DISTINGUISHING GEOLOGIC UNITS AND ALTERATION MINERALOGY AT MARS 2020 CANDIDATE LANDING SITES WITH VISIBLE-TO-NEAR-INFRARED (VNIR) ORBITAL SPECTROSCOPY: IMPLICATIONS FOR THE MASTCAM-Z INSTRUMENT

The upcoming NASA Mars-2020 rover mission will need to perform remote geological and mineralogical reconnaissance to identify compelling regions of interest for in-situ investigation and sampling. Mastcam-Z, a visible to near-infrared (VNIR) stereoscopic, zoom-enabled multispectral imaging system, will be a critical reconnaissance instrument [1]. The mineralogy of the Mars-2020 candidate landing sites (Jezero crater, Northeast Syrtis, and Columbia Hills) has been mapped from orbit by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). However, previous work has focused on spectra from the CRISM IR detector (1000-3900 nm) [2-4], and the VNIR spectral variability among geologic units at these sites is not well constrained. In this work, we aim to develop spectral parameters that can distinguish key geologic units at these sites in Mastcam-Z resolution. We convolved representative CRISM VNIR observations for each landing site to theoretical Mastcam-Z bandpasses (Mastcam-Z’s filters are still in development) and analyzed each scene to identify spectral parameters that differentiated prominent geologic and mineralogic units previously identified by CRISM IR. For Jezero crater and NE Syrtis, CRISM VNIR spectra exhibit significant variability in Mastcam-Z resolution and spectral parameters can distinguish a variety of geologic/mineralogic units from orbit. At Jezero, these include the deltas, exposed crater floor units, and olivine/Mg-carbonate deposits; at NE Syrtis these include the olivine/Mg-carbonate deposits, phyllosilicate units, sulfate deposits, lava flows capping the regional stratigraphy, and mafic sands. In the Columbia Hills, we found spectral parameters that can broadly distinguish mafic sand dunes and the volcanic plains from the Columbia Hills en masse. Based on previous observations with Spirit’s Pancam instrument in the Columbia Hills, we also expect Mastcam-Z to be sensitive to known spectral variabilities at smaller spatial scales. These results highlight several Mastcam-Z spectral parameters that may be useful in NE Syrtis and Jezero Crater.

[1] Bell et al. (2016), LPI Contrib., 1980; [2] Goudge et al (2015), J. Geophys. Res. Planets, 120, 775-808; [3] Ehlmann & Mustard (2012), J. Geophys Res. Lett., 39; [4] Carter & Poulet (2012), Icarus, 219, 250-253.