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D. A. Glenar (NASA Goddard Space Flight Center), R. E. Samuelson (University of Maryland), J. C. Pearl, G. L. Bjoraker (NASA Goddard Space Flight Center), D. L. Blaney (Jet Propulsion Laboratory)
We present an update of an on-going program of ground based, whole-disk Mars drift scan measurements using infrared grating spectrometers at KPNO (Cryogenic Spectrometer, CRSP) and the IRTF (SpeX), and spanning 1.9-4.0 microns wavelength. Data sets are reformatted into image cubes having two spatial and one spectral dimension, with moderately high spectral resolution (R = 700-2200) and corrected for telluric absorption. Ground based spectral imaging of Mars provides hemispherical and diurnal coverage, which is not achievable using sun-synchronous orbiting spacecraft, despite their other advantages. This makes such measurements well suited to studies of clouds and surface ice, both large scale and time-variable phenomena.
Seasonal coverage includes the 1999 aphelion season at Ls=130, and 2001 northern fall, just prior to (Ls=182) and during (Ls=195) the early season dust storm. Band strength maps of CO2 ice spectral features near 2 microns show the spatial distribution of ice grains near the south polar cap. The presence of narrow but fully resolved "forbidden" spectral features of CO2 ice near 2.3 microns indicate larger grain sizes and can be used to separate the surface ice component from CO2 clouds. Water ice at the north polar cap is observed and mapped using the spectral shape of the strong 3 micron band, also grain size dependent.
We discuss the process (and challenges) of data reduction, reformatting and the supporting modeling work now in progress.
This work is supported by the NASA Planetary Astronomy Program, RTOP 344-32-51-02.
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Bulletin of the American Astronomical Society, 34, #3< br> © 2002. The American Astronomical Soceity.