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THEMIS‐VIS Investigations of Sand at Gale Crater

Gale crater is the landing site of the Mars Science Laboratory (MSL) rover, Curiosity. Here we present Thermal Emission Imaging System Visible Imaging Subsystem (THEMIS‐VIS) mosaics in gray scale and in false color of Gale crater. We use these data products, in addition to THEMIS thermal infrared decorrelation stretch (DCS) mosaics, thermal inertia derivations, and near‐infrared spectra to investigate the MSL traverse area and sand across Gale crater. We identified several THEMIS‐VIS color units in the MSL traverse area that may correlate to the amount of sand cover that is present on each unit. This suggests that THEMIS‐VIS color is extremely useful in identifying dark basaltic sand, which appears as blue in THEMIS‐VIS false color images. We test this hypothesis by identifying small (~several pixels) blue patches on the southeast side of the central mound in Gale crater and confirming that they are patches of sand in High Resolution Imaging Science Experiment (HiRISE) images. Sand dunes on the crater floor exhibit variations in all data sets utilized in this study, with the Bagnold dunes and the western sand sea exhibiting the most notable differences. We propose that these differences are the result of a thin layer of dust that covers the western sand sea, although we do not rule out possible effects from grain size sorting.