THE DYNAMIC ENVIRONMENT OF JEZERO CRATER, MARS (Invited Presentation)

Despite their importance to Mars geomorphology, weather, and exploration, the processes that move sand and raise dust to maintain Mars’ ubiquitous dust haze, cause dust storms, and modify the surface, have not been well quantified in situ, with missions lacking either the necessary sensors or a sufficiently active aeolian environment. The Perseverance rover’s novel environmental sensors (which include the ability to track dust devils and dust clouds around/over the rover, instantly detect local surface dust removal, and record sounds), the Ingenuity helicopter's active interactions with surface grains, and Jezero crater’s active aeolian environment, remedy this. For example, in Perseverance’s first 216 sols, four convective vortices raised dust locally, while an average of four passed the rover daily, over 25% of which were significantly dusty (“dust devils”). More rarely, dust lifting by nonvortex wind gusts was produced by daytime convection cells advected over the crater by strong regional winds. One such imaged ‘gust-lifting’ event covered 10 times more area than the largest imaged dust devil, suggesting that dust devils and wind gusts could raise equal amounts of dust in total, even under non-storm conditions. Perseverance also made the first detailed observations from an active dust source region during an early regional dust storm, including imaging of increased dust lifting by not only winds but also dust devils. Wind patterns and modern aeolian surface features are found to be controlled by regional and local slopes. Regional Isidis basin slopes drive strong daytime upslope winds from the SSE/SE/ESE, peaking in the afternoon, while nighttime downslope winds are weaker and peak after midnight at the rover’s position, though likely strengthen closer to the crater rim. Stronger daytime winds result in estimated net sand transport toward ≈276° over this period. This is consistent with (i) modeled Isidis basin upslope winds, (ii) orbital observations of sand transport from ~ESE, and (iii) rover imaging of wind tails. By contrast, fluting in ventifacts imaged along the rover traverse shows dominant transport from the WNW, consistent with nighttime wind directions but inconsistent with the much larger daytime wind speeds to date. This could suggest that the ventifacts formed during a past climate epoch.