Planetary spectroscopy

by: Fink, U.

ABSTRACT

The main goal of the research is charge coupled device (CCD) spectroscopic
and imaging studies of the solar system in support of spacecraft investiga-
tions. Studies include the physical behavior of comets, the atmosphere of
the gaseous planets, and the solid surfaces of satellites and asteroids.
The major observing program consisted of approximately 50 nights of photo-
metry of Comet Halley in order to resolve the controversy over this comet's
rotation period. This data is presently being analyzed. Additional obser-
ving projects included the spectroscopic occultation of Charon by Pluto,
reflection spectroscopy of Mercury, and a spectrum of the satellite Oberon.
Mercury data does not corroborate the Fe() absorption feature reported by
McCord and Clark at 8800 A but instead potentially shows a weaker feature
at longer wavelengths. This position is in much closer accord with expec-
tations for Mercury since a band center near 8800 A implies too little
Fe() on Mercury, especially if band shifts with temperature are considered.
The Pluto project proved that the deep methane absorptions visible in
their combined specta are due soley to Pluto with Charon showing a flat
and featureless spectrum. It appears that if Charon ever contained a subs-
tantial methane component, the satellite's low surface gravity could not
hold it and the methane evaporated and escaped.

NASA, Washington, Reports of Planetary Astronomy, p 43-44, N89-16624 08-89,
1989