Degradation of Endeavour Crater Based on Orbital and Rover-Based Observations in Combination With Landscape Evolution Modeling

Abstract

Exploration of Endeavour crater's Shoemaker formation rim rocks by the Opportunity rover, combined with extensive observations from the Mars Express and Mars Reconnaissance Orbiters, provides unique and quantitative insights into the processes that have degraded this 22-km diameter Noachian age impact crater. These insights are informed by comparisons between Endeavour and the relatively young, and morphologically fresh appearing, 19-km diameter Bopolu crater located 65 km to the southwest. Analyses of rover and orbiter data, combined with landscape evolution modeling using Bopolu topography as a starting point, demonstrate that significant weathering and fluvial degradation of Endeavour occurred during the Noachian Period, with 0.3 km of vertical rim removal, 0.9-km backwasting of the rim, and deposition of 0.5 km of fluvial-deltaic-lacustrine sediments on the crater floor, sourced from rim erosion. Pediments formed on external rim segments, with characteristic thin regolith covers over graded bedrock. Late Noachian to Early Hesperian age Grasberg formation draping sediments, and Burns formation sulfate-rich sandstones, subsequently embayed all but high standing Shoemaker formation rocks. Burns formation strata accumulated in the crater interior up to a depth of 0.8 km. Subsequent wind erosion of the interior deposits is indicated by an interior mound and moat, together with yardangs carved into Shoemaker formation rocks, and graded topographic profiles from Grasberg and Burns formation rocks up and through the interior rim Shoemaker formation outcrops. Up to 0.4 km of Burns formation rocks were exhumed from within the crater by wind erosion to produce the mound and moat.