The Mars Multispectral Imager for Subsurface Studies (Ma_MISS) instrument is a miniaturized visible and near-infrared spectrometer that is integrated into the drilling system of the ESA Rosalind Franklin rover, which is devoted to subsurface exploration on Mars. Ma_MISS will acquire spectral data on the Martian subsurface from excavated borehole walls. The spectral data collected by Ma_MISS on unexposed rocks will be crucial for determination of the composition of subsurface rocks and optical and physical properties of materials (i.e., grain size). Ma_MISS will further contribute to a reconstruction of the stratigraphic column and acquire data on subsurface geological processes. Ma_MISS data may also inform with regard to the presence of potential biomarkers in the subsurface, given the presence of organic matter that may affect some spectral parameters. In this framework, we performed a wide range of measurements using the laboratory model of the Ma_MISS to investigate mineral/organic mixtures in different proportions. We prepared mixtures by combining kaolinite and nontronite with glycine, asphaltite, polyoxymethylene, and benzoic acid. These organic compounds show different spectral characteristics in the visible and near-infrared; therefore their presence can be detected by the Ma_MISS instrument. Our results indicate that the Ma_MISS instrument can detect organic material down to abundances of around 1 wt %. In particular, the data collected on low-concentration mixtures show that, by analyzing sediments with a grain size smaller than the Ma_MISS spatial resolution, the instrument can still discern those points where organic matter is present from points with exclusive mineral composition. The results also show that a collection of multiple contiguous measurements on a hypothetical borehole wall could help indicate the presence of organic matter in clay-rich soils if present.
Keywords: In situ spectroscopy; Mars; Organics detection; Rosalind Franklin rover mission; Subsurface analysis.