IDENTIFYING CANDIDATE LANDING AND SAMPLE TUBE DEPOT SITES AND CHARACTERIZING ROVER TRAVERSES FOR MARS SAMPLE RETURN

NASA and ESA are planning a Mars Sample Return (MSR) campaign that would retrieve the Martian rocks and regolith to be collected by the Mars 2020 Perseverance rover for possible return to Earth. Candidate sample depots, landing sites, and rover traverse paths for the MSR Sample Retrieval Lander (SRL) and Fetch Rover (SFR) must be identified in advance using orbital data from the High Resolution Imaging Science Experiment (HiRISE).

Sites for landing and sample tube deposition are constrained by average slope, abundance of visible rocks, craters, aeolian bedforms, patch size, and proximity to a Mars 2020 notional traverse. Candidate locations are classified by terrain type: smooth regolith, smooth outcrop, or mildly rough outcrop (mapped only in areas deficient of smooth regolith/outcrop). Areas within 50m of notional M2020/MSR traverse paths connecting landing/depot locations between Jezero crater and Nili Planum are classified by both terrain type and an approximate Cumulative Fractional Area (CFA) rock distribution. Traverse paths are less constrained than landing/depot sites and are characterized by eight classes: smooth regolith, smooth outcrop, rough outcrop/regolith, layered/stepped outcrop, heavily fractured, partial ripples on smooth regolith/outcrop, partial ripples on rough regolith/outcrop, or untraversable. Rock CFA is categorized into ~5%, 10%, and 15% bins.

Approximately 250 candidate landing/depot sites were identified within 500m of the notional traverse paths and provide benign patches with a typical spacing of several hundred meters. While specific path segments may be dominated by a particular terrain type, this complex region as a whole is extremely heterogeneous on the scale of tens to hundreds of meters. The majority of notional paths have ~5% rock density, although local patches of up to 15% occur on the delta and on/near the crater rim. Final selection of landing and depot sites will be contingent upon future system engineering of MSR, the post-landing performance of Mars 2020, and correlation between images taken by HiRISE and from the rover after landing, but these orbital maps provide a baseline understanding of the area that would be accessed during these missions.