Perseverance-Exposed Broken Rock Interiors and Subsurface Regolith in Jezero Crater, Mars.

From the first 1700+ sols and over 40 km of total odometry of the NASA Mars 2020 mission’s Perseverance Rover traverse, many Mastcam-Z observations exist for rocks that have been scuffed/broken by the rover wheels. Broken/scuffed rock surfaces provide clearer insight into rock interior mineralogies compared to natural surfaces, which are often further eroded or covered with a layer of dust that can mask many spectroscopic signatures (Rice et al., JGR–P, 128, 2023). Broken surfaces provide a look into the deeper interiors of rocks compared to abrasion patches, and could reveal mineral heterogeneity of the whole rock for cleaved massive rock types. In addition to broken rocks, we are investigating subsurface regolith overturned by Perseverance’s wheels via Mastcam-Z and SuperCam. Disturbed regolith in particular provides an opportunity to investigate material that contains significantly less airfall dust and could have undergone less recent transport than the surface layer from saltation creep (e.g., Sullivan & Kok, JGR–P, 122, 2017), allowing more reliable investigations into long-term historical sediment sources.

Here, we present a Mastcam-Z multispectral analysis of multiple cleaved rock interiors and crushed rocks spanning Jezero crater floor to the crater rim. We compare broken rock interiors with dusty surfaces and verify the effectiveness of previous studies in creating a ‘dust metric’ to evaluate the extensiveness of Martian dust on a surface using Mastcam-Z. Within a potential crater rim impact ejecta ‘megablock’ observed from mission Sol 1624, we identify differing mineral classes, some of which are consistent with laboratory spectra of serpentinized minerals. We also observe mineral heterogeneity on the cm- to dm-scale within this megablock. Many rock interior multispectral observations across the rover traverse are consistent with low-calcium pyroxene spectral signatures based on band ratio metrics and laboratory comparisons, with some crushed rocks (e.g., Sol 1238 in the crater rim) showing a strong agreement with crystalline iron oxide lab spectra, suggesting regional alteration. These interpretations reflect local rock units where observations occurred, and provide supportive results for inferring the origin and evolution of rock units throughout Jezero crater.