RESULTS FROM THE MARS GLOBAL SURVEYOR THERMAL EMISSION SPECTROMETER

The Thermal Emission Spectrometer spectra of low albedo surface materi als suggests that a four to one mixture of pyroxene to plagioclase, to gether with about a 35 percent dust component provides the best fit to the spectrum. Qualitative upper limits can be placed on the concentra tion of carbonates (<10 percent), olivine (<10 percent), clay minerals (<20 percent), and quartz (<5 percent) in the limited regions observe d. Limb observations in the northern hemisphere reveal low-lying dust hazes and detached water-ice clouds at altitudes up to 55 kilometers. At an aerocentric longitude of 224 degrees a major dust storm develope d in the Noachis Terra region, The south polar cap retreat was similar to that observed by Viking.