Time: 10/6/2010 4:04 PM - 4:06 PMLocaon: Exhibit HallAbstract: Owing to the parcular capabilies of the HST/STIS spectro-imaging instrument, Jovian H-Lyman-α line profiles were obtained with unprecedentedaccuracy on different locaons of the planetary disc, using the 52”x0.5” long slit in the echelle mode. This mode is allowed by STSCI but not supported forcalibraon because of potenal contaminaon from adjacent orders. In addion, the telescope poinng to any selected locaon on the planetary disc is not veryaccurate for a moving and extended target. The construcon of a sophiscated pipeline of calibraon was thus necessary to correct for all potenal imagedistoron, signal contaminaon, and mapping of the slit image over the apparent disc of the planet.These efforts represent the necessary step for checking the serendipitous discovery of supersonic turbulence in the Jovian Lyman-α bulge and the consequentthermospheric circulaon proposed in the literature, including strong winds (up to ~20 km/s) predicted in the upper layers (altudes above the ~1 nanobarpressure level) of the atmosphere (Sommeria, Ben-Jaffel, and Prangé, Icarus, 118, pp 2-24, 1995).A two-dimensional Lyman-α map of the Jovian atmosphere and its corona, corrected for all potenal contaminaon, will be presented with a preliminary analysis,

confirming our previous finding of ~60 km/s fast rotang hot hydrogen belt at equatorial latudes.11.14: A Possible Explanaon for the Diurnal Paerns of Electron Density Inferred from Saturn Electrostac Discharge MeasurementsAuthor Block: Luke Moore 1 , M. Mendillo 1 , G. Fischer 2 , I. Mueller-Wodarg 3 , M. Galand 31 Boston University, 2 Austrian Academy of Sciences, Austria, 3 Imperial College, United Kingdom.Presentaon Time: 10/6/2010 4:06 PM - 4:08 PMLocaon: Exhibit HallAbstract: Saturn Electrostac Discharges (SEDs) are radio signatures of atmospheric lightning at Saturn. Detecons of SEDs were first idenfied by the Voyagerspacecra as they flew past Saturn in 1980 and 1981, and have connued to the present following the inseron of the Cassini spacecra into Saturn orbit in2004. The low-frequency cutoff of SEDs gives an indirect measurement of the peak plasma density (NMAX) in the poron of the ionosphere between the loweratmospheric storm and the Cassini spacecra. These measurements augment the radio occultaon measurements of Saturn’s ionosphere - which give Ne(h), butonly near dawn and dusk - by sampling NMAX at all local mes. However, to-date no ionospheric model has been able to successfully reproduce the SED-deriveddiurnal trend in NMAX. We present a review of these discrepancies, from the Voyager era to the Cassini era, demonstrang that a photochemical ionospherecannot reproduce the SED-derived trend, and we posit that SEDs are actually sampling electron densies in Saturn’s low-altude layers rather than near itsphotochemical peak.11.15: Lightning-produced Carbon Species in the Atmosphere of SaturnAuthor Block: Mona Delitsky 1 , K. H. Baines 21 CSE, 2 JPL.Presentaon Time: 10/6/2010 4:08 PM - 4:10 PMLocaon: Exhibit HallAbstract: Recent studies by Baines et al (2009) indicate that thunderstorm-associated clouds on Saturn are spectrally dark from 0.7 to 4 um, darker than regularclouds. This darkening is found to be consistent with the presence of parcles of elemental carbon, such as in the form of soot parcles mixed in with spectrallybright condensates. This carbon is thought to be generated by lightning-induced dissociaon of methane. Lightning on Saturn will input large amounts of energyto a narrow column of atmosphere and generate products at high energies such as radicals and ions. Aer the column cools down, the new chemical speciesrecombine and are frozen into a new chemical equilibrium. Experimental studies in the literature of reacons of methane and other gases in plasma discharges(which simulate lightning) indicate that, even with high raos of hydrogen/methane, the elemental carbon obtained will form solid dark parcles that persist andhave a very high C/H rao. Basically, they are mostly pure carbon, in the form of soot, amorphous carbon, graphite, graphene, polycyclic aromac hydrocarbons,carbon black, carbon onions, etc. Hydrogen will act as a sealant onto the parcles and aach to dangling bonds on their growing surfaces. Even in experiments toform the most crystalline allotrope of carbon, that is, diamond, the presence of hydrogen does not inhibit diamond formaon, even at the low pressures in theatmospheres of the Jovian planets or in the interstellar medium (Allamandola et al 1991). Therefore, some form of elemental carbon is likely produced inSaturnian storm clouds and may occur as dark parcles of either amorphous carbon, PAHs or crystalline carbon in a form such as graphite. ..Refs: Baines et al.,PSS 57, 1650-1658 (2009) ; Allamandola et al., Meteorics 26, 313 (1991).11.16: Dynamics Of Saturn’S Mid-scale Storms In The Cassini Era.Author Block: Teresa Del Rio Gaztelurrua 1 , R. Hueso 1 , A. Sánchez-Lavega 11 Universidad Del Pais Vasco, Spain.Presentaon Time: 10/6/2010 4:10 PM - 4:12 PMLocaon: Exhibit HallAbstract: Convecve storms, similar to those in Earth, but of much larger scale, develop oen in Saturn’s atmosphere. During the Voyagers’ flybys of Saturn in1981 mid-scale storms, with an horizontal extension of the order of 1000-3000 km were observed to occur mainly in a narrow tropical-latude band in theNorthern hemisphere at latudes 38-40 deg North. Contrasng with the Voyagers’ era, since the starng of the Cassini mission in 2004, a similar mid-scaleconvecve acvity has concentrated in the so-called “storm alley”, a narrow band at a symmetric Southern latude of 38 deg.. In this work, we characterize thisstorm acvity using available visual informaon provided by Cassini ISS cameras and the connuous survey from the Earth by the Internaonal Outer PlanetsWatch (IOPW) and its online database PVOL (Hueso et al., Planetary and Space Science, 2010). We study the frequency of appearance of storms with sizes above2000 km, their characterisc size and life-me, as well as their interacon with surrounding dynamical features. In parcular we examine the possibility thatstorms might provide a mechanism of injecon of energy into Saturn’s jets, the influence of storms in the generaon of atmospheric vorces, and the analogiesand differences of Voyagers’ and present day jet structure at the relevant latudes.Acknowledgments: This work has been funded by the Spanish MICIIN AYA2009-10701 with FEDER support and Grupos Gobierno Vasco IT-46411.17: Cassini/CIRS Observaons of Saturn’s “Storm Alley”Author Block: Brigee E. Hesman 1 , G. L. Bjoraker 2 , R. K. Achterberg 11 Univ. Maryland/NASA GSFC, 2 NASA GSFC.Presentaon Time: 10/6/2010 4:12 PM - 4:14 PMLocaon: Exhibit HallAbstract: In the Voyager era storms on Saturn were observed predominantly in the northern hemisphere; however, in recent years storm acvity has beenconfined to a narrow range of latudes referred to as “storm alley” (~40°S planetographic latude). Throughout Cassini’s prime mission storms have beendetected by two independent instruments: ISS through dayside images and RPWS using radio emissions from Saturn Electrostac Discharges (SED’s) (Dyudina etal. 2007). Analysis of these storms indicates that the cloud tops are in the 200 - 500mbar altude range. During Saturn’s Equinox, in August 2009, ISS imagedlightning on the night side in storm alley when ring-shine was at a minimum (Dyudina et al. 2010). This study indicates that lightning may have originated asdeep as the water cloud.Recently, Cassini/CIRS was targeted at storm alley while a storm, originally detected by amateurs, was ongoing (March 2010). Phosphine can be used as a tracerof vercal transport because it is a disequilibrium species that falls off with altude in the upper troposphere. CIRS can measure temperature and phosphineabundance independently in the altude range where these cloud tops occur. Early analysis of these data shows stronger phosphine absorpon at stormlongitudes. This is an indicaon that powerful updras were dredging material upward into the upper troposphere. The results of the analysis of the March 2010CIRS observaons of storm alley will be presented.References:Dyudina, U.A. et al., 2010. Geophys. Res. Leers 37, L09205.Dyudina, U.A. et al., 2007. Icarus 190, 545-555.11.18: Clouds, Bands And Discrete Features On Saturn: Comparisons Between Cassini And Voyager

Author Block: Gabriel Muro 1 , K. M. Sayanagi 2 , S. P. Ewald 2 , A. P. Ingersoll 21 University of California, Santa Cruz / California Instute of Technology, 2 California Instute of Technology.Presentaon Time: 10/6/2010 4:14 PM - 4:16 PMLocaon: Exhibit HallAbstract: We examine new images returned from Cassini spacecra’s ISS camera to analyze tropospheric cloud morphology of Saturn. We compare our findingsto Voyager 2 observaons to search for changes in global cloud morphology. Images were acquired around the equinox and our datasets provide near-globalcoverage in mulple wavelength bands. We find that the clouds exhibit the highest contrasts in infrared connuum centered at 752 & 939 nm (CB2 & CB3 filters,respecvely) and 727 & 890 nm methane bands (MT2 & MT3).We compare the present day locaon of Saturn’s bands to those of the Voyager era. We reconfirm mulple features that were previously found in Voyager’svisible and Cassini infrared images in the northern hemisphere. First, we examine the Ribbon wave found by the Voyager missions (Sromovsky et al. 1983;Godfrey and Moore, 1986) at mulple wavelength bands. Next, we examine the behavior of a dark vortex that exhibits many similaries to the vortex labeled bySromovsky et al. as Brown Spot 1. Our data also shows a visible-light counterpart to the String of Pearls feature, which appeared as a series of planet encirclingbright spots in 5-micron VIMS images (Momary et al. 2006), suggesng that they are cloud clearings. Our images confirm that there are indeed a string of darkcloud-free spots in the region, which enable us to study their dynamics and compare our results to the VIMS measurements by Choi et al (2009). We also comparethe appearance of the north-polar hexagon at mulple wavelengths. Our data also provides good coverage in the southern hemisphere, and we compare ourresults to Voyager images in 1980-81 and images acquired during the early phase of Cassini mission.Supported by the Cassini Project and a Summer Undergraduate Research Fellowship from Caltech.11.19: Saturn’s Equatorial Plumes aer Five Years: Sll Lurking under the HazeAuthor Block: Thomas W. Momary 1 , K. H. Baines 2 , L. N. Fletcher 3 , B. J. Bura 1 , R. H. Brown 4 , R. N. Clark 5 , P. D. Nicholson 61 Jet Propulsion Laboratory, 2 SSEC, University of Wisconsin – Madison, 3 Oxford University, United Kingdom, 4 University of Arizona, 5 U.S. Geological Survey,6 Cornell University.Presentaon Time: 10/6/2010 4:16 PM - 4:18 PMLocaon: Exhibit HallAbstract: Numerous large, discrete cloud features have been observed for five years underneath Saturn’s equatorial haze. They were clearly observed on threeoccasions - June 28, 2005, April 21, 2006 and May 1, 2010 - from a vantage point directly over the knife-edge of the rings, which reduced the ring obscuraon ofthe disk to just ± 1 degrees of latude centered at the equator. These features are seen only in the 5-micron thermal window which probes large-parcle cloudsdown to the 4-bar level. In VIMS 5-micron imagery, which observes the warm glow of Saturn generated at depth, these deep clouds are observed in silhouee,appearing as dark features against the background glow. Spectral modeling indicates that they are primarily located in the 2-3 bar region. However, smallerparcles of ammonia may be present overhead as a relavely small component of the 5-micron exncon. Indeed, the correlaon of these features with theexceedingly high and thick equatorial haze layer indicates a plausible link: That these features involve vercal transport of gaseous condensibles to the uppertroposphere forming the thick haze that is observed in images taken in reflected sunlight. The features are concentrated in two narrow, symmetrical cloudy zonesbetween 4 and 8 degrees planetocentric latude in both hemispheres, where they cover significant fracons, although varying, amounts of the total area of theselatudinal bands: 55% in 2005-2006 vs 28% in 2010. The mean area of the average feature was roughly constant over all three observaons, with thelongitudinal extent of the average feature in 2005-2006 decreasing 10% from 8 degrees (~ 8000 km) to 7.1 degrees in 2010 while the mean latudinal extentincreased by 10% from 3.05 in 2005 vs 3.4 degrees in 2010.11.20: The Hemispheric Differences in the Methane and Ammonia Absorpons on Saturn near last Equinox in 2008-2010.Author Block: Victor G. Tejfel 1 , A. M. Karimov 1 , G. A. Kharitonova 1 , G. A. Kirienko 1 , V. D. Vdovichenko 11 Fessenkov Astrophysical Instute, Kazakhstan.Presentaon Time: 10/6/2010 4:18 PM - 4:20 PMLocaon: Exhibit HallAbstract: Rare situaon connected with Saturn’s equinox had given an opportunity to compare the state of the atmosphere in both hemispheres of this planetat near the same visibility condions. during 2008-2010. Our research had been directed to the study of the methane and ammonia absorpon bands behavior ondifferent latudes and comparison of their intensity at Southern and Northern hemispheres. This period is transional between primary insolaon of S-hemispherein preceding years and the growth of insolaon of N-hemisphere during next seven years. We connue the spectrophotometric scanning of Saturn’s disk asdescribed earlier (41-st DPS Annual Meeng-Abstract 14.05) and processed about 3000 zonal CCD-spectrograms .We should like here to turn aenon on thespace-me changes in the rao of equivalent widths of the CH 4 bands centered at 619 nm and 725 nm between 2008 and 2010 observaonal seasons. This raoKw=W619/W725 . is not latudinally constant and shows increase from S-latudes to N-latudes. In February 2008 at S-temperate latudes minimum value Kws=0.20-0.21, but at N-temperate latudes maximum Kwn=0.29-0.30. During next Saturn’s apparions this rao increases in S-hemisphere and decreases in N-hemisphere. In 2008-2009 Kws=0.215 and Kwn=0.265. In 2010 an amplitude of S-N differences noceably decreased: Kws =0.225 but Kwn=0.250. In the beginningof 2008 the temperate latudes showed extreme Kw values but in the next seasons the latudinal variaons of Kw within one hemisphere were smoothed. Acomparison of NH 3 643+CH 4 670 band profiles in S- and N- temperate belts detected also the growth of the ammonia absorpon in Northern hemisphere. Thesehemispheric differences may be considered preliminary as an evidence of the decreased cloud volume density in N-hemisphere11.21: A General Circulaon Model of Uranus’ Atmosphere

Author Block: Andrew James Friedson 11 JPL.Presentaon Time: 10/6/2010 4:20 PM - 4:22 PMLocaon: Exhibit HallAbstract: A three-dimensional general circulaon model of Uranus’ atmosphere has been developed with the goal of exploring the influence of ortho-parahydrogen conversion, water and hydrogen sulfide latent heat release, and seasonally-varying insolaon on the dynamics and relang these effects toobservaons of cloud locaon, cloud acvity, and latudinal variaon of microwave brightness temperatures. The model calculates the seasonal and spaalvariaon of winds, temperatures, hydrogen para-fracon, and mixing raos of trace species, hydrogen sulfide, and water between the 400-bar and 5-mbarpressure levels, allowing interacon between constuent transport, radiaon, dynamics, and latent heat effects. The model’s formulaon and preliminary resultswill be presented. This work is supported by the NASA Outer Planets Research Program.11.22: New Radiave Transfer Capability in the EP IC Atmospheric Model with Applicaon to Saturn and UranusAuthor Block: Timothy Edward Dowling 1 , T. K. Greathouse 2 , M. G. Sussman 3 , N. J. Chanover 31 Univ. of Louisville, 2 Southwest Research Instute, 3 New Mexico State Univ..Presentaon Time: 10/6/2010 4:22 PM - 4:24 PMLocaon: Exhibit HallAbstract: We have adapted radiave transfer (RT) schemes from the gas-giant seasonal models of Greathouse et al. (EGU 2010) and Sussman et al. (AGU2009) into the EPIC atmospheric model, and applied them to Saturn and Uranus. These addions give EPIC a hierarchy of RT opons to account for solar heangvia CH 4 absorpon from 5 microns to the UV, and radiave cooling due to thermal emission of CH 4 , C 2 H 2 , C 2 H 6 , and collision-induced opacity between 0 and 1600cm -1 . We have wrien an IDL tool to calculate radiave-equilibrium T(p) profiles for model inializaon. We have ported the versale DISORT RT model (Stamneset al. 1988) from Fortran to C, and are incorporang it into an IDL post-processing tool to allow us to create synthec spectra from EPIC output that accounts forthermal emission, reflected solar light, and aerosol and Rayleigh scaering. We give an update of applicaons to simulaons of middle-atmosphere temperaturesfor Saturn and zonal-wind spin-up experiments for Uranus. This research is supported by NASA Planetary Atmospheres grant NNX08AE64G and NSF PlanetaryAstronomy grant AST-0807989.11.23: Modeling Uranus' Circulaon With The EP IC GCMAuthor Block: Michael Sussman 1 , T. E. Dowling 2 , N. J. Chanover 11 New Mexico State Univ., 2 University of Louisville.Presentaon Time: 10/6/2010 4:24 PM - 4:26 PMLocaon: Exhibit HallAbstract: With a planetary energy balance near unity, Uranus' atmospheric dynamics are largely mediated by incoming solar radiaon. Combined with itsextreme axial lt of 97 degrees, the seasonal variaon of the planet's circulaon is expected to be significant. We employ the EPIC general circulaon model tostudy these seasonal effects.Uranus spin-up experiments require on the order of a century of simulaon me, and hence we have developed a new, computaonally efficient radiaon codewithin EPIC for this applicaon. We band-model the methane absorpon spectrum to determine the fracon of insolaon that is deposited at each vercal layerwithin the simulated atmosphere. Each vercal layer, in turn, re-radiates longwave infrared radiaon; opcally thick layers radiate primarily via the H2-H2collisional-induced absorpon spectrum, while opcally thin layers radiate primarily through the 7.8-micron methane emission band. By modeling theseprocesses, we find our simulated temperature-pressure profile generally agrees with the 1986 Voyager observaons.We present the results of our spin-up experiments. The zonal wind generated during equinox shows a qualitave similarity to the observed Uranian zonal winds,with two symmetric high-latude prograde jets. However, the zonal wind generated during solsce shows considerable asymmetry about the equator, a featurethat has been noted in recent observaons. We explore the underlying mechanism causing this dichotomy, and hypothesize that the zonal wind at any me is asummaon of the solsce and equinox generated winds. This work is funded by NSF grant AST-0807989.11.24: Radiave Transfer Modeling On The Atmosphere Of UranusAuthor Block: Joo Hyeon Kim 1 , L. A. Sromovsky 1 , P. M. Fry 11 SSEC/University of Wisconsin-Madison.Presentaon Time: 10/6/2010 4:26 PM - 4:28 PMLocaon: Exhibit HallAbstract: We carried out radiave transfer modeling on the atmosphere of Uranus to find the simplest 3-dimensional aerosol models that could fit theobservaons within measurement and modeling uncertaines. We used the Levenberg-Marquardt algorithm in combinaon with a radiave transfer model thataccounts for Raman scaering and polarizaon (Sromovsky 2005, Icarus 173, 245-283) to fit 2002 HST/STIS spectra calibrated by Karkoschka and Tomasko (2009,Icarus 202, 287-309) and bandpass filter imaging observaons by the HST Advanced Camera for Surveys (ACS) in 2006 and by the Wide Field/Planetary Camera 2in 2007. Preliminary results were obtained from sampling 5 different latudes with 4-6 emission angles and the 0.6-0.86 micron spectral range (chosen to allowconservave scaering and assumpon of Beer's law), using five different methane mixing raos consistent with the Lindal et al. (1987, JGR 92, 14987-15001)occultaon soluons. The best-fit mixing rao is near 2.9% at low latudes and near 2.3% at middle-high latudes, which agree with the results of Karkoschkaand Tomasko (2009). A single layer of sub-micron Mie parcles fits remarkably well, but a beer fit is obtained with two such Mie layers, which consists ofopcally thin layer at ~1.5 bar and opcally thick layer at 2.1~2.7 bar. Both layers have opcal depth increasing toward southern hemisphere.This work was supported by grants from the Space Telescope Science Instute.11.25: Detecon and Tracking of Subtle Cloud Features on UranusAuthor Block: Patrick M. Fry 1 , L. A. Sromovsky 1 , I. de Pater 2 , H. B. Hammel 3 , K. A. Rages 41 Univ. of Wisconsin, 2 Univ. of California, 3 Space Science Instute, 4 SETI Instute.Presentaon Time: 10/6/2010 4:28 PM - 4:30 PMLocaon: Exhibit HallAbstract: The recently updated Uranus zonal wind profile (Sromovsky et al. 2009, Icarus 203, 265-286) samples latudes from 71°S to 73°N. But many latudesremain grossly undersampled (outside 20-45°S and 20-50°N) due to a lack of trackable cloud features, and at some latudes most of the features have a likelyconnecon to a single eddy that generates them, so that their moons may be controlled by the generang feature rather than serving as passive tracers of themean mass flow. A more complete wind profile, reflecng the true mean mass flow, would provide numerical modelers a firmer foundaon from which to developbeer theorecal understanding of the dynamics of uranian weather systems. Offering some hope to fill these gaps is our recent discovery that there are far morecloud tracers in our Keck II NIRC2 near-IR imagery than we had previously noced. But they are only visible with imaging that has much higher signal-to-noiseraos (SNR) than previously obtained. Using 2007 observaons we made a proof-of-concept average of 11 one-minute H band exposures acquired over a 1.6-hour

aos (SNR) than previously obtained. Using 2007 observaons we made a proof-of-concept average of 11 one-minute H band exposures acquired over a 1.6-hourme span, reclinearly remapped and zonally shied to account for planetary rotaon. This increased SNR by about a factor of 3.3. A new fine structure inlatude bands appeared, small previously unobservable cloud tracers became discernible, and some faint cloud features became prominent. While we couldproduce one such high-quality average, we could not produce enough to actually track the newly-revealed features. This requires a specially designedobservaonal effort, that to be most useful should be conducted in the near future, while Uranus’ southern hemisphere is sll mostly visible. We have designedrecent HST WFC3 F845M observaons to allow applicaon of the technique, and will show results.Acknowledgements: support was provided by STScI and the NASA Planetary Astronomy program.11.26: Vercal Water Vapor Distribuon In The Atmospheres Of Uranus And Neptune As Obtained From Herschel ObservaonsAuthor Block: Christopher Jarchow 1 , P. Hartogh 1 , E. Lellouch 2 , R. Moreno 2 , H. Feuchtgruber 3 , T. Cavalie 4 , HssO Team1 Max-Planck-Instut für Sonnensystemforschung, Germany, 2 LESIA, Observatoire de Paris, France, 3 Max-Planck-Instut für extraterrestrische Physik, Germany,4 Universite de Bordeaux, Laboratoire d'Astrophysique de Bordeaux, France.Presentaon Time: 10/6/2010 4:30 PM - 4:32 PMLocaon: Exhibit HallAbstract: As part of the guaranteed me key programme "Water and related chemistry in the Solar System" (KP-GT HssO) about twenty different rotaonalwater vapor transions have been observed in the atmospheres of Uranus and Neptune with the PACS instrument of the European Space Agency's Herschel SpaceObservatory. In addion the 110-101 ground-state transion of H2O at 557 GHz has been observed in both planets at the very high resoluon of 1 MHz using theHerschel/HIFI instrument.Using a line-by-line radiaon transfer model in combinaon with the Opmal Esmaon Method as retrieval technique we analyze the data in terms ofinformaon content to derive the vercal distribuon of water vapor. The resulng distribuon, which is obtained from a simultaneous fit of the whole set oftransions, will be presented for both planets.11.27: Uranus and Neptune: Interior, Shape, and RotaonAuthor Block: Ravit Helled 1 , J. D. Anderson 2 , M. Podolak 3 , G. Schubert 11 UCLA, 2 JPL, 3 Tel Aviv University, Israel.Presentaon Time: 10/6/2010 4:32 PM - 4:34 PMLocaon: Exhibit HallAbstract: The interior structures of Uranus and Neptune are not well constrained. We present 'empirical' models (pressure vs. density) of Uranus and Neptuneinteriors constrained by the gravitaonal coefficients J2, J4, and the planetary radii and masses, using Voyager's solid-body rotaon periods. The empiricalpressure-density profiles are then interpreted in terms of physical equaons of state of hydrogen, helium, ice (H2O), and rock (SiO2) to test the physicalplausibility of the models. The interiors of Uranus and Neptune are found to be very similar. Our analysis suggests that the concentraon of heavier elementsinside both Uranus and Neptune interiors could increase gradually towards the planetary centers, without having sharp composional transions as typicallyassumed.Uranus and Neptune (solid-body) rotaon periods, 17.24h and 16.11h, respecvely, are based on Voyager 2 measurements of variaons in the planets' radiosignals and on fits to the planets' magnec fields.The realizaon that Saturn’s radio period does not represent the planet's deep interior rotaon and the complexity of the magnec fields of Uranus and Neptuneraise the possibility that the Voyager 2 radio and magnec periods might not represent the deep interior rotaon periods of the planets. We use wind and shapedata to invesgate the rotaon of Uranus and Neptune. Minimizaon of wind velocies or dynamic heights of the 1 bar isosurfaces, constrained by the singleoccultaon radii and gravitaonal coefficients of the planets, leads to solid-body rotaon periods of ~16.58h for Uranus and ~17.46h for Neptune. We deriveshapes for the planets based on these rotaon rates. Wind velocies with respect to these rotaon periods are essenally idencal on Uranus and Neptune andwind speeds are slower than previously thought. Alternavely, if we interpret wind measurements in terms of differenal rotaon on cylinders there areessenally no residual atmospheric winds.11.28: Modeling the Zonal Winds, Thermal Emissions, and Magnec Fields of Ice GiantsAuthor Block: Krista M. Soderlund 1 , J. M. Aurnou 11 UCLA.Presentaon Time: 10/6/2010 4:34 PM - 4:36 PMLocaon: Exhibit HallAbstract.Abstract: There are three global observaons of the Ice Giants, Uranus and Neptune, that hint toward their internal dynamics: atmospheric winds,thermal emissions, and magnec fields. Observaons of the cloud layers show that the surface winds are dominated by zonal (east-west) moons. The winds arewestward near the equator and flanked by eastward jets at high-latudes. Measurements of surface thermal emissions show that the energy flux paern ofNeptune peaks in the equatorial and polar regions with minima at mid-latudes. The energy flux paern of Uranus is not well constrained. The planets also haveintrinsic magnec fields with morphologies that are unique in the solar system. Their fields are not dipole-dominated like those of the Earth, Jupiter, and Saturn.Rather, the quadrupole and octopole components have strengths comparable to or greater than that of the dipole. These fields are likely generated byconvecvely-driven dynamo acon. However, it is not currently known what region(s) of the planets are convecng. If the magnec fields are driven near thesurface, a single region can simultaneously generate all three of these key observables. Here we present the results of a self-consistent planetary dynamo modelthat allows us to probe the physics of such a region. Our simulaon generates zonal wind and thermal emission paerns that qualitavely agree with those of theIce Giants and a non-dipolar dynamo consistent with the observed magnec fields. Thus, our model supports a shallow magnec field source region. Thisresearch was funded by the NASA Planetary Atmospheres Program.11.29: Simulang Ice Giant Vorces and their Bright Companion CloudsAuthor Block: Raymond P. Le Beau 1 , C. Palotai 2 , X. Deng 31 St. Louis University, 2 University of Central Florida, 3 University of California-Santa Barbara.Presentaon Time: 10/6/2010 4:36 PM - 4:38 PMLocaon: Exhibit HallAbstract: Starng with the original Great Dark Spot of Neptune, the large geophysical vorces of the Ice Giants have oen been observed with anaccompanying methane ice cloud. These long-lived orographic clouds appear as a consequence of the surrounding gas being lied over the vortex; in turn, recentnumerical simulaons suggest that the existence of these persistent clouds can significantly alter the dynamics of the vortex. Therefore, it appears that thesefeatures are more properly considered in the context of a vortex-cloud system rather than as separate phenomena.Previous simulaons with the Explicit Planetary Isentropic Coordinate General Circulaon Model (EPIC GCM) have replicated both vortex dynamics (such aslatudinal dri and shape oscillaons) and methane orographic cloud formaon similar to those observed_the challenge is now to combine these into anaccurate computaonal model of the full system. From a numerical standpoint, this requires a fuller representaon of the cloud microphysics along with

simulaons of high resoluon both in the horizontal and vercal direcons. Progress in this effort has connued to illustrate the potenal importance ofcompanion clouds in maintaining vortex stability in addion to changing the vortex dynamics. In me, further exploraon of the cloud-vortex interacon will giveus a beer understanding of the physics of the ice giant atmospheres, including possible cloud-vortex combinaons in which the vortex is largely undetectablebut crical to the apparent stability and moon of the more readily observed cloud feature.This work is supported by NASA Planetary Atmospheres Grant NNX09AB66G.11.30: Scaling Laws For Convecon And Jet Speeds On Giant Planet AtmospheresAuthor Block: Yohai Kaspi 1 , A. P. Showman 2 , G. R. Flierl 31 California Instute of Technology, 2 University of Arizona, 3 Massachuses Instute of Technology.Presentaon Time: 10/6/2010 4:38 PM - 4:40 PMLocaon: Exhibit HallAbstract.Abstract: Three dimensional studies of convecon in deep spherical shells have been used to test the hypothesis that the strong jet streams on giantplanets result from convecon throughout the molecular envelopes. Due to computaonal limitaons, these simulaons must be performed at parameter sengsfar from Jovian values and generally adopt heat fluxes much larger than the planetary values. Several numerical invesgaons have idenfied trends for how themean jet speed varies with heat flux and viscosity, but no previous theories have been advanced to explain these trends. Here, we show using simple argumentsthat if convecve release of potenal energy pumps the jets and viscosity damps them, the mean jet speeds split into different regimes depending on thestrength of the convecon. For each regime we provide a different scaling based on energy constraints, momentum constraints, and mixing length theory.Transions between these regimes are predicted and are consistent with three-dimensional numerical experiments. Our scalings provide a good match to themean jet speeds obtained in previous Boussinesq and anelasc, three-dimensional simulaons of convecon within giant planets over a broad range ofparameters. When extrapolated to the real heat fluxes, these scalings suggest that the mass-weighted jet speeds in the molecular envelopes of the giant planetsare much weaker, by an order of magnitude or more, than the jet speeds measured at cloud level.

Session Number: 12Session Title: Jovian Planets: Magnetospheres and AuroraeSession Type: Poster12.01: Invesgaons of Jovian Thermospheric Dynamics by using Ground-based SpectrometersAuthor Block: Takeru UN O 1 , T. Sakanoi 1 , M. Kagitani 1 , C. Tao 2 , T. Kitami 1 , Y. Kasaba 11 Tohoku Univ., Japan, 2 ISAS/JAXA, Japan.Presentaon Time: 10/6/2010 4:40 PM - 4:42 PMLocaon: Exhibit HallAbstract: Jupiter, the largest planet, has the strongest and largest magnetosphere in the solar system. It is driven by the dynamical and electromagneccoupling between the Magnetosphere, Ionosphere, and Thermosphere. This ‘MIT coupling system’ is the key element for the energy transfer from planetaryrotaon to overall electromagnec acvies like Jovian aurora.We have studied this system by numerical simulaons (e.g., Tao et al., 2009) and have compared them with mulple wavelength observaon data of ‘infraredaurora’ (2-4 microns) taken with a ground-based telescope. In our last run at IRTF/CHELL in Aug.-Sep. 2009, we succeeded to get the maps of brightness and drivelocity of Jovian H+ 3 aurora in its 4 um emission line. During this observaon, we also performed a test snapshot of Jovian H 2 aurora at 2.12 um for two nights.Consequently, we clearly detected the obvious morphological difference between H 2 and H+ 3 auroras (cf. Raynaud et al., 2004). It can potenally suggest thedifference of energy injecon to and the energy transfers between the neutral and plasma atmospheres.For further progress, we need to know the temporal variaons of auroral distribuons, temperatures, and wind profiles for both H 2 (neutral) and H+ 3 (plasma)lines. In Sep.-Oct. 2010, we will conduct two observaons using IRTF/CSHELL and SUBARU/IRCS. From those results, we will derive the origin of the difference inthe spaal distribuons of neutral and plasma auroras, supported by temperature (from IRCS) and velocity (from CSHELL) field profiles. It will tell the heang andenergy transfer processes, which connects the Jovian MIT coupling system.And in this presentaon, we will report our developing echelle spectrometer, which is opmized for observaon of Jovian aurora in 1-4 um, with spectralresoluon of 45,000.12.02: Comparison Of Jupiter's Infrared And Uv Aurorae With Simultaneous And Near-simultaneous HST And Ground-based ObservaonsAuthor Block: Makenzie B. Lystrup 1 , A. Radio 2 , B. Bonfond 2 , D. Grodent 21 University of Colorado Boulder, 2 Université de Liège Instut d'Astrophysique et de Géophysique, Belgium.Presentaon Time: 10/6/2010 4:42 PM - 4:44 PMLocaon: Exhibit HallAbstract: Jupiter's UV aurorae have been observed extensively for the last twenty years using the Hubble Space Telescope and the infrared aurorae have beeninvesgated using ground-based telescope observaons. The two wavelength regimes complement each other; the UV is a tracer of inputs from themagnetosphere while the infrared emissions from the H3+ molecular ion show how the ionosphere responds to those inputs.Between 1995 and 2000 Spectroscopic, J.E.P Connerney & T. Satoh carried out observaons with the NSFCAM imaging instrument at the NASA Infrared TelescopeFacility. Results from this data set have been published, although the enre data set has not been examined and there has been only limited comparison with theUV.We reanalyze this data set in order to stascally characterize the infrared aurora and compare with the UV. Here we present a detailed study of simultaneousand near-simultaneous observaons of the UV (STIS instrument on HST) and infrared northern aurorae made on July 26, 1998 and December 16, 2000. Thecomparave study addresses the main oval emissions, satellite footprints, and polar aurorae.M. Lystrup is supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-0802021.12.03: Neutral H2 And H2+ Ions In The Saturnian MagnetosphereAuthor Block: Wei-Ling Tseng 1 , R. E. Johnson 1 , M. F. Thomsen 2 , R. L. Tokar 2 , M. K. Elrod 11 UVa, 2 Los Alamos Naonal Laboratory.Presentaon Time: 10/6/2010 4:44 PM - 4:46 PMLocaon: Exhibit HallAbstract: The Saturnian system is immersed in an extended cloud of neutrals. Although water vapor ejected from Enceladus’s south pole is the dominantneutral source, photolysis and radiolysis of ices can release H2O, O2 and H2 from the icy ring parcles and the icy satellites, and Titan’s atmosphere is animportant source of H2. Once ionized, these neutrals are the source of the observed magnetospheric plasma. To understand the H2+ ion densies observed byCassini CAPS (Thomsen et al. 2010), we developed a Monte Carlo test-parcle model to simulate the spaal morphology of the neutral H2 cloud and the resulngH2+ ion source rates. The H2 lifeme is constrained by its local chemistry, which is computed from the latest plasma measurements by Cassini CAPS. The mainrings, Enceladus’ water torus, Rhea and Titan are considered as the primary sources of H2 in our model. It is seen that H2 accumulates over Saturn’s main ringsdue to thermal accommodaon with the ring parcles, and Titan is the dominant source of H2 in the outer magnetosphere (>~6 RS). From ~6 RS to ~2.5 RSphotodissociaon of water from Enceladus and H2 scaered from the ring atmosphere are comparable. H2+ ions are lost by collisions with the ring parclesinside ~ 2.5 RS, by interchange processes in the middle magnetosphere, and by flow down the tail in the outer magnetosphere. The density distribuon of H2+esmated from our ion source rates roughly agrees with CAPS observaons (Thomsen et al. 2010), and we show that the H2+ ion density near the equator overthe main rings is at least one order of magnitude smaller than O2+, possibly consistent with the non-detecon of H2+ by CAPS at SOI.12.04: Saturn Auroras Seen In Visible And Near-IR By Cassini ISSAuthor Block: Danika Wellington 1 , U. Dyudina 1 , S. Ewald 1 , A. Ingersoll 11 Caltech.Presentaon Time: 10/6/2010 4:46 PM - 4:48 PMLocaon: Exhibit HallAbstract: New data from the Cassini ISS narrow-angle camera allows us to make measurements of Saturn’s night-side auroras in both the northern and southernhemispheres. The aurora was detected in hydrogen alpha (652-661 nm), red (574-724 nm), and broad-band infrared (668-833 nm) wavelengths, and also faintly inblue (405-505 nm) and green (507-632 nm) wavelengths. The brightness in each filter appears to agree with predicted spectra for Saturnian auroras (Aguilar,2008). Along with the spectra and brightness measurements, we will present two 400+ frame movies taken in the clear filter, one showing aurora in the northernhemisphere from October 5-9, 2009, with a mestep of approximately three minutes, and the other showing the aurora in the southern hemisphere, from June 26,2010, with a mestep of approximately one minute. These movies show the aurora varying dramacally with both me and longitude. Near the limb the height ofthe aurora above its base can be measured; this height can reach more than 1200 km. The main auroral oval in the southern hemisphere appears near -72°latude, with smaller instances of auroral acvity near -75° and -77°.

Aguilar, A., J. M. Ajello, R. S. Mangina, G. K. James, H. Abgrall, and E. Roueff, “The electron-excited middle UV to near IR spectrum of H2 : Cross-secons andtransion probabilies”, Astrophys. J. Supp. Ser., 177 (2008).

Session Number: 26Session Title: Galilean SatellitesSession Type: Poster26.01: Density and Temperature of Io's Atmosphere from Mid-Infrared Observaons, 2001 to 2010: Connued Evidence for Inflaon as PerihelionApproachesAuthor Block: Constanne C.c. Tsang 1 , J. R. Spencer 1 , E. Lellouch 2 , M. J. Richter 3 , M. A. Lopez-Valverde 4 , T. K. Greathouse 11 Southwest Research Instute, 2 Observatoire de Meudon, France, 3 University of California at Davis, 4 Instuto Astrofisica de Andalucia, Spain.Presentaon Time: 10/6/2010 3:50 PM - 3:52 PMLocaon: Exhibit HallAbstract: Io's thin atmosphere is ulmately supplied by the injecon of SO 2 by constant volcanic erupons. However, the quesons of to what degree theatmosphere is directly supported by volcanic supply compared to support by the sublimaon of volcanically-derived SO 2 frost on the surface is sll debated. Wepresent a re-analysis of 19 um spectra of Io's SO 2 atmosphere from the TEXES mid-infrared high spectral resoluon spectrograph on NASA's Infrared TelescopeFacility. New data spanning between January 2005 and June 2010 have been obtained. Incorporang these with previously-published data spanning fromNovember 2001 through to January 2004, we have fied 14 blended absorpon lines of the V2 SO 2 vibraonal band to retrieve both the global mean values of SO 2column abundance and the kinec temperature of the gas. By constraining kinec temperature directly from the spectra rather than by indirect means, this newmethod provides a more resilient analysis of the complex non-LTE lines seen at 19 um. The 2001 to 2010 global mean column abundances vary with heliocentricdistance in a way that appears to be consistent with an atmosphere that is supported by the sublimaon of SO 2 surface frost, which is warmer with higher vaporpressure, near perihelion. June 2010 observaons, obtained less than a year before perihelion, showed the strongest SO 2 lines yet observed. No correlaon in thegas temperature was seen with the increasing SO 2 column densies.26.02: Thermal Model of Europa: Calculang the Effects of Surface Topography and Radiaon from JupiterAuthor Block: Kristen Benne 1 , D. Paige 1 , P. Hayne 1 , B. Greenhagen 2 , P. Schenk 31 UCLA, 2 JPL, 3 LPI.Presentaon Time: 10/6/2010 3:52 PM - 3:54 PMLocaon: Exhibit HallAbstract: Europa’s surface temperature distribuon results from global effects such as insolaon and heat flow, as well as local topography and possibly acvetectonic processes. Accurate surface temperature models will greatly benefit future orbital invesgaons searching for global-scale variaons in heat flow andlocal thermal anomalies resulng from friconal heang on faults or diapirs (Paige et al, this meeng). At the global scale, a major challenge for such models isthe strong influence of Jupiter on the solar and infrared flux at Europa’s surface. At the local scale, the thermal signature is dominated by complex topography. Inorder to address these two problems, we developed a model that modifies the Digital Moon program created by D. Paige and S. Meeker (2009) that uses a 3-dimensional geodesic gridding scheme to calculate the surface temperature of a body due to mulple scaerings of radiaon and heat flow. We can account forJupiter’s influence on Europa by including data on Jupiter’s solar and infrared radiaon (which accounts for roughly 30% of the radiaon at Europa), and onEuropa’s orbit (as Europa spends several minutes out of its 3.55 day orbital period in Jupiter’s shadow). To address the issue of Europa’s complicated terrain, wehave simulated the effects of local heat flow as well as added topography and surface roughness to the thermal model by using digital elevaon models producedby Schenk and Pappalardo (2004) that show altude changes of several hundred meters and tectonic features that may produce regions of anomalously high heatflow.26.03: Invesgang The Role Of Non-synchronous Rotaon In The Development Of Large Strike-slip Faults On EuropaAuthor Block: John G. Olgin 1 , B. R. Smith-Konter 1 , R. T. Pappalardo 21 Univ. of Texas, El Paso, 2 Jet Propulsion Laboratory, California Instute of Technology.Presentaon Time: 10/6/2010 3:54 PM - 3:56 PMLocaon: Exhibit HallAbstract: Much of Europa’s surface is crosscut by a dense network of fractured lineaments, offering many candidate faults for studying both past andpotenally present tectonic acvity. Here we invesgate the role of both diurnal and non-synchronous rotaon (NSR) dal stresses in the development of AgenorLinea, a major strike-slip fault in Europa’s southern hemisphere with strong evidence of right-lateral offsets. Preliminary calculaons suggest that diurnal dalstresses alone may be insufficient to cause Coulomb failure at Agenor Linea, thus we consider the role of NSR as a secular stress source for strike-slip faulng. Toinvesgate Europa’s combined diurnal and NSR dal stress field, we ulize the SatStress numerical code and assume a spherically symmetric ice shell ofthickness 20 km, underlain by a global subsurface ocean. We also assume an NSR period of 10 4 - 10 5 yrs, ice shell viscosity of ~ 10 22 Pa s, a coefficient of friconof 0.2, and a fault depth of 6 km. Applicaon of the Coulomb failure criterion reveals that a combinaon of NSR and diurnal dal stresses are required for AgenorLinea to succumb to right-lateral shear failure at specific porons of the orbital cycle. We further explore the relaonship of NSR to Agenor Linea’s east-westorientaon. Preliminary work suggests that if the fault were oriented in the north-south direcon, NSR would generate only le-lateral shear and compressivenormal stress, neither of which could construcvely combine to produce right-lateral offsets. This research was supported by the NASA Outer Planets ResearchProgram (NNG06GF44G, 07-OPR08-0088).26.04: Europa Composion Using Visible to Short Wavelength Infrared SpectroscopyAuthor Block: Diana L. Blaney 1 , J. B. Dalton 1 , R. O. Green 1 , K. Hibbits 2 , T. McCord 3 , S. Murchie 2 , G. Piccioni 4 , F. Tosi 41 JPL/Caltech, 2 APL, 3 The Bear Fight Instute, 4 INAF - IFSI, Italy.Presentaon Time: 10/6/2010 3:56 PM - 3:58 PMLocaon: Exhibit HallAbstract: One of the major goals of the Jupiter Europa Orbiter (JEO) is to understand the chemistry of Europa’s inorganic and organic materials. Europa’ssurface material composion is controlled by the original materials forming Europa and by their differenaon and chemical alteraons. Material is probably sllbeing transported to the surface by acve processes in the interior. At the surface, the material is exposed to the effects of vacuum and temperature, irradiatedby solar UV, and bombarded by material entrained in Jupiter’s magnec field. The materials on the surface and their distribuons are evidence of the processesoperang, both endogenic and exogenic. These processes include effects of a subsurface liquid ocean and its chemistry; the mechanisms of materialemplacement from below; and photolysis and radiolysis. Visible to Short Wavelength Infrared (VSWIR) spectroscopy is a well-understood technique for mappingkey inorganic, organic, and volale composions on remote surfaces such as Europa. Key spectral absorpon features have been detected in both the icy and thenon-icy Europa materials and many important constuents of the surface have been idenfied or proposed (e.g. hydrated salts, sulfuric acid hydrate, organics,CO2, H2O2, SO2). The determinaon of planetary surface composion from remote infrared spectroscopy depends upon adequate signal-to-noise, spectralresoluon, and spaal scale to disnguish the diagnosc spectral features of the compounds of interest. For icy satellites, laboratory reference spectra obtained

at the temperatures of the target bodies are also required. We have compared diagnosc spectral features in cryogenic laboratory spectra of hydrated saltsrelevant to Europa in order to opmize detecon of these materials under realisc mission condions. Effects of spectral resoluon, signal to noise rao, andareal mixtures are explored to determine the impacts on detecon. This work was carried out at the Jet Propulsion Laboratory / California Instute of Technologyunder contract with NASA.26.05: Spectral Properes of Chlorides and Other Oxidized Chlorine Compounds in Relaon to EuropaAuthor Block: Jennifer Hanley 1 , J. B. Dalton, III 11 Jet Propulsion Laboratory.Presentaon Time: 10/6/2010 3:58 PM - 4:00 PMLocaon: Exhibit HallAbstract: Galileo’s Near-Infrared Mapping Spectrometer (NIMS) has revealed the surface of Europa to be mostly water ice. The non-icy spectra have beencompared to those of various hydrated minerals, suggesng that the non-ice material has a heavily hydrated salt component. However, many relevant laboratoryspectra are sll not available, especially at the low temperatures and pressures of Europa. In parcular, chlorides are predicted to exist in the interior, and if thenon-ice material is of an endogenic source, hydrated chlorides might be present on the surface. Oxidaon of chlorides would result in chlorates (ClO - 3 ) and/orperchlorates (ClO - 4 ) as well. Both chlorates and perchlorates would lower the freezing point of water significantly (down to 205 K in the case of Mg(ClO 4 ) 2 ),adding new constraints to the arguments for a liquid layer below the surface.Using an environmental chamber to create the relevant pressures and temperatures of Europa, we have acquired new spectra of some of these hydrated salts,specifically MgCl 2 , Mg(ClO 3 ) 2 , NaClO 4 and Mg(ClO 4 ) 2 . These materials exhibit spectral features similar to those seen on NIMS observaons of Europa’s non-icyterrains. We will compare these spectra to those of water ice, hydrated sulfates, and the data. Preliminary analysis suggests that chlorate hydrates maycontribute to the spectral signature of Europa’s surface deposits.26.06: Low Temperature Opcal Constants of Hydrated Magnesium Sulfates For Planetary SurfacesAuthor Block: Karly M. Pitman 1 , J. B. Dalton, III 21 Planetary Science Instute, 2 Jet Propulsion Laboratory, California Inst. of Technology.Presentaon Time: 10/6/2010 4:00 PM - 4:02 PMLocaon: Exhibit HallAbstract: Quanfying surface composion is essenal to interpreng the surface features and understanding the formaon, evoluon, and interior processesof icy satellites from spacecra spectrometer and imaging data. The composion of icy body surfaces can be constrained to first order by comparing to laboratoryreflectance spectra obtained under appropriate condions of temperature and pressure, and related linear (area-based) mixture modeling. More advancedquantave determinaon of surface abundances via nonlinear mixing models requires opcal funcons or “constants” (real and imaginary indices of refracon,n(λ) and k(λ)). In this work, we invesgate three hydrated Mg sulfates (epsomite, bloedite, hexahydrite) that are spectrally similar to observaons of non-icysurface deposits on outer Solar System icy satellites and Mars. These compounds are parcularly important because they have aqueous chemistry consistent withthat predicted for subsurface oceans and paleolake basins on Europa, Ganymede, Enceladus, and Mars and may be useful indicators of astrobiological potenal.We present n(λ) and k(λ), derived from laboratory reflectance spectra (Dalton et al., 2005, Icarus 177, 472) acquired at visible to near-infrared wavelengths, forepsomite, bloedite, and hexahydrite at both 300 K (valid for Earth and Mars equatorial regions) and 120 K (opmized for Europa’s dayside temperature).Applicaons of these cryogenic n(λ), k(λ) data to radiave transfer models of telescopic observaons of icy worlds and mission data (Galileo NIMS, Cassini VIMS,and New Horizons LEISA) will be discussed. This work is supported through the NASA Outer Planets Research Program.26.07: Spaal Distribuon and Orbital Phase Behavior of Europa's Sodium CloudAuthor Block: Nicholas M. Schneider 1 , F. Leblanc 2 , C. Grava 3 , V. Mangano 4 , G. Cremonese 5 , C. Barbieri 31 Univ. of Colorado, 2 Service d’Aéronomie du CNRS/IPSL, France, 3 Diparmento di Astronomia, Università di Padova, Italy, 4 Istuto di Fisica dello SpazioInterplanetario, Italy, 5 INAF -L'Osservatorio Astronomico di Padova, Italy.Presentaon Time: 10/6/2010 4:02 PM - 4:04 PMLocaon: Exhibit HallAbstract: Contemporaneous observaons of the exospheres of Io and Europa allow a comparave study of their driving escape processes. Opcal observaonsof sodium emission at 589nm provide the highest S/N informaon on these two tenuous atmospheres. We report on extensive observaons obtained in 2007 and2009 with the SARG echelle spectrograph on the Telescopio Nazionale Galileo in the Canary Islands. Although Europa's emissions are considerably fainter thanIo's, SARG/TNG's sensivity and spaal resoluon allow mapping the structure of the corona and its evoluon as Europa orbits Jupiter. Column abundancevariaon around the orbit provides clues on exospheric origin. Previous observaons found a variaon factor of five of the sodium emission intensity over theorbit (Leblanc et al., Icarus, 159, 132, 2002; Leblanc et al., Icarus, 178, 367, 2005), and aributed the variaon to a net source of sodium at Europa. Alternavely,Cipriani et al., (GRL 35, L19201, 2008) interpreted the variaon to transient events in Jupiter's magnetopshere. We will present the more recent Europa data inthe context of these compeng theories, as well as a comparison against Io.This work has been supported by NSF's Planetary Astronomy Program, INAF/TNG and the Diparmento di Astronomia and CISAS of Università degli Studi diPadova, through a contract by the Italian Space Agency ASI.26.08: Prospects For Earth-Based Measurements Of Europa's LibraonsAuthor Block: Jean-Luc Margot 1 , D. B. Campbell 2 , S. J. Peale 31 University of California, Los Angeles, 2 Cornell University, 3 University of California, Santa Barbara.Presentaon Time: 10/6/2010 4:04 PM - 4:06 PMLocaon: Exhibit HallAbstract: The exploraon of Europa is of great interest because it may be hospitable to certain life forms [1]. Several lines of evidence suggest that asubsurface ocean exists beneath an icy shell [2,3], but there is debate about the thickness of the shell [4], which impacts Europa's astrobiological potenal. As inthe case of Mercury, it may be possible to determine whether an outer shell is decoupled from the interior and to evaluate the shell thickness by measuring theamplitude of forced longitude libraons [5,6]. In the simplest configuraon of a rigid shell decoupled from a spherically symmetric interior, the libraon amplitudeis amplified from the nominal value of ~18" by C/Cs, where C is the polar moment of inera of the body and Cs is that of the outer shell that parcipates in thelibraons. For a 100-km thick shell, the libraon amplitude would reach ~200", an esmate that remains valid even in the presence of gravitaonal couplingbetween asymmetrical layers [7]. If there are significant departures from rigid behavior, the shell may deform with the ocean underneath and exhibit a libraonamplitude of ~52" [8]. Europa reaches closest approach in October 2011, offering a once-in-a-decade opportunity to measure spin rate variaons by trackingradar speckles, as advocated by Holin [9,10]. Libraons of a rigid shell thinner than 100 km would be detectable. We will describe the experimental design andexpected sensivity.

References:[1] NRC, Europa Science Strategy, 1999.[2,3] Kivelson et al, Greeley et al, in Jupiter, CUP, 2004.[4] Greenberg, Unmasking Europa, Praxis, 2008.[5] Peale, Nature 262, 1976.[6] Margot et al, Science 316, 2007.[7] van Hoolst et al, Icarus 195, 2008.[8] Goldreich and Mitchell, Icarus, in press.[9] Green, in Radar Astronomy, McGraw-Hill, 1968.[10] Holin, Radiophys. Quant. Elec. 31, 1988.26.09: Impact Debris With Biological Material In The Inner Solar SystemAuthor Block: Carlos E. Chavez 1 , M. Reyes-Ruiz 11 Intuto de Astronomia UNAM Sede Ensenada.Presentaon Time: 10/6/2010 4:06 PM - 4:08 PMLocaon: Exhibit HallAbstract.Abstract: Here we revisited the arcle published by Gladman et al. 2005 in which is assumed that asteroidal and cometary impacts onto Earth canliberate material containing viable microorganisms, we studied the subsequent distribuon of the escaping impact ejecta throughout the inner Solar System onme scales of 30,000 years. We reproduce their results and found that there are impacts with Jupiter too, that is relevant since the satellites Europa andGanymede are believed to have liquid oceans below their surfaces.26.10: Study Of The Coorbital Satellites Existence In JupiterAuthor Block: Ana Paula Marins Chiaradia 1 , B. Y. P. Masago 1 , D. C. Mourao 1 , O. C. Winter 11 UNESP, Brazil.Presentaon Time: 10/6/2010 4:08 PM - 4:10 PMLocaon: Exhibit HallAbstract: The main goal of this work is to invesgate the coobital satellite existence of the galilean satellites. We used the integraon package of N-bodyproblems in celesal mechanics, Mercury (Chambers, 1999). The Mecury package has been adapted to simulaons of satellite systems of Jupiter. The input dataof the Galilean satellites (posion and velocity), were given in Cartesian coordinates according Avdyushev (2004). Simulaons were made over a period of100,000 years, where parcles were placed around each Galilean satellite. Coorbitals parcles were simulated around each satellite neglecng the disturbanceamong the galilean satellites. The obtained results were consistent with the expected results in resonances, with increasing in eccentricity and stability in semimajoraxis. We were also simulated the orbits of parcles coorbitals around each satellite, in this case without mutual disturbance between them and theparcles, obtaining results of tadpole and horseshoe orbits in the Jupiterian system.The authors thank the FAPESP (2009/06343-1).26.11: Simulated Ionian Column DensiesAuthor Block: Andrew C. Walker 1 , D. B. Goldstein 1 , P. L. Varghese 1 , L. M. Traon 1 , C. H. Moore 11 University of Texas at Ausn.Presentaon Time: 10/6/2010 4:10 PM - 4:12 PMLocaon: Exhibit HallAbstract: The sublimaon atmosphere of Io is modeled using the direct simulaon Monte Carlo (DSMC) method. These three-dimensional simulaons improveupon previous work by implemenng a more accurate two-component surface temperature model. This surface temperature model solves the one-dimensionalheat conducon equaon with depth for every 1° by 1° surface element. It also includes the following physics: Jovian eclipse, reflected sunlight from Jupiter,latent heat of sublimaon/condensaon, hot spots, endogenic heang, and independent thermal ineras and albedos for the frost and non-frost surfaces. Thesesimulaons model only the dominant dayside atmospheric species, SO 2 . The non-equilibrium rotaonal and vibraonal energy states of SO 2 are treated as well asphoto-emission from those states. Plasma heang of the atmosphere by high energy ions and electrons from the Jovian plasma torus is also modeled via aplasma energy flux. Resulng column densies are compared to recent observaons in an aempt to constrain the thermal parameters for the frost and non-frostsurfaces.26.12: Io Volcanism: Modeling Vapor And Heat TransportAuthor Block: Daniel R. Allen 1 , R. R. Howell 11 University of Wyoming.Presentaon Time: 10/6/2010 4:12 PM - 4:14 PMLocaon: Exhibit HallAbstract: Loki is a large, acve volcanic source on Jupiter’s moon, Io, whose overall temperatures are well explained by current cooling models, but there areunexplainable subtlees. Using the SO 2 atmospheric models of Ingersoll (1989) as a starng point, we are invesgang how volales, specifically sulfur, aretransported on the surface and how they modify the temperatures at Loki and other volcanoes. Voyager images reveal light colored deposits, colloquially called“sulfur bergs,” on Loki’s dark patera floor that may be sulfur fumaroles. Galileo images show the presence of red short-chain sulfur deposits around the patera.We are invesgang the mechanisms that lead to these features. The light deposits are a few kilometers across. Calculaons of the mean free paths for day mecondions on Io indicate lengths on the order of 0.1 km while poorly constrained night me condions indicate mean free paths about 100 mes greater, on theorder of what is needed to produce the deposits under ballisc condions. Preliminary calculaons reveal horizontal transport length scales for diffuse transportin a collisional atmosphere of approximately 30 km for sublimang S 8 sulfur at 300 K. These length scales would be sufficient to move the sulfur from the warmpatera floor to the locaons of the red sulfur deposits. At a typical Loki temperature of 300 K, the sublimaon/evaporaon rate of S 8 is a few tens of microns/day.It then requires just a few days to deposit an opcally thick 100 µm layer of material. Preliminary length scales and sublimaon rates are thus of sufficient scaleto produce the deposits. Invesgaons into the sulfur transport and its effect on temperature are ongoing.

Session Number: 30Session Title: Mars PostersSession Type: Poster30.01: Observaons Of Thermal Tides In The Atmosphere Of Mars By The Spicam InstrumentAuthor Block: Robert Pra 1 , J. Russo 1 , P. Withers 1 , J. Bertaux 2 , F. Montmessin 21 Boston University, 2 Service d'Aeronomie, France.Presentaon Time: 10/6/2010 4:00 PM - 4:02 PMLocaon: Exhibit HallAbstract.Abstract: Aerobraking accelerometer observaons have shown that non-migrang thermal des, such as the diurnal Kelvin wave, have large effects onthe structure of the maran atmosphere above 120 km altude. Here we extend studies of these des downwards into the middle atmosphere using SPICAMstellar occultaon measurements. These des, which are created by interacons at the surface of Mars, are significant at altudes as low as 80 km. Aspreviously observed at 130-160 km, the phases of the dominant dal modes vary lile with changing altude, indicang long vercal wavelengths. Thecharacterisc vercal lengthscale of the rate of change of amplitude with altude can be used to infer the importance of dissipave processes in the middleatmosphere. Unlike atmospheric measurements from many infra-red instruments, the SPICAM temperature and pressure profiles are referenced to an absolutealtude scale. Analysis of dal amplitudes and phases in density/pressure data alone is limited in its ability to disnguish between the underlying dal modesresponsible for observed zonal structure. However, the direct comparison of dal amplitudes and phases in both pressure and temperature data from SPICAMprovides valuable tools for determining whether one or several dal modes contribute to an observed component of the zonal structure.30.02: Oxidant Component In The Maran Atmosphere Observed By Mex/pfsAuthor Block: Yasumasa Kasaba 1 , S. Aoki 1 , H. Nakagawa 1 , I. Murata 1 , V. Formisano 2 , M. Giuranna 2 , A. Geminale 21 Tohoku Univ., Japan, 2 IFSI-INAF, Italy.Presentaon Time: 10/6/2010 4:02 PM - 4:04 PMLocaon: Exhibit HallAbstract: Previous observaons have been suggested that the large and fast variaons of methane in the Maran atmosphere would be caused by oxidaonloss with H2O2. These results also suggested that H2O2 would be produced in quanes much larger than foreseen by water photochemistry during dust stormsand dust devils by means of electrostac charging of the dust grains. However, past ground-based observaons of H2O2 mixing raos were few and contradictorywith photochemical model.In this study, we tried to detect the Maran H2O2 from the connuous observaons with Planetary Fourier Spectroscopy (PFS) onboard Mars Express (MEX) overseveral Mars years. Based on the possible H2O2 line at 362 cm-1 which is not contaminated by strong water lines, the derived H2O2 mixing rao shows variesbetween 0 and 50 ppb with an average and standard deviaon of ~20-30 ppb, respecvely. The result itself is good consistent with the photochemical model.However, the credibility of this innovave result shall be established. We tried to evaluate the results with the one in other lines at 379, 416 and 433 cm-1. At themoment, the results from these four lines are inconsistent.In order to clarify the true absorpon of H2O2, the following two things are tried: (1) The removal of the side lobe effects in the instrumental funcon (i.e.Adopon of the apodizaon into the interferogram analysis.) (2) Idenficaon of the arficial enhancement at the H2O2 absorpon lines (i.e., the H2O2absorpon in the condion with very low H2O mixing rao. Less absorpon shall be expected in average.). This paper will reflects the updated results based thistrials.In addion, we will also briefly report our recent ground-based acvies, i.e., (1) submm observaons of Maran minor elements and (2) the development ofinfrared heterodyne spectrometer.30.03: Preliminary P CA/TT Results on MRO CRISM Mulspectral ImagesAuthor Block: David R. Klassen 1 , M. D. Smith 21 Rowan Univ., 2 NASA Goddard Space Flight Center.Presentaon Time: 10/6/2010 4:04 PM - 4:06 PMLocaon: Exhibit HallAbstract: Mars Reconnaissance Orbiter arrived at Mars in March 2006 and by September had achieved its science-phase orbit with the CompactReconnaissance Imaging Spectrometer for Mars (CRISM) beginning its visible to near-infrared (VIS/NIR) spectral imaging shortly thereaer.One goal of CRISM is to fill in the spaal gaps between the various targeted observaons, eventually mapping the enre surface. Due to the large volume of datathis would create, the instrument works in a reduced spectral sampling mode creang “mulspectral” images. From these data we can create image cubes using64 wavelengths from 0.410 to 3.923 µm.We present here our analysis of these mulspectral mode data products using Principal Components Analysis (PCA) and Target Transformaon (TT) [1]. Previouswork with ground-based images [2-5] has shown that over an enre visible hemisphere, there are only three to four meaningful components using 32-105wavelengths over 1.5-4.1 µm; the first two are consistent over all temporal scales. The TT retrieved spectral endmembers show nearly the same level ofconsistency [5].The preliminary work on the CRISM images cubes implies similar results; three to four significant principal components that are fairly consistent over me. Thesecomponents are then used in TT to find spectral endmembers which can be used to characterize the surface reflectance for future use in radiave transfer cloudopcal depth retrievals. We present here the PCA/TT results comparing the principal components and recovered endmembers from six reconstructed CRISM mulspectralimage cubes.References:[1] Bandfield, J. L., et al. (2000) JGR, 105, 9573. [2] Klassen, D. R. and Bell III, J. F. (2001) BAAS 33, 1069. [3] Klassen, D. R. and Bell III, J. F. (2003) BAAS, 35, 936.[4] Klassen, D. R., Wark, T. J., Cuglioa, C. G. (2005) BAAS, 37, 693. [5] Klassen, D. R. (2009) Icarus, 204, 32.30.04: Mapping Water Ice Clouds and Ozone on Mars with MRO/MARCIAuthor Block: Michael J. Wolff 1 , R. T. Clancy 1 , B. A. Cantor 21 Space Science Instute, 2 Malin Space Science Systems.Presentaon Time: 10/6/2010 4:06 PM - 4:08 PMLocaon: Exhibit HallAbstract: The Mars Color Imager (MARCI) instrument (aboard the Mars Reconnaissance Orbiter, MRO) is a``push-frame,'' wide-angle imager whose overallcomponents, capabilies, and performance (including calibraon methodology) are described in recent publicaons (e.g., Malin et al., 2008, Icarus; Bell et al.,2010, Icarus). Of parcular note for atmospheric studies is the presence of two ultraviolet (UV) bands (centered near 265 and 330 nm) which allow for the directretrieval of column-integrated water ice cloud opcal depths and ozone abundances. MARCI observaons in the UV provide global daily mapping of these two

atmospheric constuents. For computaonally efficiency, the retrievals employ the "look-up table" approach, where each of the relevant input parameters(photometric angles, aerosol opcal depths, ozone abundance) is tessellated over the sampled or expected range of values (table generaon employs the DISORTpackage developed by K. Stamnes and collaborators). The UV aerosol properes are taken from the recent analyses of the MARCI 2007 global dust eventobservaons (Wolff et al., 2010, Icarus) and the empirical extension of the TES solarband water ice properes (e.g., Clancy et al., 2003, JGR). Empricial studiesindicate that a precision of 0.05 on cloud opcal depths and 1-2 micron-atm for ozone. In our presentaon, we will focus on a synopsis of the general seasonalbehavior observed during the first MRO mapping year.This work was supported by NASA through JPL Contract 127577630.05: Maran Middle-Latude Atmospheric Staonary Waves as Manifested in MRO MCS Retrieved Temperature DataAuthor Block: David Teal 1 , J. R. Murphy 1 , M. A. Kahre 21 New Mexico State University, 2 Bay Area Environmental Research Instute.Presentaon Time: 10/6/2010 4:08 PM - 4:10 PMLocaon: Exhibit HallAbstract: Large scale waves in the Maran atmosphere can play a significant role in the meridional transport of climacally important gases and aerosols.Banfield et al. (2003) examined forced waves in the Maran atmosphere in MGS TES nadir temperature data from ~6.1 to ~0.18 mbar. In September 2006, MarsReconnaissance Orbiter's Mars Climate Sounder instrument began its limb sounding campaign, measuring atmospheric pressure, temperature, andgaseous/aerosol opacies from ~6.1 to ~0.0001 mbar at a similar (~0.5 scale height) vercal resoluon as TES. Using the extended pressures probed by MCS, Leeet al. (2009) have examined the thermal de components of the forced waves in the MCS temperature data, but not the staonary wave components.Our project analyzes MCS data that is publicly available through NASA's Planetary Data System's Atmospheres Node and currently contains more than 1.5 Maranyears worth of retrievals. Our work focuses on the magnitude, longitudinal phase, and vercal propagaon of the staonary wave components manifested in theMCS temperature data. Model results will be used to minimize aliased wave signatures. Our results agree with those of Lee et al. (2009) and extend Banfield etal. (2003)'s analysis with the larger pressure range provided by MCS.This research was funded by the NASA PDS Atmospheres Node.Banfield, et al., Icarus, 2003.Lee, et al., JGR, 2009.30.06: MCS Observaons of Ice and Dust LayeringAuthor Block: Jennifer L. Benson 1 , D. M. Kass 1 , MCS Team1 JPL/Caltech.Presentaon Time: 10/6/2010 4:10 PM - 4:12 PMLocaon: Exhibit HallAbstract: Mars Climate Sounder (MCS) on Mars Reconnaissance Orbiter (MRO) has collected limb observaons starng in September 2006. MCS is a ninechannel infrared radiometer with limb staring arrays opmized for atmospheric sounding. Retrievals have been performed on the observaons to produce vercalprofiles of temperature, dust opacity and water ice opacity, extending from the surface to ~80 km. The limb sounding geometry is sensive to very modest layersof dust and ice due to the factor of 50 increase in the path length compared to nadir sounding.The sensive MCS profiles show that at many seasons, a layer of ice is seen above the bulk of the dust in the atmosphere. A moderate or thin layer of ice (withvisible column opacies

Presentaon Time: 10/6/2010 4:14 PM - 4:16 PMLocaon: Exhibit HallAbstract.Abstract: Mars Climate Sounder (MCS) temperature profiles are assimilated into the GFDL Mars Global Circulaon Model (MGCM) using the LocalEnsemble Transform Kalman Filter (LETKF) to accurately depict the state of the Maran atmosphere. The enhanced vercal resoluon of the MCS retrievalsexpands data coverage to more than 80 km in altude. Results are improved through careful consideraon of ensemble spread, including the use of varied dustopacity distribuons among the ensemble members, in addion to bias correcon to align the model climatology more closely with that of the data. Performanceis evaluated using short term forecasts compared to independent observaons, and the MCS analyses are compared to those generated by the assimilaon ofThermal Emission Spectrometer (TES) profiles during a similar Maran season.30.09: Ensemble Data Assimilaon of the Maran Atmosphere Using Temperature and Radiance Data from the Thermal Emission SpectrometerAuthor Block: Christopher Lee 1 , M. I. Richardson 1 , W. G. Lawson 2 , J. L. Anderson 31 Ashima Research, 2 Point Carbon, 3 UCAR.Presentaon Time: 10/6/2010 4:16 PM - 4:18 PMLocaon: Exhibit HallAbstract.Abstract: Observaons from the Thermal Emission Spectrometer (TES) aboard the Mars Global Surveyor (MGS) are being used to constrain theevoluon of a General Circulaon Model of the Maran atmosphere, MarsWRF, using an ensemble Kalman filter data assimilaon framework, DART. We describethe setup of MarsWRF to allow its use within the data assimilaon framework, including accurate posioning of TES observaons and evoluon of mulpleperturbed states within DART. Details of the interface between MarsWRF and DART are given and data requirements for future assimilaon work is outlined. Wedescribe the TES observaons being ingested by the data assimilaon process and outline the radiance forward model being used to simulate upwellingradiances. We assimilate TES retrieved temperatures and calibrated radiances using DART and compare the resulng simulaons.30.10: Mars Upper Atmosphere NetworkAuthor Block: Hermann Opgenoorth 1 , O. Witasse 2 , P. Withers 31 IRF, Sweden, 2 ESA, Netherlands, 3 Boston University.Presentaon Time: 10/6/2010 4:18 PM - 4:20 PMLocaon: Exhibit HallAbstract: Mars Express and other spacecra obtain a wide range of measurements of the complex upper atmosphere, ionosphere, and space environment ofMars. The ionosphere and space environment of Mars form a unique plasma laboratory due to Mars’s intense, small-scale crustal magnec fields. This region ofMars is involved in many atmospheric loss processes. Collaboraons that bring together instrument teams, modellers and others are powerful mechanisms forstudying Mars with a broad range of tools, enabling discoveries that cannot be made by isolated groups. Consequently, the Mars Upper Atmosphere Network wascreated as a self-sustaining scienfic enterprise in early 2009.This presentaon will provide an overview on the composion and acvies of this Network, including a focused observing campaign on the upper atmosphere,ionosphere, and space environment of Mars conducted by Mars Express in March 2010. At this me, Earth and Mars were on the same arm of the solar wind'sParker spiral, which permits extensive comparisons of upstream solar wind data at Earth to observaons from Mars.30.11: Trajectory And Atmospheric Structure From Entry Probes: Demonstraon Of A Real-me Reconstrucon Technique Using A Simple Direct-toearthRadio LinkAuthor Block: Paul Withers 11 Boston University.Presentaon Time: 10/6/2010 4:20 PM - 4:22 PMLocaon: Exhibit HallAbstract: The reconstrucon of the trajectory and atmospheric structure associated with an entry probe has tradionally relied upon onboard accelerometermeasurements. Here we outline an equivalent reconstrucon technique that uses Doppler-shied direct-to-Earth transmissions instead. A crical assumpon isthat the entry probe’s angle of aack is zero. The technique is successfully demonstrated on the atmospheric entry of the Mars Exploraon Rover Opportunity,terminang at parachute deployment. This technique can be applied in real-me, which supports mission operaons and public engagement. It can also beapplied to entry probes that fail during their high-risk atmospheric entry.30.12: Coronal Hydrogen Emission: Model vs. Mars ExpressAuthor Block: Michael S. Chaffin 1 , J. Chaufray 2 , N. Schneider 1 , I. Stewart 11 University of Colorado, 2 Laboratoire de Météorologie Dynamique, France.Presentaon Time: 10/6/2010 4:22 PM - 4:24 PMLocaon: Exhibit HallAbstract: We present a comparison of theorecal radiance calculaons to observaons of the hydrogen corona of Mars. The altude-dependence of Lymanalpha airglow (observed by spacecra limb sounding) provides a means of measuring the temperature and density of hydrogen atoms at the exobase.Characterizing the temperature allows us to esmate the escape rate of hydrogen from the atmosphere of Mars, with important implicaons for water loss ratesand the early habitability of the Maran surface. In the present work, I compute the intensity and altude-dependence of Lyman alpha airglow from Mars'hydrogen corona based on a theorecal model accounng for the producon and diffusion of hydrogen through a background atmosphere of CO 2 below theexobase. Above the exobase, the distribuon of hydrogen takes the form of a classical Chamberlain exosphere without satellite parcles. Because the Lymanalpha airglow is opcally thick, a full account of resonance-line radiave transfer is developed, according to principles established by Chaufray et. al. . Theradiave transfer equaon is solved numerically, and modeled intensity profiles are developed for comparison with observaons made by SPICAM on MarsExpress. Based on the model, we extract informaon sufficent to determine the temperature and density variability of hydrogen in the exosphere of Mars. Resultswill be presented on coronal variaon across a set of observaons made by SPICAM.References:Chaufray et. al. 2008 “Observaon of the hydrogen corona with SPICAM on Mars Express” Icarus 195, 598-613.30.13: Monitoring Mars for Electrostac Discharges with the DSNAuthor Block: T. B. H. Kuiper 1 , W. A. Majid 1 , G. Bower 2 , D. Catling 3 , C. Garcia Miro 4 , S. Marnez 5 , I. de Pater 2 , N. O. Renno 6 , C. Ruf 7 , A. Siemion 21 Caltech JPL, 2 UC Berkeley, 3 U. Washington, 4 Ingeniería y Servicios Aeroespaciales, Spain, 5 Instuto Nacional de Técnica Aeroespacial, Spain, 6 U. Michigan, 7 UMichigan.Presentaon Time: 10/6/2010 4:24 PM - 4:26 PMLocaon: Exhibit Hall

Abstract: The Deep Space Network antenna DSS-13 was used during 43 sessions of approximately twelve hours duraon between Feb. 4 and Apr. 23, 2010, tomonitor Mars for electrostac discharges. Such discharges had been detected with a special detector installed at DSS-13 by Ruf et al. (GRL 36, L13202, 2009) inJune of 2006. The discharge signature was enhanced kurtosis (the fourth moment of the signal normalized to the second moment, which is proporonal to power)modulated by the Schumann resonance (circum-planet light travel me) of Mars.Although DSS-13 is an R&D staon, the receivers and data processing equipment used were idencal to those used by operaonal DSN staons which rounelytrack Mars. The signals in four adjacent pairs of ½ MHz channels were digized and processed to produce samples of kurtosis in real-me. These were thenrecorded for later analysis. To verify that Mars was the source of any possible events, the antenna was moved off Mars for 45 sec every 5 min. We demonstratedthat the DSN can monitor Mars rounely during normal operaons without any addional equipment by including a down-link signal in one channel and seeingthe kurtosis change as expected as the antenna poinng was changed. We saw no anomalous kurtosis during local thunderstorms. We will report on the analysisof kurtosis data for Mars events.In a student research project connuing this acvity, the signals from operaonal DSN antennas in Spain engaged in normal down-link operaons are beingprocessed for the kurtosis signature which characterizes electrostac discharges.This work was performed by the California Instute of Technology Jet Propulsion Laboratory under contract to the Naonal Aeronaucs and Space Administraon.30.14: Electric Discharge in the Maran Atmosphere, Paschen Curves and Implicaons for Future MissionsAuthor Block: Heidi L.K. Manning 1 , I. L. ten Kate 2 , S. J. Bael 3 , P. R. Mahaffy 21 Concordia College, 2 NASA Goddard Space Flight Center, 3 Bael Engineering.Presentaon Time: 10/6/2010 4:26 PM - 4:28 PMLocaon: Exhibit HallAbstract: Electric discharge between two electrically charged surfaces occurs at a well-defined, gas-dependent combinaon of atmospheric pressure and thedistance between those two surfaces, as described by Paschen’s law. The understanding of when the discharge will occur in the condions present on Mars isessenal for designing space flight hardware that will operate on the Maran surface as well as understanding electrical discharge processes occurring in theMaran atmosphere. We present experimentally measured Paschen curves for a gas mixture representave of the Maran atmosphere and compare our resultsto breakdown voltages of carbon dioxide, nitrogen, and helium as measured with our system and from the literature. We will discuss possible implicaons forinstrument development as well as implicaons for processes in the Maran atmosphere. The DC voltage at which electric discharge occurred between twostainless steel spheres was measured at pressures from 10-2 to 100 torr in all gases. We measured a minimum voltage for discharge in the Mars ambientatmosphere of 410±10 volts at 0.3 torr cm. As an applicaon, the breakdown properes of space-qualified, electrical wires to be used in the Sample Analysis atMars (SAM) instrument suite on the Mars Science Laboratory (MSL) were studied.H. Manning was funded in the framework of the Sample Analysis at Mars development; I. ten Kate was funded by the Goddard Center for Astrobiology.30.15: Search for Electrostac Discharges on MarsAuthor Block: Marin Anderson 1 , A. Siemion 1 , D. Werthimer 1 , I. de Pater 1 , G. C. Bower 1 , W. C. Baro 21 University of California, Berkeley, 2 Embry-Riddle.Presentaon Time: 10/6/2010 4:28 PM - 4:30 PMLocaon: Exhibit HallAbstract: The Allen Telescope Array was used to monitor Mars between March 8 and June 1, 2010 over a total of approximately 42 hours, for signals indicaveof electrostac discharge using a wideband signal processor developed at the Center for Astronomy Signal Processing and Electronics Research (CASPER),following the report by Ruf et al., 2009, of the possible detecon of electrostac discharge on Mars. In conjuncon with the ATA, simultaneous observaons weredone by JPL on the Deep Space Network antenna.The 1024-channel spectrometer receives complex-baseband voltage data from the ATA beamformer, from which it computes power and spectral kurtosis of theinput signal in real-me. For this experiment, the ATA beamformers, each of which delivers a 104.8 MHz bandwidth, were tuned to 3.2 and 8.0 GHz.The spectral kurtosis is calculated using the method suggested in Nita et al., 2007, using a rao between power and power squared. Variaons in the kurtosis areindicave of non-Gaussianity in the signal, which can be used to detect variable cosmic signals as well as radio frequency interference -- in parcular, lightningdischarge in the Maran atmosphere measurable as a variaon in the kurtosis corresponding to Mars’ Schumann resonance. In the presence of a Gaussian signal,the kurtosis takes on a constant value. Interference, and the non-thermal emission associated with electrostac discharge, are non-Gaussian, and thus cause thekurtosis to deviate from the Gaussian value.The instrument and analysis were tested on a variety of known sources of non-Gaussian emission, including the Crab pulsar and a number of terrestrial sources,such as satellites, which showed appropriate deviaons in power and kurtosis corresponding to radio interference, and in the case of the Crab pulsar, giantpulses.30.16: Atmospheric Modeling of Mars Methane PlumesAuthor Block: Michael A. Mischna 1 , M. Allen 1 , S. Lee 11 JPL.Presentaon Time: 10/6/2010 4:30 PM - 4:32 PMLocaon: Exhibit HallAbstract: We present two complementary methods for isolang and modeling surface source releases of methane in the maran atmosphere. From recentobservaons, there is strong evidence that periodic releases of methane occur from discrete surface locaons, although the exact locaon and mechanism ofrelease is sll unknown. Numerical model simulaons with the Mars Weather Research and Forecasng (MarsWRF) general circulaon model (GCM) have beenapplied to the ground-based observaons of atmospheric methane by Mumma et al., (2009). MarsWRF simulaons reproduce the natural behavior of trace gasplumes in the maran atmosphere, and reveal the development of the plume over me. These results provide constraints on the ming and locaon of release ofthe methane plume.Addional detecons of methane have been accumulated by the Planetary Fourier Spectrometer (PFS) on board Mars Express. For orbital observaons, whichgenerally have higher frequency and resoluon, an alternate approach to source isolaon has been developed. Drawing from the concept of natural seleconwithin biology, we apply an evoluonary computaonal model to this problem of isolang source locaons. Using genec algorithms that ‘reward’ best-fitmatches between observaons and GCM plume simulaons (also from MarsWRF) over many generaons, we find that we can potenally isolate source locaonsto within tens of km, which is within the roving capabilies of future Mars rovers. Together, these methods present viable numerical approaches to restricng theming, duraon and size of methane release events, and can be used for other trace gas plumes on Mars as well as elsewhere in the solar system.

30.17: Is There Methane on Mars?Author Block: Kevin Zahnle 1 , R. S. Freedman 2 , D. C. Catling 31 NASA Ames Research Center, 2 SETI Instute, 3 University of Washington.Presentaon Time: 10/6/2010 4:32 PM - 4:34 PMLocaon: Exhibit HallAbstract.Abstract: There have been several reports of methane on Mars at the 10-30 ppbv level. The most compelling of these also suggest that maranmethane is both seasonally and latudinally variable. We review why variable methane on Mars is physically and chemically implausible, and then we cricallyreview the published reports. We use the HITRAN database to generate synthec terrestrial and maran spectra encompassing the frequencies of the publishedobservaons. These reveal significant compeng telluric and maran spectral features that are most problemac in just those cases where methane's signatureseems most clearly seen. The most compromised observaons are of the 12CH4 v3 R0 and R1 lines seen in blueshi (obtained when Mars was approaching Earthin early 2003). For these the Doppler shi moves the two maran lines into near coincidence with telluric 13CH4 v3 R1 and R2 lines that are 20-50 mes strongerthan the inferred maran lines. The best cases among the published datasets are also of the 12CH4 v3 R0 and R1 lines, but observed in redshi when Mars wasreceding from Earth. For these observaons and analyses are consistent with no methane on Mars at the 3 ppbv level. We therefore conclude that the upper limitis on the order of 3 ppbv.30.18: Invesgaon of the Destrucon Lifeme of Maran Atmospheric MethaneAuthor Block: Malynda Chizek 1 , J. R. Murphy 1 , R. M. Haberle 2 , M. A. Kahre 21 New Mexico State University, 2 NASA ARC.Presentaon Time: 10/6/2010 4:34 PM - 4:36 PMLocaon: Exhibit HallAbstract: The announcement of recent detecons of Maran methane [1,2,3,4] resulted in many quesons, including "how is it being destroyed so quickly?"The expected destrucon mechanism, photochemistry, has a lifeme of ~350 Earth years in the Maran atmosphere [3,5] which is about 600 mes longer thanthe 0.6 Earth year lifeme esmated from the observaons [1]. No mechanism has yet been idenfied to answer this queson, but a few possibilies have beenproposed including surface reacons with peroxide or perchlorate [1].The sparse number of methane detecons provide lile constraint on the destrucon mechanism. NASA Ames GCM [6] simulaons provide a tool to invesgatethe gas abundance as well as the destrucon lifeme needed to produce the observaons. Previous work simulang the gas abundance has shown that thesource magnitude required to produce the observed abundance is at least an order of magnitude larger than esmated by [1],[5,7].Destrucon lifeme will be invesgated considering the availability of the gas within the boundary layer for an interacon with a chemical on the surface. As thedestrucon mechanism may be dependent on the temperature or dust column abundance, sensivity to these quanes will be invesgated.This work is funded by New Mexico Space Grant.[1] Mumma, et al., Science, 2009[2] Krasnopolsky, et al., Icarus, 2004[3] Formisano, et al., Science, 2004[4] Fon and Marzo, A&A, 2010[5] Lefevre and Forget, Nature, 2009[6] Kahre et al., JGR, 2006[7] Chizek et al., DPS, 200930.19: Using Assimilaon Techniques To Model Mars' Dust Cycle With The N ASA Ames And N OAA/GFDL Mars General Circulaon ModelsAuthor Block: Melinda A. Kahre 1 , R. J. Wilson 2 , J. L. Hollingsworth 1 , R. M. Haberle 11 NASA Ames Research Center, 2 Geophysical Fluid Dynamics Laboratory.Presentaon Time: 10/6/2010 4:36 PM - 4:38 PMLocaon: Exhibit HallAbstract.Abstract: The dust cycle plays a crical role in Mars' current climate. However, modeling the dust cycle connues to prove challenging for MarsGeneral Circulaon Models (MGCMs). In this study, we ulize assimilaon techniques to model the dust cycle in the NASA Ames and NOAA/GFDL MGCMs. Dustis injected from the surface when necessary to match TES-observed column dust opacies as a funcon of locaon and season. This scheme allows us toradiavely force the model with reasonable spaal and temporal dust fields while allowing the vercal profiles of dust concentraon and parcle size to be selfconsistentlydetermined by the condions predicted by the MGCM. The goals of the work are to infer dust sources and sinks, to increase our understanding ofhow the vercal distribuon of dust and dust parcle sizes changes in me and space, and to put constraints on the development of more physically appropriatedust liing parameterizaons. We present simulated spaal and temporal paerns of dust, temperature, and winds, and show that the two MGCMs robustlysuggest that cap edge liing provides the source for the majority of the observed atmospheric dust loading.30.20: Modeling the Maran Climate with a New General Circulaon Model: The water vapor greenhouse on MarsAuthor Block: Richard Urata 1 , O. B. Toon 11 University of Colorado.Presentaon Time: 10/6/2010 4:38 PM - 4:40 PMLocaon: Exhibit HallAbstract: We have adapted the Naonal Center for Atmospheric Research (NCAR) Community Atmosphere Model (CAM3.0) to Maran condions.Modificaons to the model include adjusng the planetary parameters such as gravity and albedo to Maran values, changing the atmospheric composion,replacing the radiave transfer scheme, changing the calendar to cover a Maran year, and the addion of a carbon dioxide condensaon scheme. The Maranatmosphere is composed of 95% carbon dioxide, and as much as 25% of the atmosphere can condense out at the winter pole, having a significant impact on thedynamics as well as the energy budget.We have performed simulaons of the current climate at a resoluon of 2x2.5 degrees (lat-lon), and have tuned the model to match the Viking Lander annualpressure cycle. Comparisons to vercal temperature profiles from the Thermal Emission Spectrometer (TES) show agreement to within +/- 5 K during northernspring through northern summer, but a consistently cooler atmosphere in the model during autumn and fall.We have applied this model to invesgate the water vapor greenhouse in an ancient atmosphere with 500 mbar of CO 2 . It is water vapor, not CO 2 , whichdominates the greenhouse effect in such an atmosphere, just as is the case for modern Earth. We invesgate the distribuon of water vapor and ice clouds andtheir impacts on this climate system.30.21: The Effects of Radiavely Acve Water Ice Clouds on the Maran Global Seasonal Water CycleAuthor Block: Robert M. Haberle 1 , F. Montmessin 2 , M. A. Kahre 1 , J. L. Hollingsworth 1 , J. Schaeffer 1 , A. de Brouchoven de Bergeyck 3 , J. Wilson 4

1 NASA Ames Research Center, 2 Laboratoire Atmosphères, Milieux, Observaons Spaales, France, 3 ISAE-SUPAERO, France, 4 NOAA Geophysical Fluid DynamicsLaboratory.Presentaon Time: 10/6/2010 4:40 PM - 4:42 PMLocaon: Exhibit HallAbstract: Recently, Mars General Circulaon Models (MGCM) have begun implemenng cloud microphysics packages to beer account for their role in thewater cycle. Here, we discuss the importance of their radiave effects. For the past several years we have been implemenng and tesng a state-of-the-art cloudmicrophysics package into the NASA/Ames MGCM. This package accounts for the nucleaon, growth, transport, and seling of a size distribuon water ice cloudparcles in a self-consistent fashion. The model also has flags to acvate their solar and infrared radiave effects, which depend on the size and dust content ofthe ice parcles.We have performed two simulaons of the global water cycle on Mars: one in which the clouds are radiavely inert, and one in which they are radiavely acve.We find that the thermal structure of the atmosphere in the radiavely acve cloud run compares beer with MGS TES and MRO MCS data. However, the watercycle dries out considerably with radiavely acve clouds. There are several reasons for this but the main reason appears to be related to a cooling of the NorthPolar Residual Cap (NPRC) in the model that is brought about by the reflecve nature of the clouds that develop in the lower atmosphere immediately above theNPRC. These clouds increase the planetary albedo at these latudes and reduce the solar flux at the surface, which is not sufficiently compensated for by anincrease in downward infrared emission. Our conclusion at this point, based upon comparison with MRO MCS and MARCI data, is that the model is overpredicngthe cloud fields in the vicinity of the NPRC.30.22: Mars’ Northern Dunes: Volales and GeologyAuthor Block: Candice Hansen 1 , N. Bridges 2 , M. Bourke 3 , S. Byrne 4 , S. Diniega 4 , C. Dundas 4 , K. Herkenhoff 5 , A. McEwen 4 , G. Portyankina 6 , N. Thomas 6 , C. Colon 21 JPL, 2 APL / JHU, 3 PSI, 4 University of AZ, 5 USGS, 6 University of Bern, Switzerland.Presentaon Time: 10/6/2010 4:42 PM - 4:44 PMLocaon: Exhibit HallAbstract: Mars has a vast sea of sand dunes at high northern latudes known as the north polar erg. These dunes are blanketed with seasonal CO2 frost in thewinter and early spring. Sharp dune crests, steep slipfaces and lack of craters suggest that these northern dunes have experienced geologically recentresurfacing. The High Resoluon Imaging Science Experiment (HiRISE) on the Mars Reconnaissance Orbiter (MRO) imaged a limited number of sites in the duneswith resoluon beer than 1 m to look for changes.New HiRISE images show extensive erosion of northern hemisphere dunes associated with seasonal CO2 ice sublimaon in the spring. With ~2 Mars years ofobservaons we have observed the CO2-ice-free state of the dunes in the first year, frost-covered in late winter, the spring sublimaon process, and the ice-freestate of the dunes again in the second year. Temporal sequences of images of individual sites were acquired to monitor the sublimaon process throughoutspring.Ice-free images have been compared between northern summer in MRO year 1 (Mars Year 29) and MRO year 2. New alcoves and aprons are detected onnumerous dunes in several sites. In one parcular barchan dune field 20% of the dunes show substanal changes and 20% show minor changes. These changescan be traced to locaons of early enhanced CO2 ice sublimaon. The sublimaon acvity manifests itself on the dunes as cracks along the dune crest fromwhich dark streaks of sand and dust move down the slipface. The sand travels out onto paerned ground, enabling measurement of the extent of the new aprons,in some cases meters from the dune boundary one year earlier.In order to maintain fresh dunes against such erosion the dune-building processes must sll be at work on Mars today.This work was parally supported by JPL/CIT/NASA.30.23: The Distribuon of Possible Hydrovolcanic Features in the Vicinity of Gusev Crater, MarsAuthor Block: Annabelle Basta 1 , M. Rice 2 , W. Waers 2 , J. Bell 21 Wellesley College, 2 Cornell University.Presentaon Time: 10/6/2010 4:44 PM - 4:46 PMLocaon: Exhibit HallAbstract.Abstract: The Mars Exploraon Rover Spirit landed in Gusev Crater, Mars in 2004. For the past four years of its mission, Spirit has been exploring thevicinity of Home Plate, a plateau of layered rocks interpreted to be a pyroclasc deposit caused by the explosive interacon of magma with ground water or ice[1]. Thus, the origin of Home Plate and the regional distribuon of similar features have implicaons for the history of water at Gusev Crater. To test thehypothesis that hydrovolcanic acvity may have been widespread throughout the region, we have performed a survey of images from the HiRISE and CTX camerasonboard the Mars Reconnaissance Orbiter (MRO), and from the MOC camera onboard the Mars Global Surveyor (MGS) spacecra. We have mapped thedistribuon of geomorphic structures resembling Home Plate as a means of indicang locaons of potenal hydrovolcanic acvity. We have also searched forfeatures indicave of ice-rich terrain, such as precipitous boundaries and columnar joinng in the Gusev plains lavas, and hummocky terrain. In this work wepresent a map of these geomorphic features that indicates potenal hydrovolcanic acvity in several disnct locaons within Gusev Crater, notably to the westand southeast of the Columbia Hills. [1] Squyres, S. W., et al. (2007), Science 316, 738-742.

Session Number: 39Session Title: Asteroids: Lutetia & Other Main-Belt AsteroidsSession Type: Poster39.01: ESA/Rosea Encounters the Main Belt Asteroid (21) Lutea: First Results on Lutea Cratering HistoryAuthor Block: Simone Marchi 1 , C. Barbieri 1 , S. Besse 2 , M. Kueppers 3 , F. Marzari 1 , M. Massironi 1 , S. Moola 4 , G. Naleo 1 , H. Sierks 5 , OSIRIS Team1 Univ. di Padova, Italy, 2 Univ. of Maryland, 3 ESAC, Spain, 4 DLR-Berlin, Germany, 5 M PI-Lindau, Germany.Presentaon Time: 10/6/2010 4:10 PM - 4:12 PMLocaon: Exhibit HallAbstract.Abstract: On July 10, 2010 the ESA Rosea spacecra flown by the 100-km across main belt asteroid (21) Lutea. According to present asteroidcollisional models, Lutea could be a primordial body, i.e. that survived intact to eons of fiery collisions within the main belt. Lutea is the largest asteroid evervisited by a spacecra so far, therefore it is the best candidate for understanding the formaon and evoluon of asteroids, which sll remain elusive in manyrespects. These circumstances make of Lutea flyby a milestone for the whole planetary community. The many instruments on board Rosea gathered a greatdeal of informaon about Lutea physical properes (e.g. surface composion, geology, shape, density). In this work, we present a preliminary analysis of thesurface features detected on Lutea thanks to the imaging system OSIRIS. The closest approach distance of Rosea to Lutea was about 3160 km, correspondingto a best resoluon of about 60 m/pixel. Lutea shows a very complex surface morphology and shape, possibly sculpted by large impacts. Impact craters havebeen counted down to diameters of about 300 m, while the largest detected crater has a size of about 60 km. We invesgate the Lutea cratering history andgive a preliminary interpretaon of the observaons in terms of the current collisional models.39.02: Surface Physical Properes of (21) Lutea: Results from OSIRIS Observaons During the Rosea Fly-byAuthor Block: Sonia Fornasier 1 , C. Barbieri 2 , M. A. Barucci 1 , V. Da Deppo 3 , J. De Leon 4 , M. Fulchignoni 1 , S. F. Hviid 5 , L. Jorda 6 , H. U. Keller 5 , M. Küppers 7 , F. LaForgia 2 , L. M. Lara 4 , M. Lazzarin 2 , C. Leyrat 1 , S. Magrin 2 , S. Marchi 2 , S. E. Schröder 5 , H. Sierks 5 , P. Vernazza 8 , OSIRIS Team1 LESIA-Observatoire De Paris, France, 2 University of Padova, Italy, 3 CNR-IFN UOS, Italy, 4 Instuto de Astrofisica de Andalucia-CSIC, Spain, 5 Max Planck Instute,Germany, 6 Laboratoire d'Astrophysique de Marseille, France, 7 ESA-ESAC, Spain, 8 ESA-ESTEC, Netherlands.Presentaon Time: 10/6/2010 4:12 PM - 4:14 PMLocaon: Exhibit HallAbstract: On July 10, 2010, the ESA Rosea mission successfully flew by the asteroid 21 Lutea, the biggest asteroid ever encountered by a space mission. TheOSIRIS imaging system onboard Rosea, equipped with a Narrow Angle Camera (NAC) and a Wide Angle Camera (WAC), observed the asteroid in 20 filtersextending from 240 to 980 nm with a maximum spaal resoluon of 60 m/px.Several color sequences were obtained at different rotaonal phases for the asteroid. Images with the Orange (647 nm) and OI (630 nm) filters of the NAC andWAC cameras were connously repeated to invesgate the phase funcon in a wide phase angle range, from 0 to 156 degrees.In this work we will present unresolved spectrophotometry results, the albedo map and the phase funcon of 21 lutea derived by the OSIRIS instrument.Potenal albedo variaons will be presented as well. We will finally discuss the implicaons for the mineralogy and the surface evoluon of the asteroid.39.03: Properes And Distribuon Of The Craters Of Asteroid (21) Lutea From The Rosea\Osiris Fly-byAuthor Block: Sebasen Besse 1 , P. Lamy 2 , L. Jorda 2 , O. Groussin 2 , S. Marchi 3 , S. Debei 3 , V. Da Deppo 3 , F. Ferri 3 , H. U. Keller 4 , M. Kueppers 5 , M. Massironi 3 , R.Moissl 6 , H. Sierks 6 , N. Thomas 7 , C. Tubiana 6 , J. Vincent 6 , OSIRIS Team1 University of Maryland, 2 Laboratoire d'Astrophysique de Marseille, Universite de provence & CNRS, France, 3 University of Padova, Italy, 4 University ofBraunschweig, Germany, 5 ESA European Space Astronomy Centre, Spain, 6 Max-Planck-Instut for Solar System Research, Germany, 7 University of Bern,Switzerland.Presentaon Time: 10/6/2010 4:14 PM - 4:16 PMLocaon: Exhibit HallAbstract.Abstract: The Rosea spacecra of the European Space Agency performed successfully its second flyby of an asteroid on July 10 2010 on its way to itsfinal target comet 67p/Churyumov-Gerasimenko. Main belt asteroid (21) Lutea has been observed by the OSIRIS experiment at a distance of 3160 km. The bestresoluon of the images is about 59 meters per pixel, numerous geological features can be disnguished at this scale. We report on here the physicalcharacteriscs and properes of the craters of the largest (100km in diameter) asteroid ever observed in-situ. The values of the diameter and the depth of thecraters are essenal to determine the age of the surface based on crater counng and the evoluon of the surface. Preliminary observaons already aest for ahighly impacted surface with very large craters. Displacement of regolith is seen on the surface and especially in the walls of craters. The properes of thecraters will help understand the history and evoluon of this large scale and possible primordial body.39.04: Asteroidal Polarimetry, As Compared To Cometary Polarimetry; The Case Of 21 LuteaAuthor Block: A. Ch. Levasseur-Regourd 1 , E. Hadamcik 11 Univ. Paris (UPM C), France.Presentaon Time: 10/6/2010 4:16 PM - 4:18 PMLocaon: Exhibit HallAbstract: Polarimetric measurements provide clues to the classificaon of solar system objects and to their local properes, through experimental andnumerical simulaons. Asteroidal polarimetry originates in solar light scaered by an irregular surface, as opposed to cometary polarimetry that comes fromscaering by a low-density dust cloud. In both cases, polarimetric phase curves are somehow comparable, with key parameters such as the minimum inpolarizaon, the inversion angle, the maximum in polarizaon, and their wavelength dependence. Differences between observaons obtained at similar phaseangles and wavelengths may be aributed to local changes, e.g. variagaon of the surface revealed by the rotaon for asteroidal polarimetry and existence ofhalos and jet features with different dust parcles for cometary polarimetry.New observaons of 21 Lutea have been recently obtained in three colors and interpreted through laboratory simulaons (1); they will be compared with otherobservaons (2) and discussed in relaon with the surface images obtained during the Rosea flyby on 10 July 2010. Also, conclusions about the properes ofdust in the coma of 67P/Churyumov-Gerasimenko, the rendezvous target of the Rosea mission, as inferred from polarimetric observaons, will be summarized(3,4).Support from CNES is acknowledged.(1) Hadamcik et al., ELS XII (K. Muinonen et al. eds., Helsinki University Print), 70-73, 2010(2) Belskaya et al., A&A, 515, A29, 2010(3) Levasseur-Regourd et al., IAU Symposium 263, 259-262, 2010(4) Hadamcik et al., A&A, in press, 2010

39.05: Radiave Transfer Simulaons of Earth Spectra as Registered by ROSETTA/VIRTISAuthor Block: Jane Hurley 1 , P. Irwin 1 , A. Adriani 2 , M. Moriconi 2 , F. Oliva 2 , A. Coradini 21 University of Oxford, United Kingdom, 2 Istuto di Fisica dello Spazio Interplanetario, Italy.Presentaon Time: 10/6/2010 4:18 PM - 4:20 PMLocaon: Exhibit HallAbstract: Rosea, part of ESA's Horizon 2000 programme, will orbit and land on the comet 67P/Churyumov-Gerasimenko in May 2014. However, launched inMarch 2004, its trajectory has thus far muchly consisted of a series of planetary fly-bys and gravitaonal assists using Mars (2007) and Earth (March 2005, 2007and 2009). During these close fly-bys Rosea captured measurements of these planets - and of parcular interest are those registed by the Visual InfraredThermal Imaging Spectrometer VIRTIS of Earth, which were taken to help calibrate VIRTIS.Rosea/VIRTIS measures at high spectral resoluon from 0.25 - 5.0 microns, a spectral range which has been well studied by Earth observing instruments such asMeteosat Second Generaon Spinning Enhanced Visible and Infrared Imager (MSG/SEVIRI) and the Advanced Along-Track Scanning Radiometer (AATSR). Earthobserving instruments, whilst having superior spao-temporal coverage to the data provided during the Rosea/VIRTIS fly-bys, are typically constrained tomeasuring in only a few spectral channels. Hence, Rosea/VIRTIS should yield more detailed spectral informaon than these instruments - and is a goodcandidate for intercomparison studies.To this end, the radiave transfer soware NEMESIS (Irwin et al., 2009) is employed for the first me on Earth simulaons, having been used extensively for otherbodies such as Venus, Mars, Jupiter, Saturn, Neptune, Uranus and Titan. This work compares Rosea/VIRTIS measurements with NEMESIS-simulated spectra,concentrang on quanfying the ability of NEMESIS to reproduce spectral features associated with different surface topographies (such as ocean, desert andvegetaon) in combinaon with clear and cloudy atmospheric states. Preliminary esmaons of temperature and trace-species concentraons and distribuonsare presented as sample products.39.06: Phase Angle-induced Photometric And Spectral Effects On Vesta: Implicaons For The Dawn MissionAuthor Block: Vishnu Reddy 1 , A. Nathues 2 , K. A. Archer 3 , J. A. Sanchez 2 , M. J. Gaffey 1 , H. Sierks 2 , R. A. Archer 31 Univ. of North Dakota, 2 Max-Planck Instute for Solar System Research, Germany, 3 Ironwood Remote Observatory.Presentaon Time: 10/6/2010 4:20 PM - 4:22 PMLocaon: Exhibit HallAbstract: 4 Vesta is the largest basalc asteroid that remains mostly intact today and can be considered as a model for the early stages of planetarydifferenaon. The NASA DAWN mission is currently on its way to Vesta and is expected to rendezvous in July 2011 for a one year orbital characterizaonmission. Phase angle-induced spectral effects impact the band depth of an absorpon feature, the overall spectral slope and photometric calibraon. Gaffey et al.(1981), Gradie and Veverka (1986), Reddy et al. (2005) and Nathues (2000 and 2010) have proven these spectral effects on laboratory and telescopicobservaons. We have obtained rotaonally resolved near-IR (0.7-2.5 µm) spectra of Vesta in four different phase angle intervals (5-25°) using the SpeXinstrument on NASA IRTF. Simultaneously, we obtained photometric lightcurves of Vesta through the DAWN FC filter set using a small telescope at IronwoodRemote Observatory over ten nights covering a phase angle range of 3.9-24.4°. Using these two data sets we intend to constrain phase angle induced spectraleffects, and photometric phase coefficients that would be helpful in calibrang early DAWN FC and VIR data. Preliminary results from this effort will be presentedat the meeng. VR’s research was supported by NASA NEOO Program Grants NG04GI17G and NASA PGG Program grant NNX07AL29G. Porons of this work weresupported by PAST grant NNG05GF90G.39.07: Constraining Thermophysical Models of Vesta with DawnAuthor Block: Mark V. Sykes 1 , P. Tricarico 1 , J. Li 11 Planetary Science Instute.Presentaon Time: 10/6/2010 4:22 PM - 4:24 PMLocaon: Exhibit HallAbstract.Abstract: The Dawn mission will be entering orbit about Vesta in July 2011, providing new insights into one of perhaps two surviving protoplanetarybodies in the asteroid belt. Vesta is differenated and sll possesses its basalc crust. A giant impact excavated a large crater covering its modern south pole,forming a large family of asteroids and a source of the HED meteorites on Earth. Dawn's Visible-Infrared mapping spectrometer (VIR) is provided by the ItalianSpace Agency (ASI INAF) and will map the surface of Vesta from 0.25 to 5 microns. Vesta's surface will be sufficiently warm in its subsolar region that thereshould be measurable thermal emission at the long-wavelength end of VIR's sensivity, allowing surface thermophysical properes at central and southernlatudes to be constrained, disnguishing between rocky and dusty surfaces with good spaal resoluon.39.08: Formaon of the Giant Impact Crater on Asteroid VestaAuthor Block: Marn Jutzi 1 , E. Asphaug 11 UCSC.Presentaon Time: 10/6/2010 4:24 PM - 4:26 PMLocaon: Exhibit HallAbstract: Vesta is the second or third most massive asteroid, and the most terrestrial. A year from now Vesta will be orbited by NASA's Dawn mission. Here wenumerically model the impact event that blasted off its southern hemisphere to help establish the geologic seng.We use a smoothed parcle hydrodynamics (SPH) code to model the impact event. Recently this impact code was extended to include a model adapted for porousmaterials. We use a newly implemented model of dense granular flow to simulate the granular post-impact regolith. Central gravity is used to model gravity as anexternal force; this speeds up the calculaon dramacally compared to a self-gravity approach, allowing for millions of parcles, and is appropriate for this classof impact, where the target remains mostly intact throughout the collision.We assume a completely differenated target of D = 540 km diameter with a ducle iron core of Dc = 240 km. We perform impact simulaons with no inialrotaon and also with rotang targets (rotaon period P = 5.3 h). The crater dimension and central peak structure produced in our simulaons are in a goodoverall agreement with the Hubble-based topography modeling. Our simulaons using a rotang target indicate that an impact of this magnitude, on a planetthat spins this rapidly (every ~ 5 hr), exposes many strata, and leaves variably-shaped and abruptly-terminated ejecta deposional sequences that may bemistaken for other geologic forms.39.09: Asteroid Age Distribuons determined by Space Weathering and Collisional Evoluon ModelsAuthor Block: Robert Jedicke 1 , M. Willman 11 Instute for Astronomy.Presentaon Time: 10/6/2010 4:26 PM - 4:28 PMLocaon: Exhibit HallAbstract.Abstract: We provide evidence of consistency between asteroid ages determined from their dynamical evoluon and their color evoluon due to space

weathering. The dynamical age of an asteroid's surface is esmated as the me since its last catastrophic disrupon event which is a funcon of the object'sdiameter. The age of an S-complex asteroid's surface may also be determined from its color using a space weathering model. We used a sample of 95 S-complexasteroids from SMASS and obtained their absolute magnitudes and u,g,r,i,z filter magnitudes from SDSS. The absolute magnitudes yield a size-derived agedistribuon. The u,g,r,i,z filter magnitudes lead to the principal component color which yields a color-derived age distribuon by inverng our color-agerelaonship, an enhanced version of the `dual tau' space weathering model of Willman et al. 2010. We fit the size-age distribuon to an 'enhanced dual tau'model and found characterisc weathering and gardening mes of 2050+/-80 Myr and 4400+700-500 Myr respecvely. The fit also suggests an inial principalcomponent color of -0.05+/-0.01 for fresh asteroid surface with a maximum possible change of the probable color due to weathering of dPC1 = 1.34+/-0.04. Ourpredicted color of fresh asteroid surface matches the color of fresh ordinary chondric surface of PC1 = 0.17+/-0.39.39.10: Using The Youngest Asteroid Clusters To Constrain The Space Weathering And Gardening Rate On S-complex AsteroidsAuthor Block: Mark Willman 1 , R. Jedicke 1 , N. Moskovitz 2 , D. Nesvorny 3 , D. Vokrouhlicky 4 , T. Mothé-Diniz 51 Univ. Of Hawaii, 2 Department of Terrestrial Magnesm, 3 Dept. of Space Studies, SwRI, 4 IoA, Charles University, Czech Republic, 5 UFRJ / Observatorio doValongo, Brazil.Presentaon Time: 10/6/2010 4:28 PM - 4:30 PMLocaon: Exhibit HallAbstract: We extended our earlier work on space weathering of the youngest S-complex asteroid families to include results from asteroid clusters with ages≤10 6 years and to newly idenfied asteroid pairs with ages ≤5×10 5 years. We idenfied three S-complex asteroid clusters amongst the set of clusters with ages inthe range 10 5-6 years---(1270)Datura, (21509)Lucascavin and (16598)1992YC2. Their average color agrees with the color predicted by the space weatheringmodel. SDSS 5-filter photometry of members of the very young asteroid pairs with ages ≤10 5 years was used to determine their taxonomic classificaon. Theirtypes are consistent with the background populaon near each object. The average color of the S-complex pairs is PC 1 =0.49±0.03, over 5σ redder than predicted.This may indicate that the most likely pair formaon mechanism is a gentle separaon due to YORP spin-up leaving much of the aged and reddened surfaceundisturbed. If so then our color measurement allows us to set an upper limit of ~0.64 on the fracon of surface disturbed in the separaon process. Using preexisngcolor data and our new results for the youngest S-complex asteroid clusters we have extended our space weather model to explicitly include the effectsof regolith gardening and fit separate weathering and gardening characterisc mescales of τ w =960±160My and τ g =2000±290My respecvely. The first principalcomponent color for fresh S-complex material is PC 1 =0.37±0.01 while the maximum amount of local reddening is Δ PC 1 =0.33±0.06. Our first-ever determinaon ofthe gardening me is in stark contrast to our calculated gardening me of τ g ~270My based on main belt impact rates and reasonable assumpons about craterand ejecta blanket sizes. A possible resoluon for the discrepancy is through a `honeycomb' mechanism in which the surface regolith structure absorbs smallimpactors without producing significant ejecta. This mechanism could also account for the paucity of small craters on (433)Eros.39.11: Mining The Sdss-moc Database For Main-belt Asteroid Solar Phase Behavior.Author Block: Thien-Tin Truong 1 , M. D. Hicks 21 California State University - LA, 2 JPL/Caltech.Presentaon Time: 10/6/2010 4:30 PM - 4:32 PMLocaon: Exhibit HallAbstract: The 4th Release of the Sloan Digital Sky Survey Moving Object Catalog (SDSS-MOC) contains 471569 moving object detecons from 519 observingruns obtained up to March 2007. Of these, 220101 observaons were linked with 104449 known small bodies, with 2150 asteroids sampled at least 10 mes. It isour goal to mine this database in order to extract solar phase curve informaon for a large number of main-belt asteroids of different dynamical and taxonomicclasses. We found that a simple linear phase curve fit allowed us to reject data contaminated by intrinsic rotaonal lightcurves and other effects. As expected, arunning mean of solar phase coefficient is strongly correlated with orbital elements, with the inner main-belt dominated by bright S-type asteroids andtransioning to darker C and D-type asteroids with steeper solar phase slopes.We shall fit the empirical H-G model to our 2150 mul-sampled asteroids and correlate these parameters with spectral type derived from the SDSS colors andposion within the asteroid belt. Our data should also allow us to constrain solar phase reddening for a variety of taxonomic classes. We shall discuss errorsinduced by the standard "g=0.15" assumpon made in absolute magnitude determinaon, which may slightly affect number-size distribuon models.39.12: Applicaon of the AutoClass Arficial Intelligence Program to Asteroidal DataAuthor Block: Julie Ziffer 1 , M. Walker 1 , H. Campins 2 , Y. Fernandez 2 , T. Harvell 1 , M. Reulliard 11 University of Southern Maine, 2 University of Central Florida.Presentaon Time: 10/6/2010 4:32 PM - 4:34 PMLocaon: Exhibit HallAbstract: As our digital databases grow, datasets become less tractable and invesgang alternave analysis techniques such as arficial intelligencealgorithms becomes more important. One such program, AutoClass, which was developed by NASA’s Arficial Intelligence Branch, uses Bayesian classificaontheory to automacally choose the most probable classificaon distribuon to describe a dataset. To invesgate its usefulness to the Planetary community, wetested its ability to reproduce the taxonomic classes as defined by Tholen and Barucci (1989). We started our evaluaon by entering all Tholen idenfied C, S, or Xtype Eight Color Asteroid Survey asteroids with a color difference error of less than +/- 0.05 magnitudes. Of these 406 asteroids, AutoClass was able to firmlyclassify 346 (85%), idenfying the remaining 60 asteroids as belonging to more than one class. Of the 346 asteroids that AutoClass classified, all but 3 (

determinaon in other fields. These methods of period determinaon are explored for both synthec and less than ideal real data sets, comparing the resultswith the published values. These techniques can give us a wider range of tools to extract addional informaon from noisy or poorly sampled light curves.39.14: A Proposed Standard For Reporng Asteroid Lightcurve DataAuthor Block: Robert D. Stephens 1 , B. D. Warner 2 , A. W. Harris 31 Goat Mountain Astronomical Research Staon/MoreData!, 2 Palmer Divide Observatory/MoreData!, 3 MoreData!.Presentaon Time: 10/6/2010 4:36 PM - 4:38 PMLocaon: Exhibit HallAbstract: Unlike astrometric data on asteroids, there is no generally accepted central repository for raw asteroid lightcurve data. There are several sites thataccept such data, but each one has its own formang and minimum data requirements, making it a me-consuming task to prepare raw data for submission.This is especially true for the “backyard astronomers”, the group that has contributed the vast majority of asteroid lightcurves in the last 5-7 years. As a first steptowards correcng this problem and making asteroid lightcurve data “universal”, we propose a standard reporng format for asteroid lightcurve observaons,much as the Minor Planet Center uses for astrometric observaons. Like the FITS standard, metadata and data would be defined by a set of mandatorykeyword/value pairs to assure the data’s usability along with oponal pairs to further describe the observaons and data. This would allow someone to write asingle parsing program to extract data from any number of observers to be used as he needs. We will establish a central upload point for lightcurve observaons.Those data submied using the new format will be immediately parsed into a set of database tables and then regularly converted as to needed to be used on along-term archiving service, e.g., Strasbourg. Eventually, we hope that the Minor Planet Center or other enty might take over the enre system: standard, uploadpoint, and data. Archival data and those not in the standard format could sll be uploaded to our intermediate site. We will enlist volunteers to convert the datawhenever possible and make it part of the archive. Those data that cannot be converted will remain available “as-is” for a researcher to do with them as he can.39.15: New Asteroid Models Based on Combined Dense and Sparse PhotometryAuthor Block: Josef Hanuš 1 , J. Durech 21 Astronomical Instute of Charles University, Czech Republic, 2 Astronomical Instute of Charles University, Prague, Czech Republic.Presentaon Time: 10/6/2010 4:38 PM - 4:40 PMLocaon: Exhibit HallAbstract: For thousands of asteroids we invesgated several ten thousands of sparse photometric data from astrometric projects. These data are available onAstDyS server (Asteroids -- Dynamic Site, hp://hamilton.dm.unipi.it). We picked 7 astrometric surveys and used their calibrated photometry in lightcurveinversion method for determinaon of asteroid's convex shapes and rotaonal states. We present nearly 100 new asteroid models derived from combined denseand sparse data sets, where sparse photometry is taken from AstDyS server and dense lightcurves are from the Uppsala Asteroid Photometric Catalogue (UAPC)and from several individual observers.39.16: Asteroidal Occultaon Silhouees Combined with Asteroid Models Derived by Lightcurve InversionAuthor Block: Josef Durech 1 , M. Kaasalainen 2 , D. Herald 3 , D. Dunham 4 , B. Timerson 4 , J. Hanus 1 , E. Frappa 5 , J. Talbot 6 , T. Hayamizu 7 , B. D. Warner 8 , F. Pilcher 9 , A.Galad 101 Charles University in Prague, Czech Republic, 2 Tampere University of Technology, Finland, 3 IOTA, Australia, 4 IOTA, 5 Asteroid Occultaon Observers in Europe,France, 6 Royal Astronomical Society of New Zeland, New Zealand, 7 Japan Occultaon Informaon Network, Japan, 8 Palmer Divide Observatory, 9 Organ MesaObservatory, 10 Modra Observatory, Slovakia.Presentaon Time: 10/6/2010 4:40 PM - 4:42 PMLocaon: Exhibit HallAbstract.Abstract: Asteroid sizes can be directly measured by observing occultaons of stars by asteroids. When there are enough observaons across the pathof the shadow, the asteroid's projected silhouee can be reconstructed. We present our analysis of occultaon data we combined with convex asteroid models.Asteroid shape models derived from photometry by the lightcurve inversion method enabled us to compute the orientaon of an asteroid for the me ofoccultaon. By scaling the shape models to fit the occultaon chords, we determined the asteroid sizes with a relave accuracy of typically 10%. We combinedshape and spin state models of 44 asteroids (14 of them were new or updated models) with the available occultaon data to derive asteroid effecve diameters.In many cases, occultaons allowed us to reject one of two possible pole soluons that were derived from photometry. Our results demonstrate the possibility ofderiving unique physical models of asteroids by combining shape models obtained from lightcurve inversion with occultaon mings.39.17: Albedos of Small Hilda AsteroidsAuthor Block: Erin L. Ryan 1 , C. E. Woodward 11 Univ. of Minnesota.Presentaon Time: 10/6/2010 4:42 PM - 4:44 PMLocaon: Exhibit HallAbstract: We present albedo results for ~70 small Hilda dynamical family members detected by the Spitzer Space Telescope in mulple archival programs. ThisSpitzer data samples Hildas with diameters between 2 and 11 kilometers. Our preliminary analysis reveals that the mean geometric albedo for this sample is p v =0.05, matching the mean albedo derived for large (20 to 160 km) Hilda asteroids observed by IRAS (Ryan and Woodward 2010). This mean albedo is significantlydarker than the mean albedo of asteroids in the outer main belt (2.8 AU < a < 3.5 AU), possibly suggesng that these asteroids did not originate from the outermain belt . This is in direct conflict with some dynamical models which suggest that the HIldas are field asteroids trapped from an inward migraon of Jupiter(Franklin et al. 2004), and may provide addional observaon support for delivery of dark Kuiper Belt contaminants to the inner solar system as per the NiceModel (Levison et al. 2009).39.18: Asteroid 65 Cybele: Detecon Of Small Silicate Grains, Water-Ice And OrganicsAuthor Block: Zoe Landsman 1 , J. Licandro 2 , H. Campins 1 , M. Kelley 3 , K. Hargrove 1 , N. Pinilla-Alonso 4 , D. Cruikshank 4 , A. S. Rivkin 5 , J. Emery 61 Physics Department, University of Central Florida, 2 Instuto de Astrofisica de Canarias, Spain, 3 Department of Astronomy, University of Maryland, 4 NASA AmesResearch Center, 5 Johns Hopkins University Applied Physics Laboratory, 6 Earth and Planetary Science Department, University of Tennessee.Presentaon Time: 10/6/2010 4:44 PM - 4:46 PMLocaon: Exhibit HallAbstract: We have carried out a spectroscopic study of asteroid 65 Cybele in the 2 - 4 μm and 5 - 14 μm regions, using NASA’s IRTF and Spitzer SpaceTelescope, respecvely. We compare these spectra with those of Trojan asteroids and asteroid 24 Themis. Our target is the largest member of the Cybelepopulaon; these asteroids represent a transion group between primive inner-main belt asteroids and Trojans, and may provide clues to the origin of theasteroid belt and the solar system.Our 2 - 4 μm spectrum shows a clear absorpon band centered at 3.1 μm, similar to that in the spectrum of 24 Themis (Campins et al. 2010, Rivkin & Emery

Our 2 - 4 μm spectrum shows a clear absorpon band centered at 3.1 μm, similar to that in the spectrum of 24 Themis (Campins et al. 2010, Rivkin & Emery2010), which can be modeled using water-ice. Absorpon bands in 65 Cybele’s 3.2 - 3.6 μm region also suggest the presence of complex organic solids. Nohydrated silicates are detected. We fit the 5 - 14 μm connuum using the NEATM (Harris 1998) and derived a diameter D = 290 ± 5 km (consistent with Müllerand Bloemmaert 2004), beaming parameter η = 0.967 ± 0.014, and albedo p V = 0.05 ± 0.01. Once the connuum has been divided out, the 5 - 14 μm emissivityspectrum clearly exhibits an emission plateau at about 9 - 12 μm with a spectral contrast of about 5%. A similar feature is seen in the spectra of Trojan asteroidsand may be due to fine-grained silicates imbedded in a transparent matrix, or to a very under-dense surface structure (Emery et al. 2006). We conclude that 65Cybele is covered by fine anhydrous silicate grains, with a small amount of water-ice and complex organic solids. This is similar to comets where non-equilibriumphases coexist, e.g. water-ice and anhydrous silicates; thus we conclude that this is a very primive object.39.19: (379) Huenna’s Satellite: A Chip Off The BlockAuthor Block: Francesca E. DeMeo 1 , B. Carry 1 , F. Marchis 2 , M. Birlan 3 , R. P. Binzel 4 , S. J. Bus 5 , P. Descamps 3 , A. Nedelcu 3 , H. Bouy 61 Observatoire De Paris, France, 2 University of California at Berkeley, 3 IM CCE, France, 4 M IT, 5 Instute for Astronomy, 6 ESAC, Spain.Presentaon Time: 10/6/2010 4:46 PM - 4:48 PMLocaon: Exhibit HallAbstract:We present near-infrared spectral measurements of Themis family asteroid (379) Huenna (D98km) and its 6km satellite using SpeX on the NASAIRTF. The companion was farther than 1.5" from the primary at the me of observaons and was 5 magnitudes dimmer. We describe a method for separang andextracng the signal of a companion asteroid when the signal is not enrely resolved from the primary. The spectra of (379) Huenna and its secondary are verysimilar, suggesng the secondary is either a fragment of the primary from a past collision or is a fragment from the collision that created the Themis family.39.20: A Search for OH Outgassing from Icy Asteroid (24) ThemisAuthor Block: Amy J. Lovell 1 , Y. R. Fernández 2 , H. Campins 2 , D. G. Schleicher 31 Agnes Sco College, 2 University of Central Florida, 3 Lowell Observatory.Presentaon Time: 10/6/2010 4:48 PM - 4:50 PMLocaon: Exhibit HallAbstract: (24) Themis is a Main-Belt asteroid and the largest member of a family that includes at least two Main-Belt Comets. Recent reports have announcedthe existence of water ice on Themis's surface (Rivkin and Emery 2010, Campins et al. 2010). This suggests that Themis may itself possess a faint gas coma,where sublimated water would photo-dissociate into OH. We report here radio and UV observaonal searches for OH emission around Themis, made using theNaonal Radio Astronomy Observatory (NRAO) 100-m Green Bank Telescope (GBT) and with the Lowell Observatory 1.1-m Hall Telescope. Despite the widecoverage of ice on Themis's surface, the asteroid did not appear acve, and we did not detect the emission in either wavelength regime. The most sensive 3σupper-limit suggests Themis has a (water) gas producon rate less than ~1x10 28 molecules/s. This result can constrain the physical state, temperature, anddurability of Themis's ice.39.21: The Spin Vector of (832) KarinAuthor Block: Stephen M. Slivan 1 , L. A. Molnar 21 Wellesley College, 2 Calvin College.Presentaon Time: 10/6/2010 4:50 PM - 4:52 PMLocaon: Exhibit HallAbstract: We observed rotaon lightcurves of Koronis family and Karin cluster member (832) Karin during its four consecuve apparions in 2006-2009, andcombined the new observaons with previously published lightcurves to determine its spin vector orientaon and preliminary model shape. Karin is a prograderotator with a period of 18.352 h, spin obliquity near 41°, and pole eclipc longitude near either 51° or 228°. Although the two ambiguous pole soluons are nearthe clustered pole soluons of four Koronis family members whose spins are thought to be trapped in a spin-orbit resonance (Vokrouhlický et al., 2003), Karindoes not seem to be trapped in the resonance; this is consistent with the expectaon that the 6 My age of Karin (Nesvorný et al., 2002) is too young for YORPtorques to have modified its spin since its formaon. The spin vector and shape results for Karin will constrain family formaon models that include spinproperes, and we discuss the Karin results in the context of the other members of the Karin cluster, the Karin parent body, and the parent body's siblings in theKoronis family.39.22: Taxonomic Classificaon of Asteroids via Broadband Near-Infrared PhotometryAuthor Block: Eric Petersen 1 , C. Thomas 2 , D. Trilling 2 , J. Emery 3 , M. Delbo 4 , M. Mueller 4 , R. Dave 31 Simon Fraser University, Canada, 2 Northern Arizona University, 3 University of Tennessee, 4 Observatoire de la Cote d'Azur, France.Presentaon Time: 10/6/2010 4:52 PM - 4:54 PMLocaon: Exhibit HallAbstract.Abstract: For faint asteroids, it is not praccal to obtain near-infrared spectra. However, it may be possible to use broadband photometry to inferspectral classificaons and study composion. As a test of this, we processed SpeX near-infrared asteroid spectral data to simulate colors that would be obtainedthrough photometry. We have found that certain color combinaons (for example, z-J and H-K) can prove diagnosc in asteroid spectral classificaon. To this end,we have defined certain color-color regions that make it possible to define an asteroid as being a likely candidate for a certain spectral type. The regionsidenfied define V and D type asteroids, the S-Q group, and the C-X group. Knowledge and use of these regions will significantly increase the usefulness of NIRbroadband photometry in the study of near earth objects and allow characterizaon of asteroids that are too faint to be observed spectroscopically. Work on thisproject is made possible through the NSF REU program at Northern Arizona University and by funding from the Spitzer Space Telescope/JPL/Caltech.39.23: Mid-IR Spectroscopy Of Main-belt Asteroids From MIRSI At The IRTFAuthor Block: Lucy F. Lim 1 , J. P. Emery 2 , A. S. Rivkin 3 , J. L. Hora 4 , M. Kassis 51 NASA / GSFC, 2 University of Tennessee, 3 JHU/APL, 4 Harvard-Smithsonian Center for Astrophysics, 5 Keck Observatory.Presentaon Time: 10/6/2010 4:54 PM - 4:56 PMLocaon: Exhibit HallAbstract: Thermal emission spectra (8-13 microns) of 19 Fortuna, 4 Vesta, 1 Ceres, and several other large main-belt asteroids were measured at IRTF in 2009and 2010. The new "MIRSI 2" (2008) interface to the Mid-Infrared Spectrometer and Imager ("MIRSI") instrument (Kassis et al. 2008, PASP 120) was used toacquire these data. The thermal emission spectra of these asteroids will be presented together with evaluaons of the S/N achievable in low-resoluonspectroscopy with MIRSI at IRTF. Techniques for addressing instrumental issues parcular to MIRSI (Kassis et al. 2008; Sako et al. 2003, PASP 115) in the context

of spectroscopic observaons will also be discussed.39.24: Rotaon Properes of Three Jovian Trojan AsteroidsAuthor Block: Susan M. Lederer 1 , L. M. French 2 , D. A. Rohl 2 , K. Friedrich 3 , T. Hufford 4 , F. Luzia Jasmim 5 , A. Khairunnisa 6 , J. Šilha 71 NASA JSC/Cal State Univ SB, 2 Illinois Wesleyan Univ., 3 Universität Bonn, Germany, 4 Loyola Univ., Univ. of Georgia, 5 Observatório Nacional, Brazil, 6 InstutTeknologi Bandung, Indonesia, 7 Comenius University, Slovakia.Presentaon Time: 10/6/2010 4:56 PM - 4:58 PMLocaon: Exhibit HallAbstract: The spin properes of the Jovian Trojan asteroids have not been extensively studied due to their distance from the Sun and their low albedos. Wepresent a progress report on a program to determine well-sampled light curves for the Jovian Trojans. Rotaon data will be presented for 884 Priamus, 448988AK, and 4834 Thoas.Data were obtained in October 2009 and July 2010 using the SMARTS 1.0-meter and 0.9-meter telescopes, respecvely, at Cerro Tololo Interamerican Observatorynear La Serena, Chile. Images were processed and measured with IRAF, and periods determined using the Canopus soware package.This research was supported by Corell College Science Award grants from the Research Corporaon (LMF and DAR; SML) and support from the Lunar andPlanetary Instute (SML).39.25: Updated Masses and Densies of Asteroids from Recent Mars Orbiter Range DataAuthor Block: Eugene G. Fahnestock 1 , W. M. Folkner 1 , A. S. Konopliv 11 NASA Jet Propulsion Laboratory.Presentaon Time: 10/6/2010 4:58 PM - 5:00 PMLocaon: Exhibit HallAbstract: We present new soluons for the masses of asteroids through new soluons for the Mars ephemeris determined at JPL using recent tracking datafrom spacecra orbing Mars. This work builds upon the previous soluons for the Mars ephemeris and asteroid masses presented in (Konopliv et al., 2010,Icarus, in press), by incorporang about one addional year of range data from each of MRO, Mars Odyssey, and Mars Express spanning from July 2009 throughJune 2010. Doppler data also provide each spacecra's orbit with respect to Mars along with the Mars global gravity soluon of (Konopliv et al., 2010). This,added to the tracking staon to spacecra range, provides the distance between Earth and Mars centers to one to two meter accuracy. Each asteroid's mass isesmated along with Earth and Mars orbits, while the solar mass parameter, solar J2, Earth-Moon mass rao, Sun's mass loss rate, and PPN parameters are alsoesmated concurrently. The studied asteroids are selected as those which most perturb the orbit of Mars on a mescale matching the span of all data used. Alarger set of other perturbing asteroids have their orbits and masses used as consider parameters. A sll larger set of perturbing asteroids have their orbits fixedand assumed perfectly known, but masses computed from IRAS nominal diameters and (also esmated) average bulk densies for the three main taxonomicclasses. We also use IRAS and MSX nominal diameters and all more recent asteroid photometry observaons we could obtain for the asteroids to update theirvolumes, which together with the new masses constrain their bulk densies and likely macroporosies.39.26: Spitzer/IRS Observaons Of Mulple Main-Belt And Binary Near-Earth AsteroidsAuthor Block: J. Emilio Enriquez 1 , F. Marchis 2 , J. P. Emery 3 , S. Im 41 SETI Instute, 2 UC-Berkeley/SETI Instute, 3 U. of Tennessee, 4 NASA - Ames Research Center / SETI Instute.Presentaon Time: 10/6/2010 5:00 PM - 5:02 PMLocaon: Exhibit HallAbstract: Since the discovery of Ida’s companion in 1993, 195 companions of asteroids have been discovered. To understand the formaon process of theseinteresng bodies, their physical properes such as their bulk density, size, shape, and surface roughness need to be determined.During the Spitzer Cycle-4, we obtained IRS thermal emission spectra (5-42 um) of 23 known binary systems. The majority of asteroids are from the main-belt(16), while the rest are NEOs (7). Aer extracng the thermal spectra, we used a modified Standard Thermal Model (STM) to calculate their equivalent diameter(from 0.8 km to 237 km), their albedo (from 0.04 for C-type to 0.394 for a V-type) and their beaming factor related to the surface roughness and thermal inera.We derive their emissivity spectra, which is useful to detect silicate features.Combining these measurements with 3D-models of these mulple asteroid systems obtained by lightcurve inversion, we should be able to derive an accurateesmate of their bulk-density and contrast them with their taxonomic classes. Preliminary studies by Marchis et al. (2008) 1 , suggested a relaonship betweenbulk density and the taxonomic class of asteroids, which varies from 0.9 g/cc for C-complex to 2.4 g/cc for S-complex asteroids.The Naonal Science Foundaon supported this research under award number AAG-0807468. It was conducted with the Spitzer space telescope, which isoperated by JPL under a contract with NASA.1Marchis et al. , 2008, “Mid-infrared Spectra of Binary Asteroids With Spitzer/IRS”, 40th DPS Meeng, Bullen of the American Astronomical Society, 40, 50839.27: Exploring the Enigma of 4709 EnnomosAuthor Block: Mark Reuillard 1 , T. Harvell 1 , J. Ziffer 1 , Y. Fernandez 2 , M. Walker 11 University of Southern Maine, 2 University of Central Florida.Presentaon Time: 10/6/2010 5:02 PM - 5:04 PMLocaon: Exhibit HallAbstract: Large Trojan asteroids are characteriscally dark, having albedos that are typically in the range 0.03 to 0.08 (Fernandez et al., 2003). One notableexcepon is 4709 Ennomos with an unusually high measured albedo of about 0.13 (Fernandez et al., 2003). This corresponds to an albedo of more than 10standard deviaons above the mean of the group of 32 large Trojans sampled by Fernandez et al (2003). There are two main explanaons for the anomalousalbedo: Ennomos’s surface composion may truly be different from similarly-sized Trojans and be richer in more highly-reflecve species, or the assumpons thatgo into the modeling used to derive diameter and albedo are inapplicable to Ennomos because of unusual physical or thermal properes. For the first hypothesis,so far only upper limits to composional signatures have been found (e.g. Yang and Jewi 2007). In this work we address the second hypothesis. One plausibleexplanaon is that Ennomos’ rotaon period is sufficiently fast or its thermal inera is sufficiently high so as to preclude the use of a zero-thermal memorythermal model (Lebofsky and Spencer 1989, Harris 1998) i.e. the model actually used to calculate its albedo. An alternave explanaon is that shape ortopographic anomalies conspired to reduce the thermal emission, causing the model - which assumes a spherical body - to underesmate the diameter. Toaddress these issues, we obtained BVRI me-series CCD photometry of Ennomos with the University of Hawaii’s 88 inch telescope on February 8, 9, and 10, 2003.The goals were to determine Ennomos’ rotaon period, basic shape, and visible colors, and we will present these results. We will also discuss what the resultsimply about the nature of Ennomos’s surface.39.28: The Contribuon Of The Oblateness Of An Asteroid On The Orbital Evoluon Of Its SatellitesAuthor Block: Othon Cabo Winter 1 , L. G. Boldrin 1 , E. Vieira Neto 1 , R. Gomes 2

1 UNESP, Brazil, 2 Observatorio Nacional, Brazil.Presentaon Time: 10/6/2010 5:04 PM - 5:06 PMLocaon: Exhibit HallAbstract: About five years ago was discovered the first asteroid to have a pair of small satellites. That was 87 Sylvia with its satellites Romulus and Remus(Marchis et al. 2005). Nowadays a few more cases are known. A preliminary study of the long term dynamics of Romulus and Remus (Winter et al. 2009) showedthat their trajectories would be highly unstable if Sylvia had a symmetrically spherical gravitaonal potenal. However, Sylvia is highly oblate, J2=0.17.Consequently, the inclusion of J2 in the dynamics results in very stable trajectories for Romulus and Remus. That is mainly due to the fact that the orbital angularmomenta of the satellites increase significantly due to J2. In the present work we show the results of a study of the evoluon of the spin axis of the main asteroidand its effects on the orbital moon of the small satellites. In the dynamics of the spin is taken into account the perturbaon of the Sun and Jupiter. The orbitalplanes of the satellites follow the equatorial plane of the asteroid.Acknowledgements: This work has the support of FAPESP, CNPq and CAPES39.29: A Census of Asteroid Families Between the J5/2 and J7/3 ResonancesAuthor Block: Lawrence A. Molnar 1 , C. L. McKay 11 Calvin College.Presentaon Time: 10/6/2010 5:06 PM - 5:08 PMLocaon: Exhibit HallAbstract: Significant theorecal progress has been made in recent years in modeling the history of the main asteroid belt. In parcular, the size-frequencydistribuons of individual collisions (as a funcon of impact properes) and the collisional rate (as a funcon of target size) have been computed.In this work we test these results against observaons of asteroids between the J5/2 and J7/3 mean moon resonances. We select this parcular zone because1) the asteroid density is low enough that the extent and membership of all families may be determined unambiguously, 2) the boundary resonances isolate itfrom families in other zones, and 3) other resonances within the zone have had relavely lile effect on the orbits of its families.In parcular, we computed synthec proper elements for 16,111 mulopposion asteroids. We used proper a, e, i and absolute magnitude to idenfy membershipin 19 collisional families. For two of these_the Karin and Koronis clusters_we also used proper longitudes of node and perihelion. The absolute magnitude isimportant for excluding large interlopers when a Yarkovsky signature clearly idenfies them as such. For example, (293) Brasilia is probably not a member of thefamily previously idenfied as the Brasilia family. We corrected size-frequency distribuon (SFDs) using the local background rates. Finally, we inferred collisionalages (or limits) from evidence of Yarkovsky broadening of the distribuon in a.We will present and discuss the empirical collision rate funcon implied by our results and the SFDs of the families and of the background asteroids. We will alsopresent and discuss the average Sloan Digital Sky Survey colors for each family.This work was funded by a Kuiper endowment and a Calvin Research Fellowship.

Session Time: 10/7/2010 8:30 AM

Session Number: 41Session Title: Jovian Planets: SaturnSession Type: Oral41.01: A Strong High Altude Narrow Jet At Saturn’S Equator From Cassini/ISS ImagesAuthor Block: Enrique Garcia-Melendo 1 , A. Sánchez-Lavega 2 , J. Legarreta 2 , S. Pérez-Hoyos 2 , R. Hueso 21 Esteve Duran Observatory, Spain, 2 Universidad del País Vasco, Spain.Presentaon Time: 10/7/2010 8:30 AM - 8:40 AMLocaon: Ballroom BCAbstract: The intense equatorial eastward jets observed at cloud level in Jupiter and Saturn, represent a major challenge for geophysical fluid dynamics.Saturn’s equatorial jet is of parcular interest in view of its three dimensional structure, suspected large temporal variability, and related stratosphericsemiannual oscillaon. Here we report the discovery at the upper cloud level of an extremely narrow and strong jet centered in the middle of the broad equatorialjet. Previously published works on Saturn’s equatorial winds at cloud level provided only a paral coverage. Automac correlaon of brightness scans andmanually tracked cloud features, retrieved from images obtained by the Cassini Imaging Science Subsystem (ISS), show that the jet reaches 430 ms -1 with a peakspeed difference of 180 ms -1 relave to nearby latudes at 60 mbar and 390 ms -1 at depths > 500 mbar. Images were obtained in two filters: MT3, centred at the889nm strong methane absorpon band, and CB3 centred at the near infrared 939nm connuum, which are sensive to different altude levels at the upperclouds and hazes. Contrarily to what is observed in other latudes, its velocity increases with altude. Our findings helps to extend the view we have of theequatorial stratospheric dynamics of fast rotang planets beyond the best known terrestrial environment, and extract more general consequences of theinteracon between waves and mean flow. It remains to be known if this equatorial jet structure, now determined in detail in three dimensions, is permanent orvariable with the seasonal solar insolaon cycle, including the variable shadow cast by the rings. EGM, ASL, JL, SPH, and RH have been funded by the SpanishMICIIN AYA2009-10701 with FEDER support and ASL, JL, SPH, and RH by Grupos Gobierno Vasco IT-464-0741.02: Cassini ISS Analysis of Meandering Jets on Saturn: Ribbon and HexagonAuthor Block: Kunio M. Sayanagi 1 , G. D. Muro 2 , S. P. Ewald 1 , A. P. Ingersoll 11 California Instute of Technology, 2 University of California Santa Cruz / California Instute of Technology.Presentaon Time: 10/7/2010 8:40 AM - 8:50 AMLocaon: Ballroom BCAbstract: The jetstreams on Saturn at 47N and 77N planetographic latude are notable in exhibing wavy cloud morphologies that have been called the Ribbonand the Hexagon, respecvely. Recent laboratory and numerical experiments idenfied several disnct scenarios that can lead to meandering zonal jets. For theRibbon, the 3D numerical model of Sayanagi et al. (in print, JAS) predicts that the jet is in a dynamical regime where its path connuously shis over shortmescales. For the Hexagon, laboratory experiments by Barbosa Aguiar et al. (2010, Icarus) and 3D numerical simulaons by Morales-Juberias et al. (underreview, Icarus) demonstrate that a barotropically unstable zonal jet can equilibrate into a steady vortex street. The dominant wavenumber depends on jetparameters, and wavenumber 6 is a possible outcome. We also present a scenario, based on the shallow water equaons, in which a steady jet meanders arounda sharp potenal vorcity gradient without an accompanying vortex street. We test these theories against observaon. The Ribbon emerged from the ringshadows in mid-2007. Today, we find cloud morphologies substanally different from those of the Voyager era (Godfrey and Moore, 1986 Icarus), although the47N jet exhibits similar wave acvity. We use the temporal dynamics of the waves to test the predicons of Sayanagi et al. The Hexagon has been illuminated bysunlight since late 2008 and we have confirmed that its structure retains the characteriscs found by Voyager (Godfrey, 1988 Icarus) and Cassini VIMS (Baines etal., 2009 P&SS). We measure the vorcity field in the Hexagon region to determine whether the structure is consistent with a vortex street. We also compare thezonal wind profiles of the regions against past measurements.Our study is supported by the Cassini project.41.03: Saturn’s “String of Pearls” Aer Five Years: Sll There, Moving Backwards Faster in the Voyager SystemAuthor Block: Kevin H. Baines 1 , T. W. Momary 2 , L. N. Fletcher 3 , B. J. Bura 2 , R. H. Brown 4 , R. N. Clark 5 , P. D. Nicholson 61 SSEC, University of Wisconsin – Madison, 2 Jet Propulsion Laboratory, 3 Oxford University, United Kingdom, 4 University of Arizona, 5 U.S. Geological Survey,6 Cornell University.Presentaon Time: 10/7/2010 8:50 AM - 9:00 AMLocaon: Ballroom BCAbstract: Since July 2005, the Visual Infrared Mapping Spectrometer (VIMS) onboard the Cassini Orbiter has been following an enigmac feature centered at33.9 degrees (planetocentric ) north latude. Observed in detail on 14 occasions between July 2005 and July 2010, the feature is seen only in the 5-micronthermal window which probes large-parcle clouds down to the 4-bar level. This feature is comprised of a main cloud layer near 1.5-3 bar which has 21-25regularly spaced, near- uniformly-sized, circularly-shaped clearings which together span, on average, 94 degrees of longitude. In VIMS 5-micron imagery, whichobserves the warm glow of Saturn generated at depth, these regularly spaced and shaped clearings appear bright while the surrounding cloud, observed insilhouee, appears dark- hence the colloquial name “String of Pearls”. Each clearing is about 1 degree of longitude (900 km) wide, and is, on average over thefive-years period, 4.3 degrees of longitude from its neighbor. In latude, adjacent pearls are typically 0.4 degrees - or about 1 pearl radius - apart. At variousmes over the past five years of observaons, the longitudinal length has varied from 76 to 104 degrees and the mean separaon between clearings has variedfrom 3.6 to 5.0 degrees, while the mean latude of the structure has ranged from 32.9 to 34.8 degrees - or by 2 mean diameters of the pearls. The pearl structuremoves retrograde in the Voyager system (Desch and Kaiser, Geophys. Res. Le 8, 253-256, 1981) with an average speed over five years of 21.84 ± 0.02 m/s. Sincelate 2007, the mean latude increased from 34.0 ± 0.2 to 34.5 ± 0.2 deg as the retrograde speed increased from 21.73 ± 0.09 m/s to 22.02 ± 0.08 m/s, making itthe fastest moving retrograde feature observed by Cassini/VIMS in non-polar regions.41.04: Detecon of Visible Lightning on SaturnAuthor Block: Ulyana A. Dyudina 1 , A. P. Ingersoll 1 , S. P. Ewald 1 , C. C. Porco 2 , W. S. Kurth 3 , G. Fischer 4 , R. A. West 51 Caltech, 2 CICLOPS, Space Science Instute, 3 University of Iowa, 4 Austrian Academy of Sciences, Austria, 5 JPL.

Presentaon Time: 10/7/2010 9:00 AM - 9:10 AMLocaon: Ballroom BCAbstract: Unl now, evidence for lightning on Saturn has been indirect - through radio emissions and cloud morphology. Here we report the first visibledetecon of lightning (Dyudina et al., 2010), on the night side on August 17, 2009 at −36.4° ± 0.1° planetocentric latude and 10.6° ± 0.9° west longitude. Noother locaons produced lightning detectable by either imaging or radio. This is the same latude band on the planet that the imaging team has called `stormalley' for the last 6 years: i.e., where we observe all of the major storms that are believed to produce lightning because of the radio emissions and cloudmorphology. The lightning images are consistent with a single cloud flashing once per minute. The visible energy of a single flash is comparable to that on Earthand Jupiter, and ranges up to 1.7 X 10 9 Joules. The diameter of the lightning flashes is 200 km, which suggests the lightning is 125-250 km below cloud tops.This depth is above the base of the liquid H2O-NH3 cloud and may be either in the NH4SH cloud or in the H2O ice cloud. Saturn’s lower internal heat transportand likely 5-10 fold enrichment of water largely explain the lower occurrence rate of moist convecon on Saturn relave to Jupiter.Dyudina, U. A., A. P. Ingersoll, S. P. Ewald, C. C. Porco, G. Fischer, W. S. Kurth, and R. A. West (2010), Detecon of visible lightning on Saturn, Geophys. Res. Le.,37L0920541.05: Saturn's Very Axisymmetric Magnec Field: Implicaon for the Interior of the PlanetAuthor Block: Hao Cao 1 , C. T. Russell 1 , U. R. Christensen 2 , M. K. Dougherty 31 IGPP, UCLA, 2 Max Planck Instute for Solar System Research, Germany, 3 Imperial College, United Kingdom.Presentaon Time: 10/7/2010 9:10 AM - 9:20 AMLocaon: Ballroom BCAbstract: Saturn's intrinsic magnec field is very spin-axisymmetric as found by Pioneer 11 and confirmed by the Voyager 1 and 2 flybys. Since 2004, the Cassinispacecra has been providing connuous measurements of the magnec field from Saturn orbit. Orbits with high inclinaon and low altude provide a gooddataset for the study of the intrinsic magnec field of the planet. Our invesgaon shows no evidence for any detectable non-axisymmetric intrinsic magnecfield. The biggest possible dipole lt we can find is 0.06 degree, which is the noise level of the analysis. Our axisymmetric model for Saturn's intrinsic magnecfield is characterized by Schmidt-normalized spherical harmonic coefficients g11 = 21191nT, g20 = 1586nT, g30 = 2374nT. No significant degree 4 or 5 terms can bedetermined from the current data. Compared with the SPV model, which fits the measurements from Pioneer 11, Voyager 1 and 2 equally well, the secularvariaon is found to be an order of magnitude smaller than for similar terms of the Earth's field for degree 1 and 2. This implies no fast decay of the Saturn'sdipole moment, which is fundamentally different from the current secular variaon of the Earth's field.The extremely high degree of axisymmetry of Saturn's magnec field is challenging for dynamo theory. Our analysis of the magnec measurement from Cassinirequires a damping factor of 0.006 if the dipole lt in the dynamo region is 10 degrees. To meet this damping factor, the stable layer must has significantthickness, L, is greater than or equal to 4,000km. This thicker stable layer is also favored by the predicon of Saturn's observed dipole moment from scalingtheory. Numerical dynamo models with predicted damping factors are needed to determine possible limits to the degree of axisymmetrizaon by a conducnglayer.41.06: Propagaon of Gravity Waves in Saturn Stratosphere and Upper TroposphereAuthor Block: Kaa Matcheva 11 University of Florida.Presentaon Time: 10/7/2010 9:20 AM - 9:30 AMLocaon: Ballroom BCAbstract: Atmospheric gravity waves contribute to the overall mixing in a planetary atmosphere impacng the vercal and the horizontal transport of chemicalspecies. They have been studied as a potenal source of energy and momentum in the thermosphere of giant planets and are most likely responsible for theobserved small-scale layered structure of the lower ionosphere of Jupiter and Saturn.We focus on the filtering properes of Saturn's middle atmosphere (troposphere and stratosphere) as waves propagate from deep atmospheric layers to higheraltudes. The simulated waves propagate through a realisc atmosphere with temperature and winds varying with hight and latude in agreement with theCassini spacecra visible and infrared observaons. Varying background temperature or strong wind variaons with hight result in wave reflecon and/or ducngprevenng waves to reach high altudes. Waves can encounter crical levels or experience breaking deposing their momentum in the atmosphereaccelerang/decelerang the zonal mean flow. We study the thermal and the dynamical forcing that results from the interacon of the waves with thebackground atmosphere and esmate the spectral properes of the gravity waves that can reach the upper atmosphere.41.07: Detecon of H2 Quadrupole Emission from SaturnAuthor Block: Laurence M. Traon 1 , S. Miller 2 , T. Stallard 31 Univ. of Texas, Ausn, 2 UCL, United Kingdom, 3 Univ. of Leicester, United Kingdom.Presentaon Time: 10/7/2010 9:30 AM - 9:40 AMLocaon: Ballroom BCAbstract: We report the first detecon of near-IR H 2 quadrupole emission from Saturn. Such emission had been previously detected in the near-IR spectra ofJupiter’s aurorae, and in the thermosphere and aurorae of Uranus, but the low intensity had prevented detecon in Saturn’s spectrum. Although H+ 3 emission hasbeen detected for all three planets, it is similarly the dimmest on Saturn, a fact that may result from Saturn’s having the lowest thermospheric temperature withpossibly the highest homopause altude. Unlike for H + 3 , which is destroyed by hydrocarbons below the homopause, H 2 emission is not restricted to arising fromabove the homopause. Comparison of the H 2 emission to the H+ 3 emission may therefore help to constrain Saturn’s homopause altude, which plays a crical rolein characterizing Saturn’s thermospheric chemistry and energy balance. Comparison of temperatures may also be diagnosc. Simpliscally, a hot H 2 temperaturewould imply hot H + 3 , and so a lower H+ 3 column to explain the observed brightness, and hence a higher homopause. Conversely, cool H 2 would imply cool H + 3 , alonger H3+ path, and a lower homopause, as Melin et al (2007; Icarus 186, 234) suggest may be the case.The observaons were done at the IRTF telescope using the CSHELL spectrograph at R=21,500 during Jan 19-20, 2008, when we first detected H 2 Q(1) emission inSaturn’s southern aurora, and on Jan 8-9, 2009, when we similarly observed three of the four targeted K-band auroral H 2 emission lines, S(1), Q(1), and Q(3).Observing me ran out before S(0) could be observed. We present the observaons and discuss preliminary results in terms of Saturn’s homopause.41.08: New Laboratory Measurements of the Cenmeter-Wavelength Properes of Ammonia Under Deep Jovian Atmospheric CondionsAuthor Block: Kiruthika Devaraj 1 , P. G. Steffes 1

1 Georgia Instute of Technology.Presentaon Time: 10/7/2010 9:40 AM - 9:50 AMLocaon: Ballroom BCAbstract: Over 800 measurements of the opacity of ammonia have been made in the 5-20 cm wavelength range at pressures ranging from 0.05-96 bars,temperatures from 330-450K, and mixing raos from 0.05-100% in a hydrogen-helium atmosphere using an ultra-high pressure system. An ammonia absorpvitymodel that is accurate under very high pressure condions is necessary for the Juno microwave radiometer (MWR) to successfully retrieve the deep abundanceprofile of Jupiter. Current and future measurements of the opacity of ammonia under simulated deep jovian condions, and an esmaon of compressibility ofammonia under the same condions will be used to create a new model that more accurately characterizes the cenmeter-wavelength properes of ammonia insupport of the Juno MWR. Furthermore, at least one laboratory measurement study indicates that water vapor can efficiently broaden the 572 GHz rotaonaltransion of ammonia (Belov et al., 1983), and this could be true for the inversion transions of ammonia as well. Future work will involve laboratorymeasurements of the opacity of mixtures of ammonia and water vapor under simulated jovian condions using the ultra-high pressure system. Thesemeasurements will directly improve our understanding of cenmeter-wavelength absorpon by ammonia in the jovian planets, and improve retrievals from theJuno MWR at Jupiter.This work was supported by NASA Contract NNM06AA75C from the Marshall Space Flight Center supporng the Juno Mission Science Team, under Subcontract699054X from the South-west Research Instute41.09: The 890 nm Methane Band: Line by Line Parameters for the Outer Solar SystemAuthor Block: D. Chris Benner 1 , J. J. O'Brien 2 , S. Shaji 2 , V. Malathy Devi 1 , P. T. Spickler 3 , C. P. Houck 3 , J. A. Coakley 3 , K. J. Haga 3 , J. D. Dolph 31 College of William & Mary, 2 University of Missouri, St. Louis, 3 Bridgewater College.Presentaon Time: 10/7/2010 9:50 AM - 10:00 AMLocaon: Ballroom BCAbstract: The near infrared bands of methane were the first observed in the outer planets and Titan. With the very long paths of rays within the atmospheres ofthese objects, scaering, pressure and temperature inhomogeneies are important. The spectrum of methane is very complex and long laboratory gas cells aredifficult to cool to outer solar system temperatures. The absorpon is usually modeled stascally. Violaons of the modeling assumpons cause poorextrapolaons of simulaons based upon laboratory parameters. These band models generally do not provide transmissions that are mulplicave, so propermodeling of scaering and inhomogeneous atmospheres is not possible.The Intra Cavity Laser Spectrometer of the University of Missouri, St. Louis obtained low temperature (99-161K), low pressure (~few Torr), long path (few km) andhigh resoluon (~0.01 cm -1 HWHM) spectra of methane covering the enre 890 nm feature (10925-11500 cm -1 ), the deepest band below 1.1 µm. At thesetemperatures fewer spectral lines are visible and the Doppler width is substanally smaller than at room temperature. The result is a dense, but manageablespectrum from which line posions, intensies and lower state energies are derived on a line by line basis by the William and Mary mulspectrum nonlinear leastsquares fing technique. For temperatures less than ~160K, simulaon of the spectrum at infinite resoluon is possible. Simulaons at various physicalcondions will be shown and compared to band models and other laboratory spectra.Support at William and Mary was provided by NASA through grant NNX08AF06G. Support at UM, St. Louis provided by NASA through grant NAG5-12013, from NSFthrough grant CHE-0213356 and by the University of Missouri Research Board. Paral support at Bridgewater College was provided by its Marn ScienceResearch Instute and from an AAS Small Research Grant.

Session Number: 42Session Title: Mars Atmosphere I: ObservationsSession Type: Oral42.01: First Detecon Of O 2 Recombinaon Nightglow Emission At 1.27 µm In The Atmosphere Of Mars With Omega On Mars Express.Author Block: Jean-Loup Bertaux 1 , B. Gondet 2 , J. Bibring 2 , F. Montmessin 1 , F. Lefèvre 11 LATM OS/IPSL/CNRS/UVSQ, France, 2 IAS,University Paris Sud, France.Presentaon Time: 10/7/2010 8:30 AM - 8:40 AMLocaon: Ballroom DAbstract: The OMEGA hyperspectral imager on board Mars Express is primarily dedicated to day side observaons of both the surface and the atmosphere ofMars. However, observaons on the night side were also performed occasionally, and in parcular above the planetary limb. Along its 6 years of operaon todate, OMEGA has acquired hundreds of night side limb profiles of the Maran atmosphere, at a variety of seasons and latudes. In some of them, the O2emission at 1.27µm is observed. In one parcular case acquired at Ls= 120° and 76.5° S latude, the peak intensity reached 14 MegaRayleigh at an altude of 42km. We interpret this emission as originang from the recombinaon of oxygen atoms, similar to the corresponding emission observed in the Venus night side.Specifically, for both Venus and Mars, CO2 and N2 are photo-dissociated during the day in the thermosphere; O and N atoms are transported by thermosphericcirculaon to the night side, where air is descending. During descent, O2 recombines and emits diagnosc lines, detected by OMEGA in the NIR. This nightglow issimilar to that of NO previously detected by SPICAM/Mars Express in the UV. The newly observed recombinaon O2 emission is produced in the night side by atotally different mechanism than the Maran day side emission at 1.27 µm, due to photo-dissociaon of ozone. These first observaons of O2 recombinaon arecompared with predicons of a 3D GCM developed at LMD, showing that downward transport from the thermosphere is occurring mainly in the polar night. TheOMEGA observaons will help to quanfy the atmospheric downward vercal transport from the thermosphere. It is worth to note that air coming from thethermosphere is void of methane, which lifeme at high altudes is one week, instead of 200 years at ground level.42.02: CRISM Limb Observaons of O2 Singlet Delta Nightglow in the Polar Winter Atmosphere of MarsAuthor Block: R. T. Clancy 1 , B. J. Sandor 1 , M. J. Wolff 1 , M. D. Smith 2 , S. L. Murchie 3 , F. P. Seelos 3 , A. Kleinbohl 4 , D. M. Kass 4 , F. Lefevre 5 , F. Forget 61 Space Science Inst., 2 GSFC/NASA, 3 APL, 4 JPL, 5 LATM OS, France, 6 LM D, France.Presentaon Time: 10/7/2010 8:40 AM - 8:50 AMLocaon: Ballroom DAbstract: CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) near-IR spectroscopic imaging of the Mars atmospheric limb supports vercalprofiling of aerosol (ice and dust) and gas [H2O, CO, CO2, O2(1Δg)] constuents versus season (Ls), latude, and (to a limited degree) longitude. These CRISMlimb observaons are obtained approximately every two months (15° Ls), over a full range of sunlighted latudes for two MRO (Mars Reconnaissance Orbiter)orbits centered on equatorial longitudes of 100W and 300W. Daylight limb spectra indicate strong 1.27 µm atmospheric emission from the excited singlet delta ofmolecular oxygen, associated with photolysis of Mars atmospheric ozone. Limb observaons extending to un-illuminated, polar night latudes present a newsource of O2(1Δg) emission at higher altudes (40-55 km), associated with three body recombinaon of atomic oxygen [O+O+CO2 -> O2(1Δg) +CO2]. Thisnightglow requires strong poleward supply of atomic oxygen, produced from photolysis of CO2 at sunlighted latudes and transported at high altudes (above 70km) into polar night altudes of 40-60 km. CRISM limb observaons indicate disncve latudinal and longitudinal distribuons of this polar nightglow thatevolve over the Feb-Aug 2010 (Ls=50-140°) period of observaons for the southern winter. New observaons include planned full orbit mapping (12 orbits) inAugust 2010 to characterize these spaal variaons in more detail. Key comparisons with co-located MCS (Mars Climate Sounder) temperature and aerosol profileretrievals and LMD (Laboratoire Météoroligie Dynamique) GCM photochemical simulaons provide new insights into poorly constrained meridional transport intopolar winter latudes on Mars.42.03: Diurnal Variaon Of The O2 Singlet-delta Emission And The H2O And HDO Column Densies Near Mars’ AphelionAuthor Block: Robert E. Novak 1 , M. J. Mumma 2 , G. L. Villanueva 2 , P. Sanstead 1 , R. Bebawee 1 , D. Nunes 11 Iona College, 2 NASA's GSFC.Presentaon Time: 10/7/2010 8:50 AM - 9:00 AMLocaon: Ballroom DAbstract: On Mars, O 2 in the excited singlet-Delta state originates from the photolysis of ozone. This metastable state is quenched by carbon dioxide at lowaltudes, but radiave decay predominates above 20 km. Since ozone and water are an-correlated in abundance, the O 2 singlet-Delta emission also tests theabundance of water above 20 km. Near Mars’ aphelion, the atmosphere cools and lowers the hygropause below 20 km altude, perming increased ozoneabundance above the hygropause and thus increased singlet-Delta emission. We report detecon of this effect along with near simultaneous detecons of H 2 Oand HDO.On April 3, 2010 (L s = 72 o ), we posioned the slit of CSHELL (NASA-IRTF) East-West on Mars centered on the sub-Earth point (14 o N). We accumulated databetween 5:00 and 9:00 UT as the sub-Earth longitude went from 264 o to 322 o W (from Isidis Plania through Syrs Major). We connuously took data at O 2singlet-Delta (7908 cm -1 ), HDO (2772 cm -1 ), and H 2 O (2996 cm -1 ) sengs. For each seng, we integrated on Mars for four minutes giving an E-W map of theemission or column density across Mars. Over the four-hour terrestrial me period, 12 sets of O 2 /HDO/H 2 O data were obtained. We thus trace specificgeographical locaons on Mars through a local me of 3.8 hours (sols). The data extracted from these observaons show the O 2 singlet-Delta emission peakingat mid-day and the HDO and H 2 O column densies increase during the morning hours. Column densies of H 2 O and HDO are greater over Isidis Plania(elevaon ~ -3 km) than over Syrs Major (+2 km). The difference in elevaon between these two regions does not affect the O 2 singlet-Delta emission.We acknowledge support from NSF RUI-Program (AST-0505765 and AST-0805540) and thank the administrators and the staff of the NASA-IRTF for use of thetelescope to acquire the data.42.04: Cross-Instrument Calibraon of Atmospheric Temperatures Observed by Mars Global SurveyorAuthor Block: David P. Hinson 1 , M. D. Smith 21 SETI Instute, 2 Goddard Space Flight Center.Presentaon Time: 10/7/2010 9:00 AM - 9:10 AMLocaon: Ballroom DAbstract.Abstract: Mars Global Surveyor (MGS) monitored temperatures in the Maran atmosphere through infrared sounding by the Thermal EmissionSpectrometer (TES) as well as radio occultaon (RO) experiments. Direct comparisons between TES nadir and RO temperature profiles have generally confirmedthe accuracy of the results at high northern latudes during spring and summer (Hinson et al., J. Geophys. Res., 109, E12002, 2004). We now extend thesecomparisons to observaons obtained at high northern latudes during autumn, when the temperatures are colder and the dynamics are more vigorous than in

spring and summer. This research addresses two important quesons concerning the thermal structure, dynamics, and energy balance of the polar atmosphere.First, how reliable are measurements that indicate super-saturaon of carbon dioxide? Our inial comparisons between nearly coincident TES and ROmeasurements reveal situaons where TES gives a false indicaon of strong super-saturaon in the lowest scale height above the surface. The accuracy of thetemperature profiles is affected by several factors, but one factor appears to be largely responsible for this discrepancy. The limited vercal resoluon of the TESprofiles reduces their accuracy in cases where the stac stability varies strongly with height. Second, what is the relave performance of the two sounders inobservaons of shallow baroclinic eddies? We have addressed this queson by applying the same method of space-me analysis to both types of data. Theresults agree closely with few excepons, providing consistent characterizaons of both baroclinic eddies and staonary waves. The weather in the lowest scaleheight above the surface varies strongly in response to baroclinic wave transions, abrupt shis in the frequency and zonal wave number of the dominant eddymode. This research is supported by grant NNX08AL24G of the Mars Data Analysis Program.42.05: Maran Climatology from MCSAuthor Block: David M. Kass 1 , A. Kleinboehl 1 , M. D. Smith 2 , D. J. McCleese 1 , J. T. Schofield 11 JPL, 2 NASA Goddard Space Flight Center.Presentaon Time: 10/7/2010 9:10 AM - 9:20 AMLocaon: Ballroom DAbstract: Mars Climate Sounder (MCS) on Mars Reconnaissance Orbiter (MRO) has collected limb observaons starng in September 2006. MCS is a ninechannel infrared radiometer with limb staring arrays opmized for atmospheric sounding. Retrievals have been performed on a majority of the valid limbobservaons. This has produced over 2 million profiles of temperature, dust opacity and water ice opacity, extending from the surface to ~80 km and spanningover two Mars years.We have binned selected parameters to produce zonal mean me series, using 2 degree Ls bins and 5 degree latude bins. Binned quanes include column dustopacity, column water ice opacity, surface temperature, and atmospheric temperature at 50 Pa, 5 Pa and 0.5 Pa (corresponding to ~25 km, ~45 km and ~65 kmabove the surface). For all quanes, we have produced both dayme and nighme me series. These products show a number of interesng features includingthe difference in the impact on most parameters of the 2007 global dust storm and the 2009 large regional storm in the southern hemisphere. Winter polarwarming is quite evident at the lower pressure levels and at the 0.5 Pa level, there is a very strong seasonal paern in thermal dal structure.By including comparable MGS/TES and ODY/THEMIS observaons, where available, the climatology can be extended to cover 6 consecuve Mars Years. Thetemperature structure at 50 Pa and the dayme dust column opacity show the disnct and different effects of several major and moderate dust storms occurringduring the southern spring and summer. At other seasons, the atmosphere shows less, but sll noceable, interannual variability.42.06: Transport-driven Formaon Of An Ozone Layer On Venus And Mars As Evidenced By Spicam And SpicavAuthor Block: Franck Montmessin 1 , J. Bertaux 1 , F. Lefèvre 1 , B. Gondet 2 , E. Marcq 1 , A. Reberac 1 , V. Sarago 11 LATM OS, France, 2 IAS, France.Presentaon Time: 10/7/2010 9:20 AM - 9:30 AMLocaon: Ballroom DAbstract.Abstract: Cross-hemispheric circulaon of the atmosphere is a major feature of the Maran troposphere and Venusian thermosphere. On Mars, it isdriven by the latudinal gradient of insolaon at the surface, which generates a global summer-to-winter Hadley cell reversing orientaon during equinoxes andmaximizing intensity at solsces. On Venus, it is driven by a longitudinal gradient between the dayside and the nightside and takes place above the superrotangmesosphere and troposphere. This subsolar-to-ansolar (SSAS) circulaon is known to induce major observaonal features, such as the vast O2 and NOemission zones observed close to midnight. Recently, SPICAV onboard Venus Express has detected for the first me the presence of ozone on Venus, accounngfor a thin thermospheric layer at about 100 km. We suggest that this ozone layer forms as a result of O atoms carried from the dayside and recombining in thesubsiding branch of the SSAS where the O2 singlet delta emission is also observed. Interesngly, a similar feature was recently idenfied on Mars with SPICAM,with the presence of a &gt;10 km thick ozone layer in the southern winter hemisphere near the pole. Contrarily to the ozone layer otherwise observed on Marswhich extends from the surface and is controlled by reacon with HOx radicals, this layer is only related to O atoms produced in the summer hemisphere andcarried via global circulaon towards the polar night where they can recombine, yielding the newly detected O2 emission feature evidenced by OMEGA.42.07: Herschel Space Observatory Observaons Of Mars: First ResultsAuthor Block: Paul Hartogh 1 , C. Jarchow 1 , B. M. Swinyard 2 , E. Lellouch 3 , M. Blecka 4 , M. de Val-Borro 1 , M. Rengel 1 , R. Moreno 3 , S. Sidher 2 , H. Feuchtgruber 5 , H.Sagawa 6 , G. Portyankina 7 , HssO Team1 Max Planck Instute for Solar System Research, Germany, 2 STFC Rutherford Appleton Laboratory, United Kingdom, 3 LESIA Observatoire de Paris, France,4 Space Research Centre, Polish Academy of Sciences, Poland, 5 Max Planck Instute for Extraterrestrial Physics, Germany, 6 Environmental Sensing & NetworkGroup, NICT, Japan, 7 University of Bern, Switzerland.Presentaon Time: 10/7/2010 9:30 AM - 9:40 AMLocaon: Ballroom DAbstract: Herschel has observed Mars with its three instruments, the Heterodyne Instrument for the Far Infrared (HIFI), the Photodetector Array Camera &Spectrometer (PACS) and the Spectral and Photometric Imaging Receiver (SPIRE) as part of the HssO Key programme. SPIRE provided for the first me a farinfrared spectrum of Mars from 0.45 to 1.55 THz. From these observaons during Ls = 5°, water vapor and carbon monoxide mixing raos of 100 ppm and 900ppm respecvely were derived. PACS observed Mars twice during Ls = 340 ° and Ls = 108 ° in the frequency range from 1.43 to 5.26 THz. The spectra show highsignal-to-noise- rao (SNR) carbon monoxide and water lines including water isotopes. HIFI has observed Mars around Ls = 78° and Ls = 108° and performed linescans from band 1a to 6b (for technical reasons excluding band 5b). Furthermore dedicated observaons on carbon- and oxygen isotopes in carbon monoxide andoxygen- and hydrogen isotopes in water vapor as well as hydrogen peroxide, hydrogen chloride and molecular oxygen were executed. The laer presents the firstobservaon of molecular oxygen in the submm wave regime. From the very high SNR spectrum a (constant with altude) volume mixing rao of 1400 ppm hasbeen derived, consistent with ground-based observaons in the oxygen A band (around 763 nm) from the early 1970s. Finally from the analysis of 2 carbonmonoxide isotopes a globally averaged volume mixing rao of constant 980 ppm and a vercal temperature profile have been retrieved. Compared to generalcirculaon model calculaons the observaons show up to 10 K lower temperatures in the middle atmosphere of Mars.42.08: Ensemble Kalman Filter Data Assimilaon of TES RetrievalsAuthor Block: Mahew J. Hoffman 1 , S. J. Greybush 2 , E. Kalnay 2 , R. N. Hoffman 3 , J. Eluszkiewicz 3 , T. Miyoshi 2 , K. Ide 2 , R. Wilson 41 Johns Hopkins University, 2 University of Maryland, 3 AER, Inc., 4 GFDL.Presentaon Time: 10/7/2010 9:40 AM - 9:50 AMLocaon: Ballroom DAbstract.Abstract: Temperature profiles from the Mars Global Surveyor (MGS) Thermal Emission Spectrometer (TES) are assimilated into the GFDL Mars GeneralCirculaon Model (MGCM) using the local ensemble transform Kalman filter (LETKF) data assimilaon scheme. The LETKF tuning for the Maran atmosphere and

TES data will be discussed along with results evaluang the performance of the MGCM-LETKF assimilaon. Aer tuning of the MGCM-LETKF system and using anensemble of dust opacity of distribuons in the MGCM, the assimilaon of the TES profiles from the PDS is found to lead to improvements of approximately 3degrees in the model temperature field over the free running model (in the absence of data assimilaon). This study is a second step toward creang the MGCM-LETKF Maran Atmosphere Reanalysis, which will be incorporang temperature and dust observaons from the MGS TES instrument and possibly the MarsClimate Sounder.42.09: Probing Maran Atmospheric Structure With Sunset And Twilight ImagingAuthor Block: Mark T. Lemmon 1 , S. Grounds 11 Texas A&M University.Presentaon Time: 10/7/2010 9:50 AM - 10:00 AMLocaon: Ballroom DAbstract: We study the vercal distribuon of dust at the two Mars rover landing sites using Pancam images. The Maran twilight can be imaged more than 2hours aer the sun has set due to forward scaering of sunlight by atmospheric dust. That scaering must start high in the atmosphere, as “noclucent” dustregions. Thus, the fall-off of brightness with me is somewhat diagnosc of the vercal distribuon of dust over several scale heights from the surface. Closer to,and shortly before, sunset, the atmospheric imaging becomes increasingly sensive to low-altude dust. Analysis of sky images as the Sun sets shows thatbrightness is sensive to dust variaons in and around the boundary layer. Specifically, our proof-of-concept data set is modeled with a factor of several dustconcentraon disconnuity around 10 km altude at each site. The sense of the disconnuity is opposite at the two sites, with more dust in the boundary layer atthe dusty Gusev site and more dust in the free atmosphere above the Meridiani site.This work was supported by the NASA Mars Exploraon Project Parcipang Scienst Program.

Session Number: 43Session Title: Asteroid Lutetia: Results from RosettaSession Type: Oral43.01: Hints on the Puzzling 21 Lutea Nature from OSIRIS Rosea DataAuthor Block: Maria Antonieta Barucci 1 , H. Sierks 2 , C. Barbieri 3 , D. Koschny 4 , P. Lamy 5 , H. Rickman 6 , R. Rodrigo 7 , U. H. Keller 8 , OSIRIS Team1 Obs. de Paris, France, 2 Max-Planck-Instut für Sonnensystemforschung, Germany, 3 University of Padova, Italy, 4 ESA-ESTEC, Netherlands, 5 LAM, France,6 Department of Astronomy and Space Physics, Uppsala University, Sweden, 7 Instuto de Astrofisica de Andalucia, CSIC, Spain, 8 Instut für Geophysik undExtraterrestrische Physik (IGEP), Germany.Presentaon Time: 10/7/2010 8:30 AM - 8:40 AMLocaon: Ballroom EAbstract: From the ground based observaons, 21 Lutea appeared to be a puzzling asteroid different from all the other asteroids. Its nature was uncertainbecause of contradictory observaons, either favoring an M type or a C type asteroid. From polarimetry (Belskaya et al. 2010, AA, 515, 29), Lutea appeared anatypical object with a surface covered by a fine-grained regolith.From the amazing images received by OSIRIS imaging system (Keller et al. 2007 SSRev. 128, 433), on board of ESA Rosea spacecra, Lutea reveals a complexand morphologically diverse surface.Lutea seems to be a very old object with an irregular shape which is the result of its collisional history. Some smooth younger areas have been also observed.The asteroid lifelong bombardment produced several big craters (tens of kilometers), and many different generaons of smaller craters. An apparently thickregolith layer probably covers most of the surface of the asteroid and its presence is revealed by the unique land slide structures along the walls of some craters,most likely generated by impact-induced seismic acvity. The presence inside some big craters of sparse boulders, apparently dark, indicates a complex impactmechanism. Moreover images display a great richness of different structures: pits, craters chains, ridges, scarps and wide younger terrains. More details will beavailable at the me of the presentaon. An overview of the obtained results will be presented.The first analysis of the data shows the extreme diversity of Lutea which does not resemble any other space explored asteroid. The variety of shapes,morphologies, structures, histories provides us with an invaluable patrimony of informaon.43.02: Overview of the Rosea Fly-by of 21-Lutea as Observed by the OSIRIS Camera SystemAuthor Block: Stubbe Hviid 1 , C. Barbieri 2 , A. M. Barucci 3 , I. Berni 2 , L. Baglivo 2 , S. Besse 4 , V. Da Deppo 5 , S. Debei 2 , M. DeCecco 6 , F. Ferri 2 , S. Fornasier 3 , O.Groussin 7 , P. J. Guérrez 8 , L. Jorda 7 , H. U. Keller 9 , M. Küppers 10 , C. Leyrat 3 , L. Lara 8 , M. Lazzarin 2 , J. De Leon 8 , S. Magrin 2 , S. Marchi 2 , M. Massironi 2 , R. Moissl 1 , W.Sabolo 8 , S. E. Schröder 1 , M. Perle 6 , H. Sierks 1 , C. Snodgrass 1 , N. Thomas 11 , C. Tubiana 1 , J. Vincent 1 , P. Vernazza 12 , M. Zaccarioo 2 , OSIRIS Team1 Max Planck Instute for Solarsystem Research, Germany, 2 University of Padua, Italy, 3 LESIA, Observatoire de Paris, France, 4 University of Maryland, 5 CNR-IFNUOS Padua LUXOR, Italy, 6 Univerty of Padua, Italy, 7 Laboratoire d'Astrophysique de Marseille, Université de Provence, France, 8 Instuto de Astrofisica deAndalucia, CSIC, Spain, 9 Instut für Geophysik und extraterrestrische Physik (IGEP), Germany, 10 ESA-ESAC, Spain, 11 Physikalisches Instut, Universität Bern,Switzerland, 12 ESA-ESTEC, Netherlands.Presentaon Time: 10/7/2010 8:40 AM - 8:50 AMLocaon: Ballroom EAbstract: On July 10th 2010 the ESA Rosea spacecra flew past the asteroid 21-Lutea on the way to it’s 2014 rendezvous with Comet 67P/Churyumov-Gerasimenko. The closest distance to the asteroid was 3160 km. During the fly-by the scienfic camera system OSIRIS observed the asteroid. The resolvedobservaons started 9hours 30min before the closest approach and finished 18 min aer the closest approach. During this period the camera system acquired234 images with the Narrow Angle Camera (NAC) and 228 images with the Wide Angle Camera (WAC). The highest resoluon obtained on the surface was 59m/pixel.21-Lutea is the largest asteroid yet visited by a spacecra. The surface shows a highly impacted surface with the largest impact craters reaching ~60km. Thesurface also shows evidence of thick regolith layers and grooves as previously seen on the moon Phobos. This paper will give an overview of the observaonsmade by the OSIRIS cameras.43.03: Shape and Physical Properes of Asteroid 21 Lutea from OSIRIS ImagesAuthor Block: Laurent Jorda 1 , P. Lamy 1 , S. Besse 2 , C. Capanna 1 , B. Carry 3 , G. Faury 1 , R. Gaskell 4 , G. Gesquière 5 , O. Groussin 1 , P. Guérrez 6 , M. Kaasalainen 7 , W.Sabolo 6 , H. Sierks 8 , S. Spjuth 8 , OSIRIS Team1 Laboratoire d'Astrophysique de Marseille, France, 2 University of Maryland, 3 Observatoire de Paris - Meudon, France, 4 Planetary Science Instute, 5 Laboratoiredes Sciences de l’Informaon et des Systèmes, France, 6 Instuto de Astrosica de Andalucía, Spain, 7 Tampere University of Technology, Finland, 8 Max-Planck-Instut für Sonnensystemforschung, Germany.Presentaon Time: 10/7/2010 8:50 AM - 9:00 AMLocaon: Ballroom EAbstract: The Rosea spacecra of the European Space Agency flew by the asteroid 21 Lutea on July, 10, 2010 on its way to its final target, comet67P/Churyumov-Gerasimenko. A total of 460 images have been acquired by OSIRIS during the flyby, with a minimum pixel scale of 64 m at closest approach(hereaer “CA”) with the narrow angle camera. Several filters have been used, covering a wavelength range from the far UV (0.25 microns) to the end of thevisible spectrum (1.0 microns). The phase angle went through 11°-0°-160°, reaching opposion 18 min before CA. We report here on a preliminary interpretaonof the images of the asteroid acquired by OSIRIS, the imaging system aboard Rosea. These images are combined with pre-flyby light curves and adapve opcsmeasurements to retrieve the shape and the rotaonal parameters of the asteroid. The bulk physical properes: size, surface, volume, moments of inera, gravityfield, are then extracted from the shape.43.04: Geomorphology of 21 Lutea from Rosea/OSIRIS ObservaonsAuthor Block: Nicolas Thomas 1 , C. Barbieri 2 , A. M. Barucci 3 , S. Besse 4 , G. Cremonese 2 , V. Da Deppo 5 , S. Debei 6 , F. Ferri 2 , O. Groussin 7 , S. F. Hviid 8 , L. Jorda 7 , H.U. Keller 9 , J. Knollenberg 10 , E. Kuehrt 10 , S. Marchi 2 , W. J. Markiewicz 8 , M. Massironi 2 , R. Moissl 8 , F. Scholten 10 , H. Sierks 8 , C. Tubiana 8 , J. -. Vincent 8 , OSIRIS Team1 Space and Planetary Sciences Division, University of Bern, Switzerland, 2 University of Padova, Italy, 3 Observatoire de Paris, France, 4 University of Maryland,5 CNR-IFN UOS, Italy, 6 CISAS - University of Padova, Italy, 7 Laboratoire d'Astrophysique de Marseille, France, 8 Max-Planck-Instut fuer Sonnensystemforschung,Germany, 9 Instut fuer Geophysik und extraterrestrische Physik, Germany, 10 DLR-PF, Germany.Presentaon Time: 10/7/2010 9:00 AM - 9:10 AM

Locaon: Ballroom EAbstract: The Rosea spacecra performed a fly-by of the asteroid, 21 Lutea, on 10 July 2010. The closest approach (CA) distance was around 3160 km. Thescienfic imaging system, OSIRIS[1], acquired images throughout the fly-by through both its narrow-angle (NAC) and wide-angle (WAC) cameras. The highestspaal scale in the NAC was around 60 m px -1 (slightly higher spaal scale than the Galileo SSI at 243 Ida). At closest approach, the 100 km diameter asteroidfilled the field of view of the NAC giving 2000 pixels across the object.The images reveal a remarkably diverse object characterized by the presence of geologically old surfaces, as witnessed by crater stascs, in close proximity torelavely recent, large impact craters. Grooves (aligned topographic structures) similar to but more weakly defined than those seen on the Maran moon, Phobos,are pervasive and are observed to cut many craters. Some are roughly concentric about the most recent impact craters, others are not. It is not clear, at this stageof the analysis, whether the most recent impacts were responsible for their producon.Boulder fields with objects >200 m in diameter are evident. In the most extensive boulder field, the boulders appear to have been covered and possibly moved bylandslides acng under the tenuous gravity. Downslope moon, indicave of destabilizaon through impact and seismic acvity, has been observed on smallerbodies (e.g. Deimos and 433 Eros). Numerous unusual structures have also been observed although albedo markings, which cannot be aributed to topographicrelief, are subtle and rare.The presentaon will provide an overview of the highest resoluon data and will detail some of these aspects.[1] Keller, H.U., and 68 colleagues, (2007), OSIRIS-The Scienfic Camera System Onboard Rosea, Space Sci. Rev., 128, 433-506.43.05: OSIRIS Observaons of Asteroid 21 Lutea: Geomorphology and Colour VariegaonAuthor Block: Horst Uwe Keller 1 , S. E. Schröder 2 , S. F. Hviid 2 , S. Spjuth 2 , L. Jorda 3 , O. Groussin 3 , N. Thomas 4 , A. M. Barucci 5 , S. Fornasier 5 , C. Leyrat 5 , S. Besse 6 , V.Da Deppo 7 , S. Debei 8 , F. Ferri 8 , S. Marchi 8 , R. Moissl 2 , C. Tubiana 2 , J. B. Vincent 2 , L. M. Lara 9 , J. de Leon 9 , M. Küppers 10 , S. Magrin 8 , M. Lazzarin 8 , P. Vernazza 11 , C.Barbieri 8 , H. Sierks 2 , OSIRIS Team1 Instut für Geophysik und extrarerrestrische Physik (IGEP), Germany, 2 M PI für Sonnensystemforschung, Germany, 3 Laboratoire d'Astrophysique de Marseille,France, 4 Physikalisches Instut, Universität Bern, Switzerland, 5 LESIA, Observatoire Paris, France, 6 University of Maryland, 7 CNR-IFN UOS Padova LUXOR, Italy,8 University of Padova, Italy, 9 Instuto de Astrofisica de Andalucia, CSIC, Spain, 10 ESA-ESAC, Spain, 11 ESA-ESTEC, Netherlands.Presentaon Time: 10/7/2010 9:10 AM - 9:20 AMLocaon: Ballroom EAbstract.Abstract: On July 10, 2010, the ESA Rosea mission successfully flew by the big asteroid 21 Lutea. The scienfic camera system OSIRIS took 462images through 24 filters of the narrow angle (NAC) and wide angle (WAC) cameras. Near closest approach (CA) the whole body (northern hemisphere) of Luteawas imaged with a scale of 60 m per pixel. As expected the surface morphology of Lutea is dominated by large impact craters, some comparable to the radius ofthe asteroid. Smooth near craterless terrains indicate recent impacts and ejecta. Features found on discernable regional units include craters, grabens, scarps,pits, ridges, contacts, and large boulders. Craters with sharp and steep walls (some with landslides), some with irregular shapes and others almost filled withregolith are found. A topographic shape and photometric model of Lutea as developed for the interpretaon of the OSIRIS results of asteroid Steins (Jorda et al.2010, Spjuth et al. 2010) will provide local slopes and gravity. The OSIRIS filters have been extensively calibrated in-flight and images will be used to constructphoto-metrically accurate colour rao maps which have been shown to be of importance for the study of geological units and morphological features.43.06: Spaal Variaons of Spectral Properes of (21) Lutea as Observed by OSIRIS/RoseaAuthor Block: Cedric Leyrat 1 , H. Sierks 2 , C. Barbieri 3 , A. Barucci 1 , V. Da Deppo 4 , J. De Leon 5 , M. Fulchignoni 1 , S. Fornasier 1 , O. Groussin 6 , S. F. Hviid 2 , L. Jorda 6 , H.U. Keller 2 , F. La Forgia 3 , L. Lara 5 , M. Lazzarin 3 , S. Magrin 3 , S. Marchi 3 , N. Thomas 7 , S. E. Schroder 2 , OSIRIS Team1 LESIA/Observatoire de Paris-Meudon, France, 2 Max Planck Instute, Germany, 3 University of Padova, Italy, 4 CNR-IFN UOS Padova, Italy, 5 Instuto deAstrofisica de Andalucia - CSIC, Spain, 6 Laboratoire d'Astrophysique de Marseille, France, 7 Physikalisches Instut Universitaet Bern, Switzerland.Presentaon Time: 10/7/2010 9:20 AM - 9:30 AMLocaon: Ballroom EAbstract: On July 10, 2010, the Rosea ESA/NASA spacecra successfully flew by the asteroid (21) Lutea, which becomes the largest asteroid observed by aspace probe. The closest approach occurred at 15H45 UTC at a relave speed of 15km/s and a relave distance of 3160 km. The Narrow Angle Camera (NAC) andthe Wide Angle Camera (WAC) of the OSIRIS instrument onboard Rosea acquired images at different phase angles ranging from almost zero to more than 150degrees. The best spaal resoluon (60 m/pixel) allowed to reveal a very complex topography with several features and different crater's surface densies.Spectrophotometric analysis of the data could suggest spaal variaons of the albedo and spectral properes at the surface of the asteroid, at least in thenorthern hemisphere. Numerous sets of data have been obtained at different wavelengths from 270nm to 980nm. We will first present a color-color analysis ofdata in order to locate landscapes where surface variegaon is present. We will also present a more accurate study of spectral properes using the shape modeland different stascal methods. Possible variaons of the surface spectral properes with the slope of the ground and the gravity field orientaon will bediscussed as well.43.07: The Mass and Density of (21) Lutea from Radio Tracking During the Rosea FlybyAuthor Block: Marn Paetzold 1 , T. Andert 2 , B. Häusler 2 , S. Tellmann 1 , J. D. Anderson 3 , S. W. Asmar 3 , J. Barriot 4 , M. K. Bird 51 Rheinisches Instut für Umwelorschung, Abt. Planetenforschung, Germany, 2 Universität der Bundeswehr München, Germany, 3 Jet Propulsion Laboratory,Caltech, 4 Géosciences du Pacifique du Sud, Université de la Polynésie francaise, French Polynesia, 5 Argelander Instut für Astronomie, Universität Bonn,Germany.Presentaon Time: 10/7/2010 9:30 AM - 9:40 AMLocaon: Ballroom EAbstract: The Rosea spacecra flew by its second asteroid target (21) Lutea on 10th July 2010. The flyby and recording of the radio carrier signals went verywell. The frequency noise recorded at NASA´s DSS-63 70-m antenna near Madrid was lower than expected. The asteroid perturbed the flyby trajectory and velocityof the spacecra (closest approach was at 3160 km). The mass of the asteroid was determined from the Doppler shi of the radio signal carrier frequencies. Apreliminary analysis of the flyby data and the housekeeping data show contribuons from the rotaon of the spacecra body during flyby which sll need to becorrected (The abstract is wrien one week aer data recepon at the instute). Pre-flyby simulaons showed that a mass determinaon of the asteroid to anaccuracy of 1% or beer shall be possible even tough the flyby geometry was subopmal and there was a tracking gap at closest approach. The bulk density willbe derived from the determined mass and the volume. Volume esmates from the OSIRIS camera and from ground observaons will be applied. Knowledge of themass and bulk density is an important contributor to understand the asteroid´s composion, internal structure and porosity and may probably also give clues forthe definion of the asteroid´s type. Lutea is considered to be a major perturber of a number of smaller asteroids. The derived mass from the flyby will thereforebe compared with those mass values derived from asteroid orbit perturbaons.43.08: Large Boulders on (21) Lutea: Implicaons for Cratering Processes and Internal Structure

Author Block: Michael Kueppers 1 , C. Tubiana 2 , H. Sierks 2 , N. Thomas 3 , S. Marchi 4 , M. Massironi 4 , F. Ferri 4 , S. Besse 5 , L. Jorda 6 , O. Groussin 6 , R. Moissl 2 , J. B.Vincent 2 , P. J. Guerrez 7 , S. Debei 4 , V. da Deppo 4 , H. U. Keller 8 , OSIRIS Team1 ESA European Space Astronomy Centre, Spain, 2 Max-Planck-Instut for Solar System Research, Germany, 3 University of Berne, Switzerland, 4 Univ. of Padova,Italy, 5 Univ. of Maryland, 6 Lab. Astroph. Marseille, France, 7 IAA-CSIC, Spain, 8 Univ. of Braunschweig, Germany.Presentaon Time: 10/7/2010 9:40 AM - 9:50 AMLocaon: Ballroom EAbstract: During the flyby of Lutea by the Rosea spacecra, the OSIRIS narrow angle camera (NAC) imaged the asteroid with a resoluon of up to 60m/pixel. One of the geological features visible on the close-up images of Lutea during the flyby of the Rosea spacecra is the appearance of numerous largeboulders (100s of meters in diameter) on the surface of the asteroid. Those are the largest rock fragments found so far on small bodies in the solar system. Theyare most likely created by the largest impacts on Lutea.We will present the number, size distribuon and spaal distribuon of the boulders. The trajectory of boulders ejected from various craters will be calculated,and, together with scaling laws for impact cratering, will be used to esmate how many boulders have been released by each of the large impacts. This is a directmeasure of the high end of the size distribuon of ejecta from individual impacts, allowing to test impact scaling relaons and to constrain the strength andinternal structure of different regions of Lutea before the impacts.43.09: Ultraviolet Exploraon of 21 Lutea by the Alice UV Spectrometer Aboard RoseaAuthor Block: S. Alan Stern 1 , J. Parker 1 , A. Steffl 1 , M. A'Hearn 2 , P. Feldman 3 , H. Weaver 4 , M. Versteeg 1 , E. Birath 1 , A. Graps 1 , L. Feaga 5 , J. Scherrer 1 , D. Slater 1 , N.Cunningham 6 , J. Bertaux 71 SwRI, 2 U. Md., 3 JHU, 4 JHU-APL, 5 U. Md, 6 Nebraska Wesleyan U., 7 Service d'Aeronomie, France.Presentaon Time: 10/7/2010 9:50 AM - 10:00 AMLocaon: Ballroom EAbstract: The NASA Alice UV imaging spectrometer aboard the ESA Rosea comet orbiter successfully conducted an array of flyby observaons of asteroid 21Lutea in the days surrounding Rosea’s closest approach to Lutea on 10 July 2010. Lutea is over 100 km across, and is the largest asteroid yet reconnoiteredby spacecra. Alice observaons included a search for emission lines from gas around Lutea, rotaonally resolved FUV spectral observaons of the surface, andspaally resolved studies of surface variegaon made near closest approach. All these observaons were successful and achieved useful SNR. As a result of theAlice observaons, Lutea is the first asteroid to be spaally resolved in the UV by a flyby spacecra. We will summarize the Rosea-Alice Lutea dataset, andpresent preliminary results of each of the invesgaons outlined above. We will also compare the FUV/EUV reflectance of Lutea to the E-type asteroid 2867Steins, which was also observed by Alice when Rosea encountered that much smaller body on 5 September 2008. Among our findings, we report that Lutea issignificantly redder than Steins in the FUV.

Session Time: 10/7/2010 10:30 AM

Session Number: 44Session Title: Jovian Planets: Uranus and NeptuneSession Type: Oral44.01: Self-Consistent Model Atmospheres and the Cooling of the Solar System's Giant PlanetsAuthor Block: Jonathan J. Fortney 1 , M. Ikoma 2 , N. Neelmann 1 , T. Guillot 3 , M. S. Marley 41 University of California, Santa Cruz, 2 Tokyo Instute of Technology, Japan, 3 Observatoire de la Côte d’Azur, France, 4 NASA Ames Research Center.Presentaon Time: 10/7/2010 10:30 AM - 10:40 AMLocaon: Ballroom BCAbstract.Abstract: We compute grids of radiave-convecve model atmospheres for Jupiter, Saturn, Uranus, and Neptune over a range of intrinsic fluxes andsurface gravies. The atmosphere grids serve as an upper boundary condion for models of the thermal evoluon of the planets. Unlike previous work, wecustomize these grids for the specific properes of each planet, including the parcular chemical abundances and incident fluxes appropriate for each planet, asa funcon of solar system age. Using these grids, we compute new models of the thermal evoluon of the major planets in an aempt to match their measuredluminosies at their known ages, and compare these calculaons to previous work. For all planets, we employ simple "standard" cooling models that featureadiabac temperature gradients in the interior H/He and water layers, and an inially hot starng point for the calculaon of subsequent cooling. For Jupiter wefind a model cooling age 10% longer than previous work, a modest quantave difference. This may indicate that current models overesmate the temperaturesin the deep interior of the planet. For Saturn we find a model cooling age 20% longer than previous work. However, an addional energy source, such as that dueto helium phase separaon, is sll clearly needed. For Neptune, unlike in work from the 1980s and 1990s, we match the measured Teff of the planet with a modelthat also matches the planet's current gravity field constraints. This is predominantly due to advances in the high-pressure equaon of state of water. This mayindicate that the planet possesses no barriers to efficient convecon in its deep interior. However, for Uranus, our models exacerbate the well-known problemthat Uranus is far cooler than calculaons predict, which could imply strong barriers to interior convecve cooling.44.02: Flaening of Two-Layer Models of Rotang PlanetsAuthor Block: Gerald Schubert 1 , K. Zhang 2 , D. Kong 2 , J. D. Anderson 3 , R. Helled 11 UC, Los Angeles, 2 Exeter University, United Kingdom, 3 Jet Propulsion Laboratory (Rered).Presentaon Time: 10/7/2010 10:40 AM - 10:50 AMLocaon: Ballroom BCAbstract.Abstract: To a first approximaon, most planetary objects consist of a dense core region surrounded by a low-density envelope. The flaening of thecore-envelope interface and the surface can reveal important informaon about internal structure and rotaon. The flaening of the internal interface is alsoimportant for constraining the dynamics of moons in a liquid core. We determine the flaening of the core-envelope boundary and the surface for constantdensity layers. The flaening is calculated in two ways. One approach makes use of an exact semi-analycal soluon. A second approach is based on the theoryof figures valid to third order in the standard smallness parameter. We evaluate the accuracy of the approximate theory of figure soluons by comparing thesesoluons for first, second, and third order in the smallness parameter with the exact soluon. We find that the flaening at the core-envelope interface can besignificantly different from that at the planetary surface.44.03: Mechanisms Of Jet Formaon On The Giant PlanetsAuthor Block: Junjun Liu 1 , T. Schneider 11 Caltech.Presentaon Time: 10/7/2010 10:50 AM - 11:00 AMLocaon: Ballroom BCAbstract.Abstract: The giant planet atmospheres exhibit alternang prograde and retrograde jets of different speeds and widths, with an equatorial jet that isprograde on Jupiter and Saturn and retrograde on Uranus and Neptune. The jets are variously thought to be driven by differenal radiave heang of the upperatmosphere or by intrinsic heat fluxes emanang from the deep interior. But exisng models cannot account for the different flow configuraons on the giantplanets in an energecally consistent manner. Here a three-dimensional general circulaon model is used to show that the different flow configuraons can bereproduced by mechanisms universal across the giant planets if differences in their radiave heang and intrinsic heat fluxes are taken into account. Whether theequatorial jet is prograde or retrograde depends on whether the deep intrinsic heat fluxes are strong enough that convecon penetrates into the uppertroposphere and generates strong equatorial Rossby waves there. Prograde equatorial jets result if convecve Rossby wave generaon is strong and low-latudeangular momentum flux divergence owing to baroclinic eddies generated off the equator is sufficiently weak (Jupiter, Saturn). Retrograde equatorial jets result ifeither convecve Rossby wave generaon is weak or absent (Uranus) or low-latude angular momentum flux divergence owing to baroclinic eddies is sufficientlystrong (Neptune). The different speeds and widths of the off-equatorial jets depend, among other factors, on the differenal radiave heang of the atmosphereand the altude of the jets, which are vercally sheared. The simulaons have closed energy and angular momentum balances that are consistent withobservaons of the giant planets. They exhibit temperature structures closely resembling those observed, and make predicons about as-yet unobserved aspectsof flow and temperature structures. The transion to superrotaon as a funcon of drag parameters, baroclinicty, and strength of intrinsic heat fluxes isinvesgated systemacally through GCM simulaons.44.04: Unveiling Uranus' Clouds: New Observaons From Gemini-North N IFS And N IRIAuthor Block: Patrick G. J. Irwin 1 , N. A. Teanby 2 , G. R. Davis 3 , L. N. Fletcher 1 , G. Orton 4 , D. Tice 11 Oxford Univ., United Kingdom, 2 Bristol University, United Kingdom, 3 Joint Astronomy Centre, 4 Jet Propulsion Laboratory.Presentaon Time: 10/7/2010 11:00 AM - 11:10 AMLocaon: Ballroom BCAbstract: Observaons of Uranus were made in September 2009 with the Gemini-North telescope in Hawaii, using both the NIFS and NIRI instruments. Adapveopcs were used to achieve a spaal resoluon of approximately 0.1 arcsec.NIRI images were recorded with three spectral filters to constrain the overall appearance of the planet: J, H-connuum and CH4(long), and long slit spectra (1.49to 1.79 microns) were obtained with the slit aligned on Uranus’ central meridian. In addion, the NIFS instrument was used to acquire spectra from other pointson the planet, stepping the NIFS 3 x 3 arcsec field of view across Uranus’ disc. These observaons were combined to yield complete images of Uranus at 2040wavelengths between 1.476 and 1.803 microns with a spectral resoluon of 5000.The observed spectra along Uranus central meridian were analyzed with the NEMESIS retrieval tool and used to infer the vercal/latudinal variaon in cloudopcal depth. We find that the 2009 Gemini data perfectly complement our observaons/conclusions from UKIRT/UIST observaons made in 2006-2008 and showthat the north polar zone at 45N has connued to steadily brighten while that at 45S has connued to fade. The improved spaal resoluon of the Geminiobservaons compared with the non-AO UKIRT/UIST data remove many of the earlier ambiguies inherent in the previous analysis.Overall, Uranus appeared to be less convecvely acve in 2009 than in the previous 3 years, which suggests that now the equinox (which occurred in 2007) is

over the atmosphere is seling back into the quiescent state seen by Voyager 2 in 1986. However, one discrete cloud was captured in the NIFS observaons andwas esmated to lie at a pressure level of 300-400 mbar.44.05: Modeling Of The Uranian Atmosphere Using Near-infrared Spectra From Ir/spexAuthor Block: James Norwood 1 , N. Chanover 21 Jet Propulsion Laboratory, 2 New Mexico State University.Presentaon Time: 10/7/2010 11:10 AM - 11:20 AMLocaon: Ballroom BCAbstract: We present results from modeling the atmosphere of Uranus to reproduce near-infrared spectra. Our spectral dataset consists of spectra from 0.8-2.5μm (R = 1200), obtained using the instrument SpeX at NASA's Infrared Telescope Facility on Mauna Kea. These spectra were obtained over three nights each inSeptember 2006 and September 2007. During these observaons, we oriented the 0.5" × 15" spectrographic slit perpendicular to Uranus' central meridian,obtaining simultaneous spectral informaon from center to limb with each slit placement, while minimizing the range of latudes contribung to each spectrum.For this analysis we employed an adding-doubling code, modeling the Uranian atmosphere as a vercal series of homogeneous layers and solving primarily forthe pressure levels and opcal depths of the haze and cloud layers. With the observaons in our dataset, we have invesgated latudinal variaons in theatmospheric structure of Uranus, as well as temporal changes occurring between 2006 and 2007, most notably the fading of the polar collar at 45° S and theappearance of its counterpart at 45° N.This project was funded by a NASA Earth and Space Science Fellowship.44.06: Neptune From Keck: Tracking Down The ScaerersAuthor Block: Kathy Ann Rages 1 , H. Hammel 2 , I. de Pater 31 SETI Instute, 2 Space Science Instute, 3 UC-Berkeley.Presentaon Time: 10/7/2010 11:20 AM - 11:30 AMLocaon: Ballroom BCAbstract: In July 2004, disk-resolved images of Neptune were obtained in nine near-infrared filters using adapve opcs on the Keck 10-meter telescope onMauna Kea. Images in the H, J, and K' filters have been analyzed to determine the vercal structure of cloud-free porons of Neptune’s atmosphere at lowsouthern latudes. The observaons favor stratospheric haze models with substanal parcle charge(~32 electrons / μm diameter) and high producon rates(~6.5×10 -15 g cm -2 s -1 ), i.e. a large number of relavely small stratospheric haze parcles. Tropospheric (i.e. methane) cloud properes are less well determined,but there are indicaons that the methane cloud has substanal opcal depth (~4) and resides fairly deep, between about 1.8 and 1.95 bars; the depth of theopcally thick cloud at the base of the visible atmosphere is about 5 bars. While this atmospheric model was derived for regions of Neptune’s atmosphere whichappeared devoid of bright features, we have not found any region on Neptune which can be relied on to be free of local albedo variaons. Even latudes far fromthe major acvity centers (in 2004) at southern mid-latudes display localized brightness enhancements on scales of ~10° in longitude..This work was funded through the NASA Planetary Atmospheres program.44.07: Neptune's Global Deep Haze and its Depleted Methane at high Southern LatudesAuthor Block: Erich Karkoschka 11 Univ. of Arizona.Presentaon Time: 10/7/2010 11:30 AM - 11:40 AMLocaon: Ballroom BCAbstract: Neptune's HST-STIS image cube of 2003 gives an unprecedented ability to disnguish whether features seen in methane bands are due to haze andclouds or due to changes in the methane mixing rao.The global brightness asymmetry observed is caused by a depleon of methane at high southern latudes by up to a factor of 2.7, while the tropics have aconstant methane mixing rao of 0.04 +/- 0.01 up to the methane condensaon layer near 1.8 bars. The depleon indicates that methane-dry air sinking fromhigher altudes is enriched in methane more slowly than expected.The two bands just south of the equator and near -60 degrees latude have relavely low single scaering albedos, and they have Neptune's thinnest andthickest haze, respecvely. The laer one has already displayed an unusual shape in Voyager images of 1989.All observaons are consistent with a uniform haze layer extending two scale heights down from the methane condensaon level. The depleon of methane andthe deep uniform haze on Neptune are quite similar to results about Uranus (Karkoschka and Tomasko 2009, Icarus 202, 287).In deep methane bands, short-lived cloud features near the tropopause dominate the view. The methane abundance above these clouds was constant throughouteach hemisphere, 0.0026 and 0.0017 km-am in the southern and northern hemisphere, respecvely, in perfect agreement with Sromovsky et al. (2001, Icarus 149,459).While HST images have shown changes in the distribuon of clouds over me, they also indicate remarkable stability of some features. New analysis of Voyagerimages reveals other subtle features associated with these stable features that may give important insights about interacons between Neptune's interior and itsobservable atmosphere.This research was supported by NASA grant NNX08AE74G and by STScI grants HST-GO-09725.01-A and HST-AR-11259.01-A.44.08: Meridional Variaons of Stratospheric Temperatures and Hydrocarbon Abundances in Neptune’s StratosphereAuthor Block: Thomas K. Greathouse 1 , J. Moses 2 , T. Encrenaz 3 , G. Orton 4 , H. Hammel 2 , M. Ricther 5 , J. Lacy 61 Southwest Research Instute, 2 Space Science Instute, 3 Observatory de Paris, France, 4 Jet Propulsion Laboratory, 5 University of California at Davis, 6 Universityof Texas at Ausn.Presentaon Time: 10/7/2010 11:40 AM - 11:50 AMLocaon: Ballroom BCAbstract: Using TEXES - the Texas Echelon cross Echelle Spectrograph - mounted on the GEMINI North 8-m telescope in October 2007, we mapped the spaalvariaon of H 2 , CH 4 , C 2 H 2 and C 2 H 6 thermal infrared emissions on Neptune. We employ the high spectral and spaal resoluon mid-infrared ground-basedobservaons of the ν 4 band of methane and the S(1) line of molecular hydrogen to retrieve detailed informaon on Neptune’s stratospheric vercal andmeridional thermal structure. We then use the inferred temperatures to model the emissions of C 2 H 2 and C 2 H 6 in order to derive stratospheric mixing raos as afuncon of pressure and latude. At R=80,000, these observaons provide the highest spectral resoluon of any spaally-resolved thermal-infrared spectra todate. As such, they offer a unique glimpse into the state of Neptune’s stratosphere in October 2007. The results are compared with a radiave seasonal model ofNeptune to place the observaons in some context.

We also present the first high resoluon observaons of C 2 H 4 in Neptune’s stratosphere. The spectra, retrieved in June 2003 using TEXES mounted on the NASAIRTF, was never published due to the lack of observaons capable of first inferring the temperature of Neptune’s stratosphere. We now present an analysis of theobservaons modeled using an average of the inferred temperature profiles retrieved from the 2007 observaons.This work was funded by NASA PAST grant NNX08AW33G and NASA PATM grant NNX08AL95G.44.09: The Physical Structure and Chemical Composion of Neptune's Atmosphere from Combined Herschel and Spitzer Spectral ObservaonsAuthor Block: Glenn S. Orton 1 , R. Moreno 2 , E. Lellouch 2 , L. N. Fletcher 3 , P. Hartogh 4 , H. Feuchtgruber 5 , C. Jarchow 4 , T. Cavalie 6 , L. Lara 7 , M. Rengel 4 , A.Gonzalez 4 , M. Line 8 , Herschel HssO Key Project Team1 JPL, 2 Observatoire de Paris, France, 3 University of Oxford, United Kingdom, 4 Max Planck Instute for Solar System Research, Germany, 5 Max Planck Instutefor Extraterrestrial Research, Germany, 6 Universite de Bordeaux, France, 7 Instuo de Astrofisica de Andalucia, Spain, 8 California Instute of Technology.Presentaon Time: 10/7/2010 11:50 AM - 12:00 PMLocaon: Ballroom BCAbstract: We report the analysis of thermal-infrared observaons of Neptune's disk by experiments on the Spitzer and Herschel Space Telescopes. The Spitzerdata were obtained by the IRS instrument at wavelengths between 5.2 and 21.5 microns at a spectral resolving power, R ~ 70, and at wavelengths between 10and 21.5 microns at R ~ 600. The Herschel observaons were made by the PACS instrument's integral field spectrometer between 51 and 220 microns at R ~ 3000,within the framework of the Key Project, ``Water and Related Chemistry in the Solar System''. Our analysis is set in the context of lower-resoluon spectraobtained by the ISO LWS and SWS spectrometers covering wavelengths between 28 and 185 microns and the Akari IRC spectrometer covering wavelengthsbetween 5.8 and 13.3 microns at R ~ 40, together with spaally resolved ground-based studies of thermal emission. Our results indicate that that global-meantropospheric temperatures are lower than those derived from the Voyager radio-occultaon experiment, and consistent with the ISO results. Preliminary results(Lellouch et al. 2010 Astron. & Astrophys. In press) indicate that the D/H rao is 4.5±1.0 x 10 -5 , consistent with enrichment of deuterium over the protosolarvalue, and the stratospheric column of H 2 O is 2.1±0.5 x 10 14 cm -2 . The peak CH 4 abundance in the stratosphere is orders of magnitude larger than if it were coldtrappedbelow the mean ~54-Kelvin tropopause minimum temperature - but consistent with injecon from Neptune's warmer south polar region. Good fits to avariety of other stratospheric emission features are obtained: CO, CH 3 , CO 2 , C 2 H 2 , C 2 H 4 , C 2 H 6 , C 3 H 8 , C 4 H 2 . It is also possible to obtain a beer fit to a spectralregion dominated by C 2 H 6 emission by adding 50-100 ppt of C 6 H 6 .

Session Number: 45Session Title: Mars Atmosphere II: ModelingSession Type: Oral45.01: Self-Consistent Model of an Ozone Layer on Ancient MarsAuthor Block: Jusn Deighan 1 , R. E. Johnson 11 University of Virginia.Presentaon Time: 10/7/2010 10:30 AM - 10:40 AMLocaon: Ballroom DAbstract.Abstract: When modeling thick, early Maran atmospheres, it is oen assumed that the mixing raos of CO2, O2, CO, and O3 were similar to thoseobserved today. Even when photochemical models are used to determine the composion of past atmospheres, a temperature profile similar in form to thatcurrently observed is oen imposed as a simplificaon. However, neither of these may be accurate assumpons. A 1D line-by-line radiave-convecve modelcoupled self-consistently with a simple photochemical model is presented here to explore the relaxaon of these assumpons. A primary consequence is thepossibility of a substanal O3 layer on ancient Mars. Areas of impact considered include the loss of H2O to space, an enhanced greenhouse effect, inhibion ofCO2 condensaon in the stratosphere, and reduced surface UV.45.02: 3d Modeling Of The Early Maran Climate And Water CycleAuthor Block: Francois Forget 1 , R. Wordsworth 1 , E. Millour 1 , J. Madeleine 1 , V. Eymet 2 , R. M. Haberle 31 LM D, IPSL, France, 2 LAPLACE, France, 3 NASA Ames Research Center.Presentaon Time: 10/7/2010 10:40 AM - 10:50 AMLocaon: Ballroom DAbstract: Missions to Mars regularly reveal new evidence suggesng that the early environmental condions were very different from today, with liquid waterflowing on the surface. Which climac or geophysical processes enabled such condions? Were the condions episodically suitable for liquid water, or stable onlong me-scales? Can we explain the distribuon of the valley networks and other ancient landforms? To help understand these key issues, we have developed anew 3D global climate model (GCM). We wish to understand the possible climate that would occur on Mars if 1) the solar luminosity is decreased by 25%, as wasthe case 3.8 billion years ago, and 2) the surface pressure is increased up to several bars (no other greenhouse gases than CO2 and H2O are assumed to bepresent). We paid parcular aenon to the radiave transfer in dense CO2 atmospheres, where collision-induced absorpon can be significant. We found thatprevious parameterisaon of this phenomenon overesmated the greenhouse effect, and derived a new approach based on recent studies.We analyse the effects of clouds and water vapour on the surface temperature and discuss the likely nature of the early hydrological cycle. CO2 ice clouds form inthe middle atmosphere above 10 km. They cause significant surface warming through their scaering greenhouse effect. However, their effect is partlycounterbalanced by the the albedo effect of the water ice clouds, which form much lower. Overall, it is difficult to achieve annual mean surface temperaturesignificantly above 0°C anywhere on the planet for pressures below 2 bar. Nevertheless, temperatures above freezing can occur, especially in the lower plains,due to atmospheric adiabac warming. On such a planet, the water cycle and precipitaon strongly depend on the amount of water available at the surface, thelocaon of the main surface reservoirs and the obliquity.45.03: High-altude CO2 Clouds On Mars: A View From MEx Observaons, The LMD MGCM, And Convecve Potenal CalculaonsAuthor Block: Anni Maaanen 1 , F. Montmessin 2 , B. Gondet 3 , H. Hoffmann 4 , F. Scholten 5 , F. Gonzalez-Galindo 6 , A. Spiga 7 , F. Forget 7 , E. Hauber 4 , J. Bertaux 1 , J.Bibring 3 , G. Neukum 81 LATM OS (Laboratoire Atmospheres, Milieux, Observaons Spaales), Université Versailles St Quenn, France, 2 LATM OS (Laboratoire Atmospheres, Milieux,Observaons Spaales), Université Versailles St Quenn, France, 3 Instut d'astrophysique spaale, France, 4 German Aerospace Center (DLR), Germany,5 German aerospace center (DLR), Germany, 6 Instuto de Astrosica de Andalucía (CSIC), Spain, 7 Laboratoire de météorologie dynamique, Université Pierre etMarie Curie, France, 8 Freie Universitaet, Germany.Presentaon Time: 10/7/2010 10:50 AM - 11:00 AMLocaon: Ballroom DAbstract.Abstract: We will summarize 3.5 Maran years (Mars Years 27-30) of high-altude CO2 cloud data from MEx/OMEGA and selected results fromMex/HRSC. The 3-year dataset shows that the equatorial cloud acvity is centered around the northern summer solsce with a pause at the aphelion, and thattheir appearance is limited in latude and longitude. HRSC-measured altudes and cloud speeds provide a rare dataset for comparison with GCMs. A comparisonwith the LMD Mars Global Climate Model shows a good agreement between the model-predicted winds and those observed by the HRSC. The LMD-MGCMpredicts a strong diurnal variaon of temperature at the cloud observaon altudes due to the propagaon of the diurnal thermal de. The coldest temperaturesin the near-equator cloud altude range (60-85 km) are observed towards the end of the aernoon, whereas the warmest temperatures are found in the earlymorning hours. Most of the observed clouds are cirrus-type, filamented clouds, but some OMEGA-observed clouds exhibit round, clumpy structures that havebeen suggested to be of convecve origin. We asses the plausibility of the hypothesis of mesospheric convecon in light of observaons and theorecalConvecve Available Potenal Energy calculaons. Esmates of convecve potenal and vercal velocies based on observed cloud properes suggest that theconvecve clouds could most likely be clusters of smaller scale convecve updras. SPICAM stellar occultaons have revealed large supersaturaons at highaltudes: to aain the esmated values of CAPE and vercal velocity, most probably only moderate deviaons from saturaon are required. Based on nucleaonmodeling, such deviaons may imply cloud formaon via heterogeneous nucleaon onto small condensaon nuclei.45.04: Simulaon of the Equatorial CO2 Ice Clouds on Mars using a General Circulaon ModelAuthor Block: Takeshi Kuroda 11 Instute of Space and Astronaucal Science, Japan Aerospace Exploraon Agency, Japan.Presentaon Time: 10/7/2010 11:00 AM - 11:10 AMLocaon: Ballroom DAbstract: The OMEGA and HRSC onboard the Mars Express have observed the CO 2 ice clouds above the height of ~60 km of equatorial atmosphere on Mars. AMars General Circulaon Model (MGCM) developed in LMD predicts that the equatorial temperature can be lower than the CO 2 condensaon level at that height,especially two short periods before and aer the aphelion, when the CO 2 ice clouds were observed. We introduced a CO 2 ice cloud formaon scheme into ourMGCM called DRAMATIC (Dynamics, RAdiaon, MAterial Transport and InteraCons between them, formerly CCSR/NIES/FRCGC), and simulated the distribuonsof the clouds. In the preliminary results the CO 2 ice clouds were formed in the equatorial region at ~60km height in northern spring and summer, at ~70km heightin northern fall and winter, with maximum mass mixing rao of ~25 ppm in the daily average. In this presentaon we will show the vercal and seasonalvariaons of simulated CO 2 ice clouds and the dependence of cloud formaons on the local me, as well as the discussions in comparison with the observaons.Acknowledgement: This work is supported by the Research Fellowships of the Japan Society for the Promoon of Science (JSPS) for Young Sciensts, Grant-in-Aid

20-1761.45.05: Seasonal Variability Of Eddies In The Maran Atmosphere Simulated By MarsW RFAuthor Block: Huiqun Wang 1 , M. I. Richardson 2 , A. D. Toigo 31 Harvard-Smithsonian Center For Astrophysics, 2 Ashima Research, 3 Cornell.Presentaon Time: 10/7/2010 11:10 AM - 11:20 AMLocaon: Ballroom DAbstract.Abstract: Observaons indicate that traveling waves in the Maran atmosphere have disnct seasonality and are greatly influenced by major duststorms. In the northern hemisphere, traveling waves in the first few scale heights appear weakest around the winter solsce and suppressed following the onsetof a major dust storm, and those at higher levels exhibit different behavior. These waves are very important for eddy transport and flushing dust stormdevelopment. We have performed a series numerical simulaons using the MarsWRF model to examine the general seasonality and variability of variousplanetary waves and the effects of major dust storms. We will present results derived from mul-year simulaons where dust distribuons are specified torepresent both the background annual cycle and major dust storms at various solar longitudes. This experiment will help us beer understand the observedbehavior of frontal events and the response of various wave modes to major dust storm during different season. The experiment may also provide hint for beersimulang flushing events - an important link in the global dust cycle. This study is supported by NASA Planetary Atmospheres program.45.06: Integraon of Mars Global Surveyor Observaons of the MY25 Planet-encircling Dust Storm on Mars: Implicaons for Atmospheric Modeling andDynamicsAuthor Block: John Noble 1 , R. M. Haberle 2 , R. J. Wilson 3 , J. R. Barnes 4 , A. F. C. Bridger 1 , J. L. Hollingsworth 2 , J. R. Murphy 5 , M. A. Kahre 2 , B. A. Cantor 6 , M. C.Malin 6 , M. D. Smith 71 NASA/Ames Research Center, San Jose State University, 2 NASA/Ames Research Center, 3 Geophysical Fluid Dynamics Laboratory, NOAA, 4 Oregon StateUniversity, 5 New Mexico State University, 6 Malin Space Science Systems, 7 NASA Goddard Space Flight Center.Presentaon Time: 10/7/2010 11:20 AM - 11:30 AMLocaon: Ballroom DAbstract: We have synthesized all available Mars Global Surveyor (MGS) observaons of the MY 25 (2001) global dust storm on Mars in order to beerunderstand the underlying dynamics of storm iniaon and expansion, and to develop a qualitave and quantave descripon of storm evoluon that may beused to constrain both esmates of horizontal dust distribuon and modeling of storm growth. MGS data include Mars Orbiter Camera (MOC) daily globalweather maps, MOC dust (visible) opcal depth measurements, TES measurements of atmospheric temperature and 9-μm dust opacity, and Mars Horizon SensorAssembly (MHSA) measurements of middle atmosphere temperatures. Together these data allow for the juxtaposion of temperature and opacity fields withvisual imagery to enable a more comprehensive assessment of storm development.FFSM-filtered (Fast Fourier Synopc Mapping) TES 3.7 hPa temperature data show the presence of transient baroclinic eddies in the longitude sector 0-60E at 60Swith a period of about two sols. Combining these data with MOC visible storms has revealed a correlaon between eastward propagang cold anomalies and theemergence/progression of storms along similar trajectories.We hypothesize that construcve interference of these eddies with addional circulaon components may have contributed to the periodic growth of local stormsand the expansion into regional storms at ~Ls=184°.Known limitaons of TES observaons result in significant spaal gaps in data, especially at high latudes and in regions with very high dust opacity. Wesupplement MGS data with MGCM-derived opacity esmates that are interpolated from simulaons with varied fixed opacies that yield brightness temperaturesbrackeng TES surface temperature observaons. We have produced 2 gridded datasets (column opcal depth evoluon, and regions of acve dust liing), andare using these data as input into the NASA/NOAA Mars General Circulaon Model (MGCM).45.07: Simulang Dust Storms on Mars with Variable Surface Dust Abundance and Parcle Size Distribuons.Author Block: Claire E. Newman 1 , C. Lee 1 , Y. Lian 1 , M. I. Richardson 1 , A. D. Toigo 21 Ashima Research, 2 Applied Physics Laboratory, Johns Hopkins University.Presentaon Time: 10/7/2010 11:30 AM - 11:40 AMLocaon: Ballroom DAbstract: To date, no numerical model of the maran atmosphere has fully captured the range and variability of the large dust storms that occur duringsouthern spring and summer. A major difficulty is properly esmang the abundance and size distribuon of sand and dust on the surface and how this varieswith me.Storm onset should occur in regions where BOTH the surface wind stress exceeds some size-dependent liing threshold AND sufficient parcles of this size arepresent, with a size-dependent injected dust flux. Once injected, the atmospheric size distribuon is affected by size-dependent sedimentaon and scavenging(forming cloud condensaon nuclei for CO2 and water ice), and in turn affects radiave transfer, interacons with the CO2 and water cycles, and the evolving sizedistribuon of surface dust. Dust storm decay occurs more rapidly than simulated in models, suggesng that scavenging reduces dust opacity more rapidly,and/or that source regions are depleted of dust parcles during the largest storms, causing liing to cease.We will examine the impact on storms produced of varying first the overall abundance then size distribuon of surface dust parcles. We will first assume asingle parcle size, inialize the enre planet with uniform dust cover, and allow liing and deposion to redistribute the surface dust distribuon over manyyears. We will then assume unlimited surface dust and specify size-dependent injecon rates chosen to reproduce the observed atmospheric size distribuon. Wewill conclude by discussing the difficules of allowing both the surface dust abundance and size distribuon to vary simultaneously in the absence of strongerobservaonal constraints.45.08: Impacts Of Radiavely-Acve Aerosols On Mars’ Current Climate: Simulaon Results With The N ASA ARC Mars GCMAuthor Block: Jeffery L. Hollingsworth 1 , M. A. Kahre 2 , R. M. Haberle 1 , F. Montmessin 3 , B. Herin 4 , F. Laamoumi 4 , R. J. Wilson 5 , J. Schaeffer 61 NASA Ames Research Center, 2 BAER Instute/NASA Ames Research Center, 3 Laboratoire Atmospheres Mileux, Observaons Spaales (LATM OS), France,4 ISAE-SUPAERO, France, 5 NOAA/GFDL, 6 Perot Systems/NASA Ames Research Center.Presentaon Time: 10/7/2010 11:40 AM - 11:50 AMLocaon: Ballroom DAbstract.Abstract: Recent upgrades to the NASA Ames Research Center (ARC) Mars general circulaon model (GCM) include a fundamentally new andmodernized radiave transfer package which permits radiave effects and interacons of suspended atmospheric aerosols (e.g., water ice clouds, water vapor,dust, and their mutual interacons) to influence the net diabac heang rate within the atmosphere. Such aerosols are crically important in determining thenature of atmospheric thermal structure and hence the overall climate of the planet. Our Mars GCM simulaons indicate that radiavely-acve water ice cloudsprofoundly affect the seasonal and annual mean climate in a variety of ways. In parcular, preliminary results suggest that the bulk thermal structure andresultant (i.e., balanced) circulaon paerns are strongly modified near the surface and alo. Generally speaking, we find a bulk warming of the atmosphere in

upper layers, a cooling of the atmosphere in the lower and near-surface regions, and, increases in the mean pole-to-equator temperature contrasts (i.e., strongermean polar vorces). A variety of results from our baseline and control simulaons (i.e., where the radiave/physical effects are examined in isolaon and whencombined) will be presented. Comparisons with MGS/TES and MRO/MCS measurements indicate beer agreement between the model's simulated climatecompared to that observed. Using a state-of-the-art Mars GCM, these results highlight important effects radiavely-acve aerosols have on physical anddynamical processes acve in the current climate of Mars.45.09: Mars MITgcm and Argon in the Maran AtmosphereAuthor Block: Yuan Lian 1 , M. Richardson 2 , C. Newman 1 , C. M. Lee 1 , A. Toigo 3 , M. Mischna 4 , J. Campin 51 Ashima Research, 2 Caltech, 3 Cornell University, 4 JPL, 5 Massachuses Instute of Technology.Presentaon Time: 10/7/2010 11:50 AM - 12:00 PMLocaon: Ballroom DAbstract.Abstract: Mars Odyssey observed that Argon abundance was greatly enhanced during winter solsce at southern pole in Maran atmosphere. TheArgon enrichment factor can reach as high as 6-7. Several studies have examined the mechanisms that cause such enrichment. Current Mars GCMs can producethe seasonal variaon of Argon enhancement to some degree. However, they only reproduce aspects of the trend and generally predict an enhancement factor ofabout 2-3 mes smaller than observed. To address the problem of Argon transport, we have developed a new Mars GCM based on the MITgcm, a state-of-artglobal circulaon model, and the Mars atmospheric physics as implemented in PlanetWRF. The Mars MITgcm uses cube-sphere grid finite volume numerics andhas several opons for the tracer advecon scheme. The Mars MITgcm includes topography, a subsurface scheme, a planetary boundary layer, atmospheric dustdistribuon, radiave transfer and a CO2 cycle. Our model results show close agreement with the annual variability of pressure measured at the Viking Landersites, as well as matches to MCS temperature profiles. For Argon, unlike prior studies, we tested various tracer advecon schemes and found significant variaonsdepending on the quality of the schemes used. We suggest that much of the variaons between different prior modeling studies is plausibly related to differencesin the advecon schemes used. We found that, at 2.5-degree grid resoluon, advecon schemes with flux limiters provide good match to the Argon enhancementfactor for observaons for 75 degree poleward in southern winter. Preliminary diagnoses of model results suggest that the polar Argon enhancement duringsummer solsce results from: first, Argon is transported poleward and trapped by polar vortex; second, the enhancement factor gets larger when more CO2 iscondensed. Our work thus far suggests that the Mars MITgcm is ready for solving future scienfic quesons.

Session Number: 46Session Title: Lutetia and Other Main-Belt AsteroidsSession Type: Oral46.01: Pre-flyby Determinaon Of The Size, Shape, Pole, Density, And Satellites Of (21) Lutea From Ground-based ObservaonsAuthor Block: William J. Merline 1 , B. Carry 2 , J. D. Drummond 3 , A. Conrad 4 , C. R. Chapman 1 , M. Kaasalainen 5 , C. Leyrat 2 , H. A. Weaver 6 , P. M. Tamblyn 1 , J. C.Christou 7 , C. Dumas 8 , A. Kryszczynska 9 , F. Colas 2 , L. Bernasconi 10 , R. Behrend 11 , F. Vachier 2 , M. Polinska 12 , R. Roy 13 , R. Naves 14 , R. Poncy 15 , P. Wiggins 161 Southwest Research Inst., 2 Obs. Paris, France, 3 AFRL, 4 Keck Obs., 5 Tampere Univ. of Technology, Finland, 6 JHU/APL, 7 Gemini Obs., 8 ESO, Chile, 9 AdamMickiewicz Univ., Poland, 10 Les Engarouines Obs., France, 11 Geneva Obs., Switzerland, 12 Adam Mickiewicz, Poland, 13 Blauvac Obs., France, 14 Obs. Montcabre,Spain, 15 Le Cres Obs., France, 16 Wiggins Obs..Presentaon Time: 10/7/2010 10:30 AM - 10:40 AMLocaon: Ballroom EAbstract: Prior to the flyby of (21) Lutea by Rosea, we iniated a campaign of observaons to characterize the system, primarily using ground-basedadapve opcs (AO) on large telescopes, including Keck, Gemini, and VLT. We coordinated these efforts with HST observaons (Weaver et al. 2010 A&A in press)made in support of the Rosea ALICE UV spectrometer. Lutea was 0.10" in diameter, allowing disk-resolved imaging with AO and tracking of its shape duringrotaon. We modeled the shape using both a triaxial-ellipsoid model (Drummond et al. 2010 A&A submied) and a full 3D radius-vector model (Carry et al. 2010A&A submied, in which we combine AO imaging with decades of lightcurve data to produce an improved 3D model using our inversion algorithm KOALA). Toovercome limitaons in each model, we combined the best aspects of each to produce our best-esmate 3D shape model, a hybrid having ellipsoid-equivalentdimensions of 124 x 101 x 93 km (± 5 x 4 x 13 km) and effecve diameter 105 ± 7 km. We find the spin axis of Lutea to lie within 5 deg of [long, lat (52,-6)] or[RA DEC (52,+12)], and determine an improved sidereal period of 8.168270 ± 0.000001 h. We predicted the geometry of Lutea during the flyby and showed thatthe southern hemisphere would be in seasonal shadow at that me. The model suggests the presence of several concavies that may be associated with largeimpacts. Using two separately determined masses and the volume of our hybrid model, we esmate a density of 3.5 ± 1.1 or 4.3 ± 0.8 g/cc, favoring an enstatechondritecomposion for this large M-type asteroid, although other composions are formally allowed. No satellites larger than 1 km diameter were detected inthe AO-data over a significant fracon of the Hill sphere (10-240 asteroid radii).46.02: The KOALA Shape Modeling Technique Validated at (21) Lutea by ESA Rosea MissionAuthor Block: Benoit Carry 1 , W. J. Merline 2 , M. Kaasalainen 3 , A. Conrad 4 , J. D. Drummond 5 , C. Dumas 6 , M. Kueppers 7 , OSIRIS Instrument Team1 LESIA, Paris Observatory, France, 2 Southwest Research Instute, 3 Tempere University of Technology, Finland, 4 Keck Observatory, 5 Starfire Opcal Range,6 European Southern Observatory, Chile, 7 ESAC, European Space Agency, Spain.Presentaon Time: 10/7/2010 10:40 AM - 10:50 AMLocaon: Ballroom EAbstract: We recently developed a shape reconstrucon algorithm, dubbed KOALA (Kaasalainen, IPI 2010; Carry et al., Icarus 2010), which allows thedeterminaon of the size, shape, and spin properes of asteroids from a combined data set of disk-resolved images, opcal lightcurves, and stellar occultaons.Using adapve opcs (AO) imaging systems on the Keck and VLT telescopes, we acquired more than 300 images of the main-belt asteroid (21) Lutea in 2007and 2008. We combined these images with 50 lightcurves spanning some 48 years and including data taken almost up unl the me of flyby. We produced a 3Dshape model of Lutea and determined the spin pole and rotaon rate (Carry et al., submied to A&A).On 2010 July 10, the Internaonal Rosea Mission of the European Space Agency successfully encountered (21) Lutea. The images recorded by the OSIRIScamera on-board Rosea revealed our shape predicon to be accurate. We will present the KOALA (Knied Occultaon, Adapve-opcs, and Lightcurve Analysis)method, and a comparison of our shape model with the high-resoluon images acquired by Rosea during the flyby.46.03: Pre-Rosea Composional Studies of Asteroid 21 LuteaAuthor Block: Clark R. Chapman 1 , W. J. Merline 1 , B. Carry 2 , H. A. Weaver 3 , A. Conrad 4 , J. D. Drummond 51 Southwest Research Inst., 2 Paris Observatory, France, 3 JHU/APL, 4 Keck Observatory, 5 AFRL.Presentaon Time: 10/7/2010 10:50 AM - 11:00 AMLocaon: Ballroom EAbstract.Abstract: On 10 July 2010, Rosea successfully flew by the large main-belt asteroid 21 Lutea, providing a rare chance to compare close-up, spaallyresolved observaons and composional interpretaons with the lengthy, detailed record of Earth-based telescopic data. Lutea (and two other asteroids)originally defined the M taxonomic type (Zellner &amp; Gradie 1976, AJ 81, 262). This mnemonic for "metal" never exclusively meant "iron core," but includedenstate chondrites (EC), which are colored by metal grains. In the mid-1990s, some M-types (W's) were found to have 3 micron absorpon bands indicanghydraon; Rivkin et al. (2000 Icarus 145, 351) originally included Lutea in this class. During four decades, Lutea has been observed by radiometry, polarimetry,lightcurve photometry, spectrophotometry (UV into mid-IR), thermal IR, radar, and direct imaging. Lutea's esmated mass, size, and shape tend to rule out low(carbonaceous chondrite) or high (nickel-iron) densies, but are not definive. Relavely dense, high-albedo CV and CO chondrites were suggested as analogs forLutea (cf. Barucci et al. 2005 A&amp;A 430, 313) but are marginal or ruled out by spectral traits that define the M/W types and separate them from C-like types.W's are uncommon but not extremely rare in the main belt, so one would expect sampling by meteorites, yet the only hydrated ECs are clasts within the unusualKaidun meteorite. If Lutea is not a hydrated EC, then it may be either (a) not significantly hydrated, (b) masked by unknown surface properes analogous tospace weathering, (c) a mixture of known meteorite types (like the 2008 TC3 = Almahata Sia meteorite), or (d) an unknown or extreme kind of meteorite, likeAllende but with a superabundance of CAIs. Since Rosea's remote-sensing techniques resemble those employed from Earth, it may not fully resolve theseissues.46.04: 21 Lutea: Groundbased Near-infrared Spectroscopy Prior The Rosea FlybyAuthor Block: Mirel Birlan 1 , A. Nedelcu 2 , P. Vernazza 3 , R. Binzel 4 , B. Carry 5 , F. DeMeo 6 , A. Barucci 6 , M. Fulchignoni 61 IM CCE Observatoire de Paris, France, 2 Astronomical Instute of the Romanian Academy, Romania, 3 Research and Scienfic Support Department, ESTEC,Netherlands, 4 4Department of Earth, Atmospheric, and Planetary Sciences, M IT, 5 LESIA, Observatoire de Paris, France, 6 LESIA, Observatoire de Paris, France.Presentaon Time: 10/7/2010 11:00 AM - 11:10 AMLocaon: Ballroom EAbstract: The Roseta mission flyby of the asteroid 21 Lutea was scheduled for July 10, 2010 and the event was accomplished with a brilliant success. 21Lutea has an “esmated” diameter of (98.3 ± 5.9) km and is the largest body in the main-belt ever visited unl now by a space mission. The asteroid is locatedin the inner part of the main belt, in an orbit with low eccentricity and inclinaon (a=2.4348 a.u., e=0.16, i=3°.06). The large amount of colors and spectral data ofLutea, and the polarimetric and radiometric albedoes are giving puzzling results, with non-unique soluon of the asteroid taxonomy.We present near-infrared observaons in the 0.8-4 µm spectral range performed during the last opposion in 2010, a few months before the flyby of the Rosea

spacecra. Our observaons were obtained with SpeX/IRTF in remote observing mode from CODAM - Paris Observatory in March 1 and 2, April 15, and May 16,2010. The data of March and May were obtained in remarkable weather condions (humidity between 1 and 4% and no wind). Three spectra in Prism mode (0.8-2.5 micron) and four spectra in LXD mode (2.2-3.8 micron) will be presented together with the physical ephemeris of the asteroid. We reached a SNR of 200 inPrism mode and of about 80 in LXD mode. The North Pole geometry of the object covers almost all latudes between +90° and -30°.These high S/N spectra show very important spectral homogeneity for Lutea. The spectra are flat and independent of the Lutea’s rotaonal phase. In the 0.8-1.6 micron, 1.6-2.4 micron and 2.8-3.3 micron wavelength ranges, we do not see any absorpon band at the 0.5% level. This implies a dry surface. This impliesalso that signature of silicates such olivine and iron-rich pyroxenes are not present on the asteroid surface.46.05: Characteriscs of Known Triple Asteroid Systems in the Main BeltAuthor Block: Franck Marchis 1 , J. Berthier 2 , K. J. Burns 1 , P. Descamps 2 , J. Durech 3 , J. P. Emery 4 , J. E. Enriquez 5 , V. Lainey 2 , A. E. Reiss 5 , F. Vachier 21 SETI/UC-Berkeley, 2 IM CCE, France, 3 Astronomical Instute, Charles University, Czech Republic, 4 University of Tennessee, 5 SETI Instute.Presentaon Time: 10/7/2010 11:10 AM - 11:20 AMLocaon: Ballroom EAbstract: Since the discovery of “Sylvia Remus II” [1], around the binary asteroid (87) Sylvia [2] using the VLT/NACO instrument, the number of known triplesystems increased significantly. Using the same instrument, a second moonlet was discovered around the binary (45) Eugenia [3] in 2007 [4]. Using an improvedW.M. Keck II AO system, [5] announced the discovery of two 3 & 5-km moons orbing the M-type asteroid (216) Kleopatra and more recently, [6] revealed thepresence of two ny 4-km moons around the C-type (93) Minerva. 3749 Balam is a different triple asteroid system whose existence was suggested by combininglightcurves and AO observaons [7].The properes of these triple systems have been derived individually and published recently [1, 8,9,10]. We will review and contrast their characteriscs,including the orbital parameters of the satellite orbits, the size and shape of the primary and the satellites, their taxonomic classes, their bulk densies, and theirages. The goal of this study is to uncover clues concerning the formaon and evoluon of these mini-planetary systems.The Naonal Science Foundaon supported this research under award number AAG-0807468.1. Marchis et al. Nature 20052. Brown et al., IAU 7588, 20013. Merline et al. Nature 401, 19994. Marchis et al. IAU 1073, 20075. Marchis et al. IAU 8980, 20086. Marchis et al., IAU 9069, 20097. Marchis et al., IAU 8928, 20088. Marchis et al., A Dynamical Soluon of the Triple Asteroid System (45) Eugenia , Icarus in press, 20109. Descamps et al, Triplicity and Physical Characteriscs of Asteroid 216 Kleopatra Icarus, in revision, 201010. Marchis et al., Triplicity and Physical Characteriscs of the main-belt Asteroid (93) Minerva, Icarus submied 201046.06: (6) Hebe Really is the H Chondrite Parent BodyAuthor Block: William Boke 1 , D. Vokrouhlicky 2 , D. Nesvorny 1 , L. Shrbeny 31 Southwest Research Inst., 2 Charles U., Czech Republic, 3 Imperial College, United Kingdom.Presentaon Time: 10/7/2010 11:20 AM - 11:30 AMLocaon: Ballroom EAbstract.Abstract: In the 1990's, several authors argued that (6) Hebe, a 200 km diameter asteroid, was the source of the H chondrites (HCs). They favored itover other candidate asteroids because: (i) Hebe has the right spectroscopic signature for HCs (e.g., S (IV) class), (ii) it is located near the J3:1 mean moon andnu6 secular resonances, both key transportaon routes for delivering material to Earth, and (iii) Hebe is sufficiently large that cratering events could directlyinject HCs into the J3:1 and nu6 resonances. By the 2000's, though, it became increasingly clear that Yarkovsky thermal forces provide sufficient mobility tometeoroids that asteroid families far from key resonances could sll dominate the delivery flux. This weakened (ii)-(iii); Hebe has no observed family, and the CREages for HCs peak near 7-8 Ma rather than at 1-2 Ma. New collisional, dynamical, and meteorical work, however, allowed us to re-evaluate the situaon. (a) Ar-Ar shock degassing ages are frequently produced by cratering events on large asteroids. The HCs have such ages ranging from nearly today to 4.5 Ga. If the HCswere coming from an asteroid family, few ages should exist between now and the age of the family-forming event. (b) Cratering events on Hebe should producesteep fragment distribuons, thereby creang numerous meteoroids without producing an detected family. (c) The 7-8 My CRE age peak among HCs is bestexplained by Hebe's meteoroids being pummeled by ejecta from the 8.2 Ma Veritas family-forming event. L and LL meteoroids, thought to come from the Gefionand Flora families, respecvely, are out of range of Veritas ejecta. (d) Our new meteoroid source predictor model shows of the 6 HC falls with solid orbits, 3 comefrom the J3:1 and 3 come from the nu6 resonance. These results are consistent with Hebe's locaon.46.07: Space Weathering of Small Koronis Family MembersAuthor Block: Crisna A. Thomas 1 , A. S. Rivkin 2 , D. E. Trilling 1 , M. Enga 1 , J. A. Grier 31 Northern Arizona University, 2 JHU-APL, 3 Planetary Science Instute.Presentaon Time: 10/7/2010 11:30 AM - 11:40 AMLocaon: Ballroom EAbstract.Abstract: Oen debated topics in asteroid science are the space weathering process and its implicaons for the relaonships between S- and Q-typeasteroids and ordinary chondrite meteorites. Q-type asteroids have been shown to display the best spectral match to ordinary chondrites (McFadden et al. 1985).While the Q-types and ordinary chondrites share some spectral features with S-type asteroids, the S-types have significantly redder slopes than the Q-types. Thisreddening of spectral slope is aributed to the effects of space weathering on the observed surface composion. The analysis by Binzel et al. (2004) provided amissing link between the Q- and S-type bodies in near-Earth space by showing a reddening of spectral slope in objects from 0.1 to 5 km that corresponded to atransion from Q-type to S-type asteroid spectra. However the link was not complete. The existence of Q-type asteroids in the main-belt had not been verified.We have completed a photometric survey of the Koronis family using the Ki Peak 2.1m telescope. This provides a unique opportunity to compare the effects ofthe space weathering process on potenally ordinary chondrite-like bodies within a populaon of idencal inial condions. We find a trend in spectral slope forobjects 1-5 km that shows the transion from Q- to S-type in the main-belt. We have also idenfied potenal Q-type asteroids in the main-belt. This data set willprove crucial to our understanding of the space weathering process and its relevant mescales.46.08: The Reliability of Wide-Field Asteroid Photometric SurveysAuthor Block: Alan W. Harris 1 , B. D. Warner 2 , P. Pravec 31 MoreData!, 2 Palmer Divide Observatory, MoreData!, 3 Astronomical Instute AS CR, Czech Republic.Presentaon Time: 10/7/2010 11:40 AM - 11:50 AM

Locaon: Ballroom EAbstract.Abstract: It has recently become possible to do a photometric survey of many asteroids at once, rather than observing single asteroids one (oroccasionally a couple) at a me. We evaluate two such surveys. Dermawan et al. (2002, BAAS 34, 860) observed one night on Subaru 8.2 m telescope, andMasiero et al. (2009, Icarus 204, 145-171) observed six nights over two weeks with the 3.6 m CFHT. Dermawan claimed 83 rotaon periods from 127 detectedasteroids; TALCS claimed 218 rotaon periods from 828 detecons. Both teams claim a number of super-fast rotators (P &lt; 2.2 h) among mainbelt asteroidslarger than 250 m diameter, some up to several km in diameter. This would imply that the spin rate distribuon of mainbelt asteroids differs from like-sized NEAs,that there are larger super-fast rotators (monolithic asteroids) in the main belt than among NEAs. In the process of entering the new data in our LightcurveDatabase (Warner et al. 2009, Icarus 202, 134-146), we have applied the same criteria for reliability of results that we apply to all results listed in the database.In doing so, we assigned reliability esmates judged sufficient for inclusion in stascal studies for only 27 out of 83 (33%) periods claimed by Dermawan, andonly 87 out of 218 (40%) periods reported by TALCS; none of the super-fast rotators larger than about 250 m diameter claimed by either survey received areliability rang judged sufficient for analysis. Both Dermawan and Masiero kindly provided us with their data. Aer re-analyzing data for each of the claimedlarge superfast rotators using our own analysis soware, we concluded that none of the results were of sufficient reliability to jusfy a provocave claim ofdiffering rotaon stascs between NEAs and MBAs. Our analysis presents a cauonary message for future surveys.46.09: Potenal Biases In Future Asteroid Lightcurve SurveysAuthor Block: Brian D. Warner 1 , A. W. Harris 21 Palmer Divide Obs., 2 MoreData!.Presentaon Time: 10/7/2010 11:50 AM - 12:00 PMLocaon: Ballroom EAbstract: A goal of recent and upcoming surveys is securing a large number of asteroid rotaon periods via lightcurves. While a worthwhile effort, the“shotgun” approach being applied in many cases may not add significant new informaon about rotaon rates and be biased against crical types of objects:fast/slow rotators, binary and mulple asteroids, and tumblers. We examined different observing strategies to determine the success rate for finding the correctperiod and how they might be biased against crical objects by generang ~11,000 synthec lightcurves combined into ~2,500 composite curves covering a rangeof periods from 0.3 to 400 hours and amplitudes from 0.1 to 2.0 magnitudes and included random noise. These lightcurves were “sampled” to approximateexisng and planned strategies. As with studies by Mann et al. and Masiero et al., we found a high success rate with lightcurves of relavely short periods andmoderate to high amplitudes - P ≤ 8 h, A ≥ 0.3 mag - especially if “success” included finding a period that was 0.5x or 2.0x the true period. On the other hand,many lightcurves of low amplitude and long period - P ≥ 24 h, A ≤ 0.1 mag - were inially found to have periods of P ≤ 1 h which, if adopted, would badly skewrotaonal stascs. Overall, we found that relying on minimum of data, even if obtained over one more weeks, did not produce a significant percentage ofstascally useful periods and there was a strong potenal for biases against crical types of objects. A beer method to advance our understanding of rotaonrate and evoluon and the underlying causes appears to be to concentrate on a more limited number of objects and follow each one unl a reasonable soluon isfound.

Session Time: 10/7/2010 1:30 PM

Session Number: 47Session Title: Extrasolar Planetary Mission HighlightsSession Type: PlenarySession Description: Sagan Award presented to Carolyn Porco (CICLOPS/Space Science Inst.), presented by Ann Druyan 1:30pm - 1:40pm47.01: Characterizing Exoplanet AtmospheresAuthor Block: Jonathan J. Fortney 11 University of California, Santa Cruz.Presentaon Time: 10/7/2010 1:40 PM - 2:20 PMLocaon: Plenary BallroomAbstract: Forty years ago the first work on understanding the composion, infrared spectra, and temperature structure of the atmospheres of the solar system'sgiant planets was just geng underway. Now we are doing similar 1st-order reconnaissance and modeling to understand the atmospheres of exoplanets, whosecategories include Jupiter-class, Neptune-class, and un-classifiable planets. One driving force behind this work is that as the data gathered becomes beer, theprospect exists to understand the atmospheres of the solar system’s planets in the context of similar exoplanets. Over the past few years, planets that transittheir parent stars, predominantly in short-period orbits, have allowed us the best access to informaon about exoplanetary atmospheres. Mostly thanks to theSpitzer and Hubble space telescopes, we have now been able to begin the first reconnaissance of these hot planets, some of which orbit their parent stars in lessthan one day. We have made inial aempts to classify the atmospheres of the Jupiter-class transing planets in terms of the presence or absence oftemperature inversions, but finding a sasfactory theory to explain the observaons has been a challenge. The atmospheric characterizaon of "super Earth"atmospheres such as GJ 1214b is now underway, showing us a clear pathway towards characterizing even smaller planets.47.02: CoRoT : A Mid-Term status Report on the Exoplanets Transit Detecon ProgrammeAuthor Block: Daniel Rouan 11 Observatoire de Paris-Meudon, France.Presentaon Time: 10/7/2010 2:20 PM - 2:55 PMLocaon: Plenary BallroomAbstract.Abstract: CoRoT, the french-european satellite of high-precision photometry was put in operaon early 2007 and the mission has recently beenextended for 2.5 years. This mid-term milestone is a good occasion to make a status report on the extrasolar planets program which is based on the transitdetecon technique. Aer a brief descripon of CoRoT specificaons and in-flight performances, a summary of the 15 discoveries of exoplanets and browndwarves will be done, with emphasis on several specific cases, such as the small size Corot-7b object or the long period planet Corot-9b. The results will be alsopresented in terms of stascal analysis. Finally, the prospects for the extended period will be discussed in the light of the experience gained by the CoRoT team.47.03: Kepler Planet Detecon Mission: Highlights of the First ResultsAuthor Block: William J. Borucki 1 , D. Koch 1 , Kepler Science Team1 NASA Ames Research Center.Presentaon Time: 10/7/2010 2:55 PM - 3:30 PMLocaon: Plenary BallroomAbstract: An important step in discovering the extent of life in our galaxy is to determine the number of terrestrial planets in the habitable zone (HZ) of solarlikestars. The Kepler Mission is designed specifically to determine the frequency of terrestrial planets in the HZ. It was launched on March 6, 2009 and is nowmeasuring the brightness variaons of 150,000 solar-like stars to detect paerns of transits that provide the size of the planet relave to the star and its orbitalperiod. Combining these measurements with ground-based spectroscopy fixes the stellar parameters, the planet radius, orbital semi-major axis, and the locaonrelave to the HZ.The first six weeks of data show the presence of hundreds of candidate planets, and thousands of eclipsing binary stars, and variable stars of amazing variety.Discoveries of five new exoplanets are shown and compared with known exoplanets with respect to mass, size, density, and orbital period. Over 750 planetarycandidates found in the first year of data; with many smaller than Neptune.. The released data include five possible mul-planet systems. One of these has twoNeptune-size (2.3 and 2.5 Earth-radius) candidates with near-resonant periods. Data for these discoveries were released in June. Examples of many of thesediscoveries and their distribuons are presented and discussed.. Support by the NASA Astrophysics Division is gratefully acknowledged.

Session Time: 10/7/2010 3:30 PM

Session Number: 13Session Title: Near-Earth Asteroids, Dynamics, and MeteoritesSession Type: Poster13.01: A Search for Vulcanoids Using STEREO Heliospheric Imager DataAuthor Block: Andrew J. Steffl 1 , N. J. Cunningham 2 , A. L. Graps 1 , D. D. Durda 1 , S. A. Stern 11 Southwest Research Instute, 2 University of Nebraska-Lincoln.Presentaon Time: 10/7/2010 3:40 PM - 3:42 PMLocaon: Exhibit HallAbstract: Interior to the orbit of Mercury, between 0.07 and 0.21 AU, is a dynamically stable region where a populaon of asteroids, known as Vulcanoids, mayreside. As seen from Earth, the Vulcanoid zone lies between 4-12 degrees from the sun, making observaons difficult. The best previous search used data fromthe LASCO C3 coronagraph on the SOHO spacecra to place an upper limit on the apparent brightness of any Vulcanoids of V=8.0, corresponding to an objectdiameter of ~55km. Here, we present results from our campaign to analyze data from the Heliospheric Imagers aboard NASA's two STEREO spacecra forVulcanoids transing through the instrument’s field of view. At present, we have not detected any Vulcanoids, even though our search is sensive to objects assmall as approximately 5 km in diameter--nearly 100 mes fainter than the SOHO search. These limits place significant constraints on the formaon andevoluon of the putave Vulcanoid populaon.13.02: The Populaon of Natural Earth SatellitesAuthor Block: Mikael Granvik 1 , J. Vaubaillon 2 , R. Jedicke 31 Univ. of Hawaii, 2 Observatoire de Paris, France, 3 University of Hawaii.Presentaon Time: 10/7/2010 3:42 PM - 3:44 PMLocaon: Exhibit HallAbstract: We present the first debiased size-frequency and orbit distribuons for a steady-state populaon of temporary-captured, natural Earth satellites (NES)excluding the Moon. We use orbital integraons to esmate the capture probability as a funcon of orbital elements and ulize the steady-state near-Earthobject(NEO) model by Boke et al. (2002) to esmate the steady-state populaon of NESs.For much of the 20th century NESs other than the Moon were not discussed in their own right but menoned in the published literature only as a populaonproducing meteors that travel far in the Earth's atmosphere or as a populaon explaining shallow meteorite impacts. Only during the last two decades has acouple of these objects been detected in space; 1991 VG and 2006 RH120. The origin and evoluon of 1991 VG, e.g., whether it is a man-made or a naturalobject, can be debated, but 2006 RH120 is certainly natural with an absolute magnitude H of about 29.9. To gain understanding of this lile studied and barelydetected populaon's origin and evoluon, we try to answer quesons such as: At any instant, how many objects are in temporary capture as a funcon of theirsize? What are the characteriscs of their pre- capture geocentric trajectories and heliocentric orbits? What is the typical duraon of the temporary capture? Howmany orbits do NESs typically complete around the Earth? What are the characteriscs of their geocentric orbits?We ancipate that the interest in this small and nearby populaon will increase in the future as NESs are easily accessible targets for proposed NEO samplereturnmissions. Their typically small sizes could allow us to bring back an enre asteroid with the benefit that, e.g., microscopic surface or near-surface effectssuch as space weathering and lightscaering could be studied on a prisne body in ground-based laboratories.13.03: Co-orbital Asteroids of Earth as Candidates for Asymmetric Impactors on the MoonAuthor Block: Youngmin JeongAhn 1 , R. Malhotra 11 Univ. of Arizona.Presentaon Time: 10/7/2010 3:44 PM - 3:46 PMLocaon: Exhibit HallAbstract: The observed leading/trailing asymmetry of rayed lunar craters may be owed to impactors having lower average encounter velocity than that of thecurrent model of Near Earth Objects [NEOs] (Ito and Malhotra 2010). We are invesgang the possibility that currently undetected co-orbital asteroids of Earthmay parally account for the missing low velocity impactors. First, we obtain the dynamical lifemes of asteroids in the co-orbital region of Earth's orbit. Weadopt the realisc model of the eight major planets of the solar system and examine a wide range of inial orbital parameters of Earth co-orbital asteroids: semimajoraxis, eccentricity, inclinaon, and relave longitude; we compare our results with those of a previous study (Tabachnik and Evans 2000, Evans andTabachnik 2002). Then, we trace the escaping objects from the co-orbital region and determine their impact velocity with the Moon. We confirm that theseobjects have typical impact velocies much lower than the average impact velocity of NEOs. We esmate the current co-orbital populaon that may account forthe leading/trailing asymmetry of lunar rayed craters. We discuss mechanisms for the possible origin and re-supply of co-orbital asteroids and the role ofhypothecal primordial co-orbitals on the lunar crater asymmetry.This research is supported by NSF grant AST-0806828.13.04: Low Delta-v Near Earth Objects: A Survey Of Suitable Targets For Space MissionsAuthor Block: Elisabea Doo 1 , D. Perna 1 , F. De Luise 2 , F. Bernardi 3 , M. A. Barucci 4 , J. R. Brucato 5 , A. Rossi 6 , E. Perozzi 7 , S. Fornasier 4 , G. B. Valsecchi 31 INAF-Osservatorio Astronomico di Roma, Italy, 2 INAF-Osservatorio Astronomico di Collurania, Italy, 3 INAF-IASF, Italy, 4 LESIA-Observatoire de Paris, France,5 INAF-Osservatorio Astrofisico di Arcetri, Italy, 6 CNR-ISTI, Italy, 7 Telespazio, Italy.Presentaon Time: 10/7/2010 3:46 PM - 3:48 PMLocaon: Exhibit HallAbstract: In the last years, scienfic and technological goals pushed space agencies to plan and launch space missions to Near Earth Objects (NEOs). In thisrespect, observaonal programs devoted to the study of the physical nature of NEOs are needed in support of such a future space mission.Starng from the classical definion of "accessibility" of a celesal body in terms of the velocity change (delta-V) needed to realize a rendez-vous mission (e.g.orbing around an object), it is possible to show that NEOs can be more accessible than the Moon or as difficult to reach as Jupiter and beyond.Our survey is therefore devoted to the study of NEOs that are suitable targets for a future space mission, due to their low delta-V (and short mission duraon).The observaons of NEOs with favorable accessibility from the Earth, is fundamental in the target selecon process, in order to guarantee both technicalfeasibility and high scienfic return.13.05: Ultra-low Delta-v Neos As Prime Nasa TargetsAuthor Block: Marn Elvis 1 , J. C. McDowell 1 , R. P. Binzel 2 , J. Hoffman 21 Harvard-Smithsonian CfA, 2 M IT.Presentaon Time: 10/7/2010 3:48 PM - 3:50 PMLocaon: Exhibit Hall

Abstract.Abstract: Missions to near-Earth asteroids (NEOs) are key desnaons in NASA's new "Flexible Path" approach. NEOs are also of interest for science,for the hazards the post, and for their resources. We examine the selecon criteria for target NEOs for human exploraon to define a set of "Potenally VisitableObjects" (PVOs). Ultra-low delta-v from LEO to NEO rendezvous is the primary criterion, as this choice doubles the payload to NEO. Choices for NEOs as humandesnaons are currently very limited. Only 5 of the 6699 known NEOs have delta-v &lt;4km/s, 2/3 of typical LEO-NEO delta-v. Even these are small and hard torecover. Other criteria - long launch windows, a robust abort capability, and a safe environment for proximity operaons - will further limit the list of PVOs.Potenally there are at least an order of magnitude more PVOs but, to find them all on a short enough mescale (before 2025) requires a dedicated survey in theopcal or mid-IR, opmally from a Venus-like orbit because of the short synodic period for NEOs in that orbit, plus long arc determinaon of their orbits.13.06: Los Alamos Radiaon Hydrocode Models of Asteroid Migaon by an Internal ExplosionAuthor Block: Robert Weaver 1 , C. Plesko 1 , W. Dearholdt 11 Los Alamos Naonal Lab.Presentaon Time: 10/7/2010 3:50 PM - 3:52 PMLocaon: Exhibit HallAbstract: Migaon of a potenally hazardous object (PHO) by a convenonal or nuclear subsurface burst is considered. This intervenon methodology hasbeen popularized in media presentaons and is considered as one possible method of impact-hazard migaon. We present RAGE radiaon hydrocode models ofthe shock-generated disrupon of PHOs by subsurface nuclear bursts and deflecon from shallow buried bursts using scenario-specific models from authencRADAR shape models. We will show 2D and 3D models for the disrupon by a large energy source at the center and near the edge (migaon) of such PHOmodels (1-10 Mton TNT equivalent), specifically for asteroid 25143 Itokawa. Parametric studies will be done on: the value of the source energy (from 1 Mton to 10Mton), the parameters in the Steinberg-Guinan strength model used and the internal composion of the object from uniform composion to a “rubble pile”distribuon. Specifically we are interested in assessing the opmum depth of burial and energy required to essenally disrupt and/or move the PHO and thereforemigate the hazard. Recollecon will be considered.13.07: Numerical and Laboratory Invesgaons of Regolith DynamicsAuthor Block: Naomi Murdoch 1 , P. Michel 2 , C. Berardi 3 , W. Losert 3 , D. C. Richardson 3 , B. Rozis 4 , K. J. Walsh 2 , S. F. Green 4 , T. de Lophem 41 The Open University, PSSRI, United Kingdom and University of Nice-Sophia Anpolis, CNRS, Observatoire de la Cote d'Azur, France, 2 University of Nice-SophiaAnpolis, CNRS, Observatoire de la Cote d'Azur, France, 3 University of Maryland, 4 The Open University, PSSRI, United Kingdom.Presentaon Time: 10/7/2010 3:52 PM - 3:54 PMLocaon: Exhibit HallAbstract: Surfaces of planets and small bodies in our Solar System are oen covered by a layer of granular material that can range from a fine regolith to agravel-like structure of varying depths. Therefore, the dynamics of granular materials is involved in many events occurring during planetary and small-bodyevoluon and contributes to their geological properes.However from planets to asteroids, surface gravies vary by many orders of magnitude. Bodies with low surface gravity can be sensive to processes that appearirrelevant in the case of larger planetary bodies. For instance, seismic vibraon induced by small impacts has been proposed to explain the lack of very smallcraters on Eros and Itokawa.To increase our understanding of regolith behaviour we have performed a series of numerical simulaons and microgravity experiments. The numerical code is amodified version of the N-body code pkdgrav that has been adapted to handle hard-body collisions. The granular dynamics modificaons consist primarily ofproviding wall “primives” to simulate the boundaries of the experimental apparatus [1].Our simulaons currently focus on experiments for which we have experimental data. This allows direct comparisons to be made with laboratory experiments.Some specific examples which will be presented are the collecve moon of granular materials in a dense regime as a result of shaking, avalanching behaviourand granular flows with a tumbler.The microgravity experiment, AstEx that flew in November 2009 as part of ESA’s ‘Fly your Thesis’ programme will also be presented. The experimental aim was tocharacterise the response of granular material to rotaonal shear forces in a microgravity environment.This work benefits from financial support from TAS, the OU, the French Programme Naonal de Planétologie, ESA and the RAS. DCR acknowledges support fromNASA (Grant No. NNX08AM39G).Reference: [1] Richardson, D.C. et al., Icarus (2010), submied.13.08: Brick-pile To Rubble-pile Impact TransionsAuthor Block: Donald Korycansky 1 , E. Asphaug 11 University of California Santa Cruz.Presentaon Time: 10/7/2010 3:54 PM - 3:56 PMLocaon: Exhibit HallAbstract: One of the chief lines of evidence that asteroids are "rubble piles", (loose aggregates of rock and/or ice held together by gravity and fricon) is theunder-density that many of them exhibit compared to the density of solid rock as inferred from surface composions. Under-densies up to 50% or greater havebeen found for some objects (Bri and Consolmagno 2002). However, lile is known of the internal structure of these bodies. Under-density may be due to"microporosity", i.e. porosity at the level of grains, or "macroporosity" in which void space is provided by the mis-match of large structural blocks that comprisethe bulk of the object.We present work that models sub-catastrophic impacts into "brick piles", i.e. close-fing aggregates with lile or no void space. Calculaons follow the paral orcomplete dispersal of an asteroid and its reassembly. Aer reassembly, the post-impact volume of the object is compared to the pre-impact object to derive avoid fracon.Model calculaons were carried out with programs based on the Open Dynamics Engine library that has been used by us for a number of studies (Korycansky andAsphaug 2009, Korycansky 2010a,b LPSC). Inial brick-pile objects were constructed by means of quasi-random Voronoi decomposions of an inial volume thatis the hull of the pre-impact object. We will present results on the amount and distribuon of void space of post-impact rubble piles and compare to the observeddistribuon of inferred void space, and characterize our results in terms of body and impact parameters, such as numbers and size distribuon of pre-impact brickpiles and impact velocies and geometry.This work has been supported by NASA Planetary Geology and Geophysics program grant NNX07AQ04G.13.09: The Toasty Solar System: Inside Earth's OrbitAuthor Block: Sarah Greenstreet 1 , H. Ngo 1 , B. Gladman 11 University of Brish Columbia, Canada.Presentaon Time: 10/7/2010 3:56 PM - 3:58 PMLocaon: Exhibit Hall

Abstract: In 2011 the Canadian Space Agency will launch the NEOSSat spacecra (Near-Earth Object Surveillance Satellite). This space telescope will surveythe sky at low solar elongaons for 1-2 years and be especially sensive to near-Earth objects (NEOs) with semimajor axes smaller than 1 AU, including objectsat heliocentric distances as small as that of Venus. The search will be opmized to obtain informaon on the NEO orbital distribuon for Aten (Q>0.983 AU buta

growth in mean anomaly compared to a Keplerian system by observaons of mutual events between binary system components. Fits of a binary model toobserved mutual events in previous apparions gave a mean error of the mean anomaly measurements of 2-3 degrees with good-quality photometricobservaons (errors 0.01-0.02 mag). We idenfied seven binary NEA systems that are candidates for detecon of the BYORP effect with such observaons in theirnext apparions during 2010-2015: (7088) Ishtar, (65803) Didymos, (66063) 1998 RO1, (88710) 2001 SL9, (137170) 1999 HF1, (175706) 1996 FG3 and (185851)2000 DP107. Their predicted quadrac growth in mean anomaly is 0.24 to 3.3 deg/yr 2 . Photometric observaons using telescopes with sizes about 2 m andsmaller in their apparions with V < 21 during 2010-2015 will give us data on event epochs in 4-6 apparions (including their previous observed apparions),allowing detecon of BYORP in them.13.14: A Simple Monte Carlo Model Describing Near-Earth Asteroid Color Distribuons.Author Block: Michael D. Hicks 1 , K. Lawrence 11 JPL.Presentaon Time: 10/7/2010 4:06 PM - 4:08 PMLocaon: Exhibit HallAbstract: The spectral color distribuon of small S-family near-Earth asteroids differ from their main-belt analogues, with a significant fracon of small Near-Earth Asteroids (NEAs) having visible/near-IR spectra resembling Ordinary Chondrites (OCs) while others NEAs resemble S-family main-belt asteroid or withintermediate colors. Binzel et al. (2010) has found a strong correlaon between recent dal interacons with the Earth and NEAs with OC-like colors, supporngthe theory that periodic dal refreshing events can counter the effects of space weathering for small rubble-pile asteroids.Over the past three years we have systemacally collected long-slit spectroscopy at the Palomar 5-m Hale telescope of NEAs scheduled for radar observaon atthe Goldstone/Arecibo facilies. These asteroids, dominated by Potenally Hazardous Asteroids (PHAs), provide a self-consistent dataset by which to testtheories of spectral alteraon. The S-family NEAs in our survey show a color distribuon that is quite disnct from the main-belt S-family asteroids archived in theSMASS II spectral survey. We have developed a simple numerical Monte Carlo model that combines space-weathering with surface freshening events in a steadystatesoluon. Our model can evolve the observed populaon of main-belt S-family asteroids to the color distribuon observed in the PHAs. Our model can notdisnguish the specific mechanism of resurfacing (dal interacons, YORP spin-up, or collisions) but can constrain their collecve mescales with respect tospace weathering.13.15: 009 KD5: A Photometric Signature of a Binary Near-Earth AsteroidAuthor Block: James Foster 1 , M. Hicks 2 , A. McAuley 1 , T. Truong 1 , H. Rhoades 2 , D. Mayes 2 , J. Somers 3 , K. Garcia 11 CSULA, 2 JPL/Caltech, 3 Moorpark College.Presentaon Time: 10/7/2010 4:08 PM - 4:10 PMLocaon: Exhibit HallAbstract: 2009 KD5 was discovered May 26 2009 by the Observatorio Astronomico de Mallorca LSSS (La Sagra Sky Survey) Near-Earth Object (NEO) survey(MPEC 2009-K55) and idenfied as a Potenally Hazardous Asteroid (PHA) by the Minor Planet Center. The object's 2010 closest approach to the Earth was quitedistant (delta=0.24 AU on June 29 2010). However, the 2010 apparion allows the NEO to be observed under slowly varying illuminaon and viewing geometry.We have analyzed six nights of Bessel BVRI observaons at the JPL Table Mountain Observatory (TMO) 0.6-m telescope (6/15, 6/16, 6/19, 6/20, 7/03, 7/04 UT).The PHA's averaged broad-band colors (B-R=1.300+/-0.034 mag; V-R=0.491+/-0.027 mag; R-I=0.409+/-0.027 mag) were found to be most compable with an L-type spectral classificaon (Bus & Binzel 2002). L-types asteroids are members of the S-family of asteroids and may represent surfaces highly processed bycollisional gardening and space weathering. A solar phase curve constructed from our data was consistent with an assumed solar phase parameter g=0.15,yielding an Absolute Magnitude H V = 18.39 mag. Systemac departures in the night-to-night rotaonally phase photometry suggested that the NEO is a binaryasteroid. We have fit a two-period model for the lightcurve of 2009 KD5, with the primary P 1 = 2.52 hr (very near the rotaonal break-up speed of a self-gravitangrubble pile) and secondary, presumably dally-locked, component P 2 = 21.7 hr. We have an addional two nights of unreduced photometry that should furtherconstrain the asteroid's solar phase and rotaonal properes.13.16: Opcal Characterizaon Of Planetary Radar Targets, Low-ΔV, And Potenally Hazardous Asteroids: Results From 2009-2010.Author Block: James M. Somers 1 , M. Hicks 2 , K. Lawrence 2 , H. Rhoades 2 , D. Mayes 2 , T. Barajas 3 , A. McAuley 4 , J. Foster 4 , J. Shitanishi 5 , T. Truong 4 , K. Garcia 41 Moorpark College, 2 JPL/Caltech, 3 Los Angeles City College, 4 California State University Los Angeles, 5 University of Southern California.Presentaon Time: 10/7/2010 4:10 PM - 4:12 PMLocaon: Exhibit HallAbstract: In July 2007 we began a intensive program of physical characterizaon of planetary radar targets at the Palomar Mountain 200-inch Hale Telescope(P200) and the JPL Table Mountain Observatory 0.6-m telescope (TMO), collecng CCD spectra, BVRI colors and R-band lightcurves of essenally all radar targetsobservable from the northern hemisphere. Radar observaons benefit greatly from opcal observaons, especially rotaonal lightcurves and taxonomicclassificaon. We also seek to characterize Potenally Hazardous Asteroids (PHA: MOID &#8804; 0.05 AU, H &#8804; 22.0 mag) and low-&#916;V (LDV: &#916;V&#8804; 6.29 km/s) near-Earth asteroids as they become available from our latude. Between January 2009 and July 2010 we acquired data on 38 objects over107 nights at TMO and 28 objects over 8 nights at P200. We will report our spectra, colors, and light-curve photometry for the following minor planets, with thetaxonomic classificaon (Bus Taxonomy) derived from our data listed in parenthesis: 1991 AQ10 (Sq), 1991 DB (C), 1994 CC (Sq), 1996 EN (V), 1996 FG3 (C), 1998CS1 (Sa), 1998 FW4 (Xc), 1998 OR2 (Xk), 1999 AP10 (Sa), 1999 AQ10 (S), 1999 LF6 (L), 1999 MN (Sq), 2000 TO64 (S), 2000 UJ1 (S), 2000 XK44 (S), 2001 CV26 (S),2001 FE90 (A), 2001 FM129 (Sq), 2002 VY95 (C), 2003 EF54 (V), 2003 QO104 (S), 2003 YT1 (R), 2004 FG11 (V), 2005 CW25 (T), 2005 EK70 (Sq), 2005 YU55 (C),2006 AS2 (C), 2007 MK13 (C), 2008 EE5 (Sl), 2008 EV5 (C), 2008 SV11 (CX), 2009 KC3 (CX), 2009 KD5 (L), 2009 OG (S), 2009 UD2 (S), 2009 UN3 (S), 2009 UV18(Ld), 2010 GU21 (X), 3554 Amun (X), 4486 Mithra (S).13.17: Radar Imaging and a Physical Model of Binary Asteroid 65803 DidymosAuthor Block: Lance A. M. Benner 1 , J. Margot 2 , M. C. Nolan 3 , J. D. Giorgini 1 , M. Brozovic 1 , D. J. Scheeres 4 , C. Magri 5 , S. J. Ostro 11 JPL, 2 UCLA, 3 Arecibo Observatory, 4 University of Colorado, 5 University of Maine at Farmington.Presentaon Time: 10/7/2010 4:12 PM - 4:14 PMLocaon: Exhibit HallAbstract: We report Arecibo (2380 MHz, 13 cm) and Goldstone (8560 MHz, 3.5 cm) delay-Doppler radar observaons of binary near-Earth asteroid (NEA) 65803Didymos (1996 GT) obtained on five dates between November 14-26, 2003 during the asteroid’s approach within 0.048 AU. The images achieve resoluons as fineas 15 m in range and place hundreds of pixels on the primary. The images and preliminary shape modeling indicate that the primary is about 800 m in diameter,that it has a slightly asymmetric and oblate shape resembling the one found for the primary of 1999 KW4, and that it has a prominent facet about 300 m in extentalong the ridge. The S-band circular polarizaon rao of the primary averages 0.22+-0.02 and indicates that its near-surface is somewhat less rugged atdecimeter spaal scales than the surfaces of 433 Eros or 25143 Itokawa. The secondary is roughly 150 m in diameter and its delay-Doppler signature isconsistent with rotaon that is synchronous with the 11.9-h orbital period reported by Pravec et al. (2006, Icarus 181, 63-93). Preliminary orbital fits give a

consistent with rotaon that is synchronous with the 11.9-h orbital period reported by Pravec et al. (2006, Icarus 181, 63-93). Preliminary orbital fits give asemimajor axis of about 1.2 km and an orbital period of 11.9 h that is consistent with the one esmated from photometry; together they provide a first-orderesmate of ~2 g/cm 3 for the bulk density of the system.13.18: Radar Shape Modeling of Binary Near-Earth Asteroid 2000 CO101Author Block: Nicholas Jimenez 1 , E. S. Howell 2 , M. C. Nolan 2 , P. A. Taylor 2 , L. A. M. Benner 3 , M. Brozovic 3 , J. D. Giorgini 3 , R. J. Vervack 4 , Y. R. Fernandez 5 , M.Mueller 6 , J. Margot 7 , M. K. Shepard 81 Alfred University, 2 Arecibo Observatory, 3 JPL/Caltech, 4 JHU/APL, 5 University of Central Florida, 6 Obs. Nice, France, 7 UCLA, 8 Bloomsburg University.Presentaon Time: 10/7/2010 4:14 PM - 4:16 PMLocaon: Exhibit HallAbstract: We observed the near-Earth binary system 2000 CO101 in 2009 September using the Goldstone and Arecibo radar systems and inverted these imagesto create shape models of the primary. Asteroid 2000 CO101 was discovered to be a binary system from Arecibo images taken on 2009 September 26 (Taylor et al.2009). Analyzing the images, we were able to determine approximate values for the radius of the primary (310 m) and the radius of the secondary (22 m). Themaximum observed range separaon was approximately 610 m. The images show it to appear spherical. Shape modeling of the primary of this system willconstrain the asteroid's size, spin rate, and pole orientaon. Because other NEA binary systems have exhibited shapes similar to that of 1999 KW4 (Ostro et al.2006, Scheeres et al. 2006), we inially adopted this shape for 2000 CO101 and have allowed only the linear scales along the three principal axes to adjust to theradar data. This enables us to constrain the volume. With some constraints on the orbit of the satellite we will place limits on the density of the primary.The near-infrared spectrum of 2000 CO101 was measured on 2009 September 21 and 2010 March 13. The 0.8-2.5 micron spectrum was measured on both dates,and shows a featureless, red-sloped spectrum. On September 21 we also measured the thermal emission between 2-4 microns to determine the albedo andthermal properes. Both standard thermal models and thermophysical models have been applied to these data. The albedo we derive from the thermal modelingmust also be consistent with the radar size. Characterizaon of this unusual NEA binary system will be presented.13.19: Observaons of N EAs at Arecibo Observatory and N ASA’s IRTF: Combining Radar and Thermal Measurements to Beer Understand N EAPhysical ProperesAuthor Block: Michael C. Nolan 1 , R. J. Vervack 2 , E. S. Howell 1 , C. Magri 3 , Y. R. Fernandez 4 , P. A. Taylor 1 , M. Mueller 5 , A. S. Rivkin 2 , L. A. M. Benner 61 Arecibo Observatory, 2 JHU/Applied Physics Lab, 3 University of Maine-Farmington, 4 University of Central Florida, 5 Observatoire de Nice, France, 6 Jet PropulsionLaboratory.Presentaon Time: 10/7/2010 4:16 PM - 4:18 PMLocaon: Exhibit HallAbstract: As we sample ever-smaller sizes of near-Earth asteroids (NEAs), we see an increasing variaon in the range of physical properes. Radarexperiments show a diverse range of shapes, surface features, and rotaon states among NEAs. Infrared observaons of these objects are equally varied,illustrang a range of spectral types and thermal characteriscs. While spacecra missions will reveal details of a few NEAs, only ground-based observaons willprovide an overall understanding of the populaon of these small bodies, for which the size and albedo distribuons are sll poorly understood.The goal of our invesgaon is to use both radar images and near-IR spectra to beer understand the regolith of different types and shapes of NEAs. The regolithon an asteroid surface controls its thermal properes and oen its radar reflectance as well, and at smaller sizes the irregular shape plays an increasinglyimportant role. To accomplish our goal, we have established a program in which we choose NEAs that will be observed well enough with radar to have highqualityshape models and also observe these objects with SpeX at the NASA IRTF (2-4 microns) at several different viewing geometries and rotaon phases to seehow the inferred thermal properes depend on the detailed shape. We then use this knowledge to quanfy the systemac biases in exisng thermal models thatare based on simple assumpons such as spherical shape or zero thermal inera. We will present a summary of our observaons to date and preliminary resultsof the thermal modeling.13.20: Near-infrared Spectroscopy Of N EOs: Characterizaon Of Targets Of The ExploreN EOs (Spitzer) ProgramAuthor Block: Joshua P. Emery 1 , C. A. Thomas 2 , D. E. Trilling 2 , R. Dave 1 , M. Delbo 3 , M. Mueller 31 University of Tennessee, 2 Northern Arizona University, 3 Observatoire de la Cote d'Azur, France.Presentaon Time: 10/7/2010 4:18 PM - 4:20 PMLocaon: Exhibit HallAbstract: In order to complement the ExploreNEOs program, we are characterizing surface composions of near-Earth objects (NEOs) with near-infrared (NIR)spectroscopy (0.7 to 2.5 microns). The core ExploreNEOs program is an ambious exploraon of the history of near-Earth space using NASA’s Spitzer spacetelescope. Currently in the middle of its two-year meline, that ongoing project will ulmately observe 700 NEOs using the Infrared Array Camera (IRAC) in twophotometric bands (3.6 and 4.5 microns). The proposed goals of the ExploreNEOs survey are to measure the size distribuon of NEO populaon; to measure thefracon of NEOs likely to be dead comet nuclei, with implicaons for the flux of organic material onto the Earth; to measure the albedo distribuon of NEOs; andto study properes of individual NEOs, including their thermal properes and densies, and detailed properes of a subset of "ground-truth" objects.Whereas the Spitzer photometry will provide accurate esmates of size and albedo for most targets, albedo is only a general indicator of potenal composion.NIR spectroscopy complements the Spitzer results by enabling direct determinaon of surface composions. The NIR measurements thereby contribute to theoverall goals of the ExploreNEOs program by allowing the team to assess the mix of mineralogies among NEOs and to infer the contribuons from dead cometsto the NEO populaon. NASA’s Infrared Telescope Facility (IRTF) is the main observatory used for the NIR spectral measurements. Of the 700 Spitzer targets, 127are viewable and bright enough for spectroscopy with the IRTF. Thus far, we have obtained NIR spectra of 42 of the ExploreNEO targets. We will present thesedata along with composional analysis.13.21: Thermophysical Modeling of W ISE Data on 2010 AB78Author Block: Edward L. Wright 1 , A. Mainzer 2 , T. Grav 31 UC, Los Angeles, 2 JPL, 3 JHU.Presentaon Time: 10/7/2010 4:20 PM - 4:22 PMLocaon: Exhibit HallAbstract: 2010 AB78 was the first NEO discovered by WISE in early January. It came back through the WISE scan path in February and again in July, appearing ina total of 89 frames. The lines-of-sight to the asteroid cover 180 deg in RA and 70 deg in Dec. These data are used to constrain the rotaon rate, rotaon axis,thermal ineraand size of 2010 AB78 using the rotang cratered thermophysical model of Wright (2007). All data were obtained on the same side of the WISE scan circle,

liming our ability to constrain the thermal inera. The effect of poorly constrained parameters on the size is handled using a Monte Carlo Markov Chainapproach.13.22: Spacewatch Observaons of Asteroids and Comets with Emphasis on Discoveries by W ISEAuthor Block: Robert S. McMillan 1 , T. H. Bressi 1 , J. A. Larsen 2 , C. K. Maleszewski 1 , J. L. Montani 1 , J. V. Sco 11 Univ. of Arizona, 2 US Naval Academy.Presentaon Time: 10/7/2010 4:22 PM - 4:24 PMLocaon: Exhibit HallAbstract: Astrometry and photometry of asteroids and comets by Spacewatch have expanded in their rate, telescopes used, and priories since the summary in2006 by McMillan et al. (2007 IAU Symp. 236, 329-340). Targeted recoveries of objects discovered by the Wide-field Infrared Survey Explorer (WISE) have beenadded to those on the JPL and NEODyS impact risk pages, the Minor Planet Center (MPC)'s Confirmaon Page, PHAs, comets, and other NEOs. Automaon of thedome of our 1.8-m telescope and other enhancements to soware and hardware have aided this expansion. About 3000 tracklets of NEOs are accepted by theMPC from Spacewatch each year.Recoveries of WISE-discovered objects consolidate orbits and prevent objects from being lost. V or R-band photometry is essenal to determine the albedo at thewavelength of the peak of incident solar flux, which reckons in modeling thermal properes from the WISE measurements of infrared (IR) flux. We specialize in thefainter objects and have reported astrometry and photometry of objects as faint as V=23. About 2/3rds of NEOs observed by WISE have been observed bySpacewatch, as well as half of the comets and several objects in the outer solar system discovered by WISE. Examinaon of visible-light images of objects thatlook cometary in the WISE IR imagery has confirmed some comets and not found cometary features in others.Help and advice from the NEOWISE Team led by A. Mainzer of JPL have been essenal to the selecon and finding of targets. Extensive use of the MPC's lists andfiles of observaons are made. Spacewatch is funded by NASA's NEO Observaon and Planetary Astronomy Programs, the Brinson Foundaon of Chicago, IL, andother private contributors. Time on the 2.3-m Bok telescope of Steward Observatory and the 4-m Mayall telescope of the Ki Peak Naonal Observatory isgratefully acknowledged.13.23: The Temperature History of (101955) 1999 RQ36 and other Potenal Targets of Sample Return Missions to Primive AsteroidsAuthor Block: Marco Delbo 1 , P. Michel 21 University of Nice-Sophia Anpolis-CNRS-Obs. de La Cote d'Azur, France, 2 University of Nice-Sophia Anpolis - CNRS - Obs. de La Cote d'Azur, France.Presentaon Time: 10/7/2010 4:24 PM - 4:26 PMLocaon: Exhibit HallAbstract: It is well known that the perihelion distance of Near Earth Objects (NEOs) varies with me as a consequence of dynamical mechanisms, such asresonances and close approaches with planets. As a consequence, NEOs have a complex temperature history (due to the radiave heang by the Sun), nontriviallycorrelated to the present orbits.Recently, space missions have been proposed to return samples of prebioc organic compounds, which are likely to be found on NEOs of primive types. Some ofthese organic compounds break up at relavely moderate temperatures. Using a model of the orbital evoluon of NEOs and appropriate thermal models, westudied the temperature history of (101955) 1999 RQ36 (the primary target of the mission OSIRIS-REx selected in the program New Froner of NASA) and fourother potenal sample return targets.Inial results suggest that the surface temperature excursions in some of these objects could affect the stability of some organic compounds (e.g. there is 50%probability that the surface of these objects has experienced temperatures >500 K). However, the temperature drops rapidly with depth. For example, there isindicaon that the material at a depth of 3-5 cm has experienced temperatures 100 degrees below those of the surface.13.24: Thermal Emission Spectroscopy (5.2 To 38 Microns) And Analysis Of 10 Near-earth AsteroidsAuthor Block: Riddhi Dave 1 , J. Emery 1 , D. Cruikshank 2 , M. Mueller 3 , M. Delbo 4 , D. E. Trilling 5 , M. Mommert 61 University of Tennessee,Knoxville, 2 Ames Research Center,NASA, 3 Univ. de Nice Sophia Anpolis, France, 4 CNRS,Obs. de la Cote d'Azur, France, 5 NorthernArizona University, 6 DLR, Germany.Presentaon Time: 10/7/2010 4:26 PM - 4:28 PMLocaon: Exhibit HallAbstract: Near Earth Asteroids (NEAs- 0.983AU

the asteroid was classified as a potenal threat and on February 2010 it was rated with a value of 1 on the Torino scale, but later, on April 2010, based on newdata supplied by observatories of the world it was downgraded to value 0. With the new asteroid's orbital data and radar studies made by the AreciboRadiotelescope (April 19 thru 21) is well known that in 100 years there will be no impact on Earth. The asteroid will be at approximately 324,200 kilometers fromthe Earth on November 8-2011.13.26: Acvity in Geminid Parent (3200) PhaethonAuthor Block: Jing Li 1 , D. Jewi 21 IGPP, UCLA, 2 UCLA.Presentaon Time: 10/7/2010 4:30 PM - 4:32 PMLocaon: Exhibit HallAbstract.Abstract: Asteroid (3200) Phaethon is widely recognized as the parent of the Geminid meteor stream. However, it has never shown evidence for ongoingmass loss or for any form of comet-like acvity that would indicate the connued replenishment of the stream. Following an alert by Baams and Watson(IAU Circular 9054, 2009), we used NASA's STEREO-A spacecra to image Phaethon in the period UT 2009 June 17 - 22, when the heliocentric distance was near0.14 AU. The resulng photometry shows an unexpected brightening, by a factor of two, starng UT 2009 June 20.2+/-0.2 which we interpret as an impulsiverelease of dust parcles from Phaethon. If the mean parcle radius is near 1-mm and the density near 2500 kg m-3, then the emied dust parcles must have acombined mass of about 2.5X10**8 kg. This is approximately 1/10,000 of the Geminid stream mass. To replenish the stream within its esmated 1000 yr lifemewould require about 10 events like the one observed, per orbit. Phaethon is too hot for water ice to survive, rendering unlikely the possibility that dust is ejectedthrough gas-drag from sublimated ice. Instead, we suggest that Phaethon's small perihelion distance may indirectly lead both to the producon of dust (throughthermal fracture and decomposion cracking of hydrated minerals) and to its ejecon into interplanetary space (through radiaon pressure sweeping).13.27: Origin Of The Near-earth Asteroid Phaethon And The Geminids Meteor ShowerAuthor Block: Julia de Leon 1 , H. Campins 2 , K. Tsiganis 3 , A. Morbidelli 4 , J. Licandro 51 Instuto De Astrofisica De Andalucia - CSIC, Spain, 2 University of Central Florida, 3 Aristotle University of Thessaloniki, Greece, 4 Universite de Nice -Observatoire de la Cote d'Azur, France, 5 Instuto De Astrofisica De Canarias, Spain.Presentaon Time: 10/7/2010 4:32 PM - 4:34 PMLocaon: Exhibit HallAbstract: Asteroid (3200) Phaethon is a remarkable Near Earth Asteroid (NEA). It was the first asteroid associated with a meteor shower, namely the Geminidstream 1 .Pha e thon’s unus ua l orbi t ha s a hi gh i ncl i na on a nd a ve ry l ow pe ri he l i on di s ta nce (0.14 AU). Its re fle cta nce s pe ctrum s ugge s ts a conne con wi th pri mi ve me te ori te s , be s t fing wi thCI/CM ca rbona ce ous chondri te s 2 , a que ous l y a l te re d a nd ri ch i n hydra te d s i l i ca te s . Howe ve r, i ts ori gi n i s not we l l de te rmi ne d. Re ce nt s tudi e s s ugge s t a conne con wi th the popul a on of ma i n-be l t come ts 3 , cl a s s i fyi ng Pha e thon a s a n a cva te d a s te roi d. He re we s how tha t the mos t l i ke l y s ource of Pha e thon a nd the Ge mi ni ds i s the a s te roi d (2) Pa l l a s , one of the l a rge s t a s te roi ds i nthe ma i n be l t, whi ch i s s urrounde d by a col l i s i ona l fa mi l y, conta i ni ng s e ve ra l Pha e thon-s i ze d obje cts . Pa l l a s ’ hi ghl y i ncl i ne d orbi t a nd s urfa ce compos i on, a l s o pri mi ve a nd wi th e vi de nce ofhydra on 4 , s upport thi s conne con. Our a na l ys i s re ve a l s a s tri ki ng s i mi l a ri ty be twe e n Pha e thon’s vi s ua l s pe ctrum a nd thos e of Pa l l a s fa mi l y me mbe rs . More ove r, our nume ri ca l s i mul a onss how the e xi s te nce of a robus t dyna mi ca l pa thwa y, conne cng the orbi ta l ne i ghborhood of Pa l l a s wi th tha t of Pha e thon. In thi s re s pe ct, the Pa l l a s fa mi l y ma y cons tute a s ource of pri mi veNEAs . (The author gratefully acknowledges support from the Spanish "Ministerio de Ciencia e Innovación" projects AYA2005-07808-C03-02 and AYA2008-06202-C03-02 .)Re fe re nce s1. Whi ppl e , F. L. 1983, IAU Ci rcul a r, 38812. Li ca ndro, J., Ca mpi ns , H., Mothe -Di ni z, T., Pi ni l l a -Al ons o, N. & de Le on, J. 2007, Astron. Astrophys. 461, 751-7573. Hs i e h, H. H., & Je wi , D. 2006, Science, 312, 561-5634. Ri vki n, A. S., Howe l l , E. S., Vi l a s , F. & Le bofs ky, L. A. i n Asteroids III (e ds Boke , W. F., Ce l l i no, A., Pa ol i cchi , P. & Bi nze l , R. P.) 235-253 (Uni v. Ari zona Pre s s , 2002).13.28: Matching Meteor Showers and Parents: A New ApproachAuthor Block: Marco Micheli 1 , D. J. Tholen 11 Instute for Astronomy - University of Hawaii.Presentaon Time: 10/7/2010 4:34 PM - 4:36 PMLocaon: Exhibit HallAbstract: Meteoroid streams are debris trails le behind by small solar system bodies, and most of these parents should sll reside in the current NEO andcomet populaon. We currently know at least 7000 of these objects, some of them probably related with already known meteoroid streams.The usual approach to establish these associaons has been to compare the orbit of a stream with that of each possible parent, trying to idenfy closelymatching pairs and then invesgang them dynamically to prove the connecon.Unfortunately, in most cases, the correct matching between the parent and the stream is made difficult by the fact that the orbit of the laer is poorly known(especially for weak showers), since it has been computed only from a very limited set of meteoric events.In this work, we address the problem in a different way: instead of compung an orbit for the stream, and comparing it with the well known orbit of each possibleparent, we calculate the theorecal radiant, longitude and velocity associated with each parent, and then compare them with those directly measured on thestreams. Since the laer set of parameters is more directly measured on a shower, we can eliminate a significant part of uncertainty in the idenficaon thatcomes from a poorly constrained meteoroid orbit.We tested this method on the current list of known NEOs and the IAU MDC list of established and proposed meteor showers: we produced a new list of possibleassociaons, ranked in terms of stascal significance, which includes most of the already accepted NEO-shower associaons, plus a significant number of newones.In some cases, we also obtained astrometric observaons on some of these newly proposed parents, to beer constrain their orbits and allow a meaningfuldynamical analysis that can prove the associaon.13.29: 2008 TC 3 Asteroid Internal Structure and Physical Properes Inferred from Study of the Almahata Sia MeteoritesAuthor Block: Tomas Kohout 1 , R. Kiuru 1 , M. Montonen 1 , S. Petr 2 , D. Bri 3 , R. Macke 3 , G. Consolmagno 41 University of Helsinki, Finland, 2 Academy of Sciences of the Czech Republic, Czech Republic, 3 University of Central Florida, 4 Vacan Observatory, Italy.Presentaon Time: 10/7/2010 4:36 PM - 4:38 PMLocaon: Exhibit HallAbstract: 2008 TC 3 asteroid internal structure and physical properes were inferred from the empirical study of Almahata Sia meteorites. Densitymeasurements of Almahata Sia ureilites reveal a bulk density of ~ 3.1 g/cm 3 , a grain density of ~ 3.6 g/cm 3 and microporosity around 16%. These values,together with the 2008 TC 3 asteroid shape model and albedo (standard ureilites albedos are in the range of 0.10-0.15), were used to esmate the asteroid’smass. For these values and measured ureilite bulk density our model predicts 23 ton upper limit of asteroid mass. Since asteroid 2008 TC 3 was composionallyheterogeneous and of low mechanical strength we consider the presence of addional significant macroporosity. The macroporosity lowers the asteroid’s bulk

density compared to that of the Almahata Sia ureilites. This in turn significantly lowers the 2008 TC 3 mass esmates. We conclude that the 2008 TC 3 asteroidmass in presence of significant macroporosity was most likely below 20 tons. The previously reported higher mass esmates are only possible in the case ofasteroid albedo lower than 0.10 and low macroporosity. The presence of a non-ureilic fracon and space weathering may affect the albedo and also influencethe mass esmates. However, from current data it is not possible to quanfy this effect.13.30: Spectroscopy of Almahata Sia and Goalpara Meteorites: Implicaons for Ureilite Composion and Associaon with AsteroidsAuthor Block: Janice L. Bishop 1 , T. Hiroi 2 , E. Clous 3 , M. D. Lane 4 , W. Freeman 5 , F. Marchis 6 , J. Emery 7 , P. Jenniskens 1 , M. H. Shaddad 81 SETI Instute / NASA Ames Research Center, 2 Brown University, 3 University of Winnipeg, Canada, 4 Planetary Science Instute, 5 Louisiana State University,6 SETI Instute / UC-Berkeley, 7 University of Tennessee, 8 University of Khartoum, Sudan.Presentaon Time: 10/7/2010 4:38 PM - 4:40 PMLocaon: Exhibit HallAbstract: Reflectance spectra have been acquired for several fresh surfaces of Almahata Sia meteorites (1) and one Goalpara meteorite in order tocharacterize the spectral properes of these ureilites. These data are compared to recently acquired reflectance spectra of a larger collecon of fresh andweathered ureilites (2).Ureilites are characterized by low reflectance in the VNIR range and weak absorpons near 0.3, 1 and 2 µm (1,3). The laer two features are aributed topyroxene and olivine and the low reflectance is a result of opaques including fine-grained carbon and metals. Linear mixtures of the spectra of several AlmahataSia meteorites are consistent with the spectral character of 2008 TC3 (1).VNIR reflectance spectra of fresh and external surfaces of the Goalpara meteorite exhibit a slope characterisc of thin silica coangs on basalt (4); however, mid-IR spectra are characterized by olivine and pyroxene features and only show evidence of the silica coang on the external surface.The reflectance properes from 0.28-2.5 µm of ureilites share some similaries with those observed for F-, B- and S-type asteroids. We are invesgang these inorder to provide constraints on the origin of ureilites. We hope to apply the mid-IR spectral studies of the Almahata Sia and Goalpara meteorite surfaces to mid-IR transmiance spectra of ureilites (5) and to the mid-IR Spitzer data of F-, B- and S-type asteroids to contribute towards our understanding of possible ureiliteparent bodies as well.We thank the Natural History Museum in Vienna for generously loaning us the Goalpara meteorite.References:1. Hiroi, T., et al. 2010. MAPS. in press.2. Clous, E. A., et al. 2010. MAPS. in press.3. Jenniskens, P., et al. 2009. Nature. 458, 485-488.4. Mini, M. E., et al. 2007. JGR. 112, E05015 1-24.5. Sandford, S. A., 1993. Meteorics. 28, 579-585.13.31: Invesgaon of the Origin of 2008TC3 Through Spectral Analysis of F-type Asteroids and Lab Spectra of Almahata Sia and Mineral MixturesAuthor Block: William Freeman 1 , J. Bishop 2 , F. Marchis 3 , J. Emery 4 , A. E. Reiss 5 , T. Hiroi 6 , D. Barrado y Navascués 7 , M. H. Shaddad 8 , P. Jenniskens 21 Louisiana State University & SETI Instute, 2 SETI Instute & NASA Ames Research Center, 3 SETI Instute & UC-Berkeley, 4 University of Tennessee, 5 SanFrancisco State University, 6 Brown University, 7 LAEFF-CAB & Calar Alto Observatory, Spain, 8 University of Khartoum, Sudan.Presentaon Time: 10/7/2010 4:42 PM - 4:44 PMLocaon: Exhibit HallAbstract: We are analyzing lab spectra of simulated ureilite meteorites along with observaons of F-type asteroids in an aempt to characterize the spectralfeatures of ureilite type meteorites. We have processed spectra from twelve F-type asteroids that are potenal sources of 2008 TC3. A comparave study of thelab mixtures, Almahata Sia, F-type asteroids, and 2008 TC3 is underway. We are aempng to use these data to connect the Almahata Sia meteorites and theirparent asteroid, 2008 TC3, with a specific class of asteroids.Spectra of seven main-belt, F-type, low albedo asteroids were observed with the 2.2m telescope at Calar Alto using the CAFOS low resoluon spectrograph in R-400 (0.47-1.1 µm) and B-100 (0.32-0.58 µm) modes. Targets were selected from Jenniskens et al (2010), and the data are currently being processed. The KastDouble Spectrograph was used at the Shane 3-m Telescope at LICK observatory to take spectra of five more F-type asteroids. Addional data will be taken in July2010 with IRTF and SpeX low-resoluon spectrographs in the near-infrared (1-2.5 µm) region.Reflectance spectra of simulated ureilites comprised of mixtures of olivine, pyroxene and fine-grained carbon are being acquired from 0.35-2.5 µm using an ASDspectrometer at 2 nm spectral sampling. We will aempt to characterize ureilite spectral properes using Gaussian modeling (Sunshine et al. 1993) and analysisof the band centers and depths due to the olivine and pyroxene minerals observed in spectra of the Almahaa Sia samples (Hiroi et al. 2010).Hiroi, T et al. 2010. Meteorics and Planetary Science, in press.Jenniskens, P et al. 2010. Meteorics and Planetary Science, in review.Sunshine, J. M. et al. 1993. Icarus. 105, 79-91.13.32: Mechanical Properes of Fe-Ni MeteoritesAuthor Block: Mulford Roberta 1 , B. El Dasher 21 Los Alamos Naonal Laboratory, 2 Lawrence Livermore Naonal Laboratory.Presentaon Time: 10/7/2010 4:44 PM - 4:46 PMLocaon: Exhibit HallAbstract: Iron-nickel meteorites exhibit a unique lamellar microstructure, Widmanstaen paerns, consisng of small regions with steep-iron-nickelcomposion gradients. 1,2 The microstructure arises as a result of extremely slow cooling in a planetary core or other large mass. Mechanical properes of thesestructures have been invesgated using microindentaon, x-ray fluorescence, and EBSD. Observaon of local mechanical properes in these highly structuredmaterials supplements bulk measurements, which can exhibit large variaon in dynamic properes, even within a single sample. 3 Accurate mechanicalproperes for meteorites may enable beer modeling of planetary cores, the likely origin of these objects. Appropriate values for strength are important in impactand crater modeling and in understanding the consequences of observed impacts on planetary crusts. Previous studies of the mechanical properes of a typicaliron-nickel meteorite, a Diablo Canyon specimen, indicated that the strength of the composite was higher by almost an order of magnitude than values obtainedfrom laboratory-prepared specimens. 4 This was ascribed to the extreme work-hardening evident in the EBSD measurements. This parcular specimen exhibitedonly residual Widmanstaen structures, and may have been heated and deformed during its traverse of the atmosphere. Addional specimens from the CanyonDiablo fall (type IAB, coarse octahedrite) and examples from the Muonionalusta meteorite and Gibeon fall ( both IVA, fine octahedrite), have been examined toestablish a range of error on the previously measured yield, to determine the extent to which deformaon upon re-entry contributes to yield, and to establish thedegree to which the strength varies as a funcon of microstructure.1. A. Chrisansen, et.al., Physica Scripta, 29 94-96 (1984.)

2. Goldstein and Ogilvie, Geochim Cosmochim Acta, 29 893-925 (1965.)3. M. D. Furnish, M.B. Boslough, G.T. Gray II, and J.L. Remo, Int. J. Impact Eng, 17 341-352 (1995.)4. J.J. Petrovic, J. Mater. Sci., 36 1579-1583 (2001.)

Session Number: 27Session Title: Extrasolar Planets and SystemsSession Type: Poster27.01: Extrasolar Planet Research at Universidad de ChileAuthor Block: Patricio Rojo 1 , S. Hoyer 1 , J. Jenkins 1 , M. Jones 11 Universidad de Chile, Chile.Presentaon Time: 10/7/2010 3:50 PM - 3:52 PMLocaon: Exhibit HallAbstract.Abstract: I will present the latest publicaons and current status on projects lead by researchers and doctoral candidates at Universidad de Chile inthe area of extrasolar planets. Making use of the privileged access to world-class telescopes, the research efforts are focused in ground-based observaons.Long- and short-term projects are currently underway: (1) exoplanetary atmospheric characterizaon, (2) monitoring of southern transing planets searching fortransit-ming variaons, (3) the Calan-Herordshire Extrasolar planet RV search (CHEPS), and (4) study of post main-sequence planetary hosts.27.02: Inhomogeneous Planet Evoluon: Extending the MESA Stellar Evoluon CodeAuthor Block: Neil Miller 1 , J. Fortney 1 , B. Paxton 21 UC Santa Cruz, 2 UC Santa Barbara, KITP.Presentaon Time: 10/7/2010 3:52 PM - 3:54 PMLocaon: Exhibit HallAbstract: Movaon: Inhomogeneous planet evoluon codes are necessary for modeling the coupling between composion gradients, the planet's structure,and the evoluon. The composion profile can affect structural properes and energy transport properes of the planet. If the planet has a stabilizing meanmolecular weight gradient opposing an unstable entropy gradient, then the interior may have many convecve layers separated by thin diffusive zones. This maysignificantly decrease the efficiency of convecon. These composion gradients may arise because of core erosion or Helium immiscibility. This may be useful forunderstanding observables such as the radii, luminosity or gravitaonal moments of giant planets both inside and outside of our solar system.Acon: To study these types of problems, we are extending the modular open source stellar evoluon soware,MESA, to the giant planet regime to performinhomogeneous planet evoluon. We have extended the equaon of state and opacity tables of MESA to include substances such as ices, rocks or metals usingANEOS tables. Model planet atmosphere grids are substuted to determine planet luminosies. Here, we present our first inhomogeneous planet evoluonresults. Consistent with the MESA philosophy, these planet modules will eventually be open source and freely available.27.03: Phase Space Of Equilibrium Rotaonal Dynamics Of Super-earthsAuthor Block: Nelson Callegari 1 , T. Yokoyama 11 UNESP, Brazil.Presentaon Time: 10/7/2010 3:54 PM - 3:56 PMLocaon: Exhibit HallAbstract: We invesgate the dynamics of the rotaon of exoplanets around several spin-orbit resonant states. We suppose the existence of quadrupolepermanent structure of terrestrial-like planets whose translaonal periods are of the order of a few days. In our model, the dynamics of the equilibrium rotaon isdominated by the torque of the central star on the non-spherical shape of the planet. We show analycally the possibility of chaoc rotaon of super-Earths withlarge equatorial prolateness and eccentric orbits (e.g. e>0.1). In more realisc scenarios (i.e., circular orbits and prolateness close to zero), the domains of 2:1,3:2 and 1:1 states are regular. We use surfaces of secon and spectral analyses in order to numerically confirm our analycal results. We focus our aenon onthe dynamics of GJ 436 b, GJ 1214 b, HAT-P-11 b, CoRoT-7 b, CoRoT-9 b. In this work we also present a model which allow us to quanfy the gravitaonalperturbaons of a hypothecal outer planet on the rotaon of an inner planet.27.04: M2K Planet Search: Spectroscopic Screening and Transit PhotometryAuthor Block: Andrew Mann 1 , E. Gaidos 1 , D. Fischer 2 , S. Lepine 31 University of Hawaii, 2 Yale University, 3 American Museum of Natural History.Presentaon Time: 10/7/2010 3:56 PM - 3:58 PMLocaon: Exhibit HallAbstract: The M2K project is a search for planets orbing nearby early M and late K dwarf drawn from the SUPERBLINK catalog. M and K dwarfs are highlyaracve targets for finding low-mass and habitable planets because (1) close-in planets are more likely to orbit within their habitable zone, (2) planets orbingthem induce a larger Doppler signal and have deeper transits than similar planets around F, G, and early K type stars, (3) planet formaon models predict theyhold an abundance of super-Earth sized planets, and (4) they represent the vast majority of the stars close enough for direct imaging techniques. In spite of this,only ~10% of late K and early M dwarfs are being monitored by current Doppler surveys. As part of the M2K project we have obtained low-resoluon spectra formore than 2000 of our sample of ~10,000 M and K dwarfs. We vet our sample by screening these stars for high metallicity and low chromospheric acvity. Wesearch for transits on targets showing high RMS Doppler signal and photometry candidates provided by SuperWASP project. By using “snapshot” photometry havebeen able to achieve sub-millimag photometry on numerous transit targets in the same night. With further follow-up observaons we will be able to detectplanets smaller than 10 Earth masses.27.05: Planetary Atmosphere Stability in the Habitable Zones of M-starsAuthor Block: Feng Tian 11 University of Colorado at Boulder.Presentaon Time: 10/7/2010 3:58 PM - 4:00 PMLocaon: Exhibit HallAbstract.Abstract: The tradional habitable zone depends on condions suitable for long term stability of liquid water on the surface of planets. It is suggestedthat the frequent intense stellar CME events could have led to so rapid erosion of planetary atmospheres that generally speaking there is essenally no habitablezones around Earth-mass planets around M-stars. However, fast atmosperic mass loss should put the planetary atmosphere in the hydrodynamic, in which theenergy consumpon by the oulow could have limited the atmospheric loss and make a CO2-dominant planetary atmosphere stable in the habitable zones of M-stars. In this work we will explore the atmosphere stability of broad range of habitable planets with different mass and atmospheric composion.27.06: The P TF Orion Planet-Search: Preliminary Results from the First Data SetAuthor Block: Julian C. Van Eyken 1 , D. R. Ciardi 1 , R. L. Akeson 1 , C. A. Beichman 1 , A. F. Boden 2 , K. von Braun 1 , S. R. Kane 1 , P. Plavchan 1 , S. V. Ramírez 1 , L. M.Rebull 3 , J. R. Stauffer 3 , PTF Collaboraon

1 NExScI, Caltech, 2 Caltech, 3 Spitzer Science Center, Caltech.Presentaon Time: 10/7/2010 4:00 PM - 4:02 PMLocaon: Exhibit HallAbstract.Abstract: The PTF Orion project is a part of the Palomar Transient Factory (PTF), a survey for astronomical transients being undertaken with a dedicatedwide-field CCD array installed on the Palomar 48" telescope. The Orion project is an experiment that during its first year is focusing on a single poinng in theOrion star-forming region. The project has been assigned 40 consecuve nights per year for three years -- the first 40 nights of which are now complete -- toperform intensive me-series observaons with the aim of detecng close-in, Jupiter-sized planets transing young stars. Lile is known about the distribuonand frequency of planets around stars that are 1-100 Myr old - the me frame in which the giant planets are expected to form. Our principal goal is to invesgatethe frequency of planets around stars at young ages. In addion, the observaons provide a unique data set to study a variety of stellar astrophysics, includingeclipsing binary systems for tesng star formaon and evoluon models; characterising stellar acvity and rotaonal periods; and characterising previouslyunknown young stars in the Orion region. Here we present preliminary results from the first year's data set.27.07: Glints Observed by the EP OXI Mission and Their Value for the Remote Sensing of Exoplanet Surfaces and AtmospheresAuthor Block: Ludmilla Kolokolova 1 , A. Borovoi 2 , M. Mishchenko 3 , M. A'Hearn 11 Univ. of Maryland, 2 Instute of Atmospheric Opcs, Russian Federaon, 3 NASA GISS.Presentaon Time: 10/7/2010 4:02 PM - 4:04 PMLocaon: Exhibit HallAbstract: Images of the Earth obtained at the EPOCh part of the EPOXI mission demonstrated glints associated with the terrestrial oceans. It was proposed thatthis phenomenon might reveal large bodies of water on exoplanets. However, these images show not only the ocean glints (big and fuzzy), but also small brightsparks which happen to be not above the ocean. Some of them can be glints from lakes or rivers. However, some glints cannot be associated with any waterbasin; somemes they appear even on the top of the clouds. Most likely, those glints result from the specular reflecon from cirrus. Cirrus glints are produced byplate-shaped icy parcles that easily get oriented horizontally at their free fall in the atmosphere. Unlike rough and foamy ocean surface that produces the diffuseglints of angular width more than 40 deg., these oriented parcles produce a narrow,

27.10: HD80606b Transit Observed by MOSTAuthor Block: Jessica Roberts 1 , J. W. Barnes 1 , J. F. Rowe 2 , J. J. Fortney 31 University of Idaho, 2 NASA Ames Research Center, 3 University of California - Santa Cruz.Presentaon Time: 10/7/2010 4:08 PM - 4:10 PMLocaon: Exhibit HallAbstract: We present our results of the observaons taken by the MOST telescope of the occultaon and the full ~12 hour transit of HD80606b, which occurredon January 8th and 14th, 2010 respecvely. With its unusually high eccentricity of 0.9336, HD80606b challenges our understanding of the evoluon of planetarysystems. Furthermore, with its large variance of distance from its star, the atmospheric dynamics of HD80606b are likely to be different from any other exoplanetdiscovered to date. By constraining the parameters of this system, we will beer understand the dynamics of this planet and will improve numerous planetarymodels. We determine a best fit of the primary transit for the stellar and planetary radius, inclinaon, and limb darkening parameters. We also fit for the albedoand temperature of the secondary eclipse, which is of great interest as these two variables are likely to vary enormously during the planet’s 111.436 day orbit.The difficulty in constraining our fits comes from an insufficiently understood mass of HD80606. Reported masses for HD80606 range from 0.9 to 1.1 solarmasses. We therefore determine best fits of the previously listed parameters for different stellar masses within this range. By fing for the me at transit andoccultaon, we determine the best argument of periapsis, a variable whose reported value varies largely. Lastly, we compare our results to those determined byground-based telescopes and by Spitzer to beer constrain HD80606b’s parameters as the ground-based and Spitzer results vary largely.27.11: Atmospheric Chemistry of Iron, Magnesium, and Silicon in Substellar ObjectsAuthor Block: Channon W. Visscher 1 , B. Fegley 2 , K. Lodders 21 Lunar & Planetary Instute (USRA), 2 Washington University in St. Louis.Presentaon Time: 10/7/2010 4:10 PM - 4:12 PMLocaon: Exhibit HallAbstract.Abstract: We use thermochemical equilibrium calculaons to model Fe, Mg, and Si chemistry in the atmospheres of giant planets, brown dwarfs, andextrasolar giant planets. The chemical behavior of individual Fe, Mg, and Si gases and condensates is determined as a funcon of temperature, pressure, andmetallicity. Our results are therefore, in principle, independent of any parcular model atmospheric profile. The chemistry of these elements is very stronglyeffected by the condensaon of iron metal, forsterite, and enstate, which are expected to produce the most massive cloud layers in substellar atmospheres. Ourmodel results are used to idenfy gases which may serve as indicators of weather, to predict the chemical composion of cloud layers, and to provide constraintsfor composion, structure, and opacity in the atmospheres of substellar objects.27.12: Tidal Driven Mass Loss on Water PlanetsAuthor Block: Eric Lopez 11 UC Santa Cruz.Presentaon Time: 10/7/2010 4:12 PM - 4:14 PMLocaon: Exhibit HallAbstract: Current planet formaon theory predicts that large numbers of planets form beyond the snow line and then migrate inwards to extremely short orbits.Some of these planets are likely to be Earth and Super Earth mass with large amounts of volale ices. This could create a class of close in Earth and Super mass“water planets”. We invesgate the effects of dal heang from circularizaon on such planets. The combinaon of low dal Q, low vaporizaon temperature,and low mean molecular weight make water planets uniquely vulnerable to severe mass loss from dal heang. We find that if these planets ever experiencesignificant eccentricity, the heat from their rapid circularizaon will cause significant mass loss. This could significantly affect the survivability of water planetsand the low end of the mass-period distribuon.27.13: Analysis of HD 149026b Spitzer Data Using a New Intrapixel TechniqueAuthor Block: Kevin Stevenson 1 , J. Harrington 1 , S. Nymeyer 1 , J. J. Fortney 2 , R. A. Hardy 1 , P. Cubillos 1 , W. C. Bowman 11 University of Central Florida, 2 University of California, Santa Cruz.Presentaon Time: 10/7/2010 4:14 PM - 4:16 PMLocaon: Exhibit HallAbstract: The Saturn-sized exoplanet HD 149026b transits a large, relavely hot parent star at a distance of only 0.042 AU. The planet's high average densitysuggests that most of HD 149026b's mass must be in it's large, icy/rocky core. Using the Spitzer Space Telescope to observe the system during secondary eclipse,previous authors report contradicng eclipse depths at 8.0 μm. We re-analyze these data, combine the results with two new observaons at 8.0 μm, and useaddional observaons in other Spitzer channels to present constraints on the atmospheric composion of HD 149026b. We also present a new technique thatmodels Spitzer's posion-dependent (intrapixel) sensivity effect to a high degree of precision. Spitzer is operated by the Jet Propulsion Laboratory, CaliforniaInstute of Technology under a contract with NASA, which provided support for this work.27.14: Structural Evoluon Of Hot Jupiters Under Ohmic DissipaonAuthor Block: Konstann Batygin 1 , D. J. Stevenson 1 , P. Bodenheimer 21 California Instute of Technology, 2 UCO/Lick Observatory.Presentaon Time: 10/7/2010 4:16 PM - 4:18 PMLocaon: Exhibit HallAbstract.Abstract: In presence of thermal ionizaon, that is characterisc of hot Jupiter atmospheres, the interacons of atmospheric winds and the planetarymagnec field results in an inducon of electrical current into the interior of the planet. The resulng Ohmic dissipaon in the interior may provide an adequateenergy source to explain the anomalously inflated radii of hot Jupiters. Here, we present coupled calculaons of structural evoluon and Ohmic dissipaon. Itappears that extra-solar gas giant radius anomalies can be explained in the context of the Ohmic inflaon mechanism.27.15: The Mechanical Greenhouse: How Stably Strafied Turbulence Heats Hot JupitersAuthor Block: Andrew Youdin 1 , J. Mitchell 21 Harvard Smithsonian Center for Astrophysics, 2 University of California, Los Angeles.Presentaon Time: 10/7/2010 4:18 PM - 4:20 PMLocaon: Exhibit HallAbstract.Abstract: The intense irradiaon received by hot Jupiters suppresses convecon to a depth well below the photosphere. This stably strafied regionmay be turbulent. Atmospheric circulaon from day to night sides has been proposed as a source of turbulence. Turbulence has also been invoked to explainstratospheric thermal inversions, because mixing is required to keep opacity sources such as TiO alo. We develop a model for steady state energy balance thatincludes turbulence in radiave zones. We discover a "mechanical greenhouse effect" whereby turbulence in stably strafied atmospheres provides a downward

flux of heat. This mechanism is precisely opposite to the outward flux of heat in convecve zones. Since the mechanical flux of heat penetrates below thephotosphere, it behaves analogously to the deep penetraon of visible light in the standard greenhouse effect. We find that low levels of turbulence push theradiave convecve boundary deeper in the planet, suppressing its cooling rate. Stronger turbulence can directly inflate by planet, as overshoot will inject heatand entropy into the convecve core. We esmate that the turbulence needed to explain thermal inversions via TiO absorpon may be excessive, in that theplanet would over-inflate and evaporate. More modest turbulence could explain the inflated states of many transing hot Jupiters. I will discuss prospects forincorporang our semi-analyc model into detailed simulaons of the evoluon and atmospheric dynamics of hot Jupiters.27.16: Detectability of Trojan and Co-orbital ExoplanetsAuthor Block: Anthony R. Dobrovolskis 11 UCO/Lick Observatory and NASA/Ames Research Center.Presentaon Time: 10/7/2010 4:20 PM - 4:22 PMLocaon: Exhibit HallAbstract: By now there have been many papers on the possibility of Trojan companions to planets of other stars. The purpose is of this work is to point out thatradial velocity measurements can seriously misjudge the masses of planets in such systems.In a Trojan system, where two exoplanets of similar mass share the same orbit, but are separated by 60 degrees of longitude, the radial velocity method gives asinusoidal signal 1.73 mes as great as that of each individual planet, but only 0.83 mes as great as that of a single planet with the combined mass of both.In principle, any number of planets can share the same orbit. Salo and Yoder (A & A 205, 309-327, 1988) have shown that more than 8 planets of equal masssharing a circular orbit must be equally spaced for dynamical stability.In contrast, less than 7 equal-mass planets are stable only in a configuraon where all of the planets remain on the same side of their parent star. In theintermediate cases of 7 or 8 equal-mass planets, both the equally- and unequally-spaced configuraons are stable. If they indeed exist, the lopsided "Salosystems" will produce a greater radial velocity signal than a single such planet would, but a smaller signal than if all of the planets were combined into one.In fact, such systems with 7 or 8 planets induce Doppler shis almost 4 mes as great as an individual planet, but only about half as great as their combinedmass would. By symmetry, it is clear that equally-spaced Salo systems will produce no reflex moon or radial velocity signal at all in their parent stars. This couldlead to their being overlooked enrely, unless they happen to be detected by the transit method.27.17: The Effect of Pericenter Glow from Jovian Exoplanets on Terrestrial Planet ImagingAuthor Block: Jonathan D. Fraine 1 , M. Kuchner 21 Univeristy of Maryland, 2 NASA Goddard Space Flight Center.Presentaon Time: 10/7/2010 4:22 PM - 4:24 PMLocaon: Exhibit HallAbstract.Abstract: In a planetary system with even one planet on an eccentric orbit, the zodiacal cloud will show pericenter glow caused by the secularpertubaons from the planet. This pericenter glow could complicate the detecon of exoearths by generang false posives. We examine the consequences ofthis perturbaon for direct imaging of terrestrial exoplanets using ZODIPIC, an easy-to-use modeling suite for synthesizing images and resolved-spectra ofopcally-thin debris disks. We explore a range of two planet systems, tested for long-term stability, and determine how zodiacal light complicates terresalplanet imaging.27.18: Two Secondary Eclipses of WASP-18bAuthor Block: Sarah Nymeyer 1 , J. Harrington 1 , R. A. Hardy 1 , K. B. Stevenson 1 , C. J. Campo 1 , N. Madhusudhan 2 , A. Collier-Cameron 3 , J. Blecic 1 , W. C. Bowman 1 , C.B. T. Bri 1 , P. Cubillos 1 , C. Hellier 4 , M. Gillon 5 , P. F. L. Maxted 3 , L. Hebb 6 , P. J. Wheatley 7 , D. Pollacco 8 , D. R. Anderson 41 University of Central Florida, 2 Massachuses Instute of Technology, 3 University of St. Andrews, United Kingdom, 4 Keele University, United Kingdom,5 Université de Liège, Belgium, 6 Vanderbilt University, 7 University of Warwick, United Kingdom, 8 Queen's University, United Kingdom.Presentaon Time: 10/7/2010 4:24 PM - 4:26 PMLocaon: Exhibit HallAbstract.Abstract: The transing exoplanet WASP-18b was discovered in 2008 by the Wide Angle Search for Planets (WASP) project. The Spitzer ExoplanetTarget of Opportunity Program observed secondary eclipses of WASP-18b using Spitzer's Infrared Array Camera (IRAC) in the 3.6 micron and 5.8 micron bands on2008 December 20, and in the 4.5 micron and 8.0 micron bands on 2008 December 24. We present a pressure-temperature profile, eclipse depths and brightnesstemperatures of WASP-18b, which is one of the hoest planets yet discovered, as hot as an M-dwarf star. These observaons are part of the Spitzer ExoplanetTarget of Opportunity program, which observes eclipses and transits of new exoplanets. Spitzer is operated by the Jet Propulsion Laboratory, California Instute ofTechnology under a contract with NASA, which provided support for this work.27.19: Reversing Type I Migraon in Shadowed GapsAuthor Block: Hannah Jang-Condell 11 Univ. of Maryland/NASA-GSFC.Presentaon Time: 10/7/2010 4:26 PM - 4:28 PMLocaon: Exhibit HallAbstract.Abstract: As embryonic planets grow in size, they begin to clear gaps in the protoplanetary disks in which they form. Cooling in the shadow of the gapcreates a disnct thermal signature which can affect the connuing growth and migraon of the planet. I examine the thermal effects in disks with gaps usingdetailed self-consistent radiave transfer models for the disks. Shadowing and illuminaon on the gap alters the radial temperature profile of the disk, whichalters the locaons of Lindblad resonances, which are offset from Keplerian rotaon because of pressure support. This, in turn alters the relave strengths of thetorques, and can shi the overall balance of Type I migraon torques. In some cases, the radial temperature profiles is sufficiently altered to reverse the direconof Type I migraon, resulng in the outward rather than inward migraon of planets. This mechanism may rescue planets from rapid inward migraon and loss ofthe planet onto the star, or could send Jovian-mass planets to large distances from their stars, as in the HR 8799 and Fomalhaut systems.27.20: Secular Behavior In Mul-planet Systems: 61 Virginis, 55 Cancri, Etc.Author Block: Christa Van Laerhoven 1 , R. Greenberg 11 University of Arizona.Presentaon Time: 10/7/2010 4:28 PM - 4:30 PMLocaon: Exhibit HallAbstract: Secular analycal theory can offer insight into the evoluon of a mul-planet system as well as the interacons among its planets. Major axes lockedin alignment (dominance of a single eigenfrequency) may indicate substanal dal damping; Near-separatrix behavior would suggest an early mutual scaeringevent. For the 61 Virginis system, secular theory reproduces the general behavior from numerical integraons even though the eccentricies are quite large. The

major axes of the two outer planets librate about a mutual alignment. However, rather than indicang dal evoluon, this alignment is the most likely behaviorgiven the system’s basic architecture, i.e. masses and semi-major axes. In general, an alignment of major axes of only a subset of planets does not necessarilyimply that des or any other eccentricity-damping process has been significant in the evoluon of such a system. For the published orbits (Fischer et al. 2008) ofthe five-planet 55 Cancri system: The innermost planet (“e”) has a surprisingly large eccentricity, dominated by a single frequency, which is precisely the one thatdes should damp out first; The alignment of three major axes involves three different eigenfrequencies, so it has nothing to do with damping, and is improbable;The outer two planets undergo near-separatrix libraon, which would suggest the outermost one underwent a scaering event. Recent alias correcons for 55Cancri (Dawson and Fabryky 2010) allow a good fit with a circular orbit for the inner planet. Secular theory shows the orbit remains nearly circular even under theinfluence of the other planets. Moreover, the single eigenfrequency of the system that is controlled by des has completely damped away in all the planets. 55Cancri e has apparently undergone complete dal damping, consistent with its proximity to the star. Secular theory is a valuable tool as data improve and newdiscoveries connue.27.21: Polarizaon of Directly Imaged Young Giant Planets as a Probe of Mass, Rotaon, and CloudsAuthor Block: Mark S. Marley 1 , S. Sengupta 21 NASA Ames Research Center, 2 Indian Instute of Astrophysics, India.Presentaon Time: 10/7/2010 4:30 PM - 4:32 PMLocaon: Exhibit HallAbstract: Young, hot gas giant planets at large separaons from their primaries have been directly imaged around several nearby stars. More such planets willlikely be detected by ongoing and new imaging surveys with instruments such as the Gemini Planet Imager (GPI). Efforts connue to model the spectra of theseplanets in order to constrain their masses, effecve temperatures, composion, and cloud structure. One potenal tool for analyzing these objects, which hasreceived relavely less aenon, is polarizaon. Linear polarizaon of gas giant exoplanets can arise from the combined influences of light scaering byatmospheric dust and a rotaonally distorted shape. The oblateness of gas giant planet increases of course with rotaon rate and for fixed rotaon also riseswith decreasing gravity. Thus young, lower mass gas giant planets with youthful inflated radii could easily have oblateness greater than that of Saturn’s 10%. Wefind that polarizaons of over 1% may easily be produced in the near-infrared in such cases. This magnitude of polarizaon may be measurable by GPI and otherinstruments. Thus if detected, polarizaon of a young Jupiter places constraints on the combinaon of its gravity, rotaon rate, and degree of cloudiness. We willpresent results of our mulple scaering analysis coupled with a self-consistent dusty atmospheric models to demonstrate the range of polarizaons that mightbe expected from resolved exoplanets and the range of parameter space that such observaons may inform.27.22: Finesse - A New Mission Concept For Exoplanet SpectroscopyAuthor Block: Mark R. Swain 11 JPL.Presentaon Time: 10/7/2010 4:32 PM - 4:34 PMLocaon: Exhibit HallAbstract.Abstract: FINESSE, the Fast Infrared Exoplanet Spectroscopy Survey Explorer, is a concept for an Explorer class mission to study the nature of exoplanetatmospheres. The last 15 years have witnessed extraordinary success in finding exoplanets with ground-based surveys and, more recently, the Kepler and Corotmissions collecvely idenfied hundreds of planets. FINESSE is designed to take the next step; using proven methods and an opmized design, FINESSE would bethe first mission dedicated to the spectroscopic characterizaon of exoplanets. During a two-year mission, FINESSE would conduct an extensive survey ofexoplanet systems, providing large sample for comparave exoplanetology with a range of planets represented from the most extreme hot-Jupiters to warmNeptunes and Super-Earth. FINESSE would have spectroscopic coverage from approximately 0.5 to around 3.0 microns with sensivity to important molecularbands of water, methane, carbon dioxide and other molecules. Spectral retrieval, based on FINESSE measurements, would reveal the temperature, composion,and chemistry of exoplanets in the FINESSE sample and would allow the planets to be compared in a uniform way. Significantly, the data for all wavelengths wouldbe obtained simultaneously to remove confusing effects of any variability in the star/planet system. Engineered for exquisite stability, FINESSE will rounelyobserve calibrator targets; this will allow the exoplanet emission spectra to be obtained for any point in the orbit and will also allow spectra taken at differentmes to be compared to search for indicators of atmospheric dynamics. Implemented as a rapid, low-cost mission, FINESSE is scienfically well matched to therapidly expanding area of exoplanets.27.23: Expanding Exoplanetology: The Suite of Instruments NecessaryAuthor Block: Stephen J. Edberg 11 JPL.Presentaon Time: 10/7/2010 4:34 PM - 4:36 PMLocaon: Exhibit HallAbstract: Where once the discovery of exoplanets was a dream, we are now past the threshold of learning about their properes, at least in a few cases. Withthe correct choice of instruments to study exoplanets, it is possible to discover properes spanning the range from the core of the planet through its interior andatmosphere to its magnetosphere.No one instrument on the ground or in space can collect the data necessary to characterize an exoplanet at all its levels. But with judicious choices ofinstruments, the interdependencies liming characterizaon of an exoplanet’s properes disappear and many details are learned. This presentaon illustratesthe breadth of planetary properes that can be determined when a selecon of instruments is available for invesgaons.Wes Traub laid the foundaon for the charts presented. The contribuons of a large number of researchers in the growing field of exoplanet research areacknowledged. Much of this work grew out of the efforts of parcipants in the Exoplanet Community Report (Lawson, Traub, & Unwin, 2009, JPL Publicaon 09-3,3/09).The research described was carried out by the Jet Propulsion Laboratory, Caltech, which is under contract with NASA. Copyright 2010 California Instute ofTechnology. Government sponsorship acknowledged.27.24: Constraints on the Tidal Dissipaon Rate and Love Number of the White Dwarf in 4U 1820 -30Author Block: Snezana Prodan 1 , N. Murray 11 CITA, Canada.Presentaon Time: 10/7/2010 4:36 PM - 4:38 PMLocaon: Exhibit HallAbstract: We show that the observed 170 day period in the light curve of 4U 1820-30 follows naturally from the assumpon that there is a third body in thesystem with a large inclinaon to the binary orbit, and that the system is librang around the stable fixed point in the Kozai resonance. Mass transfer drives thesystem toward this fixed point; we calculate, both analycally and via numerical integraons, that the period of libraon is of order 170 days. We show bothanalycally and numerically that the system will not be trapped in libraon if the semimajor axis is decreasing because the acon of the resonance separatrix

decreases with decreasing binary semi-major axis. The finding that the 170 day period in 4U 1820-30 results from libraon in the Kozai resonance implies that onthe secular me scale, and contrary to observaons, the orbital period of the inner binary is increasing with me; if the apparent decrease in orbital period isreal, and connues for dynamically significant mes, the Kozai resonance will be broken, indicang that the current configuraon is unstable, a situaon we finduntenable. The implicaon that the mass transfer has to win over dal dissipaon (resulng in semimajor axis expansion) allows us to give a lower limit onQ~10 8 . We conclude that the observed negave period derivave is either incorrect or not intrinsic to the system if 4U 1820-30 is a hierarchical triple.

Session Number: 36Session Title: TitanSession Type: Poster36.01: A Global Map of Titan's 13 cm Wavelength Radar ReflecvityAuthor Block: Gregory J. Black 11 Univ. of Virginia.Presentaon Time: 10/7/2010 4:00 PM - 4:02 PMLocaon: Exhibit HallAbstract: We have used radar spectra of Titan obtained with the Arecibo Observatory's radar system to produce global maps of Titan's diffuse radar reflecvityat a wavelength of 13 cm in both circular polarizaons. The data were obtained during opposions of the Saturn system from 2000 through 2008 with sub-radarlocaons between latudes 26S and 7S and well distributed in longitude [1,2]. The inversion method of Hudson and Ostro (1990) [3] was applied to reconstructthe global radar reflecvity at a resoluon of roughly 10 degrees at equatorial latudes. Titan's 13 cm radar spectrum is a combinaon of a specular componentresulng from single surface reflecons and a diffuse component resulng from mulple surface or volume scaering. The maps are constructed using only thediffuse component, which is assumed to dominate the full spectrum in the same circular (SC) polarizaon sense as transmied, and at high incidence angles inthe opposite circular sense (OC). The specular component, which appears in the OC polarizaon at low incidence angles around the sub-radar locaon, is noteasily treated in this inversion method. The resulng reflecvity maps are compared to 2.2 cm wavelength radar reflecvity (cf. [4]) and radiometry (cf. [5]) mapsfrom the Cassini RADAR instrument, smoothed to a similar resoluon, in order to look for variaons in surface structure as revealed by contrasts between thesedata sets. We acknowledge support from the NASA CDAP Program. Arecibo Observatory is part of the Naonal Astronomy and Ionosphere Center, operated byCornell University under cooperave agreement with the NSF.[1] Black et al., 2010 Icarus, In press. [2] Campbell et al., 2003 Science 302, 431. [3] Hudson & Ostro, 1990, JGR 95, 10947. [4] Wye et al., 2007, Icarus 188, 367.[5] Janssen et al., 2009, Icarus 200, 222.36.02: Sailing the Seas of Titan : Meteorology and Oceanography of Ligeia MareAuthor Block: Ralph Lorenz 1 , T. Tokano 2 , E. Stofan 31 JHU/APL, 2 Instut für Geophysik und Meteorologie, Germany, 3 Proxemy Research.Presentaon Time: 10/7/2010 4:02 PM - 4:04 PMLocaon: Exhibit HallAbstract: Ligiea Mare, about 500km across, is the second-largest sea on Titan and is the nominal target for the proposed TiME (Titan Mare Explorer) mission,which would arrive at Titan in 2023 (L s = 160 o ). A numerical model of des in Titan seas and lakes (Tokano, 2010) has now been applied to Ligeia, and shows ade that rotates an-clockwise around the sea with a maximum amplitude of ~1.2m (at the Eastern edge of Ligeia, and assuming no crustal response to des).Recent work (Hayes et al., 2010) at Ontario Lacus suggests that such depth changes may be observable in Cassini RADAR data.The magnitude of dal currents is rather small and depends on the depth. Ligeia’s bathymetry is not known (except that its overall radar darkness requires depths>6m) but assuming a 200m central depth by scaling with terrestrial lake basins , dal currents are of the order of 1 cm/s.The Global Circulaon Model of Tokano (2009) predicts surface winds of 0-1 m/s in this season : the wind paern is affected by global-scale wind, dal winds,and the local effects of the thermal contrast between the dark hydrocarbon sea and its surrounds (sea breeze). Rainfall preferenally occurs in summer and maybe slightly more intense than outside the sea.For vehicles with equal cross-secon above and below the waterline, the dri velocity will be about 1/10 th of thewindspeed (from simple drag balance, and the 100:1 difference between air and sea density). Given the winds above, the dri of the TiME capsule will ~10km per24 hours. However, the net dri depends on the variaon of wind direcon during a Titan day, so an epicyclic trajectory may result with a lower overall dri rate.We examine the possibility of drag modulaon to control direcon and speed of net dri.36.03: Potenally Acve Regions On Titan: Applicaon Of Differenal Spectroscopy On Cassini/vims Data.Author Block: Anezina Solomonidou 1 , M. Hirtzig 2 , G. Bampasidis 1 , E. Bratsolis 1 , A. Coustenis 3 , S. Le Moueĺic 4 , C. Son 5 , X. Moussas 1 , K. Kyriakopoulos 11 Naonal & Kapodistrian University of Athens, Greece, 2 LM D – IPSL, France, 3 LESIA, Observatoire de Paris, France, 4 Universite de Nantes, France, 5 JetPropulsion Laboratory.Presentaon Time: 10/7/2010 4:04 PM - 4:06 PMLocaon: Exhibit HallAbstract: The determinaon of Titan's surface chemical composion is crical in order to understand its geology and invesgate the interacons between theinterior, the surface and the atmosphere. Cassini/VIMS acquired many spectral images taken within the seven atmospheric methane windows (where themethane absorpon is weak) that revealed the complexity of Titan’s surface from several flybys. In order to extract the surface properes from these images, thecontribuon of Titan’s extended, hazy and dense atmosphere needs to be clearly defined. We apply empirical methods, such as that of “differenal spectroscopy”including an atmosphere-subtracted method and contrast analysis, on two potenally acve regions on Titan, Tui Regio (20°S, 130°W), a 1,500-km long flow-likefigure and Hotei Regio (26°S, 78°W), a 700-km wide volcanic-like terrain, which have been proposed as candidates for cryovolcanism. With our methods, we havemanaged to reduce the effect of the contribuon of the atmosphere within the atmospheric methane windows and focus on the real alteraons in surfacecomposion. We find that the flow-like area in Tui Regio presents significantly higher albedo values than the surrounding region. Regarding Hotei Regio, theimages before subtracon taken at the wavelengths corresponding to atmospheric methane windows, showed that the possible cryovolcanic terrain that seems toinclude caldera structures, which probably formed from cryovolcanic processes under tectonic zones of weakness, presents major differences of albedo valuesamongst the bright, dark and semi-dark areas. In addion, the analysis of new images obtained using the empirical methods, showed that the areas presentdifferent albedos, although the differences among the isolated areas are smaller than in the data before subtracon. As expected the cryovolcanic terrainpresents higher albedo values, while the caldera-like structures present medium values, lying almost in the average between the brighter (''volcanic area'') andthe darker (''primal surface'') at most wavelengths.36.04: Chemistry at the Organic-Mineral Interface Relevant to TitanAuthor Block: Heather Abbo-Lyon 1 , M. Dawley 1 , J. McLain 1 , G. Grieves 1 , T. Orlando 11 Georgia Instute of Technology.Presentaon Time: 10/7/2010 4:06 PM - 4:08 PMLocaon: Exhibit HallAbstract: The observaon of rivers and lakes on Titan has generated considerable interest with regard to prebioc chemistry, since these fluvial featuresprovide a liquid medium for reacons and a transportaon mechanism for catalyc mineral deposits le behind by meteorite impacts similar to the one thatcaused the Sinlap crater. Although numerous laboratory measurements and theorecal models have been used to study atmospheric chemistry applicable toTitan’s potenal astrobiology, few experiments have been performed to understand gas-/liquid-surface reacons. We are exploring heterogeneous chemistry

elevant to Titan using low energy electrons (5-50 eV) as an analog of the incident cosmic rays and secondary electrons they generate. Amorphousalkane/acetylene ices have been deposited on mineral and carbon substrates to simulate lake environments. In some cases, small amounts of amorphous waterice have been deposited at the organic-mineral boundary to model the interface of the hydrocarbon “soil” and the underlying water-ice “bedrock” of Titan.Preliminary results suggest that protonaon occurs readily even at the low temperatures observed on Titan’s surface (~100 K). These experiments are some of thefirst aimed at understanding chemistry at the organic-mineral interface under condions relevant to Titan, in parcular at the edges of hydrocarbon lakes. Thiswork has been performed as part of the NASA Astrobiology Instute “Titan as a Prebioc System” at the Jet Propulsion Laboratory.36.05: Dune Morphology and Substrate Dependence on TitanAuthor Block: Graham D. Vixie 1 , J. W. Barnes 1 , J. Radebaugh 21 University of Idaho, 2 Brigham Young University.Presentaon Time: 10/7/2010 4:08 PM - 4:10 PMLocaon: Exhibit HallAbstract.Abstract: We are using Cassini's Visual and Infrared Mapping Spectrometer (VIMS) to study Titan's sand. Specifically, we are constraining the sand'scomposion, the precise composion of which is sll unknown. Water ice has been ruled out, leaving atmospherically-derived hydrocarbons as the best fit. Wespectrally unmixed chosen pixels, each represenng one unique composion, to determine the composion of Titan's equatorial sand seas. We selected ourspectral endmembers using high resoluon VIMS IR images (noodle maps), specifically from T20. We have 5 spectral endmembers, labeled by color from VIMS IRmaps: dark brown, dark blue, Xanadu bright, equatorially bright, and 5-micron bright. The exact superposion of spectral endmembers of the sand's composionremains the subject of further study. We set up a linear model to test on mixed substrate pixels from the T20 flyby of Cassini over the northern Fensal sand dunes.Our model assumes some percent dark brown (sand) and some percent one other endmember. The product is a substrate map of Titan's dune fields, which wewill compare with RADAR maps of the same area. Our results will determine if substrate type plays a role in dune morphology and locaon.36.06: Titan's Lakes Chemical Composion: Sources Of Uncertaines And Variability, Implicaons For Noble Gases SequestraonAuthor Block: Daniel Cordier 1 , O. Mousis 2 , J. Lunine 3 , S. Lebonnois 4 , P. Rannou 5 , P. Lavvas 6 , L. Lobo 7 , A. Ferreira 71 Instut de Physique de Rennes, France, 2 Observatoire de Beasançon, France, 3 Diparmento di Fisica, Universita degli Studi di Roma ``Tor Vergata'', Italy,4 Laboratoire de Météorologie Dynamique, France, 5 Université de Reims, France, 6 LPL - Univesity of Arizona, 7 University of Coimbra, Portugal.Presentaon Time: 10/7/2010 4:10 PM - 4:12 PMLocaon: Exhibit HallAbstract.Abstract: In 2007, the instruments of the CASSINI spacecra, orbing within the system of Saturn, allowed the discovery of RADAR dark-patches in thepolar regions of the main kronian moon. These features are interpreted as hydrocarbon lakes with ethane idenfied as the main compound. In order to detail thecomposion of these lakes, numerical simulaons have been recently performed assuming thermodynamic equilibrium between the atmosphere and the liquidphase. Here we first explore the influence of thermodynamic data uncertaines on the computed lakes chemical composion. To do so, we perform Monte-Carlosimulaons in order to mimic the relevant uncertaines. In a second stage we examine the hypothesis that Titan's hydrocarbon lakes could be at the origin of thestrong noble gas depleon measured in the atmosphere by the Huygens probe.36.07: Cloud And Precipitaon Predicons On Titan With The Ipsl-gcmAuthor Block: Jeremie Burgalat 1 , P. Rannou 1 , S. Lebonnois 21 GSM A, Université de Reims Champagne-Ardenne, France, 2 L.M.D., Univ. Paris 6, France.Presentaon Time: 10/7/2010 4:12 PM - 4:14 PMLocaon: Exhibit HallAbstract: The Titan IPSL-GCM is a coupled 2D global climate model (GCM). It includes several physical processes such as clouds and haze microphysics andalso interacons between atmosphere and surface. This model has already been used to explain some features of the haze and clouds layers. With Cassini andHuygens observaons, we could improve assumpons and boundary condions to obtain beer validaon of our model. The model is implemented in severalways. First we are revising the microphysical (haze and cloud) model to simplify the descripon of the size distribuon (descripon with bins and moments) inorder to include it in a 3D model. We also modified the cloud model in order to account for more gaseous species (now methane, ethane and acetylene), to testthe structure of the aerosols, and addional physical processes such aerosols-cloud coalescence which were neglected previously. The model can be used topredict, for instance, the haze and chemical species cycles in the atmosphere and the precipitaon rates.In this work, we invesgated the sensivity of the results against parameters of the model and new processes added recently in the model. We mainly focus onthe precipitaon rates, the cloud and haze layers.In our presentaon, we will give a descripon of our results such as the main paern of the precipitaons rates on Titan that comes out from our models, and wewill discuss the sensivity with various parameters. For instance, the models all give strong rains in the polar regions, but only some setup of the model allow toproduce rains around 40° latude. Other important differences will be stressed, concerning rains, clouds and haze structures.36.08: Vercal Structure Of The Titan Atmosphere From Cassini Uvos ObservaonsAuthor Block: D. E. Shemansky 1 , Y. Yung 2 , X. Zhant 2 , X. Liu 1 , J. Kammer 21 Space Environment Technologies, 2 California Instute of Technology.Presentaon Time: 10/7/2010 4:14 PM - 4:16 PMLocaon: Exhibit HallAbstract.Abstract: The reducon and model analysis of Titan vercal atmospheric structure obtained from EUV/FUV stellar and solar occultaons from CassiniUVIS experiment will be presented. Related atmospheric emission properes will also be described. The observaons show both latude and longitudedependencies in vercal structure of the hydrocarbon species. Dayside depleon of CH4 and higher order hydrocarbons is observed at altudes above 880 km,allowing the establishment of limits on diffusion and producon rates. Hydrocarbon mixing raos show latudinal dependencies of as much as a factor of 4.Higher order hydrocarbons including exncon by aerosols show scale heights larger than CH4 below the exobase, indicang that these species are showing theimpact of forcing by chemical producon and downward diffusion. The higher order hydrocarbons show density peaks in the 500 -- 700 km region. Aerosol mixingraos decrease with decreasing altude as do the higher order hydrocarbons down to ~450 km where the distribuon makes a sudden transion to constancywith the major species. The aerosols, as the end point of hydrocarbon physical chemistry, constute the key component determining the state of the atmosphere.36.09: Topography Driven Convecve clouds on Titan: Results from Numerical SimulaonsAuthor Block: Erika L. Barth 11 Southwest Research Instute.Presentaon Time: 10/7/2010 4:16 PM - 4:18 PMLocaon: Exhibit Hall

Abstract.Abstract: Cassini radar passes have detected a number of mountain ranges on Titan. Data indicates mean peak heights of about 900m. The flow of airover topographic features can both trigger and enhance cloud formaon; mountains can provide the perturbaons needed to trigger convecve clouds. Using arange of heights and surface winds compable with Cassini/Huygens data, the Titan Regional Atmospheric Modeling System (TRAMS) has shown that peaks assmall as a few 100 meters can be a trigger for convecon if the environment is sufficiently moist. The morphology of the clouds is similar to those reported fromprevious simulaons triggered by a warm bubble. It is possible that these convecve clouds produce enough precipitaon to carve channels, if the cloud parclesare able to coalesce to millimeter sizes.36.10: Comparave Experimental Invesgaon of Titan’s Atmospheric Chemistry Driven by Solar EUV Radiaon and Energec Electron PrecipitaonAuthor Block: Hiroshi Imanaka 1 , P. Lavvas 1 , R. V. Yelle 1 , M. A. Smith 21 Lunar and Planetary Laboratory, University of Arizona, 2 Dept Chemistry and Biochemistry, University of Arizona.Presentaon Time: 10/7/2010 4:18 PM - 4:20 PMLocaon: Exhibit HallAbstract: The observaons by the Cassini Ion Neutral Mass Spectrometer (INMS) and the Cassini Plasma Spectrometer (CAPS) clearly demonstrate theimportance of complex organic chemistry in the upper atmosphere of Titan; a complex coupling of neutral and ion chemistry for organic aerosol generaoninduced by EUV photons and Saturn’s magnetospheric charged parcles. To understand the dominant energy source for aerosol formaon and its formaonchemistry, we comparavely invesgate the chemical mechanism in N 2 /CH 4 gas mixtures resulng from EUV-VUV synchrotron radiaon (50-150 nm) and tunablemono-energec electron beam irradiaon (5 eV - 2000 eV). These excitaon energy sources cover the dominant energy source available in Titan’s upperatmosphere.Our previous study of the EUV-VUV photolysis of N 2 /CH 4 gas mixtures revealed the unique role of nitrogen photoionizaon in the catalyc formaon of complexhydrocarbons and in the major nitrogen fixaon process in Titan’s upper atmosphere (Imanaka and Smith, 2007, 2009, 2010). However, relave roles of ionmoleculereacons and radical/neutral reacons in such complex chemistry remain to be determined. We characterized the electron energy distribuon byconducng the Langmuir probe measurements. Degradaon of the primary photoelectron from N 2 photoionizaon at 20.6 eV photons is clearly observed, and theelectron density rapidly decreases down to 10 9-10 cm -3 , which suggests the complex coupling of ion-molecular reacons and dissociave ion-electronrecombinaon reacons for the observed development of complex organic molecules.The electron beam irradiaon experiments at energy larger than 200 eV shows disnct gaseous product distribuon with nitrogenated gaseous species fromthose with EUV irradiaon products. The generaon of secondary electrons and mulple inelasc collisions of fast electrons might increases the nitrogen fixaonefficiency. The much less stringent spin selecon rules could provide many addional chemical pathways not open to opcal absorpon processes.We acknowledge support from the NASA grants NNX08AO13G, NNX09AM95G, NNX10AF08G, and the NAI program.36.11: A New Photochemical Model Of Titan's AtmosphereAuthor Block: Karen Willacy 1 , M. Allen 1 , D. Caratelli 2 , P. Lavvas 31 JPL, 2 Northwestern University, 3 University of Arizona.Presentaon Time: 10/7/2010 4:20 PM - 4:22 PMLocaon: Exhibit HallAbstract: The NASA Astrobiology Instute's Titan team will conduct an interdisciplinary invesgaon of the prebioc chemistry on Titan as it is possibly verysimilar to prebioc chemistry on the early Earth. As part of this acvity, we are developing a comprehensive model of the chemistry of organic compounds inTitan's atmosphere. This master model is a combinaon of previous planetary atmosphere chemical networks, which comprise mainly reacons between neutralspecies, and interstellar networks of ion-molecule chemistry, which serves as a good starng point to simulate Titan ionospheric chemistry. The model alsoincludes up-to-date descripons of photodissociaon and photoionizaon processes and treats the formaon of the Titan haze.We will present a descripon of the model with some inial results.36.12: Measurements of Isotope Effects in N 2 Photoionizaon And Implicaons for Titan's AtmosphereAuthor Block: John Randazzo 1 , P. Croteau 1 , O. Kostko 2 , M. Ahmed 2 , M. Liang 3 , Y. L. Yung 4 , K. A. Boering 11 University of California, Berkeley, 2 Lawrence Berkeley Naonal Laboratory, 3 Academia Sinica, Taiwan, 4 California Instute of Technology.Presentaon Time: 10/7/2010 4:22 PM - 4:24 PMLocaon: Exhibit HallAbstract: Isotope effects in the non-dissociave photoionizaon of molecular nitrogen (N 2 +hν→N + 2 +e - ) are likely to play a role in determining the relaveabundances of isotopic species containing nitrogen in interstellar clouds and planetary atmospheres and yet they have not been previously measured. We presentmeasurements of the photoionizaon efficiency spectra of 14 N 2 , 15 N 14 N, and 15 N 2 from 15.4 to 18.9 eV (80.5-65.6 nm) using the Advanced Light Source atLawrence Berkeley Naonal Laboratory. The spectra show significant shis in peak energies and intensies due to isotopic substuon, with the rao of theenergy-dependent photoionizaon cross-secons, σ( 14 N 2 )/σ( 15 N 14 N), ranging from 0.4 to 3.5. Assuming white light and opcally thin condions (i.e., integrangthe photoionizaon cross-secons over all wavelengths measured), the rao of the photoionizaon rate coefficients, J, are J( 14 N 15 N)/J( 14 N 2 ) = 1.02±0.02 andJ( 15 N 2 )/J( 14 N 2 ) = 1.01±0.02, suggesng that isotopic fraconaon between N 2 and N+ 2 should be small under such condions. However, in a 1D model of Titan’satmosphere, isotopic self-shielding of 14 N 2 leads to values of J( 15 N 14 N)/J( 14 N 2 ) as large as ~1.17, larger than under opcally thin condions but sll much smallerthan values as high as ~29 predicted for N 2 photodissociaon. Since modeled photodissociaon isotope effects overpredict the HC 15 N/HC 14 N rao in Titan'satmosphere, and since both N atoms and N+ 2 ions can react with hydrocarbons to form HCN, these new results suggest that including N 2 photoionizaon maycontribute to a more quantave explanaon of 15 N/ 14 N for HCN in Titan's atmosphere without the need to invoke a less well-quanfied influx of N atoms with alower 15 N/ 14 N rao from ion/electron impact of N 2 by cosmic rays and Saturnian magnetospheric electrons at the top of the atmosphere.36.13: Under-produced Ethylene In The Atmosphere Of TitanAuthor Block: Mao-Chang Liang 1 , X. Zhang 2 , Y. L. Yung 21 Academia Sinica, Taiwan, 2 Caltech.Presentaon Time: 10/7/2010 4:24 PM - 4:26 PMLocaon: Exhibit HallAbstract: The major molecules in the atmosphere of Titan are nitrogen and methane. The coupled chemistry between nitrogen and carbon leads to highabundances of nitrogen/carbon compounds. This is caused primarily by the low abundance of hydrogen, and hence processes that “recycle” photolyc productsof methane back to methane become inefficient. Though the current hydrocarbon/nitrogen kinecs schemes have been accepted for years, there remain majoruncertaines. Even ethylene, one of simplest hydrocarbons, the abundance in the stratosphere of Titan is under-esmated by most updated photochemical

models, by as much as an order of magnitude. A recent laboratory measurement carried out by Adamkovics and Boering (2003) provides an important constraintto test the hydrocarbon kinecs. One most important constraint is that the me-dependency of the abundances of hydrocarbons is observed. To fully test thesensivity of chemical reacons to the abundances of the produced products and also to resolve the issue of under-predicted ethylene, an adjoint model isdeveloped in complementary to the exisng forward Caltech/JPL KINETICS model. We find that the abundances of C2H2, C2H4, C2H6, and C4H10 can now be wellreproduced while that of C4H2 is underesmated by 1-2 orders of magnitude. The abundance of C3H4 is underesmated with Moses et al.’ (2000) kinecs butoveresmated with Moses et al.’ (2005) kinecs. This suggests a major gap in our understanding of chemical pathways to higher hydrocarbons.36.14: Aerosol Parcle Shape and Radiave Coupling in a Three Dimensional Titan GCMAuthor Block: Erik J. Larson 1 , O. B. Toon 1 , A. J. Friedson 2 , R. A. West 21 University of Colorado, 2 Jet Propulsion Laboratory.Presentaon Time: 10/7/2010 4:26 PM - 4:28 PMLocaon: Exhibit HallAbstract.Abstract: Understanding the aerosols on Titan is imperave for understanding the atmosphere as a whole. The aerosols affect the albedo, opcaldepth, as well as heang and cooling rates which in turn affect the circulaon on Titan leading to feedback with the aerosol distribuon. Correctly represenngthe aerosols in atmospheric models is crucial to understanding this atmosphere. Friedson et al. (2009, A global climate model of Titan's atmosphere and surface.Planet. SpaceSci. 57, 1931-1949.) produced a three-dimensional model for Titan using the NCAR CAM3 model, to which we coupled the aerosol microphysicsmodel CARMA. We have also made the aerosols produced by CARMA interacve with the radiaon code in CAM. We compare simulaons with radiavelyinteracve aerosols with those using a prescribed aerosol radiave effect. Preliminary results show that this model is capable of reproducing the seasonalchanges in aerosols on Titan and many of the associated phenomena. For instance, the radiavely interacve aerosols are loed by winds more in the summerhemisphere than the non-radiavely interacve aerosols, which is necessary to reproduce the observed seasonal cycle of the albedo. We compare simulaonsusing spherical parcles to simulaons using fractal aggregate parcles, which are expected from laboratory and observaonal data. Fractal parcles havehigher absorpon in the UV, slower fall velocies and faster coagulaon rates than equivalent mass spherical parcles. We compare model simulaons withobservaonal data from the Cassini and Huygens missions.36.15: A Theorecal Invesgaon For The Producon And Evoluon Of Photochemical Aerosols In Titan’s Atmosphere.Author Block: Panayos Lavvas 1 , M. Sander 2 , M. Kra 2 , H. Imanaka 11 University of Arizona, 2 University of Cambridge, United Kingdom.Presentaon Time: 10/7/2010 4:28 PM - 4:30 PMLocaon: Exhibit HallAbstract: Titan’s aerosols result from the complex atmospheric photochemistry. The parcles in the stratospheric layer have an aggregate structure with quasisphericalmonomers of 50 nm radius. Thus, a transion region is expected between a spherical growth region and a region of aggregate growth.Usually, aerosol models assume that once parcles are formed from the background photochemistry they cease to interact with the gas phase molecules, andcoagulaon controls any further growth. Yet, recent invesgaons show that chemistry at the surface of parcles can significantly affect their size and structure.Titan’s neutral chemistry is mainly driven by radical reacons. We invesgate here the role of some of these radicals in the growth of aerosols.We use a stochasc approach to simulate both the coagulaon and surface chemistry of parcles. This allows to track the evoluon of a parcle assemble fromthe inial chemical species to the final aggregate structures. The simulaon starts with the benzene molecules detected in the thermosphere, which grow toPAHs through reacon with radicals. The PAHs collide and produce primary parcles, which keep growing through reacon with the background gas species, andthrough collisions with other PAHs. The interacon of two primary parcles provides an aerosol. The chemistry connues to act on the surface of aerosolscontrolling their shape and size.Our results demonstrate that the evoluon of aerosols in terms of size, shape and density is a result of compeng processes between surface growth,coagulaon and sedimentaon. Parcles have a spherical growth region in the upper atmosphere followed by a transion to an aggregate growth region below.The transion altude ranges between 500 and 600 km based on the parameters of the simulaon.This work has been supported through NASA grants NNX09AP14G and NNX09AB58G and NASA’s Astrobiology Iniave through JPL subcontract 1372177 to theUniversity of Arizona.36.16: HST UV Observaons Of The Extended Atmosphere Of TitanAuthor Block: John T. Clarke 1 , S. Wannawichian 1 , D. Strobel 21 Boston Univ., 2 Johns Hopkins University.Presentaon Time: 10/7/2010 4:30 PM - 4:32 PMLocaon: Exhibit HallAbstract.Abstract: UV observaons of Titan using the HST ACS/SBC channel have been performed in early 2009 during the transits of Titan across the disc ofSaturn. A combinaon of absorpon of Saturn's reflected solar UV emission in transit, and extended emissions primarily from H atoms away from transit, havebeen made to learn about the structure of Titan's extended upper atmosphere. The data have been reduced and inial profiles with altude will be presented,showing both a strong absorpon edge at the altude of the haze layers and extended H Ly alpha emission corresponding to the hydrogen corona. It is hoped thatthese observaons will provide new constraints on theorecal models for a hydrodynamic flow of species through Titan's exobase level, resulng from theinterpretaon of recent Cassini measurements at Titan.36.17: Two-fluid Mhd Study On Ion Loss From Titan’S AtmosphereAuthor Block: Yingjuan Ma 1 , C. T. Russell 1 , A. F. Nagy 2 , G. Toth 2 , M. K. Dougherty 3 , T. E. Cravens 4 , A. Wellbrock 5 , A. J. Coates 5 , P. Garnier 6 , J. Wahlund 7 , F. J.Crary 81 UCLA, 2 University of Michigan, 3 Imperial College London, United Kingdom, 4 University of Kansas, 5 University college of London, United Kingdom, 6 Universityof Toulouse, France, 7 Swedish Inste of Space Physics, Sweden, 8 Southwest Research Instute.Presentaon Time: 10/7/2010 4:32 PM - 4:34 PMLocaon: Exhibit HallAbstract: This presentaon report progress on modeling of Titan’s plasma interacon. The single fluid model is improved by including an electron energyequaon in the Hall MHD model so that both electron temperature and ion temperature are self-consistently calculated. The plasma interacon with Titan isexpected to vary as the moon moves around its orbit. Using the improved model, we compare the structure of the interacon under two extreme condions,corresponding to upstream flow interacng with the nightside and dayside ionosphere respecvely. Model results show that the dayside ionosphere is moreextended and the flow is more disturbed in the 6 SLT case than in the 18 SLT case. We also calculate the ion escape rates under these condions and comparewith Cassini observaons of the available low altudes Cassini flybys in corresponding SLTs.

36.18: W ITHDRAW N: Equaon Of State Of Titan's Interior: A Thermo-chemical AssessmentAuthor Block: Michael Howard 1 , S. Bastea 1 , B. N. Khare 2 , C. P. Khare 21 Lawrence Livermore Naonal Laboratory, 2 NASA Ames Reseach Center.Presentaon Time: 10/7/2010 4:34 PM - 4:36 PMLocaon: Exhibit HallAbstract: We use a chemical equilibrium approach to model the state of nitrogen in the interior of Titan. The inial composion of Titan’s interior is alternatelytaken as either pure ammonia and water or a comet-like solar composion with hydrogen depleted by a factor 1000. The chemical equilibrium model includes anexponenal exp-6 equaon of state for fluids and a Murnaghan form for solids, the parameters for which are fied to experimental shock Hugoniot data, isotropiccompression and sound speed data from pressures of a few hundred kPa to that of a few hundred GPa.. The models allows for a variety of mixtures. For pressuresup to 2 GPa; if the carbon/nitrogen rao is less than unity then an ammonia-water ocean is stable in the interior of Titan. If the C/N rao in the interior exceedsunity then ammonia is not stable and the stable form of nitrogen is N 2 . For pressures above 2 GPa, such as expected at the core of Titan, ammonia is stable dueto the depleon of methane and the associated formaon of graphite. While not explicitly included in our model, N 2 and water ice below the surface would beexpected to form clathrate resulng in a clathrate and water-ice mixture. The dissociaon pressure of N 2 clathrate of ~ 16 MPa (at 273 K) could power gas-drivencryovolcanism on Titan and possibly other large icy worlds. This would be consistent with the evidence for cryovolcanism, and with the absence of ammonia whileproviding a source of gases (CH 4 and N 2 ) to the atmosphere. We find that the thermodynamically stable state of the solid organic material (tholin) on Titan isgraphite and H 2 or, if graphite is kinecally suppressed, then tholin decomposes to benzene.36.19: Astrobiological Implicaons of Titan Tholin in Methane LakesAuthor Block: Bishun N. Khare 1 , C. P. McKay 1 , S. McPherson 1 , D. Cruikshank 1 , D. Nna-Mvondo 2 , Y. Sekine 31 NASA Ames Research Center, 2 Centro de Astrobiologia (CSIC-INTA), Spain, 3 University of Tokyo, Japan.Presentaon Time: 10/7/2010 4:36 PM - 4:38 PMLocaon: Exhibit HallAbstract: We report here on our ongoing research in the Laboratory for Planetary Studies at NASA Ames Research Center dedicated to determine the degree ofsolubility of Titan tholin in the methane-ethane lakes. Our work is also directed toward confirming the presence of any astrobiologically significant molecules viahydrolysis and pyrolysis of a simulated lake sample.Our previous work conducted at Cornell University and subsequently in the Laboratory for Planetary Studies at NASA Ames Research Center has established thatTitan tholin produces amino acids (Khare et al. Icarus 1986) on hydrolysis, and many compounds including adenine on pyrolysis (Khare et al. Adv. Space Res.1984). Also, our previous work by Thompson et al. (Icarus 1991) has clearly indicated that when energy is supplied to Titan’s atmospheric composion (methaneand nitrogen), tholin results from hundreds of contemporary compounds, including highly reacve compounds such as azides and isocyanides. Cassini showedthat photolysis of methane produces benzene and many polycyclic aromac hydrocarbons, along with compounds with very high molecular weights (up to 10000amu), resulng from the photolyc reacons of CH 4 with nitrogen. These heavy aerosols, termed “tholins” by Sagan and Khare (Nature 1979), are alsosynthesized when Titan intercepts charged parcles from the magnetosphere of Saturn. Tholins resulng from both of these syntheses eventually descend to thesurface of Titan, where some quanty collects in the methane-ethane lakes.This research is supported by a grant from Planetary Atmospheres.36.20: Formaon Of Amino Acids And Nucleode Bases In A Titan Atmosphere Simulaon ExperimentAuthor Block: Sarah Horst 1 , R. V. Yelle 1 , A. Buch 2 , N. Carrasco 3 , G. Cernogora 3 , O. Dutuit 4 , E. Quirico 4 , E. Sciamma-O'Brien 3 , M. A. Smith 1 , A. Somogyi 1 , C.Szopa 3 , R. Thissen 5 , V. Vuion 41 University of Arizona, 2 Ecole Centrale, France, 3 Universite Versaille St-Quenn, France, 4 Universite Joseph Fourier, France, 5 Université Joseph Fourier, France.Presentaon Time: 10/7/2010 4:38 PM - 4:40 PMLocaon: Exhibit HallAbstract: Titan has been a subject of astrobiological interest since the Voyager spacecra first revealed the diversity of the organic chemistry occurring in theatmosphere. However, it was not unl the arrival of Cassini-Huygens that the chemical complexity of Titan’s atmosphere was fully appreciated. The CassiniPlasma Spectrometer (CAPS) observed negave ions with m/z values up to 10,000 u/q at 950 km [1] and posive ions with m/z up to 400 u/q [2]. CAPS has alsoobserved O+ flowing into Titan’s atmosphere [3]. While Titan’s atmosphere is relavely oxygen poor compared to terrestrial planets, CO is the fourth mostabundant molecule in the atmosphere (50 ppm). The fact that the observed O+ flux is deposited in the region now known to contain large organic moleculesleads to the excing possibility that oxygen can be incorporated into these molecules resulng in the producon of prebioc molecules.In this work, Titan aerosol analogues (or "tholins") produced in PAMPRE, a Titan atmosphere simulaon experiment, have been analyzed in a very high resoluonLTQ Orbitrap mass spectrometer. These PAMPRE tholins were produced by capacively coupled RF discharge in a mixture of N2, CH4 and CO. The tholins werefound to contain 18 molecules with molecular formulae corresponding to biological amino acids and nucleode bases. GC-MS measurements have confirmed thestructure of seven: adenine, cytosine, uracil, thymine, guanine, glycine and alanine. The producon of prebioc molecules under atmospheric condions presentsa new source of prebioc material and may increase the range of planets where life could begin.[1] Coates AJ, et al. (2007). Geophys. Res. Le. 34:22103- +.[2] Crary FJ, et al. (2009). Planet. Space Sci. 57:1847- 1856.[3] Hartle RE, et al. (2006). Geophys. Res. Le. 33:8201-+.36.21: Cloud Formaon In The Troposphere Of TitanAuthor Block: I-Chun Tsai 1 , J. Chen 1 , M. Liang 21 Naonal Taiwan University, Taiwan, 2 Academia Sinica, Taiwan.Presentaon Time: 10/7/2010 4:40 PM - 4:42 PMLocaon: Exhibit HallAbstract: Methane-nitrogen containing clouds are known to be present in the troposphere of Titan. However, their formaon mechanism and chemicalproperes remain poorly known. One major difficulty is due to the lack of laboratory constraints, resulng in great uncertaines in modeling cloud formaonusing microphysical models. Recently CH4-N2 clouds are synthesized in lab under condions similar to that of Titan, providing a crucial constraint formicrophysics model. In this study, a detail microphysical model is developed and used to analyze nucleaon and condensaon processes occurred in thetroposphere of Titan. Sensivity for the most probable unary and binary nucleaon pathways and the subsequent condensaon growth of parcles is performed

ased on observed chemical and thermodynamic condions of Titan’s atmosphere. The model is first validated using a laboratory simulaon. Comparing tolaboratory results, our model simulaon shows that binary nucleaon from CH4 and N2 produces reasonable parcle number concentraon as in Titan’satmosphere when appropriate accommodaon coefficient for vapor condensaon is applied. Applying this detailed model to a model Titan atmosphere, cloudscan be formed between 10-30 km, depending on the updra velocity, with parcle sizes of ~1-10 μm. These results provide not only informaon of the size andcomposion of parcles in Titan’s atmosphere but also help to design laboratory experiments for measuring crical thermodynamic parameters relevant to theparcle producon mechanisms, as well as for interpreng observaons.36.22: Structural Determinaon Of Titan Aerosol Laboratory SimulantsAuthor Block: Mark A. Smith 1 , K. Upton 2 , G. Liu 1 , H. Imanaka 11 Univ. of Arizona, 2 Univ. of Evansville.Presentaon Time: 10/7/2010 4:42 PM - 4:44 PMLocaon: Exhibit HallAbstract: Using 1H, 13C and 15N muldimensional NMR we have invesgated laboratory plasma tholins and EUV generated photochemical solids for commonstructural mofs. These common structures largely determine the potenal chemistry of these materials. As smulants for Titan organic haze aerosols, thesestudies yield valuable informaon regarding the complex organic solids which reside on Titan’s surface and potenally reacted with periodic liquid phaseaqueous materials. Such informaon is necessary for intelligent design of future surface mission analycal instrumentaon and also provides insights into theprebioc potenal on Titan. The results will be discussed in the context of our earlier work regarding the producon of haze aerosols under ionosphericsimulaons at the Advanced Light Source as well as hydrolyc kinec studies of laboratory tholins. This work was supported by NASA Exobiology award#NNX08AO13G and NASA Astrobiology Iniave through JPL subcontract 1372177 to the University of Arizona.

Session Time: 10/8/2010 8:30 AM

Session Number: 51Session Title: Mars: Modeling and ExperimentsSession Type: Oral51.01: Stability Analysis Of The Maran Obliquity During The Noachian PeriodAuthor Block: Ramon Brasser 1 , K. Walsh 11 Observatoire De La Cote D'Azur, France.Presentaon Time: 10/8/2010 8:30 AM - 8:40 AMLocaon: Ballroom BCAbstract: The obliquity of Mars is currently chaoc on a 100 Myr me scale, and it undergoes large-amplitude oscillaons over 125~kyr. These cause long-terminsolaon differences across Mars' surface and appropriate changes in its climate.The obliquity oscillaons result from secular forcing by the other planets, which depend on the orbital properes of the laer. However, the secular architectureof the solar system was very different during Mars' Noachian era, before the Late Heavy Bombardment (LHB). The laer was probably caused by a dynamicalinstability of the giant planets leading to a violent evoluon of mutual scaering ending with their current orbits. During the 500-600 Myr preceding the LHB theorbits of the giant planets were nearly circular, changing the forcing on Mars' obliquity.Here numerical simulaons of Mars' obliquity evoluon for a solar system configuraon prior to the LHB are presented. These include the expected orbits of thegiant planets and a range of possible terrestrial planet orbits. Generally, for less excited terrestrial planet orbits and circular giant planets, it is found that one ofthe sources of chaos currently affecng Mars' obliquity has disappeared. The current resonances affecng the obliquity are generally narrower and shied tohigher obliquity by 10 deg. When the Angular Momentum Deficit (AMD) of the terrestrial planets, which measures the deviaon of the system from circular andcoplanar orbits, before the LHB is less than 70% of the current value, there is a significant range of inial obliquies which would have been stable, and wherethe short-term oscillaon amplitude is lower than 20 deg. An unchanged AMD for the terrestrial planets before and aer the LHB would have resulted inoverlapping resonances, which are parally responsible for the chaoc evoluon observed today. However, these resonances would have been located at a higherrange of obliquies.51.02: Mars’ Low Dissipaon Factor at 11-h - Interpretaon from Anelascity-Based Dissipaon ModelAuthor Block: Julie Casllo-Rogez 1 , M. Choukroun 11 JPL/CalTech.Presentaon Time: 10/8/2010 8:40 AM - 8:50 AMLocaon: Ballroom BCAbstract: We explore the informaon contained in the rao of the dal Love number k 2 to the dissipaon factor Q characterizing the response of Mars to thedes exerted by its satellite Phobos (11-h period). Assuming that Mars can be approximated as a Maxwell body, Bills et al. [1] have inferred an average viscosityof the Maran mantle ~8.7x10 14 Pa s. Such a low viscosity appears inconsistent with Mars’ thermal evoluon and current heat budget models. Alternaveexplanaons include the presence of paral melt in the mantle [2], or the presence of an aquifer in the crust [3]. We revisit the interpretaon of Mars’ k 2 /Q usinga laboratory-based aenuaon model that accounts for material viscoelascity and anelascity. As a first step, we have computed Mars’ k 2 /Q for an interiormodel that includes a solid inner core, a liquid core layer, a mantle, and crust (consistent with the observed moment of inera, and k 2 measured at the orbitalperiod), and searched for the range of mantle viscosies that can explain the observed k 2 /Q. Successful models are characterized by an average mantle viscositybetween 10 18 and 10 22 Pa s, which rules out the presence of paral melt in the mantle. We can narrow down that range by performing a more detailed calculaonof the mineralogy and temperature profiles. Preliminary results will be presented at the meeng.References: [1] Bills et al. (2005) JGR 110, E00704; [2] Ruedas et al. (2009 White paper to the NRC Planetary Science decadal survey; [3] Bills et al. (2009) LPS 40,1712.M C is supported by a NASA Postdoctoral Program Fellowship, administered by Oak Ridge Associated Universies. This work has been conducted at the JetPropulsion Laboratory, California Instute of Technology, under a contract to NASA. Government sponsorship acknowledged.51.03: Metastable Aqueous Perchlorate Soluons At The Phoenix Landing Site: Experimental Studies Of Phase Transions Relevant To MarsAuthor Block: Raina Gough 1 , V. Chevrier 2 , K. J. Bausan 1 , M. E. Wise 1 , M. A. Tolbert 11 University of Colorado, 2 University of Arkansas.Presentaon Time: 10/8/2010 8:50 AM - 9:00 AMLocaon: Ballroom BCAbstract: Perchlorate salts, recently discovered at the Phoenix landing site, are known to readily absorb water vapor from the atmosphere and deliquesce intoan aqueous soluon at room temperature. Here we examine the deliquescence (transion from crystalline solid to liquid) and also efflorescence (transion fromliquid to crystalline solid) of perchlorate salts at low temperatures relevant to Mars. A Raman microscope equipped with an environmental cell was used todetermine the deliquescence relave humidity (DRH) and efflorescence relave humidity (ERH) of Na + and Mg 2+ perchlorate salts as a funcon of bothtemperature (-50 to 0C) and hydraon state. We find that the deliquescence of anhydrous sodium perchlorate is only slightly dependent on temperature andoccurs at 38(±3)% RH. The DRH of sodium perchlorate monohydrate, however, increases with decreasing temperature from 51% at 0C to 64% at -45C. The DRH ofmagnesium perchlorate hexahydrate, the phase most relevant to Mars, also increases with decreasing temperature from 42% at 0C to 64% at -50C. Theefflorescence of salt soluons is known to occur at a lower relave humidity than deliquescence due to the kinec inhibion of the crystallizaon process. Wefind that this hysteresis effect does occur during low temperature perchlorate phase transions, as the ERH values of sodium and magnesium perchloratesoluons are 13(±2)% RH and 19(±3)% RH, respecvely. These results indicate that perchlorate salts could exist as metastable, supersaturated, aqueousperchlorate soluons over a wide range of Maran RH and temperature condions. We esmate the salts could be aqueous soluons for up to 16 hours per dayat the Phoenix landing site.This research was supported by a NASA MFRP and NSF-ATM grant.

Session Number: 52Session Title: Extrasolar Planets and Systems ISession Type: Oral52.01: Formaon of Giant Planets by Disk Instability on Wide Orbits Around Protostars with Varied MassesAuthor Block: Alan P. Boss 11 Carnegie Inst. of Washington.Presentaon Time: 10/8/2010 8:30 AM - 8:40 AMLocaon: Ballroom DAbstract.Abstract: Doppler surveys have shown that more massive stars have significantly higher frequencies of giant planets inside ~3 AU than lower massstars, consistent with giant planet formaon by core accreon. Direct imaging searches have begun to discover significant numbers of giant planet candidatesaround stars with masses of ~1 solar mass to ~2 solar masses at orbital distances of ~20 AU to ~120 AU. Given the inability of core accreon to form giantplanets at such large distances, gravitaonal instabilies of the gas disk leading to clump formaon have been suggested as the more likely formaonmechanism for gas giants on wide orbits. Here we present five new models of the evoluon of disks with inner radii of 20 AU and outer radii of 100 AU, for centralprotostars with masses of 0.1, 0.5, 1.0, 1.5, and 2.0 solar masses, in order to assess the likelihood of planet formaon on wide orbits around stars with variedmasses. The disk masses range from 0.042 to 0.30 solar masses, with inial Toomre Q stability values ranging from ~1 in the inner disks to ~2 in the outer disks.These five models show that disk instability is capable of forming giant planets inially on orbits with semimajor axes of ~35 AU to ~60 AU and eccencies of 0to ~0.3, with inial masses of ~1 Jupiter mass to ~3 Jupiter masses around solar-type stars, with more protoplanets forming as the mass of the protostar (andprotoplanetary disk) are increased.52.02: Forming Big Moons Through Capture Around Gas Giant PlanetsAuthor Block: Darren M. Williams 11 Penn State Erie, The Behrend College.Presentaon Time: 10/8/2010 8:40 AM - 8:50 AMLocaon: Ballroom DAbstract: Agnor and Hamilton (2006 Nature 441:192-194) have convincingly demonstrated how Triton might have been captured in a three-body “binaryexchange”encounter involving Neptune and Pluto-mass binary. In such an event, a binary terrestrial object is dally disrupted by a giant planet and one memberof the binary is lost while the other member is captured. Here we consider how the process might play out for more massive binaries over a plausible range ofencounter circumstances, and we show that such encounters somemes produce moons exceeding a Mars mass around Jupiter-class planets. Binary-exchangecapture might then be the best way to form moons large enough to hold onto temperate atmospheres and harbor water-dependent life.52.03: The Impact of UV Irradiance on the Composion of ExoplanetsAuthor Block: Michael R. Line 1 , P. Chen 2 , Y. L. Yung 11 California Instute of Technology, 2 Jet Propulson Laboratory, California Instute of Technology.Presentaon Time: 10/8/2010 8:50 AM - 9:00 AMLocaon: Ballroom DAbstract.Abstract: A majority of extrasolar giant planets are within a few hundredths of an AU from their parent star. Their proximity subjects them to highamounts of UV flux compared to what bodies in our own solar system receive. Therefore, we expect photochemistry to play a significant role in the composion oftheir visible atmospheres. Here we will present photochemical results that demonstrate the effects of different UV fields for F, G, K and M stars using HD189733band GJ436b as examples. Effects of different eddy mixing strengths and metallicty will also be invesgated as they determine where the boundary betweenthermochemistry and transport occurs and thus determine the bulk composion of the visible atmosphere.52.04: Giant Planet Migraon, and Formaon and Detecon of, Terrestrial and Super-Earth Planets around M-StarsAuthor Block: Sara Rastegar 1 , N. Haghighipour 21 Center for Interdisciplinary Exploraon and Research in Astrophysics, Northwestern University, 2 Instute for Astronomy and NASA Astrobiology Instute,University of Hawaii-Manoa.Presentaon Time: 10/8/2010 9:00 AM - 9:10 AMLocaon: Ballroom DAbstract.Abstract: Models of planet formaon around M stars suggest that majority of these planets may be of Neptune size or smaller. The detecon ofJupiter-like planets in close-in orbit around M stars raises the possibility that many of these system may harbor addional planets, perhaps of smaller sizes and insmaller orbits. These planets are potenally detectable through transit photometry and transit ming variaon method. The orbital architecture of these objectsplays an important role in their detectability and is strongly affected by the migraon of their giant planets. To determine the connecon between the formaon,dynamical evoluon, and detectability of small planets and the dynamics of a migrang giant body around M stars, we have studied the late stage of terrestrialplanet formaon during the migraon of a Jupiter-sized planet. Results indicate that the in-situ formaon of close-in terrestrial planets may be unlikely as most ofprotoplanetary embryos are scaered out of the system through their interacons with the migrang giant planet. However, Earth-sized and super-Earth objectsmay form and be captured in mean-moon resonances with the giant body and migrate to stable orbital configuraons. We discuss the possibility of such orbits,and the probability of the detecon of their corresponding planets for different values of the physical and orbital parameters of the protoplanetary disk and themigrang giant body. Given that the habitable zones of M stars are in close distances (i.e., 20-50 day orbits), we will also present results of the simulaons of theformaon of habitable planets in such systems, and discuss the possibility of their detecon.52.05: The Possibility of Catastrophic Magma Ocean Degassing and Implicaons for the Formaon of Early Planetary AtmospheresAuthor Block: Linda T. Elkins-Tanton 1 , J. Suckale 11 M IT.Presentaon Time: 10/8/2010 9:10 AM - 9:20 AMLocaon: Ballroom DAbstract.Abstract: Paral or whole-planet magma oceans produced by oligarchic accreonary impacts provide a starng point for modeling planetary evoluon.A key component in these models is the formaon of an early atmosphere, which is related to understanding when volales begin to exsolve from the magmaocean and in what quanes. The idea behind this paper is to use our knowledge of the physical processes that determine bubble dynamics at the microscopicscale in order to derive constraints on degassing processes in magma oceans at the macroscopic scale. We find that for typical meteoric volale contents,degassing is likely to occur disconnuously with an inial period of negligible degassing and a catastrophic degassing event later during the solidi caon process.The two key parameters controlling the degassing of magma oceans is their inial volale content and the overall depth of the magma ocean. The insight that the

magma ocean depth, or equivalently, the extent of melng during the final stages of planetary accreon plays an important role for degassing might provide anew framework for understanding when and why some of today's di fferences between the various terrestrial planets might have originated.52.06: Views from EP OXI: Colors in our Solar System as an Analog for Extrasolar PlanetsAuthor Block: Carolyn Crow 1 , L. A. McFadden 1 , T. Robinson 2 , V. Meadows 2 , T. A. Livengood 3 , T. Hewagama 1 , R. K. Barry 4 , L. D. Deming 4 , C. M. Lisse 51 University of Maryland, 2 University of Washington, 3 NCESSE, 4 NASA Goddard Space Flight Center, 5 Johns Hopkins University/Applied Physics Lab.Presentaon Time: 10/8/2010 9:20 AM - 9:30 AMLocaon: Ballroom DAbstract.Abstract: The first visible light studies of Earth-sized extrasolar planets will employ photometry or low-resoluon spectroscopy. We analyzed thelimitaons of using photometric colors to characterize extrasolar planets using EPOCh medium-band filter photometry between 350 and 950 nm obtained with theDeep Impact (DI) High Resoluon Instrument (HRI) of the Earth, Moon, and Mars in addion to previous full-disk observaons of the other six solar systemplanets and Titan. We determined the HRI 350, 550, and 850 nm filters are opmal for disnguishing Earth from the other planets and separang planets to firstorder based on their atmospheric and surface properes. As in this study, detailed conclusions that can be drawn about exoplanet atmospheres simply from acolor-color plot are limited due to potenally compeng physical processes in the atmosphere. For example, the presence of a Rayleigh scaering atmospherecan be detected by an increase between 350 to 550 nm, but the absence or Rayleigh scaering cannot be confirmed due to the existence of atmospheric andsurface absorbing species in the UV. We also observed that methane and ammonia are the only species responsible for absorpon in the 850 nm filter in our SolarSystem. The combinaon of physical processes present on extrasolar planets may differ from those we see locally. Nevertheless, a generaon of telescopescapable of collecng such photometric observaons can serve a crical role in first order characterizaon and constraining the populaon of Earth-like extrasolarplanets.52.07: EP OXI Observaon Of Mars: Disnguishing Exo-Mars From Exo-EarthAuthor Block: Timothy A. Livengood 1 , C. M. Lisse 2 , M. F. A'Hearn 3 , D. Deming 4 , D. Charbonneau 5 , T. Hewagama 6 , L. McFadden 4 , V. Meadows 7 , S. Seager 8 , D. D.Wellnitz 3 , EPOXI-EPOCh Science Team1 NCESSE at NASA/GSFC, 2 JHU/APL, 3 Univ. of Maryland, 4 NASA/GSFC, 5 Harvard CfA, 6 UMd at NASA/GSFC, 7 Univ. of Washington, 8 M IT.Presentaon Time: 10/8/2010 9:30 AM - 9:40 AMLocaon: Ballroom DAbstract: Observaons of Mars have been obtained by NASA’s EPOXI mission to invesgate empirically the visible-to-near infrared spectral distribuon andlightcurve variaons of Mars as a plausible model for terrestrial exoplanets, and to test the ability to disnguish an “exo-Mars” from an “exo-Earth.” The EPOXImission has previously observed the Earth from within the eclipc plane and also at high inclinaon, where the view was dominated by the polar regions.Observaons of the whole disc of Mars were acquired from within the eclipc plane in late November 2009 UT at a sub-spacecra latude of 15°N at 37° phaseangle (90% illuminaon) and 1.04 AU range. The visible-light signal was sampled with 7 filters of approximately 100 nm width at 100 nm spacing over a range of350-950 nm central wavelength. Four selected filters were sampled at 15-minute intervals and the remaining three filters were sampled at 1-hour intervals. Near-IR spectroscopy at 1.05-4.5 µm was obtained at 2-hour intervals. These data will be compared to similar observaons of the Earth, to test the ability to idenfythe presence of life according to currently conceived criteria for global biomarkers.This work is supported by the NASA Discovery Program.52.08: A Spitzer IRS Secondary Eclipse of HD 209458bAuthor Block: Patricio Cubillos 1 , J. Harrington 1 , K. Stevenson 1 , N. Madhusudhan 21 University of Central Florida, 2 Massachuses Instute of Technology.Presentaon Time: 10/8/2010 9:40 AM - 9:50 AMLocaon: Ballroom DAbstract: Analyses of space-based telescope secondary eclipse observaons have idenfied several molecules in extrasolar planet atmospheres. HD 209458b,the first transing exoplanet discovered, has been studied extensively and is found to have a clear inversion layer in the upper atmosphere (Knutson et al., 2008,ApJ 673, 526-531).As part of the Spitzer Exoplanet Target of Opportunity program, we observed HD 209458 at 16 microns using the IRS blue peak-up array. Here, we present thissystem's first secondary eclipse photometric light curve at this wavelength.Combined with other Spitzer eclipse measurements from the literature, we further characterize HD 209458b's atmosphere and discuss the presence of itsinversion layer, and the chemical composion.Spitzer is operated by the Jet Propulsion Laboratory, California Instute of Technology under a contract with NASA, which provided support for this work.52.09: A New 24 micron Phase Curve for upsilon Andromedae bAuthor Block: Ian J. Crossfield 1 , B. M. S. Hansen 2 , J. Harrington 3 , J. Y. K. Cho 4 , D. Deming 5 , K. Menou 6 , S. Seager 71 University of California, Los Angeles, 2 UC Los Angeles & UCLA Instute of Geophysics & Planetary Rings, 3 University of Central Florida, 4 Queen Mary,University of London, United Kingdom, 5 NASA/Goddard Space Flight Center, 6 Columbia University, 7 Massachuses Instute of Technology.Presentaon Time: 10/8/2010 9:50 AM - 10:00 AMLocaon: Ballroom DAbstract: We report the detecon of 24 um variaons from the planet-hosng υπσιλον Andromedae system consistent with the orbital periodicity of thesystem’s innermost planet, υπσιλον And b. Fing a simple model with two hemispheres of constant surface brightness to our observaons gives a peak-to-valleyphase curve amplitude of 0.00130 mes the mean system flux. Assuming a planetary radius of 1.3 R Jup , this corresponds to a planetary temperature contrast of>900 K and an orbital inclinaon of >25 deg. We further report the largest phase offset yet observed for an extrasolar planet: the flux maximum occurs ~ 80 degbefore phase 0.5. Such a large phase offset is difficult to reconcile with most current atmospheric circulaon models. We improve on earlier observaons of thissystem in several important ways: (1) observaons of a flux calibrator star demonstrate the MIPS detector is stable to 10 4 on long mescales, (2) we note that thebackground light varies systemacally due to spacecra operaons, precluding use of this background as a flux calibrator (stellar flux measured above thebackground is not similarly affected), and (3) we calibrate for flux variability correlated with moon of the star on the MIPS detector. A reanalysis of our earlierobservaons of this system is consistent with our new result.

Session Number: 53Session Title: Asteroids: WISE Results and a Main-Belt ExtravaganzaSession Type: Oral53.01: W ISE Albedos for Tens of Thousands of Main Belt AsteroidsAuthor Block: Joseph R. Masiero 1 , A. K. Mainzer 1 , J. Bauer 1 , R. Cutri 2 , J. Dailey 2 , M. Delbo 3 , T. Grav 4 , R. S. McMillan 5 , M. Mueller 3 , R. Walker 6 , E. Wright 7 , WISEScience Team1 JPL, 2 IPAC, 3 Observatory du Cote Azur, France, 4 JHU, 5 Univ. Arizona, 6 M IRA, 7 UCLA.Presentaon Time: 10/8/2010 8:30 AM - 8:40 AMLocaon: Ballroom EAbstract: Using thermal IR data from the Wide-field Infrared Survey Explorer (WISE) mission we have calculated diameters for tens of thousands of previouslyknown Main Belt asteroids. Using archival opcal observaons we have also determined albedos for each object. We present our results from this invesgaonincluding: diameter and albedo populaon stascs for the Main Belt as a whole; preliminary size-frequency and albedo distribuons for dynamical families; andnew populaons of very high albedo asteroids. These results provide new insight into the surface chemistry and formaon history of the Main Belt asteroids.Funding for this work was provided by the NASA Postdoctoral Program, administered through Oak Ridge Associated Universies. WISE is a joint project betweenUCLA and JPL funded by the NASA MIDEX program. The NEOWISE enhancement is funded through NASA Planetary Science.53.02: W ISE Observaons of the Jupiter Trojan CloudsAuthor Block: Tommy Grav 1 , A. K. Mainzer 2 , J. M. Bauer 2 , R. Cutri 3 , J. Masiero 2 , R. S. McMillan 4 , E. L. Wright 5 , WISE Team1 Johns Hopkins University, 2 Jet Propulsion Laboratory, California Instute of Technology, 3 Infrared Processing and Analysis Center, California Instute ofTechnology, 4 Lunar and Planetary Laboratory, University of Arizona, 5 Department of Physics and Astronomy, University of California,.Presentaon Time: 10/8/2010 8:40 AM - 8:50 AMLocaon: Ballroom EAbstract: The Wide-field Infrared Survey Explorer (WISE) started its all sky survey in early January 2010. It has a 40cm cryogenically-cooled telescope with fourimagers capable of taking simultaneous exposures at 3.4, 4.6, 12 and 22 microns, with sensivies several hundred mes greater than previous surveys (Mainzeret al., 2006). As of early July, the spacecra has surveyed 99% of the sky and has covered the enre leading and trailing Jupiter Trojan clouds in a unprecedenteduniform fashion. Almost 1500 Trojans have been observed (more than one quarter of the known Trojan populaon),compiling the largest set of mid-IR observaons for this populaon.Trojans are objects that are located in the L4 and L5 Lagrangian points of a planet’s orbit and currently Jupiter is known to have almost four thousand suchobjects in its Trojan populaon. The size and relave distribuons of the two clouds are sll uncertain due to the limited area covered by current surveys, butcurrent studies suggest that the number of Jupiter Trojans is about the same as that of the main belt asteroids of similar sizes (Doo et al, 2008). The physicalcharacteriscs are even less understood, but show some similaries and differences with other populaons of minor bodies in the outer Solar System. It istherefore important to compare the physical and dynamical properes of the Jupiter Trojans with those of the Centaurs, Trans-Neptunian Objects, and outerDwarf Planets.We will present preliminary data results for the Trojan populaon observed with WISE, looking at the albedo and diameter populaons of the populaon as awhole, as well as the similaries and differences between the two clouds.53.03: The Extraordinary Disrupng Asteroid P/2010 A2Author Block: David Jewi 1 , H. Weaver 2 , J. Agarwal 3 , M. Mutchler 4 , M. Drahus 11 UCLA, 2 Applied Physics Laboraory, Johns Hopkins University, 3 ESA-ESTEC, Netherlands, 4 STSCI.Presentaon Time: 10/8/2010 8:50 AM - 9:00 AMLocaon: Ballroom EAbstract: P/2010 A2 has the orbit of an inner main-belt asteroid (a,e,i = 2.29 AU, 0.124, 5.3 and Tj = 3.6) but is the source of an extended dust tail that lies nearthe projected orbit. We used ground-based data to recognize the strange nature of this object, then secured Hubble Space Telescope (HST) observaons fromJanuary 12 to May 29 2010, in order to ascertain its nature and evoluon. Our data show that A2 consists of a leading nucleus, about 120 meters in diameter(albedo 0.15 assumed), followed by a unique, X-shaped structure that is the source of a tail (or trail) of millimeter-sized dust parcles. Examinaon of the tailshows that the parcles were emied in 2009 February/March at velocies less than 1 m/s. The combined mass of material in the tail is roughly equal to themass of a single 12-meter radius sphere. Spectroscopic observaons from the Gemini North telescope show no evidence for CN or other opcal gas lines.We consider it unlikely that ice exists in such a small, warm object so close to the inner edge of the asteroid belt. Thus, while A2 technically meets the definionof a main-belt comet, we believe its acvity has another cause. We interpret A2 as a debris cloud from a small, previously unknown asteroid that has beenimpacted by a sll smaller body. Alternave explanaons will be discussed.53.04: Dust Ejected From Asteroid P/2010 A2Author Block: Jessica Agarwal 1 , D. Jewi 2 , H. Weaver 3 , M. Mutchler 4 , M. Drahus 21 European Space Research and Technology Centre, Netherlands, 2 University of California, 3 The Johns Hopkins University Applied Physics Laboratory, 4 SpaceTelescope Science Instute.Presentaon Time: 10/8/2010 9:00 AM - 9:10 AMLocaon: Ballroom EAbstract: We present measurements and dynamical models of the dust tail of the unusual inner-belt asteroid P/2010 A2. The observed tail consists of parcleslarger than 1mm moving under the combined acon of solar gravity and radiaon pressure. The parcles originated from filaments near the nucleus that consistof cm- to m-sized boulders and that were themselves emied from the nucleus upon its earlier disrupon. We derive the dust size distribuon from the surfacebrightness as a funcon of distance from the nucleus. For grains smaller than about 10mm, the differenal size distribuon can be described by a power-law withan exponent of -3.3 +/- 0.2. The displacement of the boulders perpendicular to the orbital plane is consistent with a vercal component of the relave velocity ofless than 0.2 m/s. The me evoluon of this distance confirms the emission date (early 2009) derived independently from measurements of the tail posionangle.This work is based on images made with the HST/WFC3.53.05: Radar Observaons of Asteroids 64 Angelina and 69 HesperiaAuthor Block: Michael K. Shepard 1 , B. E. Clark 2 , M. Ockert-Bell 2 , M. C. Nolan 3 , E. S. Howell 3 , C. Magri 4 , L. A. M. Benner 5 , J. D. Giorgini 51 Bloomsburg Univ., 2 Ithaca College, 3 Arecibo Observatory, 4 University of Maine at Farmington, 5 Jet Propulsion Laboratory.Presentaon Time: 10/8/2010 9:10 AM - 9:20 AM

Locaon: Ballroom EAbstract: Using the S-band radar at Arecibo Observatory, we observed the E-class asteroid 64 Angelina and the M-class asteroid 69 Hesperia. We obtained asingle run on Angelina on 31 Jan 2010 with a signal-to-noise (SNR) of 10. We find its circular polarizaon rao (SC/OC) to be mu c = 0.8 +/- 0.1, ed with 434Hungaria for the highest value measured for any main-belt asteroid (Shepard et al. 195, 220-225, 2008). This is consistent with the high polarizaon raosobserved for the E-class asteroids in general (Benner et al. Icarus 198, 294-304, 2008). Our esmate of the echo’s bandwidth is B = 35 +/- 5 Hz. This isinconsistent with a published diameter of ~60 km (Morrison and Chapman, ApJ 204, 934-939, 1976) and published rotaon pole (lambda/beta 138/+31 deg,uncertaines +/- 10 deg, Shevchenko et al. PSS 51, 525-532, 2003). Either the pole is significantly different, the diameter is smaller, or some combinaon of these.We obtained two runs on 69 Hesperia on 3 Feb 2010 with a total SNR of 24. We esmate a bandwidth of B = 440 +/- 40 Hz that is 75% of the expected valuebased on the published diameter (IRAS, 138 km) and pole direcon (lambda/beta 73 / -45 deg, Torppa et al. Icarus 164, 346-383, 2003). We esmate a radaralbedo of 0.4 for the first run, placing it in the high-metal M-class (Mm) class defined by Shepard et al. (Icarus, 208, 221-237, 2010). Acknowledgements: Thiswork was funded by NSF grant AST-0908098 to MKS and AST-0908217 to BEC.53.06: The Composion of M-type Asteroids: Synthesis of Spectroscopic and Radar Observaons.Author Block: Maureen Bell 1 , B. E. Clark 1 , M. K. Shepard 2 , R. A. Issacs 1 , E. A. Clous 3 , S. Fornasier 4 , S. J. Bus 51 Ithaca College, 2 Bloomsburg University, 3 University of Winnepeg, Canada, 4 Observatoire de Paris, France, 5 Instute for Astronomy.Presentaon Time: 10/8/2010 9:20 AM - 9:30 AMLocaon: Ballroom EAbstract.Abstract: We have conducted a radar-driven observaonal campaign of 22 main-belt asteroids (MBAs) focused on Bus-DeMeo Xc- and Xk-type objects(Tholen X and M class asteroids) using the Arecibo radar and NASA Infrared Telescope Facilies (IRTF). Sixteen of our targets were near-simultaneously observedwith radar. We find that most of the highest metal-content asteroids, as suggested by radar, tend to exhibit silicate absorpon features at both 0.9 and 1.9microns, and the lowest metal-content asteroids tend to exhibit either no bands or only the 0.9 microns band. Eleven of the asteroids were observed at severalrotaonal longitudes in the near-infrared and significant variaons in connuum slope were found for nine in the spectral regions 1.1-1.45 microns and 1.6-2.3microns. Composional evidence is derived from our target asteroid spectra using two different methods: 1) a Chi-squared search for spectral matches in theRELAB database, and 2) parametric comparisons with meteorites. We find that for four of the seven asteroids with the highest iron abundances, our spectralresults are consistent with each other and with the radar evidence poinng to an iron meteorite composion (16 Psyche, 216 Kleopatra, 347 Pariana, and 779Nina). Four asteroids have radar analogs consistent with either our parametric comparison or our RELAB analog type (21 Lutea, 135 Hertha, 497 Iva, and 758Mancunia ). The remaining eight asteroids (22 Kalliope, 97 Klotho, 110 Lydia, 129 Angone, 224 Oceana, 678 Fredegundis, 771 Libera, and 785 Zwetana) haveambiguous composional interpretaons when comparing the spectral analogs to the radar analogs.53.07: The M-Asteroids: Mineralogic and Meteorite Analog Diversity Among a Homogeneous Asteroid Taxonomic GroupingAuthor Block: Paul S. Hardersen 1 , E. A. Clous 2 , V. Reddy 1 , M. J. Gaffey 1 , J. Emery 31 Univ. of North Dakota, 2 Univ. of Winnipeg, Canada, 3 Univ. of Tennessee.Presentaon Time: 10/8/2010 9:30 AM - 9:40 AMLocaon: Ballroom EAbstract: A near infrared spectral survey of 47 M and X asteroids has revealed significant spectral and mineralogic diversity among this group of mainbeltasteroids.Thirty of the 47 asteroids observed using the NASA IRTF and SpeX spectrograph exhibit a variety of mineral absorpon features. Among this subset of asteroids,25 exhibit weak pyroxene absorpon features in the 0.9 and, occasionally, in the 1.9 micron spectral region. Three asteroids exhibit a weak olivine absorponfeature. One asteroid spectrum suggests the variable presence of serpennite while another suggest a complex mixture of olivine and pyroxene. A minority of theasteroids are spectrally featureless, but display a wide variety of slopes alowing diverse interpretaons.Potenal meteorite or geologic analogs include CV chondrites, Bencubbinites, iron meteorites with or without low Fe pyroxene mantle material, paral melts,serpennite, enstate chondrites, and R chondrites.The suppression of mafic silicate absorpon features, which vary in band depth from 1 to 10 percent, could be due to several mechanisms, including surfacemetal, space weathering, and opaque phases present in the regolith. None of these mechanisms are known to affect band centers determinaons.Based on these results, this group of asteroids includes at least 10 different potenal meteoric or geologic interpretaons and shows the geologic diversity ofobjects that reside within a single asteroid taxonomic group. Due to this diversity, it is important to interpret each asteroid uniquely based on its exisng datawith no a priori assumpon of a similarity to other members of the same taxonomic class.The primary future challenges for the asteroid spectroscopy community include developing a robust ability to determine the primive or igneous nature of anasteroid, beer understand space weathering, and developing more robust mineral and meteorite laboratory calibraons. This research was funded by the NASAPlanetary Astronomy Program.53.08: The Diversity of Hydrated Material on Low-Albedo AsteroidsAuthor Block: Andrew S. Rivkin 11 JHU/APL.Presentaon Time: 10/8/2010 9:40 AM - 9:50 AMLocaon: Ballroom EAbstract: Introducon: Low albedo asteroids are associated with the carbonaceous chondrites. They dominate the asteroid belt, with the C complex the mostcommon spectral class in the middle to outer belt [1].Water/OH as ice or bound into minerals strongly absorbs in the 3-µm spectral region. While water in the Earth’s atmosphere makes this spectral region arelavely difficult one to work in, decades of successful observaons have been obtained [2-5], mostly using the NASA IRTF on Mauna Kea, with the SpeXinstrument the main workhorse during the 21 s t century [6].Results: We have made over 100 observaons of several dozen low albedo asteroids since 2002. This survey has led to the idenficaon of ice on the surface of24 Themis [7] and the idenficaon of brucite and carbonates on the surface of 1 Ceres [8,9]. It has also demonstrated the diversity of hydrated material in theasteroid belt, with spectral shapes ranging from CM-like to Ceres-like, and other yet-unidenfied materials. There appear to be at least 4 plausible spectralclasses, including one “anhydrous” group.I will present the results of the survey so far, implicaons of what we have found so far, and future direcons.This work is supported by the NASA Planetary Astronomy Program.References: [1] Bus S. J and Binzel R. P. 2002, Icarus. [2] Lebofsky L. A. 1978, Mon. Notes RoyalAst. Soc.. [3] Feierberg, M. A., et al. 1981, Geochem Cosmochem. Acta. [4] Jones T. D. et al. 1990, Icarus. [5] Rivkin A. S. et al. 2003, Met. Plan. Sci. . [6] Rayner, J.T. et al. 2003, Pub. Ast. Soc. Pac. . [7] Rivkin, A. S. and Emery, J. P. 2010, Nature. [8] Rivkin A. S. et al. 2006, Icarus . [9] Milliken, R. E. and Rivkin, A. S. 2009, NatureGeosc. .

53.09: Near-Infrared Spectroscopy of 12 Outer Main Belt AsteroidsAuthor Block: Driss Takir 1 , J. P. Emery 11 University of Tennessee.Presentaon Time: 10/8/2010 9:50 AM - 10:00 AMLocaon: Ballroom EAbstract: We have begun a project to quanfy the degree of aqueous alteraon in CM carbonaceous chondrites, obtain spectra of these chondrites, andmeasure spectra of possibly related outer Main Belt asteroids in order to explore the nature of aqueous alteraon on these asteroids. In this first stage of theproject, we will present the near-infrared (NIR) spectra of 12 outer Main Belt asteroids (2.59 < a < 3.96 AU). The asteroids include, 10 Hygiea, 76 Friea, 91 Aegina,107 Camila, 104 Klymene, 121 Hemione, 153 Hilda, 308 Polyxo, 334 Chicago, 361 Bononia, 401 Olia, and 790 Pretoria. We collected the spectra of theseasteroids between April 2009 and April 2010, using the long wavelength cross-dispersed (LXD) mode (1.9-4.1-µm) of the SpeX spectrograph/imager at the NASAInfrared Telescope Facility (IRTF). We also observed some of these asteroids with the prism mode (0.8-2.5-µm). For data reducon, we used Spextool, a set ofInteracve Data Language rounes provided by the IRTF.Except for 91 Aegina, all observed asteroids exhibit an absorpon feature near 3-µm, which is aributed to hydrated minerals and/or H2O ice. The hydratedmineral features on these asteroids show two different band shapes, weak “rounded” H2O-like absorpon band and deeper “checkmark” OH-like absorponband. The former band shape is much more common in our sample than the laer band shape.

Session Time: 10/8/2010 9:00 AM

Session Number: 54Session Title: Galilean Satellites IISession Type: Oral54.01: Effect Of Microstructure And Deformaon Regimes On Anelascity Of Water Ice - Implicaons For Europa, Enceladus, And TitanAuthor Block: Mathieu Choukroun 1 , J. C. Casllo-Rogez 1 , C. Walker 21 Jet Propulsion Laboratory, 2 University of Michigan.Presentaon Time: 10/8/2010 9:00 AM - 9:10 AMLocaon: Ballroom BCAbstract: Tidal dissipaon is believed to be a major heat source in planetary bodies, however the physics of aenuaon in planetary materials at satellitecondions remains to be constrained. So far, models of dal dissipaon in planetary moons neglect anelascity (e.g., Maxwell body) and do not explicitly accountfor the microstructural mechanisms involved in internal fricon. The Planetary Tides Simulaon Facility (JPL) is dedicated to mapping the mechanisms drivingaenuaon as a funcon of temperature (220-270K) and cyclic peak stress (0.02-0.5 MPa) relevant to icy satellites. Aenuaon spectra obtained formonocrystalline water ice over the frequency range 3x10 -6 - 10 -2 Hz and at a peak stress of 0.2 to 0.6 MPa can be systemacally fied with the Andrade model,whose parameter β can be wrien as an explicit funcon of defect density and mobility. We are exploring experimentally the applicability of this model topolycrystalline water ice samples deformed in the grain-boundary sliding (GBS) creep regime. Samples are synthesized from deionized H 2 O in the JPL Ice Factory,and compacted to 100 MPa to remove porosity. The microstructure before and aer mechanical tesng is assessed by opcal analyses. Understanding theinfluence of the deformaon regime on the aenuaon of icy samples is essenal to address dal dissipaon within icy shells of Europa (GBS), Enceladus (GBSor possible dislocaon), and Titan (diffusion). We will present experimental results obtained so far in two regimes, theorecal predicons for the diffusion creepregime, and address their implicaons for dal dissipaon within icy satellites.M C is supported by a NASA Postdoctoral Program Fellowship, administered by Oak Ridge Associated Universies. CW is supported by a NASA Space Grant,administered by the CalTech Student-Faculty Programs office. This work has been conducted at the Jet Propulsion Laboratory, California Instute of Technology,under a contract to NASA. Government sponsorship acknowledged.54.02: Correlaon of Sulfuric Acid Hydrate Abundance with Charged Parcle Flux at the Surface of EuropaAuthor Block: James B. Dalton 1 , C. P. Paranicas 2 , T. A. Cassidy 1 , J. H. Shirley 11 Jet Propulsion Laboratory, 2 Applied Physics Laboratory.Presentaon Time: 10/8/2010 9:10 AM - 9:20 AMLocaon: Ballroom BCAbstract: The trailing hemisphere of Jupiter’s moon Europa is bombarded by charged parcles trapped within Jupiter’s magnetosphere. Sulfur ion implantaonand impacng energec electrons strongly affect the surface chemistry of Europa. Understanding these processes is important for disentangling the extrinsic andintrinsic components of Europa’s surface chemistry. In the sulfur cycle model of Carlson et al. (Science 286, 97, 1999), hydrated sulfuric acid represents thedominant reacon product of radiolyc surface modificaon processes on Europa. In recent composional invesgaons employing linear mixture modeling,Dalton et al. (LPSC XV, #2511, 2009) and Shirley et al. (Icarus, in press, 2010) document a well-defined gradient of hydrated sulfuric acid abundance for a studyarea spanning the leading side - trailing side boundary in Argadnel Regio. Sulfuric acid hydrate abundance in this region increases toward the trailing side apex.Here we compare the derived sulfuric acid hydrate abundances at 41 locaons on Europa’s surface with independent model results describing 1) the sulfur ionflux (Hendrix et al., 2010, in preparaon), and 2) the energec electron flux, at the same locaons. We improve upon the prior calculaon of electron energy intothe surface of Paranicas et al. (2009, in Europa, U. Arizona, p529; Pappalardo, McKinnon, & Khurana eds.) by incorporang a realisc pitch angle dependence ofthe distribuon.While the sulfur ion implantaon and electron energy deposion model distribuons differ in important details, both show trailing side gradients similar to thatfound for the sulfuric acid hydrate. Correlaon coefficients exceed 0.9 in comparisons of each of these models with the sulfuric acid hydrate distribuon. Ourresults support models in which the electron energy flux drives reacons that ulize implanted sulfur to produce sulfuric acid hydrate. This work was performed atthe California Instute of Technology-Jet Propulsion Laboratory under contract with NASA’s Outer Planets Research Program.54.03: An Invesgaon Into Biologically Mediated Sulfur Cycling Under Simulated Europa Ocean CondionsAuthor Block: Damhnait Gleeson 1 , X. Amashukeli 1 , R. T. Pappalardo 11 Jet Propulsion Laboratory, Caltech Instute of Technology.Presentaon Time: 10/8/2010 9:20 AM - 9:30 AMLocaon: Ballroom BCAbstract: Current models of the composion of Europa’s ocean are constrained by the presumed sulfur-rich, non-ice materials concentrated along geologicfeatures on the moon’s surface, which may represent sites of material exchange with the ocean. On Earth microorganisms in deep ocean sengs can ulizebiogeochemical redox transformaons of sulfur to gain energy. We invesgate the energy availability, reacon rates and metabolic and isotopic products ofchemotrophic sulfur metabolisms such as sulfate reducon, sulfide oxidaon, and sulfur oxidaon and reducon, under simulated Europa ocean condions.Known piezophilic bacteria isolated from high-pressure, low-temperature, and nutrient-poor condions are tested for survival and growth under condionsmodelled for a Europa ocean and generated within a pressurized culvaon chamber developed at JPL. We idenfy reacons that prove energecally favorablefor these microorganisms under simulated Europa ocean condions and constrain rates of microbial mediaon of reacons by comparison with abioc controls.The resulng thermodynamic and kinecs will aid our understanding of whether Europa’s cold, high-pressure ocean is capable of supporng life, as we know it.Characterizing intermediate reacon species and disequilibrium products of biomediated reacons, in addion to stable isotope fraconaons and biomarkersassociated with “Europa”-adapted organisms, will help in idenfying the best organic and inorganic target molecules for future remote sensing and in situexploraon missions.54.04: In Pursuit of Analogs for Europa’s Dynamics & Potenal HabitatsAuthor Block: Britney E. Schmidt 1 , D. D. Blankenship 1 , J. S. Greenbaum 1 , D. A. Young 11 Univ. of Texas at Ausn, Instute for Geophysics.Presentaon Time: 10/8/2010 9:30 AM - 9:40 AMLocaon: Ballroom BCAbstract: Future Europa exploraon will seek to characterize the distribuon of shallow subsurface water as well as to understand the formaon of surfacefeatures through dynamic ice-shell processes. Radar sounding will be a crical tool for imaging these features, and should be of primary interest to theastrobiology community for understanding how and where life might arise on Europa. To develop successful instrumentaon and data interpretaon techniquesfor exploring Europa, we must leverage analogous terrestrial environments and processes. Airborne ice penetrang radar is now a mature tool in terrestrialstudies of Earth’s ice sheets, and orbital examples have been successfully deployed at Earth’s Moon and Mars.

It is a disnct possibility that water within or just below the ice on Europa has played a role in forming some of its dynamic terrain. Observaons of rotated blocksand dark floor materials may suggest that brines existed in the near subsurface and enabled the formaon of such features. The University of Texas HighCapability Airborne Radar Sounder (HiCARS) developed to study Antarcc ice sheet dynamics has been configured to test observaon scenarios for Europa. Wediscuss recent results from the 60 MHz HiCARS system over brine infiltrated Antarcc marine ice as an analog for processes affecng the formaon of pits andchaos.Basal melt occurring below terrestrial marine ice is directly analogous to processes that may operate on Europa if the shell is “thin,” and will be similar toprocesses occurring instead within the ice sheet in the case of a thicker, mul-layer ice sheet where enriched brines may remain liquid within the shell. A key sitefor further invesgaon of conducve and “convecve” ices is found in the polythermal glaciers in the Arcc, and the case for this exploraon will be illuminated.54.05: 3-D Topographic Thermal and Radiave Modeling of Ice Stability and Migraon on CallistoAuthor Block: Stephen E. Wood 1 , K. L. Ivarson 1 , I. Danilina 1 , S. D. Griffiths 2 , J. M. Moore 3 , A. D. Howard 4 , P. M. Schenk 51 Univ. of Washington, 2 Univ. of Leeds, United Kingdom, 3 NASA Ames Research Center, 4 Univ. of Virginia, 5 Lunar and Planetary Instute.Presentaon Time: 10/8/2010 9:40 AM - 9:50 AMLocaon: Ballroom BCAbstract: We have been modeling landscape evoluon on the Galilean satellites driven by volale transport. Callisto’s landscape shows evidence ofwidespread erosion hypothesized by Moore et al. (1999) to result from sublimaon of near-surface ice followed by mass wasng. Bright material thought to bere-deposited frost is commonly seen on upper flanks and summits of ridges, crater rims, and Callisto’s ubiquitous knobs. In order to test hypotheses related tothese landform and albedo paerns, we have developed a 3-D thermal model that calculates surface and subsurface temperatures for any given topographicshape, accounng for shadowing, reflected solar radiaon, and thermal radiaon from surrounding points. The temperatures are then used to calculatesublimaon and subsurface diffusion rates for both CO 2 and H 2 O ice. These rates are used to compute area-averaged downward vapor fluxes within balliscmolecular jump distances from vapor sources. Where net deposion is predicted, surface albedo in increased proporonal to frost thickness. Where netsublimaon occurs, the thickness of a dark dust lag is increased accordingly. We will present results pertaining to the stability of bright frost-covered knobs aswell as observed distribuon paerns of frost on the interior walls of craters.This work is supported by NASA through the Jupiter Data Analysis Program.54.06: The Other Chemistry of the Jovian Icy Satellites - Low Energy and SulfurousAuthor Block: Reggie L. Hudson 1 , M. J. Loeffler 1 , M. H. Moore 11 NASA Goddard Space Flight Center.Presentaon Time: 10/8/2010 9:50 AM - 10:00 AMLocaon: Ballroom BCAbstract: Spectra of Jupiter’s icy satellites reveal surfaces dominated by H 2 O-ice with minor amounts of SO 2 and other materials. The co-existence of H 2 O andSO 2 in surfaces exposed to jovian magnetospheric radiaon suggests that sulfuric acid (H 2 SO 4 ) also could be present. This was noted by Carlson et al. (1999),who supported this suggeson with assignments of near-IR bands in Europa spectra to hydrated H 2 SO 4 . Laboratory experiments since have demonstratedradiolycally-driven syntheses in S- and SO 2 -containing H 2 O-ices (Carlson et al., 2002; Moore et al., 2006).In the Cosmic Ice Laboratory, we recently have invesgated the thermal chemistry of SO 2 trapped in H 2 O-ice. IR spectra of H 2 O + SO 2 mixtures recorded at 10 to230 K were used to follow low-temperature reacons in the absence of radiaon effects. No SO 2 reacons were found at 10 K, but warming to more-relevantEuropa temperatures produced both HSO- 3 and S 2 O 2- 5 . Added NH 3 shied the product composion toward SO2- 3 and away from the other ions. We find that H 2 Oand SO 2 react to produce sulfur oxyanions, such as bisulfite, that as much as 30% of the SO 2 can be consumed through this reacon, and that the products remainin the ice when the temperature is lowered, indicang that these reacons are irreversible. Our results suggest that thermally-induced reacons can alter thechemistry at and below the surfaces of the icy satellites in the jovian system.This work was supported by NASA's Planetary Geology and Geophysics and Planetary Atmospheres programs, and the NASA Astrobiology Instute's GoddardCenter for Astrobiology.References:Carlson, R. W., Johnson, R. E., Anderson. M. S., 1999, Science 286, 97-99.Carlson, R. W., Anderson, M. S., Johnson, R. E., Schulman, M. B., Yavrouian,A. H., 2002, Icarus 157, 456-463.Moore, M. H., Hudson, R. L., and Carlson, R. W., 2007, Icarus, 189, 409-423.

Session Time: 10/8/2010 10:30 AM

Session Number: 55Session Title: Titan SurfaceSession Type: Oral55.01: Cryovolcanism on Titan: Latest Evidence from Cassini RADAR Imagery and TopographyAuthor Block: Karl L. Mitchell 1 , R. L. Kirk 2 , R. M. C. Lopes 1 , J. Radebaugh 3 , R. D. Lorenz 4 , Cassini RADAR Team1 Jet Propulsion Laboratory, California Instute of Technology, 2 United States Geological Survey Flagstaff, 3 Brigham Young University, 4 Johns Hopkins UniversityApplied Physics Lab.Presentaon Time: 10/8/2010 10:30 AM - 10:40 AMLocaon: Ballroom BCAbstract: Although not the pervasive agent of resurfacing in the Outer Solar System that it was once thought to be, cryovolcanism, the erupon of lowtemperaturefluids from the interior of icy worlds, appears to be an important phenomenon on several bodies. One of the icy worlds purported to becryovolcanically acve is Titan; its rich atmosphere contains non-primordial isotopic signatures and a methane abundance that cannot be sustained withoutacve outgassing, and the presence of a subsurface ocean at depth provides a source for such materials.The dominant paradigm on Titan for many years has been one of a cryovolcanically resurfaced world with a magmac chemistry that is principally ammoniawater.Owing to this, and the uniquely (for an icy world) high atmospheric pressure which suppresses explosivity, effusive erupons with complex rheologies areexpected, possibly akin to terrestrial basalc erupons, feeding flows and possibly domes.Cassini has observed several features proposed as cryovolcanic in origin on the basis of morphological consistency with expectaons. However, an alternaveparadigm of an endogenically-dead Titan has emerged recently, arguing for a crustal origin of atmosphere species, and suggesng that alternave exogenic(primarily erosional and fluvial) processes should be considered for most surface features.We present a crical re-assessment of interpretaons of cryovolcanic landforms in the context of this new paradigm, on the basis of addional imagery and newtopographic data. Some, such as Ganesa Macula and Tortola Facula, are no longer considered potenal cryovolcanoes, mostly because the more recentlymeasured topography contradicts the morphological inferences used as a basis for interpretaon. However, observaons of 200 m thick lobate forms in twolocaons, Hotei and Sotra, strengthen earlier cryovolcanic interpretaons.55.02: Dunes On Titan: Comparison Of The Fensal And Belet Dune Regions Using Mulple DatasetsAuthor Block: Alice Le Gall 1 , M. A. Janssen 1 , L. C. Wye 2 , A. G. Hayes 3 , R. D. Lorenz 4 , J. Radebaugh 5 , B. Sles 1 , Cassini Radar Team1 JPL, 2 Stanford University, 3 California Instute of Technology, 4 Johns Hopkins University Applied Physics Lab, 5 Brigham Young University.Presentaon Time: 10/8/2010 10:40 AM - 10:50 AMLocaon: Ballroom BCAbstract: Titan’s equatorial belt hosts large expanses of longitudinal dunes. As the Cassini mission connues, more of them are unveiled by the microwaveRADAR, both in the acve and passive modes and with an increasing number of viewing geometries. These observaons have revealed some variaons amongdune regions.In parcular, we find that the Belet and Fensal dune fields differ in terms of radar albedo and thermal emission. In this paper, we combine different datasets (SAR,radiometry, almetry, scaerometry and SAR-derived topography) and compare them to an electromagnec model in order to constrain the composional andphysical properes of the Belet and Fensal dunes. Differences between Fensal and Belet are well explained by various degrees of exposure of Titan’s icy crust inthe interdune regions (the troughs between the dunes). We find that a significant fracon of the Fensal interdunes must either be clear of sand, thus represenngthe dune substrate, or covered by icy gravels. This is consistent with VIMS spectra that show an enrichment in water ice in Fensal interdunes (Barnes et al.,2008). Furthermore, in many places in Fensal, dunes remain quite bright on SAR images suggesng that they are thin enough to allow waves to probe thesubstrate. Both interdune brightness and dune thinning point to the lack of available sediment supply in Fensal. In contrast, sand-sized parcles seem abundantat Belet’s locaon where the sand sheet is so thick that even the interdune flats appear radar-dark.The difference in sand supply between Fensal and Belet may be due to different wind regime and/or ground humidity. It may also be related to their respecveemplacement: Belet is laying in a deep depression and Fensal dunes encroach on Sinlap’s fresh water-ice ejecta blanket. The paper will discuss further the originof the regional variaons among Titan dunes.55.03: A Depth Profile of Titan's Ontario Lacus and Further Constraints on Wave Heights from Cassini RADAR DataAuthor Block: Lauren Wye 1 , H. A. Zebker 1 , A. G. Hayes 2 , R. D. Lorenz 31 Stanford Univ., 2 California Inst. of Technology, 3 Johns Hopkins Univ., APL.Presentaon Time: 10/8/2010 10:50 AM - 11:00 AMLocaon: Ballroom BCAbstract: Hayes et al. (JGR 2010) observed that the Cassini synthec aperture radar (SAR) imaging magnitudes collected over Titan’s Ontario Lacus varyexponenally with distance from the lake shore, as expected if there is a deepening liquid layer that is aenuang the reflecon from a roughened boom. Theydeduce near-shore slopes on the order of 10 -3 . Here, we extend this analysis across the enre width and length of the lake by applying the Hayes et al. approachto the real-aperture (beam-averaged) scaerometry and SAR mode data collected on Titan flyby T65 (12-January-2010). The real-aperture reducon provideslonger integraon mes, thereby reducing the noise in the data. Consequently, we can detect boom reflecons from greater depths within the lake..We create a depth profile along the diagonal of the lake using the T65 SAR mode data, assuming the dielectric properes inferred by Hayes et al. apply uniformlyacross the lake volume. The 8 km SAR beam footprint slightly smears out the actual depth profile. Nearly perpendicular to this track, the T65 scaerometry data,with 15 km footprints, yields a coarser depth profile across the dark waist of Ontario Lacus. The two profiles intersect at the darkest, and likely deepest, region ofthe lake. The shape of these profiles has implicaons for the lake geology..Allowing for scaer from small-scale waves on the surface of the lake, we constrain the maximum depth of the dark region to be less than 9 meters over our kmscaleresoluon cell. Depths over the rest of the lake are less than 5 meters. These shallow depths may have implicaons for the lake's composion. We alsomodel the rms wave heights to be less than 1 mm, consistent with the analysis of Wye et al. (GRL 2009). These are all conservave upper limits.55.04: Constraining Waves on Titan's Northern Lake Jingpo Lacus using VIMS Specular Reflecon ObservaonsAuthor Block: Jason W. Barnes 1 , J. M. Soderblom 2 , R. H. Brown 3 , L. A. Soderblom 4 , K. Stephan 5 , R. Jaumann 5 , S. Le Mouelic 6 , S. Rodriguez 7 , C. Son 8 , B. J.

Bura 8 , K. H. Baines 8 , R. N. Clark 4 , P. D. Nicholson 21 University of Idaho, 2 Cornell, 3 University of Arizona, 4 USGS, 5 DLR, Germany, 6 Universite de Nantes, France, 7 Laboratoire AIM, France, 8 JPL.Presentaon Time: 10/8/2010 11:00 AM - 11:10 AMLocaon: Ballroom BCAbstract.Abstract: Using the specular reflecon discovered in T58 Cassini-VIMS data by Stephan et al. (2010), we analyzed the resulng photometric lightcurveof this specular event to constrain wave acvity. Waves spread out the specular reflecve intensity on the surface of the liquid. Without waves, the intensitydistribuon would represent a perfect image of the Sun. Since VIMS does not spaally resolve the specular intensity distrubuon, we use the specular intensity'sevoluon over me to infer its properes instead. A specular intensity distribuon spread out by wave acvity will rise and diminish slowly upon a transion fromland to sea or sea to land respecvely. Without waves, the intensity will rapidly wink on and off as the specular point crosses the shoreline. We find that thewaves on Jingpo Lacus, an Ontario Lacus-sized lake in Titan's north near Kraken Mare, cannot have slopes of more than 0.2 degrees. A specular refleconlightcurve of Kraken Mare itself from T59 is harder to interpret, showing variability that could be either atmospheric scinllaon, clouds, changing windcondions, or kilometer-wavelength waves.55.05: Modeling Specular Reflecons from Hydrocarbon Lakes on Titan's SurfaceAuthor Block: Jason M. Soderblom 1 , J. W. Barnes 2 , R. H. Brown 1 , L. A. Soderblom 3 , C. A. Griffith 1 , K. Stephan 4 , R. Jaumann 4 , C. Son 5 , K. H. Baines 5 , B. J.Bura 5 , R. N. Clark 3 , P. D. Nicholson 61 University of Arizona, 2 University of Idaho, 3 US Geological Survey, 4 DLR, Instute of Planetary Research, Germany, 5 Jet Propulsion Laboratory, 6 CornellUniversity.Presentaon Time: 10/8/2010 11:10 AM - 11:20 AMLocaon: Ballroom BCAbstract: During the 58th flyby of Titan, the Cassini Visual and Infrared Mapping Spectrometer (VIMS) observed a specular reflecon of sunlight from Titan’ssurface within the 5-µm methane window (Stephan, K., and 14 colleagues, 2010). Movated by this observaon, we model the expected magnitude of thespecular reflecon of solar radiaon off a hydrocarbon lake on Titan’s surface. The intensity of this reflecon is controlled by a number of factors: the convexshape of Titan’s surface, which reduces the magnitude of the reflecon by the rao of the solid angle of the field of view to the expanded solid angle projectedoff of the convex surface, aenuaon and scaering by gases and aerosols in Titan’s atmosphere, and the reflectance of the lakes surface in a speculargeometry. We can describe the expected intensity of the specular reflecon as the I/F VIMS would observed when directly viewing the Sun reduced by thegeometric defocusing of the flux, the Fresnel reflecon of the lake surface, and aenuaon of the incoming and outgoing flux by the atmosphere. For thegeometry described by the T58 flyby, our model predicts a maximum I/F 1-3. We thus conclude the surface of this body is in fact liquid. With future observaons itwill be possible to constrain the refracve index of the liquid as well as the total aenuaon of the atmosphere at 5 µm. The Cassini Project, managed by the JetPropulsion Laboratory, California Instute of Technology and under contract with NASA, supported this work.55.06: Nitrogen Ocean/Lakes on Early TitanAuthor Block: Owen B. Toon 1 , F. Tian 1 , C. McKay 2 , J. M. Moore 2 , K. Zahnle 2 , A. D. Howard 31 Univ. of Colorado, 2 NASA Ames Research Center, 3 Univ. of Virginia.Presentaon Time: 10/8/2010 11:20 AM - 11:30 AMLocaon: Ballroom BCAbstract: Today Titan’s surface temperature is 95 K and its atmosphere contains 1.5 bars of N 2 . The standard model for Titan is that the current thickatmosphere has been present over the age of the Solar System. However, observaons of Titan present some paradoxes for the standard model: theshort life me of methane, the lack of good evidence for acve cryovolcanism, and the inadequate surface deposit to account for the photochemicalproducts that would have accumulated over 4.5 billion years. Thus alternave models are movated. Today both surface albedo and greenhouse warmingcontribute to Titan’s surface temperature and its atmosphere condion. The albedo could have been different if the surface of ancient Titan was covered by liquidnitrogen/methane or solid methane ice. The greenhouse effect depends on the existence of atmospheric methane and nitrogen. The variaons of either factorcould have made ancient Titan similar to present Triton with high surface albedo and lile atmosphere. Alternavely early Titan could have had much largerfracon of its nitrogen and methane in liquid phase (ocean/lakes), which would have interesng geological implicaons. In this work we will explore the effect ofchanging surface albedo, surface reservoirs of nitrogen and methane, and greenhouse warming on ancient Titan’s climate.55.07: Are the Basins of Tui Regio and Hotei Arcus Sites of Former Titanian Seas?Author Block: Jeffrey M. Moore 1 , A. D. Howard 21 NASA Ames Research Center, 2 University of Virginia.Presentaon Time: 10/8/2010 11:30 AM - 11:40 AMLocaon: Ballroom BCAbstract: Features observed in the basins of Tui Regio and Hotei Arcus on Titan have aracted the aenon of the Cassini-era invesgators. At both locaons,VIMS observed discrete 5-micron bright ~500-km wide features described as lobate in shape. Several studies have proposed that these materials are cryovolcanicflows; in the case of the Hotei Arcus feature this inference was buressed with SAR RADAR images showing bright and dark patches with “lobate”margins. We propose an alternave explanaon. First we note that all landforms on Titan that are unambiguously idenfiable can be explained by exogenicprocesses (aeolian, fluvial, impact cratering, and mass wasng). Suggesons of endogenically produced cryovolcanic constructs and flows have, withoutexcepon, lacked conclusive diagnosc evidence. Recently published topographic profiles across Tui Regio and the “lobate” feature region north of Hotei Arcusindicate these features appear to occur in large regional basins, at least along the direcon of the profiles. SAR images show that the terrains surrounding both 5-micron bright features exhibit fluvial networks that appear to converge and debauch into the probable basins. The 5-micron bright features themselvescorrespond to fields of discrete radar-bright depressions whose bounding edges are commonly rounded and cumulate in planform in SAR images. These fields ofdiscrete radar-bright depressions strongly resemble fields of features seen at Titan’s high latudes usually aributed to be dry lakes. Thus the combinaon of (1)the resemblance to high-latude dry lakes, (2) locaon in the centers of probable regional depressions, and (3) convergence of fluvial networks are inferred by usto best explain the 5-micron bright regions at Tui Regio and Hotei Arcus as sites of dry seas or at least paleolake clusters. Such equatorial seas, if real, may beevidence of substanally larger inventories of liquid alkanes in Titan’s past.55.08: Evidence for Lakes on Titan's Tropical SurfaceAuthor Block: Caitlin Ann Griffith 1 , J. Turner 1 , P. Penteado 2 , L. Doose 11 University of Arizona, 2 Universidade de Sao Paulo, Brazil.Presentaon Time: 10/8/2010 11:40 AM - 11:50 AMLocaon: Ballroom BCAbstract.Abstract: Cassini and Huygens observaons of Titan's methane cycle, reveal lakes, rainfall, and storms near the poles, and, in the tropics, a largely

Abstract.Abstract: Cassini and Huygens observaons of Titan's methane cycle, reveal lakes, rainfall, and storms near the poles, and, in the tropics, a largelycloudless sky with a few low and likely rain-free clouds overlying a landscape dominated by vast dunes. Several general circulaon models explain the polar lakeconcentraon through the drying of the tropics by efficient transport of methane to the poles. The only landscape sampled in detail, that by Huygens' Probe at -10latude and 192 W longitude, is shaped by fluvial erosion and extensive flooding. These features are difficult to explain as tropical clouds are too few, and toostable to invoke rainstorms, and the humidity too low to allow rain to escape evaporaon and reach the surface. Also at odds, there has been no detecon ofliquids on Titan's tropic surface, with the excepon of a surface dampness by the probe. We have analyzed, jointly, observaons from Cassini's Visual andInfrared Mapping Spectrometer (VIMS) and Huygens' Descent Imager Spectral Radiometer (DISR) to quanfy the tropical atmosphere well enough to invesgatethe spectral properes of the surface. We find evidence for the existence of lakes and rivers at low latudes. The lakes are indicated by several well definedpatches, roughly 40 km across, where the surface is black at all spectral windows. Nearby are sinuous features that have albedos 1-2% above that of a blacksurface, suggesng rivers that are sampled along with dry terrain within a single pixel. Our observaons raise quesons regarding the source of methane toTitan's atmosphere. Tropical surface liquids provide the first sign of the culprit that shaped the Huygens Probe landscape, potenally as a local source of humidityto the atmosphere, needed for rain, or potenally as a source for catastrophic floods.55.09: Evidence For Ethane On Titan's Tropical SurfaceAuthor Block: Juan Lora 1 , C. A. Griffith 1 , J. Turner 1 , P. Penteado 21 University of Arizona, 2 University of Sao Paulo, Brazil.Presentaon Time: 10/8/2010 11:50 AM - 12:00 PMLocaon: Ballroom BCAbstract.Abstract: Cassini Radar and near-IR measurements from the Visual and Infrared Mapping Spectrometer (VIMS) demonstrate the existence of liquids onTitan's surface. &nbsp; Bodies of liquid at high latudes are revealed in Radar images as radar-dark features with lacustrine characteriscs. Near-IRspectroscopy confirmed their liquid nature, although not through features due to the primary liquid component, methane. &nbsp;Such a detecon is toochallenging because the atmospheric opacity is also due primarily to methane. &nbsp;However, ethane, which exists as a component of the methane-ethanelakes, has a feature at 2 microns, a spectral region where the atmospheric opacity is low enough to allow visibility to the surface. Cassini VIMS data indicated thepresence of this 2 micron ethane feature &nbsp;in the radar-dark region Ontario Lacus, confirming that this body is a lake in Titan's south polar region (Brown etal. 2008). &nbsp; What is most notable about the liquids on Titan's surface is that they have been detected only at high north and south polar latudes.&nbsp;Most Titan general circulaon models explain this polar concentraon of liquids as resulng from a quick transport of liquids from low to high latudes,implying a generally dry equatorial region. We, however, have found preliminary evidence of surface ethane at tropical latudes on Titan, through the detecon ofthe ethane feature at 2 microns in VIMS spectral images of certain tropical terrains. &nbsp; &nbsp;Our observaons raise quesons regarding the source andtransport of methane and ethane in Titan's atmosphere and on Titan's surface.

Session Number: 56Session Title: Extrasolar Planets and Systems IISession Type: Oral56.01: Hermean Atmospheres of Hot Rocky ExoplanetsAuthor Block: Brian Jackson 11 Goddard Space Flight Center.Presentaon Time: 10/8/2010 10:30 AM - 10:40 AMLocaon: Ballroom DAbstract: The discovery of the first rocky exoplanet CoRoT-7 b suggests many stars may host rocky planets. However, with an orbital semi-major axis of only0.0172 AU, CoRoT-7 b's dayside surface temperature probably may exceed 2000 K, and current detecon biases mean that most of the inially discovered rockyexoplanets will probably be in similar orbits, with corresponding large surface temperatures. Such planets will likely have tenuous atmospheres composed ofvaporized rocky material, similar to Mercury's exosphere. In fact, inial calculaons suggest the atmospheres may have column abundances of volales,parcularly sodium, exceeding the column abundance of Mercury's exosphere by many orders of magnitude. The volales likely present in the atmospheres of hotrocky exoplanets may be detectable through observaons with sufficiently high spectral resoluon. For example, at the column abundance of sodium predictedfor CoRoT-7 b's exosphere, total opcal depths at sodium's D1 and D2 resonant scaering features may approach 10 6 . Consequently, the transit depth for CoRoT-7 b in the wavelengths of these features may be as much as 30% larger than out of the features. As for Mercury, detecon of such an atmosphere around a hotrocky exoplanet would provide important constraints on the planet's composion. In this talk, I will present preliminary results from models of such putaveatmospheres and discuss their detectability.56.02: Equilibrium Chemistry of the Atmospheres of Hot Earth-like ExoplanetsAuthor Block: Laura Schaefer 1 , K. Lodders 1 , B. Fegley 11 Washington Univ..Presentaon Time: 10/8/2010 10:40 AM - 10:50 AMLocaon: Ballroom DAbstract: The Kepler and COROT missions and Earth-based observaons have discovered putave rocky exoplanets and at least some of these are very hotbecause they orbit their stars at close distance, e.g., CoRot-7b. Here we discuss atmospheric chemistry for an Earth-like planet hot enough to vaporize its crust.We computed the chemical equilibrium composion of a system with elemental abundances of the terrestrial connental crust from 500 - 4000 K as a funcon ofpressure from 10 -6 to 10 +2.5 bars. Calculaons were done with a Gibbs energy minimizaon code. We will present results for the major volale elements H, C, N,O, and S, and the lithophile elements Na, K, Fe, Si, Mg, Al, Ca, and Ti at a nominal pressure of 100 bars as a funcon of temperature. The major gases are H 2 Oand CO 2 at low temperatures, and SiO, O, H, and O 2 at high temperatures. We also present condensaon temperatures for major compounds as a funcon ofpressure, which will be useful in determining cloud composion. These results should be useful in planning spectroscopic studies of the atmospheres of hotEarth-like exoplanets. This work was supported by the NSF Astronomy Program and the NASA Astrobiology Program.56.03: Constraints On The Volale Enrichments In Hd189733b From Internal Structure ModelsAuthor Block: Olivier Mousis 1 , J. I. Lunine 2 , K. Zahnle 3 , L. Biennier 4 , S. Picaud 1 , T. V. Johnson 5 , J. Pet 1 , J. B. A. Mitchell 4 , J. Beaulieu 6 , V. Boudon 7 , D. Cordier 4 , M.Devel 8 , R. Georges 4 , C. Griffith 9 , N. Iro 10 , M. S. Marley 3 , U. Marboeuf 11 , G. Tine 121 Instut UTINAM, CNRS-UM R 6213, Observatoire de Besançon, France, 2 Diparmento di Fisica, Università degli Studi di Roma "Tor Vergata", Italy, 3 NASAAmes Research Center, 4 Instut de Physique de Rennes, Université de Rennes 1, France, 5 Jet Propulsion Laboratory, California Instute of Technology, 6 Instutd'astrophysique de Paris, Université Pierre & Marie Curie, CNRS/INSU, France, 7 Instut Carnot de Bourgogne, Université de Bourgogne, France, 8 FEM TO-ST,CNRS, UFC, UTBM, ENSM M, France, 9 Lunar and Planetary Laboratory, University of Arizona, 10 NASA/Goddard Space Flight Center, 11 Laboratoire dePlanétologie de Grenoble, Université Joseph Fourier, France, 12 Department of Physics and Astronomy, University College London, United Kingdom.Presentaon Time: 10/8/2010 10:50 AM - 11:00 AMLocaon: Ballroom DAbstract.Abstract: Spectra of the transing hot Jupiter HD189733b support the possibility that carbon and oxygen abundances range from subsolar to oversolarin the atmosphere of the planet. Here, using a model describing the formaon sequence and composion of planetesimals in the protoplanetary disk, wedetermine the range of volale abundances in the envelope of HD189733b that is consistent with the 20-50 Earth-masses of heavy elements esmated to bepresent in the planet's envelope. We then compare the inferred carbon and oxygen abundances to those retrieved from spectroscopy and we find a range ofoversolar values that directly fit both spectra and internal structure models. In some cases, we also find that the apparent contradicon between the subsolarelemental abundances and the important mass of heavy elements predicted in HD189733b can be explained by the presence of large amounts of carbonmolecules in the form of ethylene, acetylene and hydrogen cyanide that can polymerize and form polycyclic aromac hydrocarbons and soots in the upper layersof the envelope.56.04: Thermochemical and Photochemical Kinecs on the hot Jupiter HD 189733bAuthor Block: Julianne I. Moses 1 , C. Visscher 2 , J. J. Fortney 3 , N. K. Lewis 4 , A. P. Showman 5 , M. S. Marley 6 , C. A. Griffith 5 , A. J. Friedson 71 Space Science Instute, 2 Lunar and Planetary Instute, 3 UCSC, 4 LPL -- Univ. Ariz., 5 LPL Univ. Ariz., 6 NASA Ames, 7 JPL.Presentaon Time: 10/8/2010 11:00 AM - 11:10 AMLocaon: Ballroom DAbstract.Abstract: Observaons of extrasolar planet transits and secondary eclipses -- mutual eclipse events where the planet passes in front of and behind itsparent star as seen from Earth -- can reveal key physical and chemical properes of the exoplanet, including informaon about atmospheric composion.Theorecal models are needed to interpret these observaons. We have developed a one-dimensional thermochemical and photochemical kinecs and transportmodel of the close-in transing planet HD 189733b. The model transions seamlessly from the thermochemical equilibrium regime in the deep troposphere to the"quenched equilibrium" and photochemical regimes in the upper troposphere and stratosphere. We invesgate the coupled photochemistry of neutral carbon,hydrogen, oxygen, and nitrogen species on HD 189733b and explore how parameters like planetary metallicity, elemental raos, eddy diffusion coefficients, andlocaon (longitude/latude/local me on this presumed dally locked planet) affect the model results. We compare the model with exisng transit and secondaryeclipse observaons to help explain observaons of H2O, CO, CO2, and CH4 and to make predicons regarding other potenally important observableatmospheric constuents (e.g., NH3, HCN, C2H2). We find that both photochemistry and quenching significantly affect the abundance and distribuon ofatmospheric constuents. In parcular, HCN and C2H2 are significant photochemical products in the sunlit hemisphere, whereas NH3 and CH4 are lost from theuppermost porons of the atmosphere, and many species -- methane most obviously -- are affected by transport-induced quenching.

56.05: Model Of Fluorescent Emission Of Methane In ExoplanetsAuthor Block: Pierre Drossart 1 , M. R. Swain 2 , C. A. Griffith 31 LESIA, Observatoire de Paris, France, 2 Jet Propulsion Laboratory, 3 University of Arizona, LPL.Presentaon Time: 10/8/2010 11:10 AM - 11:20 AMLocaon: Ballroom DAbstract: Anomalous emission at 3.3 micron in the spectrum of exoplanet HD189733b has been reported in Swain et al (Nature, 2010); a possible interpretaonof this suprathermal emission could be a non-LTE emission of methane induced by the strong star illuminaon followed by re-emission in the ν3 band complex ofmethane. For this purpose, a model developed for the calculaon of giant planets methane fluorescence by Drossart et al. (ESA-SP427, 1999) has been adapted tothe case of HD189733b to quantavely test this interpretaon. The model performs a frequency-redistributed radiave transfer model, including a five stepscalculaons with:- Calculaon of the absorpon of stellar light by the near infrared bands of methane- Calculaon of the populaon of the methane vibraonal levels in every atmospheric layer- Calculaon of the methane emission in the ν3 band and first two hot bands- Self-absorpon of methane emission, mostly significant for resonant fluorescence in the ν3 band- Resonant scaering of the ν3 band self-absorpon, making an addional source term in the radiave transfer equaon.The results will be presented for thermal profiles consistent with exoplanets detecon, in comparison to the HD189733b spectrum observaons. Implicaons forthe modelling of exoplanets will be discussed.56.06: Probing The Atmospheres Of Giant Exoplanets And Super-earths With Ground-based SpectroscopyAuthor Block: Giovanna Tine 1 , I. Waldmann 1 , C. Griffith 2 , M. Swain 3 , P. Deroo 3 , J. Tennyson 11 University College London, United Kingdom, 2 University of Arizona, 3 JPL.Presentaon Time: 10/8/2010 11:20 AM - 11:30 AMLocaon: Ballroom DAbstract: More than 460 exoplanets, i.e. planets orbing a star different from our Sun, are now known thanks to indirect detecon techniques. In recent years,aenon has switched from finding planets to characterising them. Among the variety of exoplanets discovered so far, special aenon is devoted to thoseplanets which transit their parent star. Most recent observaons with Hubble and Spitzer Space Telescopes, in fact, have proved being possible to use thewavelength/me dependence of the combined light star-planet to idenfy key chemical components and the thermal structure of the planet’s atmosphere.We present here new spectroscopic observaons obtained with different ground-based telescopes of select targets, including hot-Jupiters and a warm Super-Earth.56.07Abstract.Title:Embargoed: Intenonally BlankAuthor Block: Jacob Bean 1 , E. Miller-Ricci 2 , D. Homeier 31 Harvard-Smithsonian Center for Astrophysics, 2 UC Santa Cruz, 3 Instute for Astrophysics Goengen, Germany.Presentaon Time: 10/8/2010 11:30 AM - 11:40 AMLocaon: Ballroom DAbstract.Abstract: This abstract is embargoed. The text will be published online as soon as the embargo has been lied.56.08: Equatorial Superrotaon on Hot JupitersAuthor Block: Adam P. Showman 1 , L. M. Polvani 21 Univ. of Arizona, 2 Columbia University.Presentaon Time: 10/8/2010 11:40 AM - 11:50 AMLocaon: Ballroom DAbstract.Abstract: The increasing richness of hot Jupiter observaons has movated a variety of three-dimensional atmospheric circulaon models of theseplanets. Under the dally locked, strongly irradiated condions relevant to hot Jupiters, such models tend to exhibit a circulaon dominated by a fast eastward, or"superrotang," jet stream at the equator. As first predicted by Showman and Guillot in 2002, this phenomenon can cause the hoest regions to be displacedeastward from the substellar point by tens of degrees longitude. Such an offset has been subsequently observed on HD 189733b, supporng the possibility ofequatorial jets on real hot Jupiters. Despite its relevance, however, the dynamical mechanisms responsible for generang the equatorial superrotaon in hotJupiter models have not been idenfied. Here, we show that the equatorial jet results from an interacon of the mean flow with standing Rossby waves inducedby the day-night forcing. The strong longitudinal variaons in radiave heang -- namely intense dayside heang and nightside cooling -- trigger the formaon ofstanding, planetary-scale equatorial Rossby and Kelvin waves. The Rossby waves develop phase lts that pump eastward momentum from high latudes to theequator, thereby inducing equatorial superrotaon. We demonstrate this mechanism in a sequence of one-layer (shallow-water) calculaons and fully 3D models.This wave-mean-flow interacon produces an equatorial jet whose latudinal width is comparable to that of the Rossby waves, namely the equatorial Rossbydeformaon radius modified by radiave and friconal effects. For condions typical of synchronously rotang hot Jupiters, this length is comparable to aplanetary radius, explaining the broad scale of the equatorial jet obtained in most hot Jupiter models. Our theory has implicaons for the dependence of theequatorial jet speed on forcing amplitude, strength of fricon, and other parameters, as well as for the condions under which jets can form at all.56.09: Three-dimensional Atmospheric Circulaon of Hot Jupiters on Highly Eccentric OrbitsAuthor Block: Tiffany Kataria 1 , A. P. Showman 1 , N. K. Lewis 1 , J. J. Fortney 2 , M. S. Marley 31 University of Arizona, 2 University of California, Santa Cruz, 3 NASA Ames Research Center.Presentaon Time: 10/8/2010 11:50 AM - 12:00 PMLocaon: Ballroom DAbstract: Of the ~400 exoplanets detected to date, over one-tenth of these are on highly eccentric orbits (e> 0.5). Such scenarios lead to highly me-variablestellar heang on the giant planet, which has a large effect on its meteorology. However, lile is known about the basic dynamical regime of such planets, andhow it may compare to the dynamics of giant planets on more circular orbits. Therefore, we present three-dimensional atmospheric circulaon models thatinclude radiave transfer (the Substellar and Planetary Atmospheric Radiaon and Circulaon Model) for generic hot Jupiters over a wide range of eccentricies.We compare the atmospheric circulaon of the planet when placed in highly circular (e=0) up to highly eccentric (e=0.75) orbits in synchronous and pseudosynchronousrotaon around their parent stars. In parcular, we analyze the temperature structure of each of these cases, as well as the jet streams, waves, andinteracons between the two that arise for each scenario. Furthermore, we discuss the observaonal implicaons and extent to which light curves and spectra ofplanets on highly eccentric orbits will allow their meteorological and orbital properes to be inferred. We will compare these results to real observaons made on

HD 80606b, a highly eccentric (e=0.96) exoplanet.

Session Number: 57Session Title: Near-Earth Asteroids ISession Type: Oral57.01: First Results Of The New Goldstone Delay-Doppler Radar Chirp Imaging SystemAuthor Block: Marn A. Slade 1 , C. G. Lee 1 , J. S. Jao 1 , L. A. M. Benner 1 , M. Brozovic 1 , J. D. Giorgini 1 , M. W. Busch 21 JPL, 2 UCLA Department of Earth and Space Sciences.Presentaon Time: 10/8/2010 10:30 AM - 10:40 AMLocaon: Ballroom EAbstract.Abstract: We report the first results of a new delay-Doppler radar chirp waveform system at Goldstone, which improves the range resoluon by a factorof five from 18.75-m to 3.75-m. We successfully tested the new system on near-Earth asteroids (NEAs) 2010 AL30 and 2009 UN3 in January and February 2010.2010 AL30 was a target-of-opportunity observed only three days aer its discovery by LINEAR on January 10. During 2.3 hours of observaons, 2010 AL30 movedbetween 1.0 to 0.8 lunar distances from Earth en route to a close approach of only 0.34 lunar distances. Due to this short round-trip light-travel me, theobservaons were bistac with transmissions at the 70-m DSS-14 antenna and recepon at the 34-m DSS-13 antenna. 2010 AL30 has a very faint absolutemagnitude of 27.2, suggesng a diameter of less than 20 meters. We imaged 2010 AL30 at resoluons as high as 3.75-m, which reveal a somewhat elongatedshape roughly 15-m in diameter, making 2010 AL30 the smallest NEA spaally resolved at Goldstone to date. The sequence of images shows obvious rotaonthat is consistent with the period of about 9 minutes reported by W. Ryan. (pers. comm.). 2009 UN3 was discovered in October 2009 by the Siding Spring Surveyand approached within 0.037 AU (14 lunar distances) on February 9. We observed 2009 UN3 monostacally at Goldstone on February 8 and 9. Due to its moderateSNRs, we used chirp imaging at 15-m and 30-m resoluons, and binary-phase-coded imaging with 37.5-m resoluon. The images reveal an irregular, elongatedobject close to 700-m in diameter. For future research, the new 3.75-m-resoluon capability at Goldstone offers significant scienfic potenal to reveal muchmore detailed surface features than previously possible, to yield more detailed 3D shapes, and to substanally improve NEA orbits and long-term orbit predicon.57.02: Radar Images And Shape Model Of A Triple Asteroid (136617) 1994CCAuthor Block: Marina Brozovic 1 , L. A. M. Benner 1 , M. C. Nolan 2 , E. S. Howell 2 , C. Magri 3 , J. D. Giorgini 1 , P. A. Taylor 2 , J. L. Margot 4 , M. W. Busch 5 , M. K. Shepard 6 ,D. J. Scheeres 7 , L. M. Carter 81 Jet Propulsion Laboratory/California Instute of Technology, 2 Arecibo Observatory, 3 University of Maine at Farmington, 4 University of California at Los Angeles,5 California Instute of Technology, 6 Bloomsburg University, 7 University of Colorado at Boulder, 8 Smithsonian Instuon.Presentaon Time: 10/8/2010 10:40 AM - 10:50 AMLocaon: Ballroom EAbstract.Abstract: We report radar observaons and shape modeling of asteroid (136617) 1994CC, which is only the second triple system known in the near-Earth populaon, aer (153591) 2001 SN263. This object was observed at Goldstone (8560 MHz, 3.5 cm) and Arecibo (2380 MHz, 12.6 cm) from June 12 to June21, 2009. The radar images and subsequent shape modeling reveal that the primary is ~600 m in diameter with a shape that closely resembles that of 1999 KW4Alpha. The secondary is ~130 m in diameter and appears to be in a synchronous orbit with a period of ~30 hours. The terary satellite is ~90 m in diameter andhas an orbital period of ~9 days. Its semimajor axis of ~20 primary radii is the largest discovered so far among near-Earth mulple systems. Among the 37 NEAbinary or ternary systems currently known, ~80% have been observed by radar and 2/3 were discovered by radar. Since January 1999, 17% of radar-detected NEAswith diameters greater than 200 m have been found to be mulple systems.57.03: Radar Shape Modeling Of (8567) 1996 HW1 Combined With Thermal ObservaonsAuthor Block: Ellen S. Howell 1 , C. Magri 2 , M. C. Nolan 1 , P. A. Taylor 1 , R. J. Vervack Jr. 3 , Y. R. Fernandez 4 , M. Mueller 5 , L. A. M. Benner 6 , J. D. Giorgini 6 , D. J.Scheeres 7 , M. D. Hicks 6 , H. Rhoades 8 , J. M. Somers 8 , N. M. Gaonyuk 9 , Y. N. Krugly 10 , V. V. Kouprianov 11 , I. E. Molotov 11 , V. Benishek 12 , V. Protch-Benishek 12 , A.Galad 13 , D. Higgins 14 , P. Kusnirak 15 , D. Pray 161 NAIC-Arecibo Observatory, 2 University of Maine, 3 JHU/APL, 4 University of Central Florida, 5 Observatoire de la Cote d'Azur, France, 6 JPL, 7 University ofColorado, 8 Moorpark College, 9 Crimean Astrophysical Observatory, Ukraine, 10 Kharkiv Naonal University, Ukraine, 11 Russian Academy of Sciences, RussianFederaon, 12 Belgrade Astronomical Observatory, Serbia, 13 Modra Observatory, Slovakia, 14 Hunter's Hill Observatory, Australia, 15 Academy of Sciences, CzechRepublic, 16 Carbuncle Hill Observatory.Presentaon Time: 10/8/2010 10:50 AM - 11:00 AMLocaon: Ballroom EAbstract.Abstract: We observed near-Earth asteroid (8567) 1996 HW1 at the Arecibo Observatory on six dates in September 2008, obtaining radar images andspectra. By combining these data with an extensive set of new lightcurves taken during 2008-2009 and with previously published lightcurves from 2005, we wereable to reconstruct the object's shape and spin state. 1996 HW1 is an elongated, highly bifurcated object, and appears to be a contact binary. A convex shapemodel derived from the lightcurves alone produces a pole orientaon that is consistent with the pole derived from the radar data. It is instrucve to comparethese two shape models. We have also obtained near-infrared spectra at the NASA IRTF using SpeX in both prism and LXD modes. The prism spectra showpyroxene and olivine bands. We obtained LXD spectra (2-4 microns) on 19 August, 1 September and 1 October 2008. Thermal modeling using the shape modeland derived pole and rotaon constrain the regolith properes. The radar shape model and results of the thermal modeling will be presented.57.04: Characterizaon of Near-Earth Asteroid 2009 KC3 from Radar and Thermal Infrared ObservaonsAuthor Block: Patrick A. Taylor 1 , E. S. Howell 1 , M. C. Nolan 1 , L. A. M. Benner 2 , M. Brozovic 2 , J. D. Giorgini 2 , R. J. Vervack 3 , Y. R. Fernandez 4 , C. Magri 5 , M.Mueller 61 Arecibo Observatory, 2 Jet Propulsion Laboratory, 3 The Johns Hopkins University Applied Physics Laboratory, 4 University of Central Florida, 5 University of Maineat Farmington, 6 Observatoire de la Cote d'Azur, France.Presentaon Time: 10/8/2010 11:00 AM - 11:10 AMLocaon: Ballroom EAbstract.Abstract: We will report on the size, shape, spin state, and reflecve and thermal properes of C-type, Apollo-class, potenally hazardous, near-Earthasteroid 2009 KC3 (a = 3.2 AU, e = 0.7, i = 10 deg). This object was discovered by the Siding Spring Survey in May 2009 and subsequently observed in the latesummer using the Goldstone (8560 MHz, 3.5 cm) and Arecibo (2380 MHz, 12.6 cm) radar systems from August 22-29 as well as with the SpeX instrument on theNASA IRTF on August 30 and September 21. Radar images reveal a roughly spheroidal body about 1.2 km in diameter that is slightly asymmetric and elongated.Tracking of surface features and the echo bandwidth suggest a period near 12 hours, which is in agreement with a period of 11.768 hours found from lightcurveobservaons (P. Pravec, pers. comm.). A consistent decrease in echo bandwidth during the radar observaons implies the line of sight was moving away from theequator. Radar images with resoluon as fine as 7.5 m per pixel show an indentaon on the leading edge (possibly a crater) and radar-bright features beyond theleading edge. The S-band circular polarizaon rao of ~0.25 is near the median observed among near-Earth asteroids. Thermal emission between 2 and 4 microns

is essenally unchanged in SpeX observaons three weeks apart despite a change in phase angle from 98 deg to 49 degrees and an increase in heliocentricdistance by 0.1 AU. Furthermore, the thermal parameters derived for 2009 KC3 during a single observaon do not accurately predict the thermal emission at alater me in a different viewing geometry. Determinaon of the shape and spin pole will help us understand how much rotaon phase and illuminaon effectsaffected the thermal observaons.57.05: Radar Observaons and the Shape of 2008 EV5: Ridges and Craters on Near-Earth AsteroidsAuthor Block: Michael W. Busch 1 , S. J. Ostro 2 , L. A. M. Benner 2 , D. J. Scheeres 3 , J. D. Giorgini 2 , M. Brozovic 2 , M. C. Nolan 4 , E. S. Howell 4 , P. A. Taylor 4 , J. Margot 1 ,C. Magri 5 , J. S. Jao 2 , W. Brisken 61 UCLA, 2 JPL, 3 University of Colorado, Boulder, 4 NAIC, 5 University of Maine at Farmington, 6 NRAO.Presentaon Time: 10/8/2010 11:10 AM - 11:20 AMLocaon: Ballroom EAbstract: The near-Earth asteroid 2008 EV5 was discovered by the Mt. Lemmon Survey on March 4 2008, and approached to within 8.4 lunar distances inDecember 2008, when it was a very strong radar target. We observed EV5 with the Arecibo and Goldstone planetary radars and the Very Long Baseline Array, andpreviously described those observaons and obtaining EV5’s pole direcon. We have now completed a detailed model of EV5’s shape.The Arecibo delay-Doppler data provided 7.5-m spaal resoluon, showing that EV5’s overall shape is a 400 ± 50 m spheroid. The most prominent surface featureis a ridge parallel to the asteroid’s equator that is broken by a concavity 150 m in diameter. Otherwise the asteroid’s surface is shows few decameter-scalefeatures and is notably smooth - our shape model has an average surface slope of

While there are reasons to believe that primive volale-rich materials are universally low in albedo, the converse need not be true: The orbital evoluon of someobjects caused them to lose their volales by coming too close to the Sun. For all our targets, we give the closest perihelion distance they are likely to havereached (using orbital integraons from Marchi et al., 2009) and corresponding upper limits on the past surface temperature.Low-deltaV objects for which both albedo and thermal history suggest a primive composision include (162998) 2001 SK162, (68372) 2001 PM9, and (100085)1992 UY4.This work is based on observaons made with the Spitzer Space Telescope, which is operated by JPL, Caltech under a contract with NASA.57.09: Bulk Densies of Binary Asteroids from the Warm Spitzer N EO SurveyAuthor Block: John Kistler 1 , D. E. Trilling 1 , M. Mueller 2 , J. L. Hora 3 , A. W. Harris 4 , B. Bhaacharya 5 , W. F. Boke 6 , S. Chesley 7 , J. P. Emery 8 , G. Fazo 3 , A. Mainzer 7 ,B. Penprase 9 , H. A. Smith 3 , T. B. Spahr 3 , J. A. Stansberry 10 , C. A. Thomas 11 Northern Arizona University, 2 Universit´e de Nice Sophia Anpolis, France, 3 Harvard-Smithsonian Center for Astrophysics, 4 DLR Instute of Planetary Research,Germany, 5 NASA Herschel Science Center Caltech, 6 Southwest Research Instute, 7 Jet Propulsion Laboratory, California Instute of Technology, 8 Department ofEarth and Planetary Sciences, University of Tennessee, 9 Department of Physics and Astronomy, Pomona College, 10 Steward Observatory, University of Arizona.Presentaon Time: 10/8/2010 11:50 AM - 12:00 PMLocaon: Ballroom EAbstract: The Warm Spitzer NEO survey, ExploreNEOs, will observe approximately 700 Near Earth Asteroids. Several of these objects are known to be binaryasteroid systems. Binary systems are interesng due to the unique opportunity they present for determining the masses and densies of their constuent bodies.The calculaons rely on a variety of data sources. The geometric albedo and effecve diameter of the system are known via ExploreNEOs. Ground based lightcurve observaons can give the orbital period and the secondary to primary diameter rao of the system. In some cases, Arecibo radar observaons provide thesemi-major axis of the system. We report here the bulk density of one of these binaries in parcular, asteroid 1999DJ4. The density derived is 1.6 g/cm 3 .For those cases where radar data is unavailable, we address the effecveness and difficules of using transit ming of a binary asteroid to determine the semimajoraxis of the system . We discuss the viability of finding a bulk density based solely on Warm Spitzer observaons and ground based light curve data.

Session Time: 10/8/2010 1:30 PM

Session Number: 58Session Title: Titan AtmosphereSession Type: Oral58.01: The Composion Of Titan's Atmosphere As Seen By Herschel / PacsAuthor Block: Miriam Rengel 1 , P. Hartogh 1 , H. Sagawa 2 , E. Lellouch 3 , H. Feuchgruber 4 , C. Jarchow 1 , R. Moreno 3 , R. Courn 3 , HssO Team1 Max-Planck-Instut für Sonnensystemforschung, Germany, 2 Naonal Instute of Informaon and Communicaons Technology, Japan, 3 LESIA, Observatoire deParis, France, 4 Max-Planck-Instut für extraterrestrische Physik, Germany.Presentaon Time: 10/8/2010 1:30 PM - 1:40 PMLocaon: Ballroom BCAbstract: Within the framework of the Herschel guaranteed me key project called ``Water and related chemistry in the Solar System''*, new insights intoTitan's atmosphere are being facilitated by data from all three Herschel instruments (Heterodyne Instrument for the Far Infrared (HIFI), Photodetector ArrayCamera and Spectrometer (PACS), and Spectral and Photometric Imaging REceiver (SPIRE)). We present the first spectrum of Titan recorded by PACS during June2010 (covering the 51 - 220 microns), with a resolving power from 940 to 5500 depending of the wavelength. The spectrum shows many lines due to H2O, HCN,CH4, and CO, we present the inial data analysis by means of a line-by-line radiave transfer code to infer abundances of the key constuents in Titan'satmosphere. Furthermore, this study aempts to contribute to a more thorough understanding of the physical phenomena in Titan's atmosphere.*also known as ``Herschel Solar System Observaons'' (HssO) project58.02: A Year One Titan: Temporal Variaons In The Neutral AtmosphereAuthor Block: Athena Coustenis 1 , R. Achterberg 2 , G. Bampasidis 3 , S. Vinaer 4 , D. Jennings 5 , C. Nixon 5 , R. Carlson 5 , M. Flasar 51 Obs. De Paris-Meudon, France, 2 Dept. of Astronomy, Univ. of Maryland, 3 Naonal & Kapodistrian University of Athens, Greece, 4 Obs. de Paris-Meudon, France,5 NASA/GSFC.Presentaon Time: 10/8/2010 1:40 PM - 1:50 PMLocaon: Ballroom BCAbstract: We have probed Titan’s stratosphere using CIRS nadir spectra taken during the past 5 years by averaging the spectra and binning them over 10° inlatude for both medium (2.5 cm-1) and high (0.5 cm-1) resoluons. Latudinal variaons were previously inferred in a number of works (Flasar et al., 2005;Coustenis et al., 2007, 2010; Vinaer et al., 2007, 2009; Teanby et al., 2006, 2007, 2008). Here, we have looked for temporal variaons in temperature andcomposion, within the duraon of the Cassini mission with CIRS data but also with respect to the measurements taken during the Voyager encounter in 1980, aTitan year ago. From Cassini/CIRS data we look for variaons in temperature and composion as the season on Titan progresses. The results show that the gasesgenerally increase in abundance from 2004 to 2009 in the northern hemisphere and decrease in the southern in agreement with (Teanby et al. 2008). Whencompared to the Voyager/IRIS data (res=4.3 cm-1), we find the current mixing rao values for the gaseous components to be lesser in the Northern hemispherewith a possible indicaon for interannual variaons, because - for at least some of the species - the abundances will not reach the enhancement in the Northfound in 1980. The contrary trends are observed in the South. We also compare with the disk-average results from ISO (1997) and some ground-basedmeasurements. With this study we seek to set constraints on seasonal, photochemical and circulaon models and to make predicons as to the spaal variaonsof the chemical composion on Titan for the upcoming years, when the season will finally become exactly the one of the Voyager encounter in 1980 and thenmove towards summer solsce in the north during the Cassini extended Solsce mission.58.03: Preliminary Results from a New Titan Atmospheric ModelAuthor Block: Mark Allen 1 , K. Willacy 1 , P. Lavvas 2 , R. Yelle 2 , D. Caratelli 31 JPL, 2 University of Arizona, 3 Northwestern University.Presentaon Time: 10/8/2010 1:50 PM - 2:00 PMLocaon: Ballroom BCAbstract.Abstract: A new comprehensive Titan atmospheric model has been developed as part of the NASA Astrobiology Instute JPL-Titan team effort tounderstand the complexity of organic chemistry in the combined Titan atmosphere/surface system. Details of this model are available in Willacy et al. (posterthis conference). In this talk, preliminary results will be presented from the atmospheric simulaon. We will discuss the flux of molecular hydrogen in the loweratmosphere, the paroning of carbon in material seling on the surface, and the relave upper atmosphere/lower atmosphere source for this material.58.04: Titan’s Tropospheric Winds: Effects Influencing SuperrotaonAuthor Block: Jonathan L. Mitchell 11 University of California Los Angeles.Presentaon Time: 10/8/2010 2:00 PM - 2:10 PMLocaon: Ballroom BCAbstract: Several effects on atmospheric superrotaon are explored using an idealized general circulaon model (GCM) of Titan. GCMs typically do not producesuperrotaon to the degree observed in Titan’s atmosphere. Numerical experiments with an Earth-like GCM suggest large-scale disturbances of zonalwavenumbers one and two are responsible for establishing and maintaining superrotaon [Mitchell & Vallis 2010]. The global structure of these disturbances aresensive to arficial damping at all latudes, and they show extreme sensivity to damping directly at the equator. A Titan GCM with idealized physics includinggrey radiaon and moist convecon is employed to study several effects on Titan’s tropospheric superrotaon. These include “spurious” effects like numericalnoise or arficial damping and “real” effects like topographical wave forcing or the paern of seasonal convecon. For instance, Cassini measurements showTitan’s surface has zonal- degree-two (quadrupole) topographical relief of 200 m at the equator [Zebker et al. 2009; Iess et al. 2010] and mountains up to 2 kmin height [Radebaugh et al. 2007]. Based on these numerical experiments, I will suggest steps that can be taken to improve the ability of Titan GCMs to developrealisc superrotaon. I will interpret the experimental results in light of recent observaons.58.05: Latudinal Dependence of Titan’s Lower Stratospheric Organic Ice CloudsAuthor Block: Carrie Anderson 1 , R. Samuelson 21 NASA GSFC, 2 University of Maryland.Presentaon Time: 10/8/2010 2:10 PM - 2:20 PMLocaon: Ballroom BC

Abstract: Analyses of Cassini CIRS far infrared limb spectra of Titan at mulple latudes reveal a broad emission feature between 70 and 270 cm-1, restrictedto altudes in the lower stratosphere between 50 and 100 km. This broad emission feature is chemically different from Titan’s photochemical aerosol, which hasan emission feature peak around 145 cm-1. The shape of the observed broad emission feature resembles a mixture of the solid component of the two mostabundant nitriles in Titan’s stratosphere, HCN and HC3N. The 50 to 100 km altude range corresponds closely to the vercal locaon where HCN and HC3N areexpected to condense and form suspended ice crystals. This is the first clear evidence that stratospheric clouds, while less abundant, are located in regions otherthan high northern winter latudes.58.06: New Perspecves On The Upper Atmosphere Of Titan From Cassini UVIS Stellar OccultaonsAuthor Block: Tommi Koskinen 1 , R. V. Yelle 1 , B. R. Sandel 1 , P. Lavvas 1 , Y. Benilan 2 , F. Capalbo 21 Lunar and Planetary Laboratory, University of Arizona, 2 LISA, Universites Paris 7, France.Presentaon Time: 10/8/2010 2:20 PM - 2:30 PMLocaon: Ballroom BCAbstract: The Cassini UVIS archive contains several stellar occultaons that probe the upper atmosphere of Titan between the impact parameters of 400 and1400 km. Uniquely, this range includes the region between 500 and 1000 km that is believed to be the site of complex hydrocarbon photochemistry and possiblythe growth of aerosols that form the detached haze layers below. In order to beer characterize the number density profiles of the hydrocarbons and theproperes of the aerosols in this region, we have reanalyzed the occultaon of the star lambda Sco from December 2004 and begun the analysis of more recentoccultaons. Our analysis covers the wavelength range of 125 - 190 nm and impact parameters of 400 - 1400 km. We confirm the earlier detecons of CH 4 , C 2 H 6 ,C 2 H 2 , C 2 H 4 , and C 4 H 2 in the transmission spectra. We also find evidence for two disnct absorbing layers in the data near 500 km and 750 km. We note that theexncon coefficients derived from the light curves appear to correlate with the temperature profile measured by the HASI instrument. The 500 km featurecorresponds to the detached haze layer that was recently linked to a temperature maximum in the HASI profile but the properes of the 750 km feature areunknown. It is possible that this new feature is associated with another high altude aerosol layer. We note, however, that the retrieval of the opcal properesof the aerosols and thus the density and size distribuon is complicated by the possible presence of higher order hydrocarbons such as C 6 H 6 in the transmissionspectra.58.07: Titan’s Visible Haze Structure: 2004-2010Author Block: Robert A. West 1 , J. Balloch 1 , P. Dumont 11 JPL.Presentaon Time: 10/8/2010 2:30 PM - 2:40 PMLocaon: Ballroom BCAbstract: The combinaon of limb and disk views of Titan’s haze acquired by the Cassini Imaging Science Subsystem from 2004 to the present reveals a varietyof structures which evolve over many me scales. Titan’s haze structure was significantly reduced in Voyager mes relave to what ISS observed early in themission. This feature may be an indicaon of long-term secular change rather than seasonal change. Images in the 890-nm methane absorpon band reveal apolar structure which is offset from the rotaonal pole (Roman et al., Icarus 203, 242-249, 2009). Here we compile observaons of haze structure at manywavelengths from the near-UV to the near-IR including three methane bands. We describe few-km-scale structure in the vercal haze profiles and albedo changesas a funcon of latude with me sampling of several months. Mulple haze layers at or above 510 km altude are seen at most latudes. Preliminary evidencesuggests the altudes of the outer visible layers are decreasing with me. The region poleward of the polar vortex boundary near latude 55 degrees is quitecomplex. These and future observaons will constrain aerosol microphysical models and reveal detail on how seasonal change takes place. Our radiave transfermodels make use of a mul-scaer code with spherical shell symmetry. This work was performed by the Jet Propulsion Lab, California Instute of Technology58.08: Titan Haze And Cloud Layers Constrained By Photometry.Author Block: Pascal Rannou 1 , T. Cours 1 , J. Burgalat 1 , S. Lemouélic 2 , S. Rodriguez 3 , C. Son 4 , R. Brown 51 GSM A/Univ. de Reims Champagne Ardenne, France, 2 LPGN/Univ. de Nantes, France, 3 LAIM/CEA/Univ. Paris 7, France, 4 JPL/California Instute of Technology,5 LPL/Univ. of Arizona.Presentaon Time: 10/8/2010 2:40 PM - 2:50 PMLocaon: Ballroom BCAbstract: We have used several images made by VIMS onboard Cassini to study the haze and cloud layers. In our work, we focused both on the haze and thecloud layer in northern hemisphere (above 40°N). These two regions of Titan are probably the most interesng to understand the source and the sink of the hazeand consensible species. Using a radiave transfer model we found several results that constrain the cloud layers :We characterized the spaal distribuon of the haze layer above about 100 km, and the mist (mixture of haze and condensate below about 70 km) in the lowstratosphere and the troposphere.Beyond 62°N, we can see the influence of the north polar cloud in the centre and in the sides of several methane windows. The structure of the cloud and its meevoluon (studied elsewhere by Lemouélic et al., 2010) depends on the atmosph:ere circulaon. Here we focus on the best image that we have (T22). Using aradiave transfer model, we retrieved the altude and the opacity of the cloud at each pixel. We made a map of the polar cloud (altude and opacity) and wefound that the north polar cloud has two levels which probably corresponds to two different condensible species.58.09: The Detached Haze Layer Of Titan Observed By Cassini/iss ImagesAuthor Block: Thibaud Cours 1 , P. Rannou 1 , S. Rodriguez 2 , A. Brahic 2 , R. A. West 31 GSM A / Reims University, France, 2 AIM / CEA Saclay, France, 3 JPL/Pasadena.Presentaon Time: 10/8/2010 2:50 PM - 3:00 PMLocaon: Ballroom BCAbstract: Aer ISS on Voyager, in 1980 and 1981, the ISS instrument onboard Cassini observed an opcally thin detached haze layer over the main thick hazelayer of Titan. About one Titan year aer its first detecon, it surprisingly culminates 150 km higher than in 1980. It also appears layered in fine structuresprobably triggered by waves. This layer is though to be produced by the large scale circulaon. The size and the composion of the aerosols forming this layer,and the structure of the layer itself are important clues to understand the atmosphere circulaon and the formaon the aerosols from the complexphotochemistry.To characterize the detached haze layer, we used large phase angle images acquired by Cassini probe with the ISS camera at different dates between 2005 and2009, at seven different phase angles (from 112° to 161°) and with two different filters. This set of observaons reveals a strong forward peak of the aerosolphase funcon, similar to what was observed by Voyager. Our analysis shows that the signal is consistent with parcles in the range 0.2 to 0.3 [[UnsupportedCharacter - Symbol Font μ]]m. Assuming fractal aggregates made of monomers of radius r m = 0.05 [[Unsupported Character - Symbol Font μ]]m, we find thataggregates should be composed of several tens of monomers. In our presentaon we will describe in detail our results and the important consequences that can

e drawn concerning the circulaon, the aerosol size distribuon and we will discuss the connecon with chemical aspects.

Session Number: 59Session Title: Extrasolar Planets and Systems: Kepler Mission ResultsSession Type: Oral59.01: Kepler Instrument Performance: the 1 Year CheckupAuthor Block: Douglas A. Caldwell 1 , J. E. Van Cleve 1 , J. M. Jenkins 1 , J. J. Kolodziejczak 2 , V. S. Argabright 3 , N. M. Batalha 4 , S. T. Bryson 5 , H. Chandrasekaran 6 , J. L.Chrisansen 1 , E. W. Dunham 7 , J. C. Geary 8 , J. Li 1 , P. Machalek 1 , P. Tenenbaum 1 , F. C. Wieborn 5 , H. Wu 1 , D. G. Koch 5 , W. J. Borucki 51 SETI Instute, 2 NASA Marshall Space Flight Center, 3 Ball Aerospace and Technologies Corp., 4 San Jose State University, 5 NASA Ames Research Center,6 Lawrence Livermore Naonal Lab, 7 Lowell Observatory, 8 Smithsonian Astrophysical Observatory.Presentaon Time: 10/8/2010 1:30 PM - 1:40 PMLocaon: Ballroom DAbstract: The Kepler Mission is designed to detect the 80 parts per million (ppm) signal from an Earth-Sun equivalent transit. Such precision requires superbinstrument stability on me scales up to 2 days and systemac error removal to beer than 20 ppm. The sole scienfic instrument is the photometer, a 0.95 maperture Schmidt telescope that feeds the 94.6 million pixel CCD detector array, which contains both Science and Fine Guidance Sensor (FGS) CCDs. We find thatthe in-flight detector properes of the focal plane, including bias levels, read noise, gain, linearity, saturaon, FGS to Science crosstalk, and video crosstalkbetween Science CCDs, are essenally unchanged from their pre-launch values. Now that Kepler has been collecng science data for more than a year, we areable to track stars through a complete orbit of the spacecra around the Sun and its associated roll orientaons. Using these data, we can begin to disentanglethe instrument related signals from those intrinsic to the sky background and stars, measure both short- and long-term effects from cosmic rays, see interaconsof previously known image arfacts with starlight, and uncover several unexpected systemacs that affect photometric precision, including unexplained diffuseilluminaon events that occur at significant levels ~10 mes per month.Funding for this Discovery Mission is provided by NASA¹s Science Mission Directorate.59.02: Update On Kepler Photometric Precision And The Radii Of Detectable PlanetsAuthor Block: Pavel Machalek 1 , E. W. Dunham 2 , J. M. Jenkins 1 , J. Chrisansen 1 , D. A. Caldwell 3 , S. T. Bryson 4 , T. N. Gauer 5 , R. L. Gilliland 61 SETI / NASA Ames, 2 Lowell Observatory, 3 SETI / NASA Ames, 4 NASA Ames, 5 JPL, 6 STScI.Presentaon Time: 10/8/2010 1:40 PM - 1:50 PMLocaon: Ballroom DAbstract: The Kepler Mission seeks to detect an 84 parts per million (ppm) deep transit of an Earth like planet around a Sun like star at more than 4-sigma foran 6.5 hour long transit. We present an update on the removal of systemac effects in the long cadence (LC) differenal photometry ulizing the first year ofscience data. In parcular we report on the progress towards achieving 20 ppm precision per 6.5 hour long transit for a Kp = 12 mag G12 star. We further discusshow the poinng dri and focus changes; cosmic rays; CCD effects; aperture and PRF photometry and pipeline processing affect the combined Kepler photometricprecision in terms of radii of detectable planets.Funding for this Discovery Mission is provided by NASA's Science Mission Directorate.59.03: Short Cadence versus Long Cadence: Affects of Cadence Choice on Kepler Light Curve AnalysesAuthor Block: Jessie Chrisansen 1 , J. M. Jenkins 1 , D. A. Caldwell 1 , S. T. Bryson 2 , J. Van Cleve 1 , J. Kolodziejczak 3 , P. Machalek 1 , J. F. Rowe 1 , R. L. Gilliland 4 , J. D.Twicken 1 , J. L. Dotson 2 , M. R. Haas 2 , D. G. Koch 2 , W. J. Borucki 21 SETI Instute, 2 NASA Ames Research Center, 3 NASA-M SFC, 4 Space Telescope Science Instute.Presentaon Time: 10/8/2010 1:50 PM - 2:00 PMLocaon: Ballroom DAbstract: Kepler light curves come in two flavors - long and short cadence - with effecve integraon mes of 30 minutes and 1 minute respecvely. Only asmall number (up to 512) of the 150,000+ Kepler targets can be observed with the shorter cadence, and this number comprises both asteroseismology targets andplanet candidate targets. Since the number of planet candidates now exceeds the number of available short cadence slots, it is necessary to determine for whichcandidates the short cadence light curves will be most useful. These light curves will have beer me-sampling, but lower signal to noise due to the shorterintegraon me, and in addion may be more greatly affected by systemacs than the long cadence light curves. The affect of the cadence choice on the derivedplanet parameters is presented here, with invesgaon into the possible dependences on parameters such as stellar magnitude, period and planet size.Funding for this Discovery Mission is provided by NASA’s Science Mission Directorate.59.04: Inial False Posive Idenficaon for Kepler Planetary CandidatesAuthor Block: Thomas N. Gauer 1 , Kepler Science Team1 Jet Propulsion Laboratory.Presentaon Time: 10/8/2010 2:00 PM - 2:10 PMLocaon: Ballroom DAbstract: Searches for transing exoplanets inevitably generate false idenficaons of planetary transits, or false posives, due to a number of astrophysicalphenomena that produce planetary-like transit signatures. In June 2010 the Kepler project released the light curves of more than 150,000 stars. The Kepler projecthas compiled a list of false posives found while searching those 150,000 stars for planetary transits.Techniques used to idenfy Kepler's false posives include careful examinaon of the light curve for signs of eclipsing binary behavior, radial velocitymeasurements sufficient to eliminate stellar mass companions of the target star as the source of the transit signal, detailed analysis, supplemented by highresoluon imaging, of pixel values and shis in light distribuon in the Kepler photometric aperture during transit and co-analysis of the light curves with highSNR spectra to detect blended stars too closely separated to be found by shis in the light distribuon. The types of false posives in this list include backgroundeclipsing binaries blended with the target star, shallow eclipsing binaries including double-lined spectroscopic binaries and blends caused by hierarchicalmulple systems with transing components.The list of known Kepler false posives is published at the Mulmission Archive at STScI (MAST, hp://archive.stsci.edu/kepler/false_posives.html) and isupdated as new false posives are idenfied.59.05: From Lightcurve to Planet: Veng Kepler DiscoveriesAuthor Block: William D. Cochran 1 , Kepler Science Team1 Univ. of Texas, Ausn.Presentaon Time: 10/8/2010 2:10 PM - 2:20 PMLocaon: Ballroom DAbstract.Abstract: Aer a possible transit-like signal is detected in a Kepler lightcurve, a large number of checks are made in order to determine whether the

signal is due to a true planet or is a false-posive signal. The first steps include detailed inspecon of the lightcurve itself and a search for correlaon ofastrometric residuals with the photometric transit signal. Kepler Objects of Interest (KOIs) that are passed on to the Follow-up Observing Program then receivereconnaissance spectroscopy and high spaal resoluon imaging. KOIs that survive these tests may then be subjected to high-precision radial velocitymeasurements to measure the stellar reflex orbit and thus fully confirm the existence of a planet. This last step of precise radial velocity measurement can not beused on all Kepler planets because: 1) telescope resources are limited, and 2) state-of-the-art velocity precision is insufficient to measure the stellar reflex orbitof an Earth-mass planet in a 1AU orbit around the faint Kepler targets. Examples of these verificaon steps will be presented.59.06: Confirming Earth-size Planets Detecons By Modeling Kepler Transit Light Curves As False Posives.Author Block: Francois Fressin 1 , G. Torres 1 , Kepler group1 Harvard CFA.Presentaon Time: 10/8/2010 2:20 PM - 2:30 PMLocaon: Ballroom DAbstract: We model the photometry of Kepler transing planet candidates assuming it is the result of the brightness variaons of an eclipsing binary beingaenuated by the brighter candidate star. We explore both triple systems at the distance of the target, and background systems, where the eclipsing object maybe a star or a planet.We are able to idenfy which blend systems fit the data well. In many cases, we can exclude that the photometry could be due to a triple system. There are somecases where we can also rule out background blends and provide strong support for the planetary origin of the signal.For the shallow eclipses that could be due to Earth-size transing planets, we can idenfy a specific range of spectral type and magnitude difference compared tothe target for possible blends. Combining this informaon with adapve opcs imaging, speckle interferometry, spectroscopic analysis, and the centroid shi ofKepler data occurring during the transit, allows us to assign a stascal confidence level to the conclusion that the observed signal is due to an Earth-size planet.59.07: Warm Spitzer Studies of the Atmospheres of Kepler-Detected ExoplanetsAuthor Block: Jean-Michel Desert 11 Harvard University.Presentaon Time: 10/8/2010 2:30 PM - 2:40 PMLocaon: Ballroom DAbstract.Abstract: I present results from an ongoing project to use the Spitzer Space Telescope to gather near-infrared photometric measurements of theatmospheres of transing extrasolar planets detecng by the Kepler Mission. I will first briefly review the instrumental performance of the Warm Spitzer missionfor exoplanet measurements. I will then describe the atmospheric studies of the highly-irradiated transing hot-Jupiters Kepler-5b and Kepler-6b. Spitzer studiesof these objects are valuable since our near-infrared observaons are complemented by constraints on the geometric albedo in the opcal from the KeplerMission photometry. By combining secondary eclipse measurements of the reflected starlight in the opcal with esmates of the thermal emission in the nearinfrared,we are able to constrain the energy budget of these planets and compare such constraints to those for the Solar system giant planets.59.08: Transit Timing Variaon studies of Kepler exoplanetary systemsAuthor Block: Jason H. Steffen 1 , Kepler Science Team1 Fermilab.Presentaon Time: 10/8/2010 2:40 PM - 2:50 PMLocaon: Ballroom DAbstract.Abstract: When mulple planets are present in a transing exoplanetary system, dynamical interacons among the planets will cause variaons in theinterval between successive planetary transits. These transit ming variaons (TTVs) are can be used to characterize the orbits and masses of the differentinteracng bodies. I present the results of ongoing invesgaons of the TTV signal in exoplanet systems from the Kepler mission. For some systems, TTVs may beused to idenfy nontransing planets, to confirm the planet-nature of candidates, and to idenfy or constrain important orbital parameters.59.09: Kepler Stars with Mulple Transing Planet CandidatesAuthor Block: Jack J. Lissauer 1 , Kepler Science Team1 NASA Ames Research Center.Presentaon Time: 10/8/2010 2:50 PM - 3:00 PMLocaon: Ballroom DAbstract.Abstract: NASA's Kepler spacecra was launched into an Earth-trailing heliocentric orbit in March of 2009. Kepler is designed to conduct a stascalcensus of planetary system properes using transit photometry. Among the most excing early results from Kepler are target stars found to have photometricsignatures that suggest the presence of more than one transing planet. Individual transing planets provide informaon on the size and orbital perioddistribuons of exoplanets. Mulple transing planets provide addional informaon on the spacing and flatness distribuons of planetary systems. Results todate and plans for future analysis will be presented.

Session Number: 60Session Title: Near-Earth Asteroids IISession Type: Oral60.01: First Inner Solar System Results From The Pan-STARRS 1 TelescopeAuthor Block: Richard J. Wainscoat 1 , R. Jedicke 1 , L. Denneau 1 , M. Granvik 1 , J. Kleyna 1 , PS1SC ISS Team1 Univ. of Hawaii.Presentaon Time: 10/8/2010 1:30 PM - 1:40 PMLocaon: Ballroom EAbstract.Abstract: The Pan-STARRS 1 telescope has been slowly brought into operaon over the last 5 months. The telescope performance will be described,and the survey strategy will be summarized. Some of the early results from the survey will be discussed, including stascs of reporng to the Minor PlanetCenter, photometry, and astrometry.60.02: An High Resoluon Near-Earth Objects Populaon Enabling Next-Generaon Search StrategiesAuthor Block: Pasquale Tricarico 1 , E. C. Beshore 2 , S. M. Larson 2 , A. Boani 2 , G. V. Williams 31 Planetary Science Instute, 2 Lunar and Planetary Laboratory, University of Arizona, 3 IAU Minor Planet Center, Harvard-Smithsonian Center for Astrophysics.Presentaon Time: 10/8/2010 1:40 PM - 1:50 PMLocaon: Ballroom EAbstract: Over the past decade, the dedicated search for kilometer-size near-Earth objects (NEOs), potenally hazardous objects (PHOs), and potenal Earthimpactors has led to a boost in the rate of discoveries of these objects. The catalog of known NEOs is the fundamental ingredient used to develop a model for theNEOs populaon, either by assessing and correcng for the observaonal bias (Jedicke et al., 2002), or by evaluang the migraon rates from the NEOs sourceregions (Boke et al., 2002). The modeled NEOs populaon is a necessary tool used to track the progress in the search of large NEOs (Jedicke et al., 2003) and totry to predict the distribuon of the ones sll undiscovered, as well as to study the sky distribuon of potenal Earth impactors (Chesley & Spahr, 2004).We present a method to model the NEOs populaon in all six orbital elements, on a finely grained grid, allowing us the design and test of targeted and opmizedsearch strategies. This method relies on the observaonal data rounely reported to the Minor Planet Center (MPC) by the Catalina Sky Survey (CSS) and by otheracve NEO surveys over the past decade, to determine on a nightly basis the efficiency in detecng moving objects as a funcon of observable quanesincluding apparent magnitude, rate of moon, airmass, and galacc latude. The cumulave detecon probability is then be computed for objects within a smallrange in orbital elements and absolute magnitude, and the comparison with the number of know NEOs within the same range allows us to model the populaon.When propagated to the present epoch and projected on the sky plane, this provides the distribuon of the missing large NEOs, PHOs, and potenal impactors.We acknowledge support from NASA AISR and NASA NEOO programs.60.03: Rotaon Rates of Very Small Near-Earth AsteroidsAuthor Block: Eileen V. Ryan 1 , W. H. Ryan 11 NM Tech/M RO.Presentaon Time: 10/8/2010 1:50 PM - 2:00 PMLocaon: Ballroom EAbstract: Currently there exists only limited data on physical properes such as rotaon rate for the very smallest Near-Earth Asteroids (NEAs) beingdiscovered. The spin period of an asteroid can imply important informaon about its internal composion (via deducon of strength boundary limits) and degreeof fracture, and thereby its collisional history. Our objecve is to gather the data needed to test current theories of the relaonship between spin limits andoverall strength.We report on a dataset of 38 lightcurves of NEAs collected at the Magdalena Ridge Observatory’s (MRO) 2.4-meter telescope, analyzed to obtain rotaon rates.The majority of the objects targeted were less than about 200 meters in diameter, where exisng data are sparse. These small bodies have exhibited a range ofspin rates, from slow (~8 hours) to very fast (less than a minute). A lightcurve taken of NEA 2010 JL88 (esmated to be 18 meters in diameter) on May 17, 2010,revealed a rotaon period of 24.5 seconds, making this object the fastest natural rotator discovered to date. Further, we obtained a lightcurve of asteroid 2009BF2 (~27 meters in diameter) on January 17, 2009, and its rotaon period was derived to be 58 seconds (the third fastest rotator discovered). We also found 2NEAs that appear to be tumbling, indicang a recent collisional event. Although a more robust stascal sample of spin rates in this small size regime is slldesired, we are making progress toward a beer understanding of the physical processes at work as our observaonal survey of the Near-Earth zone connues.This research is funded through NASA's NEOO program and NSF’s Planetary Astronomy program.60.04: Space Weathering Trends Revealed by Principal Component Analysis: Looking Beyond the SlopeAuthor Block: Richard P. Binzel 1 , F. E. DeMeo 1 , C. A. Thomas 2 , P. Vernazza 31 M IT, 2 Northern Arizona University, 3 ESTEC/ESA, Netherlands.Presentaon Time: 10/8/2010 2:00 PM - 2:10 PMLocaon: Ballroom EAbstract: We present a quantave analysis of space weathering trends as measured in the laboratory [1], as determined through models [2], and asmeasured on asteroids in situ [3,4]. Our first step is to remove the slope from all spectra so as to analyze the effects of weathering on spectral features, such asthe strength of the 1- and 2-micron absorpon bands. Thus we perform a slope-free analysis. We compare the ‘beyond the slope’ effects of space weatheringtrends to the natural dispersion present within principal component analyses [5, 6] used for assignment of asteroid spectra to taxonomic classes. We find thataer spectral slope is removed, the remaining space weathering effects create trends in principal component space that mimic important dimensions seen withinthe dispersion of the asteroid populaon as a whole. (Note the asteroid analysis is similarly performed aer spectral slope is removed.) Quantavely ouranalysis shows that space weathering effects, independent of spectral slope, are consistent with the transion from Q- to Sq- to S-type asteroids as classified inthe Bus-DeMeo taxonomy [6].[1]Strazzulla, G. et al. Icarus 174, 31-35 (2005). [2] Shkuratov, Y. et al. Icarus 137, 235-246 (1999). [3] Chapman, C. M APS 31, 699-725 (1996). [4] Clark, B. et al.M APS 36, 1617-1637 (2001). [5] Bus, S. J. MIT Ph.D. Thesis (1999). [6] DeMeo et al. Icarus 202, 160-180 (2009).60.05: The Origin of Asteroid 101955 (1999 RQ 36 )Author Block: Humberto Campins 1 , A. Morbidelli 2 , J. de León 3 , K. Tsiganis 4 , J. Licandro 51 Univ. of Central Florida, 2 Observatoire de la Côte d'Azur, France, 3 Instuto de Astrosica de Andalucía, Spain, 4 Aristotle University, Greece, 5 Instuto deAstrosica de Canarias, Spain.Presentaon Time: 10/8/2010 2:10 PM - 2:20 PMLocaon: Ballroom E

Abstract: Near-Earth asteroid 101955 (1999 RQ36; henceforth RQ36) is parcularly interesng. It’s especially accessible to spacecra and is the primary targetof NASA’s OSIRIS-REx sample return mission; it’s also a potenally hazardous asteroid (Milani et al. 2009). We combine dynamical and spectral informaon toidenfy the most likely main-belt origin of RQ36 and conclude that it is the Polana family, located at a semi-major axis of about 2.42 AU (our approach is similarto that used by de León et al. (2010) to link 3200 Phaethon, parent body of the Geminids, to 2 Pallas).Our conclusion is based on the following results. a) Dynamical evidence favors strongly an inner-belt, low-inclinaon (2.15 AU < a < 2.5 AU and i < 10 degrees)origin, suggesng the ν 6 resonance as the preferred (95% probability) delivery route. b) This region is dominated by the Nysa and Polana families (families arefavored over single objects because small fragments have already been produced). c) The Polana family is characterized by low albedos and B-class spectra orcolors (Bus and Binzel 2002), which is the same spectral class, and albedo, as RQ36. d) The SDSS colors show that the Polana family is the branch of the Nysa-Polana complex that extends toward the ν 6 resonance; furthermore, Polana has delivered objects the size of RQ36 and larger into the ν 6 resonance. e) RQ36 isretrograde, consistent with the Yarkovsky effect having moved it inward from Polana into the ν 6 . f) A quantave comparison of visible and near-infrared spectradoes not yield a unique match for RQ36; however, it is consistent with a composional link between RQ36 and the Polana family.Finally, the Polana Family is likely the most important inner-belt source of low albedo Near-Earth asteroids.This work was supported by NASA and NSF.60.06: Asteroid (101955) 1999 RQ36: Spectroscopy from 0.4 to 2.5 microns and Meteorite AnalogsAuthor Block: Beth Ellen Clark 1 , R. P. Binzel 2 , E. Howell 3 , E. A. Clous 4 , M. Ockert-Bell 1 , P. Christensen 5 , M. A. Barucci 6 , F. DeMeo 6 , D. Laurea 7 , H. Connolly Jr. 8 ,A. Soderberg 9 , C. Hergenrother 7 , L. Lim 101 Ithaca College, 2 M IT, 3 Arecibo Observatory, Puerto Rico, 4 University of Winnipeg, Canada, 5 ASU, 6 Observatory of Paris, France, 7 University of Arizona, 8 CUNY,9 Harvard University, 10 Goddard.Presentaon Time: 10/8/2010 2:20 PM - 2:30 PMLocaon: Ballroom EAbstract.Abstract: We present reflectance spectra from 0.4 to 2.5 microns of asteroid (101955) 1999 RQ36, the target of the proposed OSIRIS-REx spacecramission. The visible spectral data were obtained at the McDonald Observatory 2.1-m telescope with the ES2 spectrograph. The infrared spectral data wereobtained at the NASA Infrared Telescope Facility using the SpeX instrument. The average visible spectrum is combined with the average near-infrared wavelengthspectrum to form a composite spectrum. We use three methods to constrain the composional informaon in the composite spectrum of asteroid (101955) 1999RQ36 (hereaer RQ36). First, we perform a least-squares search for meteorite spectral analogs using 15,000 spectra from the RELAB database. Three most likelymeteorite analogs are proposed based on the least-squares search. Next, six spectral parameters are measured for RQ36 and their values are compared with theranges in parameter values established by sets of RELAB spectra represenng relevant spectrally measured meteorite classes. A most likely meteorite analoggroup is proposed based on the depth of overlap in parameter values. The results of the least-squares search and the parametric comparisons point to CIs and/orCMs as the most likely meteorite analogs for RQ36, and CKs and ureilites as the least likely. We speculate that RQ36 is composed of a CM1-like material. Finally,RQ36 is compared to other B-type asteroids measured by Clark et al. (2010 JGR 15) and is found to be most consistent with the Themis Group B-types. This isparcularly interesng because asteroid 24 Themis was recently discovered to have H2O ice on the surface (Rivkin and Emery 2010, Nature 464; Campins et al.2010, Nature 464).60.07: Looking Before We Leap: Recent Results From An Ongoing Quantave Invesgaon Of Asteroid And Comet Impact Hazard Migaon.Author Block: Catherine Plesko 1 , R. P. Weaver 1 , D. G. Korycansky 2 , W. F. Huebner 31 Los Alamos Naonal Laboratory, 2 University of California Santa Cruz, 3 Southwest Research Instute.Presentaon Time: 10/8/2010 2:30 PM - 2:40 PMLocaon: Ballroom EAbstract: The asteroid and comet impact hazard is now part of public consciousness, as demonstrated by movies, Super Bowl commercials, and popular newsstories. However, there is a popular misconcepon that hazard migaon is a solved problem. Many people think, `we’ll just nuke it.’ There are, however,significant scienfic quesons remaining in the hazard migaon problem. Before we can say with certainty that an explosive yield Y at height of burst h willproduce a momentum change in or dispersion of a potenally hazardous object (PHO), we need to quanfy how and where energy is deposited into the rubblepile or conglomerate that may make up the PHO. We then need to understand how shock waves propagate through the system, what causes them to disrupt, andhow long gravitaonally bound fragments take to recombine.Here we present numerical models of energy deposion from an energy source into various materials that are known PHO constuents, and rigid body dynamicsmodels of the recombinaon of disrupted objects. In the energy deposion models, we explore the effects of porosity and standoff distance as well as that ofcomposion. In the dynamical models, we explore the effects of fragment size and velocity distribuons on the me it takes for gravitaonally bound fragmentsto recombine. Inial models indicate that this recombinaon me is relavely short, as lile as 24 hours for a 1 km sized PHO composed of 1000 meter-scaleself-gravitang fragments with an inial velocity field of v/r = 0.001 1/s.60.08: Almahata Sia and the Rubble Pile Asteroid 2008 TC3Author Block: Petrus M. M. Jenniskens 1 , M. H. Shaddad 2 , Almahata Sia Consorum1 SETI Instute, 2 University of Khartoum, Sudan.Presentaon Time: 10/8/2010 2:40 PM - 2:50 PMLocaon: Ballroom EAbstract: On October 6, 2008, asteroid 2008 TC3 was observed to approach Earth and impact the Nubian Desert of northern Sudan 20 hours later. Meteoriteswere recovered in the following months, with expedions held in December 2008 and February/March of 2009 (1).Here, we report on the collecon of addional meteorites from the Almahata Sia strewn field in December of 2009, following the 2008 TC3 Workshop held at theUniversity of Khartoum December 5-6. The total recovered mass in the University of Khartoum collecon now is 10.5 kg, comprised of 600 individual meteorites.Based on the density of fallen meteorites, the total fallen mass is esmated as 39 +/- 6 kg, of which only about 27 percent has been recovered so far (2).The majority of meteorites are ureilites, some of an anomalous (porous, high in carbon) polymict variety. For the first me, however, macroscopic fragments ofother meteorites were recovered as well from the same fall. 20-30 percent in mass of fresh-looking Almahata Sia meteorites consist of other meteorite types,including H5, EL6, and EH6 meteorites. Those other meteorite types shaered in a similar manner from a 37-km altude explosion as the predominant ureilites.This makes the 3 to 4 meter sized asteroid a small rubble pile, with accumulated material from different parent bodies.We will review the current status of analysis of the meteorites by members of the Almahata Sia consorum, the derived physical properes of the meteorites,and the implicaons for the physical properes of asteroid 2008 TC3, the ureilite parent body, and the possible source region of ureilites in the asteroid belt.References:1. Jenniskens, P., et al. 2009. Nature. 458, 485-488.2. Shaddad, M. H., et al. 2010. MAPS in press.

60.09: Lightcurve Inversion For Binary Asteroids Using MCMCAuthor Block: Karri Muinonen 1 , D. Oszkiewicz 2 , T. Pieniluoma 21 Univ. Helsinki Dept. Physics & Finnish Geodec Instute, Finland, 2 Univ. Helsinki Dept. Physics, Finland.Presentaon Time: 10/8/2010 2:50 PM - 3:00 PMLocaon: Ballroom EAbstract.Abstract: We study lightcurve inversion for spin, shape, and scaering properes as well as intrinsic orbital properes of a binary asteroid. Weassume, first, that the shapes of the primary and secondary components are convex and, second, that a two-body dynamical model is valid for the binary system.We search for the nonlinear least-squares parameters using stochasc opmizaon that includes ingredients from Markov chain Monte Carlo (MCMC) andsimulated annealing. In the proximity of the least-squares soluon, we map the parameter uncertaines using MCMC. We compare the inverse methods to theanalogous methods already proven successful for single-asteroid lightcurve inversion. Note that, differing from the convenonal convex lightcurve inversionmethod, shape opmizaon and inversion are carried out directly in the phase space of convex shapes. The methods can be applied to interpret the data in theAsteroid Photometric Catalogue maintained at the University of Helsinki as well as the forecoming photometric data of the Gaia mission (launch 2012). Researchsupported, in part, by the Academy of Finland through project No. 127461.

Session Time: 10/8/2010 3:30 PM

Session Number: 61Session Title: Titan: Atmosphere, Interior, and LifeSession Type: Oral61.01: Surface Temperatures on Titan: Changes During the Cassini MissionAuthor Block: Donald E. Jennings 1 , V. Coni 1 , C. A. Nixon 11 NASA Goddard Space Flight Center.Presentaon Time: 10/8/2010 3:30 PM - 3:40 PMLocaon: Ballroom BCAbstract: Surface brightness temperatures on Titan measured by the Composite Infrared Spectrometer (CIRS) aboard Cassini span the period from late northernwinter to early spring. CIRS previously reported surface temperatures from the earlier poron of the mission (2004-08) that showed a temperature of 93.7 K at theequator with decreases of 2 K toward the south pole and 3 K toward the north pole (1). From a comparison of the equinox period with data from the earlier period,CIRS now detects a seasonal shi in the latudinal distribuon of temperatures. Around the me of the equinox the meridional distribuon was more symmetricabout the equator than had been found earlier in the mission. At equinox the equatorial surface temperatures remained close to 94 K, but in the south thetemperatures had decreased by about 0.5 K and in the north had increased by about 0.5 K. The CIRS equinox results are similar to what was seen near theprevious northern vernal equinox by Voyager IRIS (2, 3). The observed surface temperatures can help constrain the type of surface material by comparison withpredicons from general circulaon models. Of the three cases treated by Tokano (4), our measurements most closely match a porous-icy regolith. As Cassiniconnues through Titan’s northern spring CIRS will extend its temporal and spaal coverage and will connue to search for seasonal variaons in surfacetemperature.(1)Jennings et al., Astrophysical Journal Leers 69, L103 (2009).(2)Flasar, F. M., Samuelson, R. E., & Conrath, B. J., Nature 292, 693 (1981).(3)Courn, R., & Kim, S. J., Planetary and Space Science 50, 309 (2002).(4)Tokano, T., Icarus 204, 619 (2005).61.02: First Observaons Of Titan With Herschel SpireAuthor Block: Regis D. Courn 1 , B. M. Swinyard 2 , T. Fulton 3 , E. Lellouch 1 , R. Moreno 1 , P. Hartogh 4 , C. Jarchow 4 , M. Rengel 4 , HssO Team1 LESIA, Obs. de Paris, France, 2 SSTD, Rutherford Appleton Laboratory, United Kingdom, 3 University of Lethbridge, Canada, 4 M PIS, Germany.Presentaon Time: 10/8/2010 3:40 PM - 3:50 PMLocaon: Ballroom BCAbstract: A Titan spectrum was recorded on June 22, 2010 with the SPIRE instrument of the Herschel Space Observatory as part of the guaranteed me keyprogramme "Water and related chemistry in the Solar System" (KP-GT HssO). This inial spectrum, corresponding to an exposure me of 1322s, was designed asa test of the full ~10h Titan observaon performed on July 16, 2010. It covers the 14.6-51.8 cm -1 interval with a unapodized spectral resoluon of 0.04 cm -1 .Despite the limited integraon me, numerous transions are detected, notably those of CH 4 , CO, HCN, and of the isotopologues 13 CO, C 18 O, H 13 CN, and HC 15 N.The analysis of this set of observaons will provide new determinaons of the abundances of these species, and hence new contraints on the isotopic raos12 C/ 13 C, 14 N/ 15 N and 16 O/ 18 O in Titan's atmosphere.61.03: Herschel/HIFI Observaons of Titan : Observaon of the H2O(110-101) 557 GHz Line and First Detecon of HN CAuthor Block: Raphael Moreno 1 , E. Lellouch 1 , P. Hartogh 2 , L. Lara 3 , R. Courn 1 , M. Rengel 2 , C. Jarchow 2 , D. Bockelée-Morvan 1 , N. Biver 1 , D. Lis 4 , HssO Team1 Obs. de Paris-Meudon, France, 2 M PIS, Germany, 3 IAA-CSIC, Spain, 4 Caltech.Presentaon Time: 10/8/2010 3:50 PM - 4:00 PMLocaon: Ballroom BCAbstract: Observaons of Titan were performed on June 14, 2010 with the HIFI heterodyne submm instrument on board of the Herschel Space Observatory, aspart of the guaranteed me key programme "Water and related chemistry in the Solar System" (HssO). The H2O(110-101) and HNC(6-5) rotaonal transions at556.936 and 543.897 GHz, respecvely, were detected in emission. This represents the first detecon of HNC in Titan's atmosphere.Preliminary analysis of these narrow lines (FWHM ~ 2 MHz), suggests that they must originate at altudes above 300 km. They can also be fied assumingemission above 800 km.HNC is expected to be produced by dissociave recombinaon reacon of the ionospheric ion HCNH+ at altudes above 1000 km (Petrie 2001). Water vapor onTitan was first detected with ISO (Coustenis et al. 1998). Micrometeoric ablaon at about 700 km is possibly the external source of Titan's water vapor (Lara etal. 1996).A comparison with vercal profiles expected from photochemical models will be presented. The analysis of these lines will constrain the abundances of thesespecies, and the HNC/HCN rao at high altudes.61.04: Origin of a Parally Differenated TitanAuthor Block: Amy C. Barr 1 , R. I. Citron 2 , R. M. Canup 11 Southwest Research Instute, 2 Laboratory for Atmospheric and Space Physics.Presentaon Time: 10/8/2010 4:00 PM - 4:10 PMLocaon: Ballroom BCAbstract: Accreonal temperature profiles for Titan are used to determine the condions needed to avoid global melng as a funcon of the ming, duraon,and nebular condions of its formaon. Titan can accrete undifferenated in a gas-starved disk (Canup & Ward 2002, 2006, 2009) even with modest quanes ofammonia mixed in with its ices (Barr et al., 2010). The metable required for formaon of an undifferenated Callisto (Barr & Canup 2008) is consistent withlimited melng in Titan during formaon.Simulaons of impact-induced core formaon (Barr & Canup 2010) are used to show that Titan can remain in a parally differenated state aer an outer solarsystem late heavy bombardment (LHB), capable of melng its outer layers, perming some of its rock to consolidate into a core. Thus, we describe a scenario forthe formaon and early evoluon of Titan consistent with its relavely high moment of inera (Iess et al., 2010). We will also discuss implicaons of the post-LHB heterogeneous density structure within Titan for interpretaon of the moment of inera coefficient.61.05: Rotaonal Dynamics and Internal Structure of TitanAuthor Block: Bruce Bills 1 , F. Nimmo 21 Jet Propulsion Laboratory, 2 University of California.Presentaon Time: 10/8/2010 4:10 PM - 4:20 PMLocaon: Ballroom BC

Abstract.Abstract: The gravitaonal field of Titan is close to that expected for a body in hydrostac equilibrium, and the spin pole orientaon is close to thatexpected for a fully damped precessional moon, or Cassini state. However, the moments of inera implied by these observaons are quite different. Thisdiscrepancy can be resolved if Titan is not precessing as a rigid body, or if the spin pole is not fully damped. Connued monitoring of the spin pole orientaon, viaCassini radar images, will eventually resolve which effect, or what combinaon of them, is responsible.61.06: Titan's Cold Accreon and its Internal StructureAuthor Block: Paul R. Estrada 1 , I. Mosqueira 11 Carl Sagan Center, SETI Instute.Presentaon Time: 10/8/2010 4:20 PM - 4:30 PMLocaon: Ballroom BCAbstract.Abstract: Recent Cassini radio tracking data has provided a normalized moment of inera for Titan of 0.34 (Iess et al. 2010). Given that the quadrupolefield is consistent with hydrostac equilibrium, a two-layer interior model implies incomplete differenaon with a ~700 km water-ice shell and anundifferenated ice and rock-metal interior. We invesgate the accreonal history of Titan in connecon with its internal structure. Our formaon model allowsfor a size distribuon of impactors with upper size cut-off constrained by Hyperion's size and a variable power-law exponent (Mosqueira et al. 2010). The burial ofimpact energy takes place in a lengthscale of order of the impactor radius, as indicated by numerical simulaons (e.g., Pierazzo et al. 1997) applied to our energyregime of interest. Our thermal model includes radiogenic heang due to short and long-lived radionuclides, latent heat of melng, gravitaonal energy releasedue to sinking rock, heat of accreon and radiave cooling. We find that melng in the interior takes place well before the satellite reaches its final size. As aresult, we expect the formaon of an ocean overlying a silicate carapace, which may spend a considerable amount of me in contact with the liquid layer. Such aframework not only facilitates the transport of heat from the interior, but also can help both in leaching Ar40 into the ocean and then releasing into theatmosphere. We consider a range of parameters such as the degree of hydraon of the rock component, the fracon of the impact energy that is deposited at thesurface of the satellite, and accreon mes. But we do not yet consider the effects of small admixtures of contaminants. We argue that models that form Titan ina cold environment may have allowed for the interior to remain cold enough as to preclude complete differenaon.61.07: Is Titan like Ganymede or like Callisto?Author Block: Ignacio Mosqueira 1 , P. R. Estrada 11 SETI Instute.Presentaon Time: 10/8/2010 4:30 PM - 4:40 PMLocaon: Ballroom BCAbstract: The Galileo mission to Jupiter yielded the normalized moment of inera of Ganymede (0.312) and Callisto (0.355), while the Cassini spacecra hasmeasured Titan's moment of inera (0.34; Iess et al. 2010). Callisto's moment of inera can be fied using a two-layer interior model with at least a ~300 kmwater-ice shell and an undifferenated ice and rock-metal interior (Schubert et al. 2004), whereas Titan's moment of inera is consistent with a thicker ~700 kmwater-ice shell, and Ganymede's moment of inera implies full differenaon. Key satellite formaon parameters that can explain this trend are the accreonmescale and the subnebula temperature at the locaon of the proto-satellite. Mosqueira and Estrada (2003a,b) invesgate a non-local model that formsGanymede in ~10 4 yrs, Titan in ~10 5 yrs and Callisto in ~10 6 yrs. Satellites located in the outer disk take longer to accrete because they derive solids from anextended, lower density region of the subnebula; indeed in this model the mescale of accreon is set by inward gas-drag dri me of (Hyperion-like) ~100 kmsatellitesimals. Since satellitesimals originate from exterior orbits, the temperature of the subnebula at the locaon of Ganymede ~ 250 K, Callisto ~150 K, andTitan ~100 K (Mosqueira and Estrada 2003a) provides a rough constraint on the interior temperature of each satellite (aer correcon for the effects ofcompression and radioacve heang) as well as the background radiaon temperature during satellite accreon. We argue that these parameters provide anatural explanaon for the observed moment of inera trend; we expect that the interior of Titan and Callisto remain too cold for full differenaon to take place(unless Titan's interior were fully differenated with a hydrated rocky core). This work is supported by NASA PG&G and OPR grants.61.08: Tholins in the Upper Atmosphere of TitanAuthor Block: Yuk Yung 1 , X. Zhang 1 , M. Liang 2 , D. E. Shemansky 31 Caltech, 2 Academia Sinica, Taiwan, 3 Space Environment Technologies.Presentaon Time: 10/8/2010 4:40 PM - 4:50 PMLocaon: Ballroom BCAbstract.Abstract: The Ultraviolet Imaging Spectrograph Subsystem (UVIS) onboard the Cassini spacecra is the only experiment with capability of measuringthe tholin distribuon from 1000 km altude to 300 km along with the high order hydrocarbons. It is clear that tholins form at high altude in the ionosphere, andprecipitate downward, resulng in the manifestaon of a large scale-height, completely different from a diffusively separated atmosphere (Liang et al. 2007).Preliminary analysis of Cassini T0 and TA encounters shows that producon of aerosols is severely depleted in the polar region where solar scaering cannot bedetected above 675 km, while in the sub-solar atmosphere aerosol scaering is measured to 1425 km altude. In addion to exncon, there is valuablecomplementary informaon to be extracted from an analysis of the UV light scaered by tholins. The opcal properes of tholins are studied using a mul-spheremethod, and the results are used in a radiave code to simulate the UVIS observaons.61.09: Possible Niches For Extant Life On Titan In Light Of The First Six Years Of Cassini/Huygens ResultsAuthor Block: David H. Grinspoon 1 , D. Schulze-Makuch 21 Denver Museum Of Nature & Science, 2 Washington State University.Presentaon Time: 10/8/2010 4:50 PM - 5:00 PMLocaon: Ballroom BCAbstract: At the 2005 DPS meeng we presented an assessment of the possibility of extant life on Titan aer the first year of the Cassini mission at Saturn. Wesuggested then that hydrogenaon of photochemically produced acetylene could provide metabolic energy for near-surface organisms and also replenishatmospheric methane (Schulze-Makuch and Grinspoon, 2005). In this talk we will offer a brief reassessment of the possibility of extant life in light of five moreyears of the Cassini/Huygens results, including the recent reports suggesng a lack of acetylene on the surface (Clark et al., 2010) and a possible sink of H2 atthe surface (Strobel, 2010). Both results are consistent with earlier predicons for the existence of an acetylene-powered biosphere on Titan (Schulze-Makuchand Grinspoon, 2005; McKay and Smith, 2005), but can potenally be explained by more prosaic phenomena.D. Schulze-Makuch and D. H. Grinspoon(2005), Biologically Enhanced Energy and Carbon Cycling on Titan? Astrobiology 5, 560-567; Clarke, R.N. et al. (2020),Detecon and Mapping of Hydrocarbon Deposits on Titan, JGR-Planets; Strobel, D.F(2010) Molecular hydrogen in Titan’s atmosphere: Implicaons of themeasured tropospheric and thermospheric mole fracons. Icarus; McKay, C.P., Smith, H.D.( 2005) Possibilies for methanogenic life in liquid methane on thesurface of Titan. Icarus 178, 274-276.

Session Number: 62Session Title: Extrasolar Planets and Systems IIISession Type: Oral62.01: Planet Masses And Radii - Theory Versus TransitsAuthor Block: Gunther Wuchterl 11 Thüringer Landessternwarte, Germany.Presentaon Time: 10/8/2010 3:30 PM - 3:40 PMLocaon: Ballroom DAbstract: Masses and radii are the primary observables to characterise exoplanets today. A self-consistent theorecal approach is presented that allows tocalculate mass- and radii-distribuons of exoplanet populaons from basic physical principles and avoids the usual parametrisaon of a multude of processes.The theorecal strategy has two steps:1) Calculate all planetary equilibria that sasfy hydrostac and thermal equilibria with planetesimal accreon as energy source in arbitrary but gravitaonallystable protoplanetary nebulae and;2) Calculate the quasi-hydrostac evoluon of the ensemble of planets found in step one, to the ages that are relevant for observaons.The resulng theorecal distribuons of planetary masses and radii are presented for stars of 0.4-2 M Sun and orbital periods from 1-128 days.(1) Mass distribuons are bi-modal with peaks near Jupiter's and Neptune's mass; the later usually containing more planets. The locaon of the peaks dependson host star mass and orbital radius.(2) The bi-modality of the mass-distribuons is enhanced in the radii-distribuons by the planetary evoluon from the formaon era into the present.(3) We discuss whether the observed planetary radii can be explained without the assumpon of extra, non-standard energy sources.(4) A wide gap is found in the distribuon of the transit signals between those of Pegasi-planets (Hot Jupiters) and the next populaon towards smaller radii: theHot Neptunes and Super-Earths.A comparison with CoRoT, Kepler and ground-based results gives a first hint that the approach is useful to understand the observed planets and provides aconcept for a basic-physics explanaon of planetary mass.The approach does not a-priori assume a core and whether planets migrate or not and thus provides a general framework to discuss planet formaon. It doesallow to test the respecve hypothesis of core-instability and a possible dominang role of orbital migraon by comparison with observaons.62.02: Hints of Period Change for OGLE-TR-113bAuthor Block: Elisabeth R. Adams 1 , M. Lopez-Morales 2 , J. L. Elliot 1 , S. Seager 1 , D. J. Osip 31 M IT, 2 CIW-DTM, 3 OCIW-LCO.Presentaon Time: 10/8/2010 3:40 PM - 3:50 PMLocaon: Ballroom DAbstract: We present six new transits of the hot Jupiter OGLE-TR-113b observed with MagIC on the Magellan Telescopes between January 2007 and May 2009.We update the system parameters and revise the planetary radius, where the error is dominated by stellar radius uncertaines. The new transit midmes revealno transit ming variaons from a constant ephemeris over two years, which places an upper limit of 1-2 Earth masses on any perturber in a 1:2 or 2:1 meanmoonresonance with OGLE-TR-113b. Combining the new transit epochs with five epochs published between 2002 and 2006, we find hints that the orbital periodof the planet may not be constant, with the best fit indicang the period is decreasing by 60±15 milliseconds per year. If real, this change in period could resultfrom either a long-period (more than 8 years) ming variaon due to an external perturber, or more intriguingly from the orbital decay of the planet. The deteconof a changing period is sll tentave and must be checked with addional observaons. If a period decay is confirmed, OGLE-TR-113b will be the first planetobserved to be falling onto its star. This would enable direct tests of dal stability and dynamical models of close-in planets and place observaonal constraintson the value of stellar dal energy dissipaon factors.This work was supported in part by NASA Origins grant NNX07AN63G and Hubble Fellowship grant HF-01210.01-A/HF-51233.01 awarded by the STScI, which isoperated by the AURA, Inc. for NASA, under contract NAS5-26555.62.03: Gliese 581d Habitable with a CO2-rich atmosphere: Results from Numerical Climate Simulaons.Author Block: Robin Wordsworth 1 , F. Forget 1 , F. Selsis 2 , J. B. Madeleine 1 , E. Millour 1 , V. Eymet 31 LM D, IPSL, France, 2 LAB, France, 3 LAPLACE, France.Presentaon Time: 10/8/2010 3:50 PM - 4:00 PMLocaon: Ballroom DAbstract.Abstract: The exoplanet Gl581d (discovered in 2007) is relavely low mass and near to the outer edge of its system's habitable zone, which has led tomuch speculaon on its possible climate. To help understand the possible condions on this planet, we have developed a new universal 3D global climate model(GCM). It is derived from the LMD GCMs already used to simulate the Earth, Mars and other terrestrial atmospheres in the solar system, and hence has alreadybeen validated over a wide range of physical condions. We have performed a range of simulaons to assess whether, given simple combinaons of chemicallystable gases (CO2, H2O and N2), Gl581d could sustain liquid water on its surface. Compared to a Sun-like star, the red dwarf Gliese 581 allows higher planetarytemperatures, because Rayleigh scaering is reduced. Taking into account the scaering greenhouse effect of both CO2 and H2O clouds, we find that severaltens of bars of CO2 are sufficient to maintain global mean temperatures above the melng point of water. As Gl581d is probably in a dally resonant orbit,condensables such as water and CO2 may be trapped on its dark sides or poles. However, we find that even with conservave assumpons, redistribuon of heatby the atmosphere is enough to allow stable condions with surface liquid water. A dense atmosphere of this kind is quite possible for such a large planet, andcould be disnguished from other cases using future observaons.62.04: Constraining The Composion Of Super-Earths: The Case Of GJ1214bAuthor Block: Nadine Neelmann 1 , J. J. Fortney 11 University of California, Santa Cruz.Presentaon Time: 10/8/2010 4:00 PM - 4:10 PMLocaon: Ballroom DAbstract: The genuine super-Earth planet GJ1214b (6.55 Earth masses, 2.68 Earth radii, 555 K equilibrium temperature) orbits a 3-10 Gyrs old M-star. Bycoupling model atmospheres to interior structure models, we compute the first thermal evoluon models of this planet assuming homogeneous envelopescomposed of H/He, H2O, or H/He/H2O atop a rock core.We find that consistency with its age excludes pure water models, narrows the overall H/He mass fracon of dry envelope models to 1-2%, and that of water-richenvelope models to below 6%.Unlike CoRot-7b, even in case of intense stellar XUV irradiaon the mass loss over me experienced by GJ1214b accumulates to less than 0.12 Earth masses,

leaving it a genuine super-Earth. Unlike Neptune or Ganymede, water at GJ1214b deep interior condions will persist in a fluid or plasma state and thereforepreferrenally be mixed into a H/He envelope ready for detecon.62.05: The Atmosphere of WASP-14b Revealed by Three Spitzer EclipsesAuthor Block: Jasmina Blecic 1 , J. Harrington 1 , K. B. Stevenson 1 , N. Madhusudhan 2 , R. A. Hardy 1 , C. J. Campo 1 , W. C. Bowman 1 , S. Nymeyer 1 , P. Cubbillos 1 , WASPconsorum1 University of Central Florida, 2 M IT Kavli Instute for Astrophysics and Space Research, and Department of Earth, Atmospheric, and Planetary Sciences, M IT.Presentaon Time: 10/8/2010 4:10 PM - 4:20 PMLocaon: Ballroom DAbstract: WASP-14b is a hot Jupiter planet (Y. C. Joshy et al. 2009, MNRAS 392, 1532-1538) with mass (7.3 Jupiter masses) and density (4.6 g/cm3) that exceedthose of most known extrasolar planets. It is very close to its host star (semimajor axis = 0.036 AU), giving it a typical equilibrium temperature of ~1800 K for 0albedo, circular orbit, and uniform reemission. In addion, its significant orbital eccentricity (0.09) suggests the possibility of a companion planet. All of the abovemakes this object very interesng for atmospheric study.Spitzer program 60021 (H. Knutson, PI) obtained a secondary eclipse light curve at 3.6 microns on 2010-03-19 and the Spitzer Exoplanet Target of OpportunityProgram (program 50517, J. Harrington, PI) obtained eclipse data at 4.5 and 8.0 microns on 2009-03-18. Analyc light curve models fit the data using aMetropolis-Hasngs Markov Chain Monte Carlo (MCMC) algorithm that incorporates correcons for systemac effects. We present esmates of infraredbrightness temperatures and constraints on atmospheric composion and thermal structure.This work is based on observaons made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Instute of Technologyunder a contract with NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech.62.06: A Methane-Free GJ 436b?Author Block: Joseph Harrington 1 , K. B. Stevenson 1 , S. Nymeyer 1 , N. Madhusudhan 2 , S. Seager 2 , W. C. Bowman 1 , R. A. Hardy 1 , D. Deming 3 , E. Rauscher 4 , N. B.Lust 11 University of Central Florida, 2 M IT, 3 NASA's GSFC, 4 Columbia University.Presentaon Time: 10/8/2010 4:20 PM - 4:30 PMLocaon: Ballroom DAbstract: We observed (Stevenson et al. 2010, Nature 646, 1161-1164) six secondary eclipses of GJ 436b, a hot Neptune-sized planet orbing an M-dwarf star,with the Spitzer Space Telescope in six photometric channels (3.6, 4.5, 5.8, 8, 16, 24 µm). Eclipse depths were 0.041 ± 0.003,

Author Block: Nikku Madhusudhan 1 , UCF Exoplanet Team (Orlando, FL), WASP Consorum (UK)1 Massachuses Instute of Technology.Presentaon Time: 10/8/2010 4:50 PM - 5:00 PMLocaon: Ballroom DAbstract.Abstract: We present a comparave analysis of atmospheric chemical abundances of several transing extrasolar planets, as inferred fromobservaons with HST, Spitzer, and ground-based facilies. We used a bayesian exoplanet atmosphere retrieval method to determine stascal limits on thechemical composions as required by the data. Our method facilitates calculang error contours in the space of chemical composion, the 1-D averagedtemperature structure, and the day-night energy redistribuon in the planetary atmosphere, given photometric and/or spectroscopic observaons. The stascaltreatment involves large-scale computaon of millions of 1D atmospheric models spanning the large model parameter space. We report constraints on theelemental and molecular abundances of transing exoplanets over a wide range in atmospheric properes, with temperatures ranging from 750 K to over 3000 K,and sizes ranging from hot Neptunes to the largest of hot-Jupiters. We present limits on equilibrium and non-equilibrium chemistry imposed by the observedatmospheric chemical composions. We show that some of the systems in our sample, including GJ 436b, show disnct deviaons from atmospheric chemistrybased on thermochemical equilibrium and solar abundances, and have important consequences for planetary formaon and evoluon. On the other hand, someobservaons are much less constraining and can be explained by equilibrium chemistry with solar abundances, for a wide range of temperature structures. Wediscuss future observaons that might be able to constrain the laer systems. Spitzer is operated by the Jet Propulsion Laboratory, California Instute ofTechnology, under a contract with NASA, which provided support for this work.

Session Number: 63Session Title: Asteroids: DynamicsSession Type: Oral63.01: The Fine-Scale Resonant Structure of the Asteroid BeltAuthor Block: Stanley F. Dermo 1 , T. J. J. Kehoe 11 Univ. of Florida.Presentaon Time: 10/8/2010 3:30 PM - 3:40 PMLocaon: Ballroom EAbstract.Abstract: We show that, in contrast to the broad-scale structure of the distribuon of asteroidal orbital frequencies that is associated with gaps,known as the Kirkwood gaps, the fine-scale structure is characterized by peaks associated with asteroids trapped in mean moon resonances. It has already beenshown that overlapping jovian resonances determine the structure of the outer belt, here we show that overlapping maran resonances determine the structureof the inner belt. Drag forces due to radiaon forces on the asteroids trapped in resonance will have resulted in small asteroids being removed from the asteroidbelt selecvely, as determined by a range of asteroidal physical properes. To understand the structure of the present belt, and its larger precursor, we need tounderstand the nature and extent of these physical selecon effects. Even if these selecon effects were small, if the present asteroid populaon is a smallremnant of the original populaon, then small but persistent selecon effects acng over the age of the solar system would have shaped the characteriscs ofthe remnant populaon. In this respect, stascs on the rotaonal characteriscs of asteroids may be of interest. There is evidence that an excess of small, slowrotators have been removed from the main belt. There also seems to be a deficiency of asteroids in the main belt with high obliquity and there are more prograderotators than retrograde rotators in the NEA populaon. We suggest that these features may be accounted for by the combined effects of Yarkovsky forces andgravitaonal resonances resulng in the selecve removal of asteroids from the main belt.63.02: Unveiling The Excess Of Slow Rotators In The Small Main Belt AsteroidsAuthor Block: Alessandro Rossi 1 , F. Marzari 2 , D. J. Scheeres 31 ISTI - CNR, Italy, 2 Universita' di Padova, Italy, 3 University of Colorado.Presentaon Time: 10/8/2010 3:40 PM - 3:50 PMLocaon: Ballroom EAbstract.Abstract: The Small Main Belt Asteroids populaon displays a significant excess of slow rotators. With a sophiscated Monte Carlo model, consideringthe effects of YORP and collisions, we have been able to reproduce the slow rotators excess without introducing any ad-hoc latency me in the large rotaonperiod states. A deeper analysis of these results shows how this excess is due to a non-linear interacon between the YORP effect and the collisions. Nosignificant excess can be found by simulang the two effects alone. On the other hand, with the effects acng at the same me, whenever the rotaon rate of anobject is slowed down by YORP, the amount of angular momentum change imparted by the collisions against larger projecle becomes comparable to the totalangular momentum of the body. This keeps the asteroid "lingering" in a slow rotaon state for a comparavely large me, leading to the observed excess. Thiseffect happens mainly for the larger objects in our sample (around 5 km of diameters). For smaller objects the YORP cycles are so short and the perturbaoninduced by collision so frequent and comparavely large, that the body is rapidly jumping from the two extreme states of slow and fast rotaon and noaccumulaon is observed. Further invesgaons are ongoing and will be reported at the meeng.63.03: Numerical Simulaons Of Catastrophic Disrupon Of Porous Bodies: Applicaon To Dark-type Asteroids And Kuiper-belt Family FormaonAuthor Block: Patrick Michel 1 , M. Jutzi 2 , D. C. Richardson 3 , W. Benz 41 University of Nice-Sophia Anpolis/CNRS/Obs. de La Cote D'Azur, France, 2 University of California, 3 University of Maryland, 4 University of Bern, Switzerland.Presentaon Time: 10/8/2010 3:50 PM - 4:00 PMLocaon: Ballroom EAbstract: Asteroids of dark (e.g. C, D) taxonomic classes as well as Kuiper Belt objects and comets are believed to have high porosity, not only in the form oflarge voids but also in the form of micro-pores. The presence of such microscale porosity introduces addional physics in the impact process. We have enhancedour 3D SPH hydrocode, used to simulate catastrophic breakups, with a model of porosity [1] and validated it at small scale by comparison with impactexperiments on pumice targets [2]. Our model is now ready to be applied to a large range of problems. In parcular, accounng for the gravitaonal phase of animpact, we can study the formaon of dark-type asteroid families, such as Veritas, and Kuiper-Belt families, such as Haumea.Recently we characterized for the first me the catastrophic impact energy threshold, usually called Q*D, as a funcon of the target’s diameter, porosity, materialstrength and impact speed [3]. Regarding the menoned families, our preliminary results show that accounng for porosity leads to different outcomes that maybeer represent their properes and constrain their definion. In parcular, for Veritas, we find that its membership may need some revision [4]. The parameterspace is sll large, many interesng families need to be invesgated and our model will be applied to a large range of cases.PM, MJ and DCR acknowledge financial support from the French Programme Naonal de Planétologie, NASA PG&G ”Small Bodies and Planetary Collisions" andNASA under Grant No. NNX08AM39G issued through the Office of Space Science, respecvely.[1] Jutzi et al. 2008. Icarus 198, 242-255; [2] Jutzi et al. 2009. Icarus 201, 802-813; [3] Jutzi et al. 2010. Fragment properes at the catastrophic disruponthreshold: The effect of the parent body's internal structure, Icarus 207, 54-65; [4] Michel et al. 2010. Icarus, submied.63.04: Asteroid Shapes Are Always Close To Fluid EquilibriumAuthor Block: Paolo Tanga 1 , C. Comito 1 , D. Hestroffer 2 , D. C. Richardson 31 Observatoire de la Cote d'Azur, France, 2 Instut de Mecanique Celeste et Calcul des Ephemerides, France, 3 University of Maryland.Presentaon Time: 10/8/2010 4:00 PM - 4:10 PMLocaon: Ballroom EAbstract: The simple evidence that asteroid are composed by solid rocks suggests that their shape can be rather far from the theorecal equilibrium forrotang fluid bodies. The possible fragmented ("rubble-pile") nature of most of them has suggested interpretaons based on elasto-plasc models (such as theMohr-Coulomb theory) that take into account the stac behavior of a granular structure. However, these approaches did not incorporate explicitly the possibleevoluon of shapes in me due to external factors such as crater forming impacts or dal deformaons.We revisited the theory of equilibrium shapes for fluids, quantavely evaluang - by appropriate metrics - the distance of the observed shapes from fluidequilibrium. This distance turns out to be much smaller than previously expected.On the basis of this evidence, we simulated numerically the evoluon of gravitaonal aggregates having a small degree of internal fricon, consistent with thetheorecal findings. Our results offer a global scenario for the evoluon of asteroid shapes under the acon of gradual stresses due to minor impacts, dal forcesand seismic shaking.We show that actual asteroid shapes are consistent with the evoluon of aggregates tending towards minimum free energy states.We are able to explain the samples of observed shapes obtained by different techniques. Our findings strongly support a highly porous and fragmented nature for

most asteroids, at least in an external layer.Reference: Tanga et al. 2009: ApJ Leers, 706, 1, L197-L202Acknowledgments: PT and CC have been supported by the "Programme Naonale de Planetologie" of France; DCR acknowledges support by the NASA (grant no.NNX08AM39G issued through the Office of Space Science) and by the NSF (grant no. AST0708110).63.05: DEM Simulaon of Rotaonal Disrupon of Rubble-Pile AsteroidsAuthor Block: Paul Sanchez 1 , D. J. Scheeres 11 University of Colorado.Presentaon Time: 10/8/2010 4:10 PM - 4:20 PMLocaon: Ballroom EAbstract: We report on our study of rotaon induced disrupon of a self-gravitang granular aggregate by using a Discrete Element Method (DEM) granulardynamics code, a class of simulaon commonly used in the granular mechanics community. Specifically, we simulate the behavior of a computer simulatedasteroid when subjected to an array of rotaon rates that cross its disrupon limit. The code used to carry out these studies implements a So-sphere DEMmethod as applied for granular systems. In addion a novel algorithm to calculate self-gravitang forces which makes use of the DEM stac grid has beendeveloped and implemented in the code. By using a DEM code, it is possible to model a poly-disperse aggregate with a specified size distribuon power law,incorporate contact forces such as dry cohesion and fricon, and compute internal stresses within the gravitaonal aggregate. This approach to the modeling ofgravitaonal aggregates is complementary to and disnctly different than other approaches reported in the literature.The simulaons use both 2D and 3D modeling for analysis. One aim of this work is to understand the basic processes and dynamics of aggregates during thedisrupon process. We have used these simulaons to understand how to form a contact binary that mimics observed asteroid shapes, how to accelerate therotaon rate of the aggregate so that it has enough me to reshape and find a stable configuraon and how to analyze a system that has an occasionallychanging shape. From a more physical point of view, we have focused on the understanding of the dynamics of the reshaping process, the evoluon of internalstresses during this reshaping and finding the crical disrupon angular velocity.This research was supported by a grant from NASA's PG&G Program: NNX10AJ66G63.06: Measuring the Binary YORP Effect and the Influence of Libraons on Binary Asteroid EvoluonAuthor Block: Jay McMahon 1 , D. Scheeres 11 University of Colorado.Presentaon Time: 10/8/2010 4:20 PM - 4:30 PMLocaon: Ballroom EAbstract: Binary YORP (BYORP) has been hypothesized to be a main driver for the evoluon of binary asteroid systems. One queson that impacts how longBYORP can secularly change a binary system is the interacon of the librang secondary body. The well observed binary system 1999 KW4 is known to have alibraonal pitch moon, however the libraon amplitude is expected to be quite small (Ostro et al.; Scheeres et al., Science, v314). Feedback between thedynamics of the mutual orbit and atude dynamics of the secondary show that if the secondary exhibits large libraons and the mutual orbit becomes eccentric,the secondary will enter a state of chaoc rotaon (Cuk and Nesvorny, Icarus, June 2010), a condion that would stop the secular evoluon of the orbit. Wepredict that the measured libraon in 1999 KW4's secondary is insufficient to lead to such chaoc evoluon, and present analysis that supports this conclusion.BYORP remains to be verified, thus a crucial next step is to observe the effect in real systems. BYORP causes a binary orbit to either grow or shrink, which resultsin a quadrac dri in mean longitude compared to a Keplerian orbit. According to our theory, we expect that the mean longitude of 1999 KW4 is currently driingat -3.7 degrees/year 2 . To detect this dri, a minimum of three occultaon/eclipse observaons of the system over a sufficiently long period of me are needed. Inthe case of 1999 KW4, a baseline of approximately 10 years between first and last measurements should allow accurate detecon of the BYORP effect. A numberof binary asteroid targets meet these requirements and may allow the BYORP effect to be detected within the next decade (see Pravec and Scheirich, 2010 DPSAbstract).This work is supported by NASA’s PGG program through grant NNX08AL51G.63.07: Dynamics of Rotaonally Fissioned AsteroidsAuthor Block: Seth A. Jacobson 1 , D. J. Scheeres 11 University of Colorado at Boulder.Presentaon Time: 10/8/2010 4:30 PM - 4:40 PMLocaon: Ballroom EAbstract: We present a model for near-Earth asteroid (NEA) rotaonal fission that results in the evoluon of all observed types of NEA systems: synchronousbinaries, asteroid pairs, doubly synchronous binaries, high-e binaries, ternary systems, and contact binaries. The model consists of “rubble pile” asteroidgeophysics, the YORP and binary YORP effects, and mutual gravitaonal interacons. An NEA can be modeled as a ``rubble pile"--a collecon of gravitaonallybound boulders with a distribuon of size scales and very lile tensile strength between them. The YORP effect torques a “rubble pile” asteroid unl the asteroidreaches its disrupon spin limit, and then two collecons of boulders will enter into orbit about each other determined by the largest distance between masscenters. This binary system dynamically evolves under the effects of non-spherical gravitaonal potenals, solar gravitaonal perturbaons, and mutual bodydes. The coupling between the spin states and orbit state chaocally drives the system into the observed asteroid classes with mass rao, q, disnguishing twoevoluonary tracks. High mass rao systems, q>0.2, evolve dally into doubly synchronous binaries and then connued to be evolved by BYORP. Low mass raosystems, q

contact should exceed their weight, implying that a collecon of such gravels should behave more like a cohesive powder (such as bread flour) than as aterrestrial gravel pile. Extending the theory to the self-gravitaon of two boulders in contact, such as in a rubble pile, predicts that mutual cohesive forcesdominate mutual gravitaon for component sizes less than a few meters. One implicaon of this is that higher rotaon rates are necessary to cause smallergrains to fission from an asteroid, while larger aggregates should be less affected and fission at lower rotaon rates, introducing a size-scale into an otherwisescale-invariant physical process. A simple model for this cohesive effect is presented and its implicaons for asteroid science are discussed.This research was supported in part by NASA's DDAP and PGG Programs via Grants NNG06GG22G and NNX08AL51G.63.09: Numerical Simulaons of Granular Dynamics: Method and TestsAuthor Block: Derek C. Richardson 1 , K. J. Walsh 2 , N. Murdoch 3 , P. Michel 2 , S. R. Schwartz 11 University of Maryland, 2 University of Nice-Sophia Anpolis/CNRS/Observatoire de la Côte d'Azur, France, 3 The Open University, PSSRI, United Kingdom andUniversity of Nice-Sophia Anpolis/CNRS/Observatoire de la Côte d'Azur, France.Presentaon Time: 10/8/2010 4:50 PM - 5:00 PMLocaon: Ballroom EAbstract: We present a new parcle-based numerical method for the simulaon of granular dynamics, with applicaon to moons of parcles (regolith) onsmall solar system bodies and planetary surfaces [1]. The method employs the parallel N-body tree code pkdgrav [2] to search for collisions and compute parcletrajectories. Parcle confinement is achieved by combining arbitrary combinaons of four provided wall primives, namely infinite plane, finite disk, infinitecylinder, and finite cylinder, and degenerate cases of these. Various wall movements, including translaon, oscillaon, and rotaon, are supported. Several testsof the method are presented, including a model granular “atmosphere” that achieves correct energy equiparon, and a series of tumbler simulaons thatcompare favorably with actual laboratory experiments [3]. DCR and SRS acknowledge NASA Grant No. NNX08AM39G and NSF Grant No. AST0524875; KJW, thePoincaré Fellowship at OCA; NM, Thales Alenia Space and The Open University; and PM and NM, the French Programme Naonal de Planétologie.References: [1] Richardson et al. (2010), Icarus, submied; [2] Cf. Richardson et al. (2009), P&SS 57, 183—192 and references therein; [3] Brucks et al. (2007),PRE 75, 032301-1-032301-4.