Conditions for aeolian transport in the Solar System

Sand dunes, which arise wherever loose sediment is mobilized by winds that exceed threshold speed and grains are sufficiently strong to survive collisions1, are ubiquitous in the Solar System2. However, current threshold theories usually neglect physical processes that become relevant under exotic conditions3,4, and are in disagreement when extrapolated to extraterrestrial planetary bodies5–9. Here we draw on results in contact10, rarefied gas11, statistical12 and adhesion13 mechanics to present a theory for the fluid and impact thresholds of aeolian transport that encompasses the various conditions present in Solar System bodies. Our theoretical predictions are consistent with available experimental threshold observations and indicate that these thresholds strongly depend on local environmental conditions everywhere but Earth. Our results suggest, among other things, that Titan’s dunes are locally sourced4 and that Mars’s high threshold makes its dunes more resistant to motion14. This work highlights the role of dunes in understanding atmospheric dynamics and surface sediment. Further studies are needed to include hitherto neglected and still poorly understood processes.