Mars - near-infrared comparative spectroscopy during the 1986 opposition

Near-IR, 0.7-2.5 micron spectra were obtained for several Martian locations during the 1986 opposition, using a continuously variable filter spectrometer; approximately 60 distinct spots were observed at 0.5-1.5 arcsec (200-460 km) resolution which are distinguishable into eight distinct geologic types: (1) volcanic regions, (2) ridged plains, (3) ridged volcanic plains, (4) scoured plains, (5) impact basins, (6) channels and canyons, (7) densely-cratered regions, and (8) layered terrain and ice. Spectral features observed in the spot-to-spot ratios for spectra from different geologic regions are used as indicators of mineralogic differences. Little difference is found among spectra from areas that appear to have very different morphologies in Viking Orbiter images. 30 references