Degradation of Rustic Canyon Crater in Gale Crater, Mars

The Rustic Canyon crater is a degraded impact structure on Mt. Sharp in Gale crater. The crater is irregular in plan form, ∼20 m across NW‐SE and ∼30 m across NE‐SW and lacks a raised rim. Using images and a Digital Terrain Model derived from a rover orthomosaic of the crater, we evaluated the amount and processes of degradation based on current versus expected original crater morphology for a crater formed by a primary, fragmenting primary, or secondary impact event. We conclude that the crater is modified predominantly by aeolian degradation of ∼50 cm and up to ∼1–2 m of down‐wasting, up to a few meters of wall back‐wasting, and 10s of cm of local infilling by aeolian debris. Nevertheless, survival of some patchy ejecta limits overall degradation that has modified the original crater form. The degradation required to modify a deeper primary crater and the absence of interior relief associated with rims or “septa” between multiple contributing craters formed by a fragmenting impactor indicate that the Rustic Canyon crater is probably a secondary impact crater. Locally prevailing NE winds cause vertical and horizontal erosion rates of 0.1 m/Myr and 1–2 m/Myr, respectively, and can produce the observed degraded crater morphology in as little as a few Ma, to most likely 10–20 Ma, but possibly up to 50–60 Ma. The erosion of the Rustic Canyon crater highlights the ongoing erosion of Mt. Sharp that has created and (or) considerably modified many landforms over 100s of Ma and up to a Ga.