Mars remote-sensing analog studies in the Badwater Basin, Death Valley, California

The search for evaporites on Mars has important implications for the role that liquid water has played in shaping the planet's geologic, climatic, and potential biologic history. Orbital investigations of surface mineralogy are crucial to this exploration effort. With the exception of coarse-grained gray hematite at a restricted number of sites and trace amounts of carbonate in globally distributed dust deposits, the Thermal Emission Spectrometer (TES) and Thermal Emission Imaging System (THEMIS) instruments have yet to find widespread mineralogical evidence of aqueously formed minerals. This may reflect the coarse spatial resolution of TES (3 × 5 km/pixel) and low spectral resolution of THEMIS (10 bands between 6.5 and 14.5 μm). Spectral mapping in the Badwater Basin, Death Valley, California, was conducted to better understand the capabilities of TES and THEMIS in detecting evaporite minerals. High-resolution MODIS/ASTER Airborne Simulator (MASTER) data, degraded to TES and THEMIS spatial resolutions, were used to evaluate the detection limits of sulfates and carbonates. To assess the validity of this spectral remote sensing, a quantitative ground truth analysis of surface mineralogy in the Badwater Basin was performed. The analysis was based on thin section petrography, X-ray diffraction, electron microprobe, and laboratory and field thermal emission spectrometer analyses. Taken together, the results of all five methods provided enough constraints for a robust interpretation that was in general agreement with the spectral remote-sensing mapping study for ∼90% of the surface samples examined.