OUTCROP-SCALE STUDIES OF A LACUSTRINE-VOLCANIC MARS ANALOG WITH A MARS 2020-LIKE INSTRUMENT SUITE

By simulating the instrument suite for the future Mars 2020 rover, we assess how the rover will identify, investigate, and sample targets of interest. A Mars analogue site in the Mojave Desert near China Ranch consisting of paleolake sediments with interbedded volcanic ashes and spring deposits (mineralogy: pyroxenes, feldspars, quartz, amorphous silica, sulfates, phyllosilicates, carbonates, iron oxides) was chosen. The Ultra-Compact Imaging Spectrometer (UCIS; 0.4-2.5 μm) was used to generate compositional and mineralogical maps of the outcrop. These maps guided sample collection, similar to the general procedure the Mars 2020 mission will follow. To simulate the Mars 2020 multispectral camera and VNIR+SWIR+LIBS+Raman point spectrometer (Mastcam-Z and SuperCam, respectively), the UCIS image was resampled to the resolutions of these spectrometers and laboratory LIBS data were acquired. To simulate in situ data, deep-UV fluorescence and Raman were taken using JPL’s SHERLOC-like prototype. We will acquire PIXL-like data and SuperCam-like Raman in the future.

Mastcam-Z like data distinguished iron oxidation state and differentiated key geologic units. The passive VNIR+SWIR point spectra from SuperCam-like data identified all major secondary mineral phases from a simulated distance of 500 m; limited spatial coverage means that in an operational context careful target selection will be required to capture the full diversity of outcrops. Oxide weight percents can be calculated using LIBS, and minor elements may be qualitatively traced. SHERLOC’s Raman identifies evaporite minerals in single point spectra (50 μm spot size) and small changes in peak center may trace solid solution series. Silicate minerals have not yet been observed in single point spectra but by averaging spectra taken over a larger spatial scale (~1 cm²) mineralogical identification may be possible. Deep-UV fluorescence results indicate prevalent organics within the samples and allow the major classes of organic molecules to be identified. These results compare favorably with ground-truth data, indicating the data collection and analysis protocols employable by Mars2020 that are required to support identification of major geologic units and evaluation of potential biosignature preservation.