Investigating the few meters below the Martian subsurface will place important constraints on the geologic history of Mars and help to better understand the evolution of surface sediments (erosion, transport, and deposition), the relationship between sediments and bedrock, and between environmental conditions and surface processes, and, of course, the possible presence of life. Ma_MISS will explore the Martian subsurface in the spectral range 0.5-2.3 µm and with a spatial resolution of 120 µm. Its high spatial resolution will be very important for exploring the variability of mineralogical composition at the scale of rock grains directly on the borehole walls. The study of reflectance spectra of subsurface materials will allow the identification of differences in lithologies, for example, distinguishing between volcanic and sedimentary rocks. Analysis of the position and shape of absorption bands will discriminate between different types of mineralogical phases between silicates, sulfates, oxides/hydroxides, hydrated phases, and opaque minerals (e.g., sulfides, iron oxides, and silica).

Recently, permafrost-related geomorphological considerations and remote sensing of hydrogen based on neutron and gamma-ray spectroscopy have inferred the presence of ice deposits in the shallow Martian subsurface. Although both the H2O and CO2 bands at 1.5 and 2 µm fall at the same wavelengths as the absorptions of hydrated minerals, through Ma_MISS unambiguous identification of ice deposits or inclusions in the subsurface layers can be performed through the location of minima and the analysis of band shapes, which is also useful for constraining ice grain sizes. The study of spectral parameters, such as continuum reflectance level and slope, can help determine important physical parameters such as different grain sizes in materials that can help us better understand the type and state of sediments in the subsurface. Different slopes and spectral shapes can also help distinguish volcanic glass from crystalline materials, thus providing clues about geological processes such as impacts or volcanic eruptions.

On Earth, our understanding of the evolution of climate and the development of life comes from studying the mineralogical, textural and geochemical signatures preserved in sedimentary rocks in stratigraphic sections. It is reasonable to assume that these features might also have been preserved in the Martian subsurface stratigraphy. By investigating the mineralogy of the deeper layers, where more limited alteration by the atmosphere has taken place, the history of erosion, transport, and deposition of loose material can be better inferred.