MARS 2020/PERSEVERANCE IN SITU GEOLOGIC CONTEXT MAPPING (GXM) INITIAL RESULTS ALONG THE TRAVERSE WITHIN JEZERO CRATER

In situ geologic context mapping (GXM) identifies the near-field geology with defined mapping confidence levels along the traverse of the Mars 2020/Perseverance rover as observed from rover imaging. The results are ground-truth records of the geologic context along the Perseverance traverse. GXM is based on Mars Exploration Rover heritage methods for recording in situ geologic observations with new refinements to document variable attributes of rover viewing geometries. The resolution and viewing incidence from the observation point (rover) vary across an image panorama and influence the data quality, the relative levels of accuracy and reliability of the near field versus far-field mapping unlike the mostly uniform resolution and consistent incidence an­gle of an orbital image used in photogeologic mapping. These differing properties, establish the confidence level of mapping within a given radius and have been assigned five levels of mapping accuracy and reliabil­ity. The result is improved documentation of campaign and sample return caches by capturing contextual data in expanding zones of pre-defined mapping confidence These characteristics are recorded in a continuous geologic strip map as the rover traverse unfolds and are analogous to a reconnaissance field geologic strip map.

As of sol 148, in situ mapping has documented at least two fundamental lithomorphologies on the floor of Jezero crater at the landing site and along the traverses: A higher-standing blocky dense dark, somewhat vesicular and presumably basaltic, unit, a widespread underlying unit with granular surfaces and polygonal fractures on meter-scale, and various types of regolith that locally obscure the polygonally-fractured lithology. In the coming months, the extent and veracity of this sequence interpretation will be tested and likely modified as a traverse of significant length takes place and new lithologies are encountered here on the crater floor.