MARS REMOTE SENSING ANALOG STUDIES IN THE BADWATER BASIN, DEATH VALLEY: ANALYSIS OF GROUND TRUTH

The search for evaporite basins on Mars provides one means of assessing the role that liquid water has played in shaping the planet’s climatic history. Orbital investigations of surface mineralogy are crucial to this exploration effort. With the exception of a few specular hematite sites, the Thermal Emission Spectrometer (TES) now orbiting Mars has yet to find significant mineralogical evidence of hydrously altered minerals. This is may reflect the coarse spatial resolution of TES (3km/pixel). This limitation will be addressed later this year by the Thermal Emission Imaging Spectrometer (THEMIS), which will map much of the planet at an improved spatial resolution of 100 meters/pixel. To better understand the limitations of TES and THEMIS in detecting evaporite minerals, Moersch and Farmer (2000) have conducted a spectral study of the Badwater Basin, Death Valley, CA. Thresholds for detecting sulfates and carbonates were examined using high resolution MASTER data, degraded to TES and THEMIS spatial resolutions. To assess the validity of this spectral mapping we performed a quantitative study of surface mineralogy in the Badwater Basin. Here we report the analysis of surface samples based on thin section petrography, X-ray diffraction, electron microprobe and laboratory thermal emission spectrometer analysis. The interpretation of spectral data in our study area can be confounded by a variety of factors, including overlaps of the spectral absorption features of different minerals especially those of sulfates and silicates. X-ray diffraction data and thin section analysis confirm that the samples indeed contain complex mixtures of evaporites and silicate minerals. A spectral library of evaporite minerals along with the Arizona State University’s TES library will be used to deconvolve the sample spectra for comparison to the abundances of these mineral groups determined by thin section analysis. Together these data provide a basis for assessing the spectrally based predictions of Moersch and Farmer (2000) and will lay the groundwork for accurate identification of these minerals on Mars.