2006 Annual Science Report

University of Hawaii, Manoa Reporting  |  JUL 2005 – JUN 2006

TES and THEMIS Study of Proposed Paleolake Basins Within the Aeolis Quadrangle of Mars

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Several studies have described photogeologic evidence for paleolacustrine basins on Mars, mostly within impact craters. If these basins contained persistent standing water subsequently lost through evaporation, they may have contained deposits of evaporite minerals. If still present and sufficiently exposed, these evaporites would be detectable in orbital thermal infrared spectra. Detection of aqueously-derived minerals is essential for identifying locations on Mars that may have been conducive to the establishment and evolution of life.

Using data from MO-THEMIS and MGS-TES, we examined proposed paleolake basins within Aeolis quadrangle, including Gusev and Gale craters. Gusev Crater is dominated by units with spectrally-intermediate to -thick layer of dust mantling the surface. This study used THEMIS data to identify small scale units that appear spectrally distinct using minimum noise fraction (MNF) rotations as well as decorrelation stretches (DCS) of the data. In addition, overlapping TES spectra were scrutinized using linear deconvolution, spectral ratios and carbonate indices to search for unique spectral signatures of aqueously-derived minerals. We have not found any unambiguous spectroscopic evidence of evaporites that might support a paleolacustrine origin for the surficial deposits in Gusev, Gale or other craters in the Aeolis quadrangle. These results do not discriminate between several previously-suggested origins (fluvial-lacustrine, aeolian or volcanic deposition) for the mound layers.

The paper describing these results underwent revisions for the Journal of Geophysical Research – Planets and was resubmitted in May 2006. The paper was officially accepted on the 23rd of June 2006 and is currently in press.