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J.F. Bell III, D. Dror (Cornell), B. Altieri (ESA), G. Lichtenberg (MPIA), D.P. Cruikshank, T.L. Roush, Y.J. Pendleton (NASA Ames)
We observed both Mars and Deimos with the ESA Infrared Space Observatory (ISO) during July and August 1997. Our observations were conducted using the infrared camera (CAM) and the short-wave spectrometer (SWS) instruments. The apparent angular diameter of the planet was small during this time (6.8\arcsec\ to 5.8\arcsec) and the phase angle was large (~0\circ), but this was the only time that ISO could observe Mars within the telescope's rather stringent pointing constraints.
CAM observations of Mars were conducted in the CAM04 CVF observing mode on 29 July and 12, 18, and 27 August 1997 UT. Each observation was separated by ~0\circ of Mars central meridian longitude in order to sample the entire surface. Images were obtained at 130 wavelengths between 2.7 and 5.1 \micron\ through CAM's CVF filter (\lambda/\Delta\lambda ~40). The spatial resolution of the images is quite poor (~500 km/pixel) because of the 1.5\arcsec\ IFOV of CAM pixels. The resolution is adequate to detect gross hemispheric-scale spectral differences, however. Sixty-four spectra were generated from the co-registered CAM images. The spectra are consistent with previous groundbased results but they reveal unique new information near wavelengths contaminated by telluric H2O and CO2 in groundbased data. Variations in the strength and nature of the ~.65 \micron\ "hydrated mineral" band are seen in the spectra, as are potential mineralogic features in the 3 to 4 \micron\ and 4.5 to 5.0 \micron\ regions.
SWS observations of Deimos were conducted on 3-4 August 1997 UT using the SWS-01 observing mode. Spectra of Deimos and Mars background flux were obtained from 3.0-3.5, 5.3-10.0, and 32.1-32.5 \micron\ at \lambda/\Delta\lambda ~ 1000-2000. Modeling efforts are underway to extract the weak Deimos signal from the strong Mars background flux.
This work was supported by NASA ISO data analysis grant NAG5-3347. We also acknowledge support from the ISO Spectrometer Data Centre at MPE Garching, funded by DARA under grant 50 QI 9402 3.
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The author(s) of this abstract have provided an email address for comments about the abstract: jfb8@cornell.edu