High Spatial Resolution Thermal Inertia Mapping of Mount Sharp and Northern Plains, Gale Crater, Mars

We have developed and implemented a log maximum likelihood approach to retrieve surface thermal inertia (TI) values using a combination of Mars Global Surveyor TES, Odyssey THEMIS, and Mars Reconnaissance Orbiter CRISM long wavelength data. TES (3 km/pixel) and THEMIS (100 m/pixel) data stabilize the retrieval results, and CRISM data are included to extend retrievals down to 18 m/pixel. This approach inverts the KRC numerical thermal model simultaneously for multiple overlapping observations to estimate TI values from observed surface temperatures and Lambert albedos.

Initial application of the approach to Gale Crater, including the plains to the north of Mount Sharp, and the northern slopes traversed by the Curiosity rover, shows TI values at 18 m/pixel that are similar in magnitude to those retrieved from 100 m/pixel THEMIS data alone. The high spatial resolution retrievals provide fine spatial details not observed before, including delineation of relatively small wind-blown sand deposits within Glen Torridon that correspond in CRISM data to a spectral dominance of high-calcium pyroxene and olivine, and in HiRISE-based elevation data to local low regions. The combination of TI values for grains size, CRISM single-scattering albedo for mineralogy, and Curiosity's observations is used in nonlinear retrievals of compositional and textural information for the various deposits, both for scientific and rover mobility purposes.