AEOLIAN TRANSPORT OF COARSE SEDIMENT IN THE MODERN MARTIAN ENVIRONMENT

Evidence of aeolian sandstone outcrops, migrating sand dunes and global dust storms on Mars demonstrate that aeolian processes have been and continue to be a dominant agent of surface modification. The mechanisms guiding aeolian transport within Mars’ low atmospheric pressure environment are still not fully understood and require a combination of modeling, experiments and ground truth observations. Here we present results obtained during ten change detection campaigns conducted over three Martian years. When the Curiosity rover makes extended stops for science targeting and solar conjunctions, identical Mastcam images are taken many sols apart, allowing for visual identification of aeolian-driven surface changes. Over the course of the mission, our results show highly variable sediment mobility, consistent with past results from orbit showing strong seasonality, with particularly strong winds occurring during southern summer. From our ground truth observations, we are also able to infer wind speed and direction at each change detection site, which helps constrain modern atmosphere-surface interactions. Of particular interest is an apparent discrepancy that exists between predicted wind speeds and the winds required to explain the motion we observe. Coarse grained sediment (>1.5mm) is often mobile in our observations, which could ultimately require an alternate explanation, such as strong but infrequent wind gusts or impact-driven creep by smaller saltating particles.