How does topography affect wind abrasion on Mars? Recently observed shifts in ventifact orientation at Gale crater

Abstract

Wind abrasion is the dominant erosive process inferred from observations by Curiosity during its traverse in Gale crater, but how and how fast wind scours Mount Sharp is unclear. Here, we infer formative wind direction from ventifacts (wind-eroded rock fragments) measured from Curiosity's recent traverse. We compare these measurements to previous ones and to wind model predictions, and attempt to estimate the current rate of wind erosion near Curiosity's location on Mount Sharp. Ventifacts in this study indicate winds blowing south-southeast, agreeing with previous studies on the floor of Gale crater, but differing from studies at the base of the mountain slope. Upslope abrasive wind flows predominate, consistent with idealized models. At some sites, ventifacts are oriented both upslope and downslope on Mount Sharp, suggesting bimodal wind direction at the mountain, agreeing with circulation models that predict diurnal reversals. Using crater-retention age statistics at one site, we estimate a ∼ 3.5 ± 0.8 μm/Earth year (yr) upslope horizontal erosion rate at Mount Sharp. We suggest the observed ventifacts formed when Mars' obliquity and climate regime were similar to those in the present day.