NASA Scientific and Technical Aerospace Reports

composition with unprecedented wavelength coverage and spectral-spatial resolution. This instrument will also provide
temperature maps of the surface of Titan to look for hot spots where life may form. On the same mission there will be a descent
imager on the Aerorover (i.e., balloon) similar to that provided by LEISA on the Pluto mission to provide compositionaltopographical
maps of Titan s surface. Other future mission will also be discussed. Improved thermal detectors could have
important applications in solar physics, specifically in the detection of far-IR synchrotron emission from energetic electrons
in solar flares. For infrared astronomy we have missions like SIRTF and JWST, which will cover the spectral range from
near-IR to far-IR in the search and probing of both new and old planetary systems in our galaxy and the measurement of the
most distant galaxies of our universe. SIRTF is scheduled to be launched in August 2003, while JWST will be launched next
decade. Another mission is TPF, which will use interferometer techniques at infrared wavelengths to search for planetary
systems beyond 2010. With regard to ground based telescopes we have, for example, the twin 10 meter Keck telescopes and
the IRTF telescope at Mauna Kea. The Keck telescopes are presently using interferometer techniques. Over the next several
decades there are plans for 50 meter to 200 meter telescopes providing near-IR to far-IR measurements with the eventual plan
to combine all telescopes using interferometer techniques to provide unprecedented spectral-spatial resolution and sensitivity.
Author
Infrared Astronomy; Ground Based Control; Observation; Infrared Spectra; Infrared Radiation; Solar Flares
20040068396 NASA Ames Research Center, Moffett Field, CA, USA
Electrical Charging of Aerosols and Conductivity of Titan’s Atmosphere
Borucki, W. J.; Whitten, R. C.; Tripathi, S. N.; Bakes, E. L. O.; Barth, E.; February 03, 2004; 1 pp.; In English; European
Geosciences Union 1st General Assembly, 25-30 Apr. 2004, Nice, France
Contract(s)/Grant(s): UPN 853-15-01; No Copyright; Avail: Other Sources; Abstract Only
We have used recent data on graphitic cloud particles in the atmosphere of Titan to compute the electrical charging of the
particles (radii ranging from 0.01 microns to 0.26 microns). The charging on the nightside was rather similar to that obtained
earlier except that charge distributions on the particles are now computed and recently obtained cloud particle sizes and density
distributions were employed. The negative charge on particles of 0.26 microns peaked at 9 at 150 km altitude. The
computations were repeated for the dayside with the addition of photoelectron emission by the particles as a result of the
absorption of solar UV radiation. Particles (except the very smallest) now became positively charged with particles of radius
0.26 microns being charged up to +47. Next, very small particles (radii approx.3x10(sup -4) microns) of polycyclic aromatic
hydrocarbons (PAHs) were introduced and treated as sources of negative ions since they could be either neutral or carry one
negative charge. Moreover, they are mobile so that they had to be treated like molecular size negative ions although much
more massive. They had the effect of substantially reducing the electron densities in the altitude range 190 to 310 km to values
less than the negative PAH densities and increasing the peak electron charge on the larger particles. Particles of radius 0.26
microns bore peak charges of approx. +47 at altitudes of approx. 250 km. The simulated effect of PAHs on the nightside proved
to be much less pronounced; at the peak negative PAH density, it was less than the electron density. The physics governing
these results will be discussed.
Author
Titan; Satellite Atmospheres; Aerosols; Electrical Resistivity; Electric Charge
20040070782 Analex Corp., Brook Park, OH, USA
Solar Powered Flight on Venus
Colozza, Anthony; Landis, Geoff, Technical Monitor; April 2004; 34 pp.; In English
Contract(s)/Grant(s): NAS3-00145; WBS 755-81-01
Report No.(s): NASA/CR-2004-213052; E-14488; No Copyright; Avail: CASI; A03, Hardcopy
Solar powered flight within the Venus environment from the surface to the upper atmosphere was evaluated. The objective
was to see if a station-keeping mission was possible within this environment based on a solar power generating system. Due
to the slow rotation rate of Venus it would be possible to remain within the day light side of the planet for extended periods
of time. However the high wind speeds and thick cloud cover make a station-keeping solar powered mission challenging. The
environment of Venus was modeled as a function of altitude from the surface. This modeling included density, temperature,
solar attenuation and wind speed. Using this environmental model flight with both airships and aircraft was considered to
evaluate whether a station-keeping mission is feasible. The solar power system and flight characteristics of both types of
vehicles was modeled and power balance was set up to determine if the power available from the solar array was sufficient
to provide enough thrust to maintain station over a fixed ground location.
Author
Planetary Environments; Venus Atmosphere; Solar Powered Aircraft; Venus Surface; Stationkeeping
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