Evidence of daily winds on Mars, which are strong enough to transport sand, is presented online in Nature Communications this week. Previous observations indicated that the Martian landscape was eroded by wind, but until recently sand-moving winds on Mars were thought to be rare due to the thin atmosphere. In addition, the strength, frequency and origin of the sand-moving winds have remained undetermined.
Francois Ayoub and colleagues present detailed measurements from the Martian Nili Patera dune field, based on a years' worth of high resolution imagery from the Mars Reconnaissance Orbiter. These measurements demonstrate ripple migration, a phenomenon commonly found in sand dunes on Earth, and show that sand movement occurs daily and is strongly seasonal. The authors use these observations and an atmospheric model to estimate a wind stress threshold (the amount of wind required for sand motion) for Mars.
The research opens new avenues for the investigation of climate conditions and geomorphic processes on Mars, and the interpretation of the landscapes revealed by orbital and rover exploration. No equivalent measurements are currently possible on Earth due to lack of adequate imagery and this study may stimulate dedicated Earth-based experiments.