Scientific and Technical Aerospace Reports Volume 39 April 6, 2001

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scopic rheological properties (FOAM = Foam Optics and Mechanics). After all, a better understanding of drainage could lead to a means by which it may be circumvented. Author (revised) Foams; Drainage; Gas Transport; Liquid-Gas Mixtures 20010024933 Illinois Univ., Theoretical and Applied Mechanics, Urbana, IL USA Foam Evolution: Experiments and Simulations Aref, H., Illinois Univ., USA; Sullivan, J. M., Illinois Univ., USA; Thoroddsen, S. T., Illinois Univ., USA; Proceedings of the Fifth Microgravity Fluid Physics and Transport Phenomena Conference; December 2000, pp. 964-983; In English; See also 20010024890; No Copyright; Avail: CASI; A03, Hardcopy; A10, Microfiche We describe several areas of work on the fluid physics of foam evolution and flow, including experimental observations, mathematical models, and numerical simulations. We have made detailed observations of the topological reconnections that occur in an evolving foam, and propose a new model for the flow there. We describe the phase transition which can happen as a foam is expanded until it exerts negative pressure on its container. We are exploring new optical tomography techniques to observe an evolving foam and reconstruct the three-dimensional structure. We compare the evolution of a real foam with simulations in Brakke’s Evolver. We can also simulate infinite periodic foams, including new mathematical possibilities for tetrahedrally closepacked (TCP) structures. Author (revised) Fluid Dynamics; Foams; Phase Transformations; Chemical Evolution 20010024934 Yale Univ., Dept. of Chemical Engineering, New Haven, CT USA Linear Viscoelastic Response of a Concentrated Emulsion Loewenberg, M., Yale Univ., USA; Blawzdziewicz, J., Yale Univ., USA; Nemer, M., Yale Univ., USA; Proceedings of the Fifth Microgravity Fluid Physics and Transport Phenomena Conference; December 2000, pp. 984-986; In English; See also 20010024890; No Copyright; Abstract Only; Available from CASI only as part of the entire parent document Analytical results for the dynamics of thin inextensible films have been incorporated in theoretical models and simulations of the dynamics of two-dimensional systems. In three dimensions, the effective interparticle-potential model has been supplemented by simple bubble-bubble frictional dissipation. However,these models cannot describe the effect of detailed drop-scale dynamics on the evolution of the system. In general, the development of theories for the rheology of foams and emulsions will require a detailed understanding of the relevant drop-level dynamics. In this presentation, we describe a numerical investigation of the role of detailed drop-scale microphysics on the linear viscoelastic behavior of dense two-dimensional emulsions; Stokes equations are assumed and surfactant effects are neglected. We consider an ordered hexagonal lattice of drops for which the linear relation between stress and strain is isotropic. The system is thus characterized by a single frequency-dependent linear viscoelastic modulus. For dispersed-phase volume fraction phi beyond a critical value phi(sub c) = pi/2(sq rt 3), the drops are in a state of compression. For small-amplitude shape perturbations, delta-x, the response of the system of the system is linear d(delta-x)/dt = A delta-x, where the linearized velocity operator A is obtained by solving the Stokes equations with the boundary-integral method. by projecting the normal modes of A onto a step strain perturbation, the corresponding contribution to the shear stress is calculated. The relaxation times and amplitudes corresponding to the normal-mode decomposition are plotted for two subcritical values of phi. Only a few modes are significantly excited. The dominant mode corresponds to the largest relaxation time, which is associated with the lubrication resistance between closely spaced drops, and diverges as phi/phi(sub c) goes to 1. The relaxation times and amplitudes are plotted for two super-critical values of phi. In this regime, the response of the system is dominated by decay on capillary relaxation time scale; a long time scale is evident but with small amplitude. The average relaxation time tau (zeroth moment of relaxation spectrum), indicates that the average relaxation time diverges as phi goes to phi(sub c)(sup -). This behavior is associated with the lubrication singularity of the zero-frequency viscosity; according to a lubrication analysis, tau diverges as a simple pole at phi = phi(sub c). by contrast, tau is nonsingular for phi is greater than phi(sub c). Author (revised) Fluid Dynamics; Viscoelasticity; Thin Films; Drops (Liquids) 20010024935 Colorado Univ., Lab. of Atmospheric and Space Physics, Boulder, CO USA Dusty Plasma Dynamics Near Surfaces in Space Robertson, Scott, Colorado Univ., USA; Sickafoose, Amanda, Colorado Univ., USA; Colwell, Joshua, Colorado Univ., USA; Horanyi, Mihaly, Colorado Univ., USA; Proceedings of the Fifth Microgravity Fluid Physics and Transport Phenomena Conference; December 2000, pp. 987-1005; In English; See also 20010024890; No Copyright; Avail: CASI; A03, Hardcopy; A10, Microfiche 90
Illumination of a space-borne objects by solar ultraviolet light produces photoelectrons which form a layer, or sheath, near its surface. Typical sheath dimensions are tens of centimeters to one meter at distances of one AU. A vertical electric field, having a sign that returns electrons to the surface, is generated by the emission of photoelectrons into this sheath. Differential charging in a photoelectron layer over small spatial scales, such as along the terminator on a rough surface, leads to horizontal electric fields in addition to the vertical field. Dust grains on a planetary surface can enter the photoelectron layer by levitation or as a result of external disturbances. Levitation can occur when grains in the regolith become electrostatically charged such that the Lorentz force overcomes gravity and adhesive forces. Particles ejected from the surface by external disturbances, such as micrometeorite impacts or human/spacecraft activity, can become charged by photoemission and electron collection when immersed in a plasma. Therefore, particles levitated or ejected from the surface can be trapped in the photoelectron sheath and transported vertically and horizontally above the surface by the electric fields. Dust grains suspended above the lunar surface have been observed on multiple ocCASIons. A horizon glow tens of centimeters above the surface of the Moon was detected by Surveyors 5, 6, and 7. At spacecraft sunrise, Apollo astronauts observed high altitude streaks due to light scattered off particles extending from the lunar surface to above the spacecraft. More recently, a horizon glow 10 to 20 km above the lunar surface was detected by the Clementine spacecraft. Furthermore, the Lunar Ejecta and Meteorite Experiment (LEAM) deployed by Apollo 17 detected evidence for horizontal dust transport on the surface of the Moon at terminator crossings. Dust transport is also important in planetary ring systems, as confirmed by Voyager’s discovery of spokes in Saturn’s B-ring in 1981. These features are most likely clouds of particles electrostatically levitated off the surfaces of larger bodies in the ring and into a plasma cloud created by meteoritic impacts. Many small, airless bodies in the solar system are coated with a dusty regolith; therefore, dust levitation and transport may occur on Mars, Mercury, planetary satellites, asteroids, comets, and even planetesimals. Understanding dust charging and dynamics is thus crucial to interpreting observations of planetary bodies. In addition, surface activity can agitate dust and inject particles into the photoelectron layer, possibly causing contamination of instruments on planetary surfaces. Therefore, the charging and dynamics of dust near planetary surfaces is a necessary component of future manned and unmanned exploration of the solar system. We have begun the investigation of dust charging and dynamics near surfaces in space by performing experiments in which dust grains are dropped through a beam of UV and dropped past a UV illuminated surface having a photoelectron sheath. The experiments are performed in vacuum, with illumination from a 1 kW Hg-Xe arc lamp having a spectrum extending to approximately 200 nm (approximately 6.2 eV). The photoemitter is a 12 cm diameter zirconium plate, which also acts as a Langmuir probe to verify the properties of the photoelectron sheath. We have examined photoelectric charging for particles 90-106 mm in diameter composed of zinc, copper, graphite, glass, SiC, lunar regolith simulant (JSC-1), and martian regolith simulant (JSC Mars-1). We find that the photoelectric charging properties of the metallic materials are consistent with charges calculated from the work function of the materials, the energy of incoming photons or photoelectrons, and the capacitance of the grains. Dust dropped through UV illumination loses electrons due to photoemission, while dust dropped past an illuminated surface gains electrons from the photoelectron sheath. The photoelectric charging properties of the non-conducting materials are difficult to interpret due to large amounts of triboelectric charging. However, the results suggest that the JSC Mars-1 is more susceptible to photoelectric charging than the JSC-1. In a second experiment, a flat surface is coated in dust (JSC-1 or JSC-Mars-1) and a photoelectron layer is generated above it. Plasma sheath characteristics are determined through Langmuir probe and floating potential probe sweeps. A window in the top of the chamber allows investigation of dust levitation and charging properties as a function of ultraviolet illumination. An agitator under the surface provides external disturbances to eject dust into the photoelectron layer. The charges of individual dust particles in the sheath can be measured by a Faraday cup, and tungsten filaments are used for ambient plasma production. The topography of the surface can be easily altered to simulate a terminator region, in order to create strong horizontal electric fields within the sheath. Dust levitation and transport in the sheath is observed by a CCD camera. These ground-based studies of dust dynamics near surfaces in space provide information on the transport of micron-sized particles. Particles of this size are in the transitional range between gravitational and electromagnetic control on a planetary surface. A microgravity environment will allow continuation of the experiments to smaller particle sizes. In microgravity, the ratio of electrostatic forces to gravitational forces is high, so the environment will also be more like that of small, dusty planetary bodies. Thus, this research provides a set of experimental techniques upon which subsequent microgravity experiments will be based. Author (revised) Dust; Levitation; Photoelectrons; Sheaths 20010024936 Boston Univ., Dept. of Aerospace and Mechanical Engineering, Boston, MA USA Rheology of Foam Near the Order-Disorder Phase Transition Holt, R. Glynn, Boston Univ., USA; McDaniel, J. Gregory, Boston Univ., USA; Proceedings of the Fifth Microgravity Fluid Physics and Transport Phenomena Conference; December 2000, pp. 1006-1027; In English; See also 20010024890; No Copyright; Avail: CASI; A03, Hardcopy; A10, Microfiche 91
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Scientific and Technical Aerospace
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Introduction Scientific and Technic
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Subject Divisions Table of Contents
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Subject Categories of the Division
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73 Nuclear Physics 263 Includes nuc
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Document Availability Information T
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Avail: NASA Public Document Rooms.
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Hardcopy & Microfiche Prices Code N
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ALABAMA AUBURN UNIV. AT MONTGOMERY
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03 AIR TRANSPORTATION AND SAFETY
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work of the JAA had established thi
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20010024868 Federal Aviation Admini
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20010023437 Defence Science and Tec
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The Models for Aeroelastic Validati
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20010025824 Pratt and Whitney Aircr
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20010023064 NASA Langley Research C
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17 SPACE COMMUNICATIONS, SPACECRAFT
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20010026207 NASA, Washington, DC US
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The objective of the proposed resea
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20010022640 Stanford Univ., Center
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ustion, showing that these can have
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20010026184 Oak Ridge National Lab.
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film. Subsequent electroless metal
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20010024029 Houston Univ., Dept. of
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equipment indicate a change in the
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interaction, the main gas products
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Contract(s)/Grant(s): W-7405-eng-48
Page 61 and 62: for detecting and measuring deviato
Page 63 and 64: work, additional significant effect
Page 65 and 66: 20010026182 Oak Ridge National Lab.
Page 67 and 68: 20010024162 Army Research Lab., Ade
Page 69 and 70: matching funds. MIRSL purchased an
Page 71 and 72: 20010023557 North Dakota State Univ
Page 73 and 74: 20010026217 Princeton Univ., NJ USA
Page 75 and 76: 20010024108 Center for Naval Analys
Page 77 and 78: 20010022631 Stanford Univ., Center
Page 79 and 80: undertaken to isolated it are descr
Page 81 and 82: 20010022648 Stanford Univ., Center
Page 83 and 84: non-buoyant axisymmetric jet issuin
Page 85 and 86: point. The other turbulent problem
Page 87 and 88: 20010024042 Houston Univ., Dept. of
Page 89 and 90: The research carried out in the Hea
Page 91 and 92: along the heater surface and depart
Page 93 and 94: cal transducers. Additionally, the
Page 95 and 96: tial for its successful commercial
Page 97 and 98: This project represents a combined
Page 99 and 100: 20010024910 Johns Hopkins Univ., De
Page 101 and 102: e caused by a non-uniform temperatu
Page 103 and 104: metric shear cell, employed upon th
Page 105 and 106: 20010024919 Alabama Univ., Huntsvil
Page 107 and 108: Newtonian fluids in the laboratory,
Page 109 and 110: Boussinesq convection where due to
Page 111: 20010024930 Creare, Inc., Hanover,
Page 115 and 116: The hydrodynamics near steadily mov
Page 117 and 118: to be done is the full coupled syst
Page 119 and 120: liquid crystal host. Since the ulti
Page 121 and 122: the inorganic synthesis using press
Page 123 and 124: when the buoyancy is removed, for e
Page 125 and 126: 20010024956 NASA Ames Research Cent
Page 127 and 128: 2.2-second drop tower at NASA Glenn
Page 129 and 130: we have examined the dynamical beha
Page 131 and 132: position of the interface. An oscil
Page 133 and 134: the first time, non-intrusive, high
Page 135 and 136: ’axial curvature pressure’. A t
Page 137 and 138: moons when disturbed by low velocit
Page 139 and 140: particle size was studied. In a den
Page 141 and 142: colliding drops. The viscous resist
Page 143 and 144: 20010024983 Notre Dame Univ., Physi
Page 145 and 146: 20010024986 TDA Research, Inc., Whe
Page 147 and 148: drop deposition, using Schiaffino a
Page 149 and 150: and extended to reduced gravity flo
Page 151 and 152: from an isolated bubble regime to a
Page 153 and 154: 20010025000 Case Western Reserve Un
Page 155 and 156: our experimental measurements and w
Page 157 and 158: sured using a hot film probe flush
Page 159 and 160: the stationary bubble entrains anot
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of the most attractive characterist
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apply either steady shear flow perp
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20010025024 NASA, Washington, DC US
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neously the gamma scattered method
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20010023125 Colorado Univ., Lab. fo
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Contract(s)/Grant(s): F19628-95-C-0
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ics Technology Letters; March 2000;
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The BOREAS RSS-1 team collected sur
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ically corrected; however, files of
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with wavelength bands specific to t
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20010022099 NASA Goddard Space Flig
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within the polygon). There are thre
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A03, Hardcopy; A01, Microfiche Cana
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storms in Africa and smoke plumes f
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Greenland, with the objective of qu
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The BOReal Ecosystem-Atmosphere Stu
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The BOREAS TGB-8 team collected dat
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Report No.(s): NASA/TM-2000-209891/
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The BOREAS TF-10 team collected tow
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cally Active Radiation (FPAR) absor
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tributing to the overall understand
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cal ’tour de force’ allows EPV
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20010023558 Texas Univ., Center for
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the atmospheric concentrations of m
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20010023278 Lembaga Penerbangan dan
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Atmospheric radiation in the infrar
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20010022976 Desert Research Inst.,
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The primary purpose of AASERT Grant
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with only small ice-covered areas r
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Task 2 - abstraction of Medical rec
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non-steroidal activators of the rec
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20010023796 Massachusetts Univ. Med
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20010024166 Chicago Univ., Chicago,
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20010025069 Cleveland Clinic Founda
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Prior to 1994, measurement of tumor
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20010025730 Illinois Univ., Broad o
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the processing for enhancement of s
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strides in detection, diagnosis, an
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20010025763 California Univ., Lawre
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The ability to detect carcinoma cel
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ations found in clinical and geneti
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20010021850 Michigan Univ., Dept. o
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20010021985 National Inst. of Healt
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20010023264 Department of Health an
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on the BBB in rats, researchers not
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navigation method shows an advantag
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ange, and for some combinations of
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consider two specific issues in app
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planning with the Remote Agent expe
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training courses for the CAD tools.
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In this report, we consider the pro
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of the neural network and hence, th
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65 STATISTICS AND PROBABILITY �
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from the Lagrangian of the system.
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The average U-235 neutron total cro
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20010026201 Sandia National Labs.,
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to be 8.5-10.5 degrees which concur
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77 PHYSICS OF ELEMENTARY PARTICLES
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20010026247 Abdus Salam Internation
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Board (Access Board) under the auth
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currently underway or planned durin
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transfer function that would cover
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90 ASTROPHYSICS ��
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strates that as the gyroradius incr
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20010023043 Jet Propulsion Lab., Ca
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climatic variations. This can only
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try), allowing the same samples, in
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This work will describe the Thermal
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20010023068 Tennessee Univ., Dept.
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is crucial to the successful landin
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flat-plate Michelson interferometer
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general public is definitely intere
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exploration, examine specific optio
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tions of water. Often, due to lower
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With the exploration strategy for M
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necessary to ensure delivery of a s
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spectral studies to the field, and
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93 SPACE RADIATION ��
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ATMOSPHERIC RADIATION, 163, 205 ATM
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DEW POINT, 165 DIAGNOSIS, 217, 220,
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GRAVITATION, 54, 84, 88, 110, 111,
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MATRIX THEORY, 270 MEASURING INSTRU
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ST-10 Q QUALITY CONTROL, 11, 213 QU
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ST-12 T TARGET RECOGNITION, 265 TAS
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A Abdelguerfi, Mahdi, 252 Abramo, R
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Cledassou, R., 311 Clemmet, J., 306
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Gorelick, N., 294 Gorevan, S. P., 4
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Kupinski, Matthew A., 256 Kuznetz,
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Parks, C. H., 249 Parr, T. P., 38 P
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Swisdak, Michael M., Jr., 37 Szalew
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