Searching for Sand Transport

Perseverance is currently stopped for sampling at Skinner Ridge rock. Sampling activities constitute an important aspect of Perseverance’s mission, and the rover’s strategic path is developed around sampling stops. During these stops, the rover must remain stationary for at least twelve sols in order to conduct proximity science and activities related to abrasion and coring. But being parked in one location for this extended period of time is also useful for something else.

Sampling stops provide rare opportunities to conduct “change detection” experiments, which are used to monitor wind-driven — or aeolian — transport of sand. The basic concept behind change detection is simple: compare identical images of the surface acquired at different times to search for wind-induced movement of sand. These observations can be used to deduce information about the relative strength and direction of winds blowing in the time between the two images. Sand deposits and aeolian bedforms (such as the sand ripples seen in the accompanying Mastcam-Z image) are ideal targets for change detection.

Perseverance is not the first spacecraft to perform this type of imaging experiment. In fact, change detection experiments have been conducted for many decades, stretching back to the earliest missions sent to Mars. Theories developed prior to robotic exploration predicted that contemporary Martian winds would rarely, if ever, be capable of transporting sand. Paradoxically, change detection images acquired from orbiting cameras have revealed active migration of sand dunes across the planet.

Developing models that can effectively explain and predict aeolian activity on Mars is vital for interpreting the planet’s climatic and geologic history, as well as mitigating risks to landed spacecraft and future human explorers. Surface missions enable researchers to study ongoing aeolian activity in greater detail and with higher spatiotemporal resolution than can be achieved from orbit, which is necessary for reconciling the discrepancy between theory and observation. Sand motion has been observed and studied in situ at spacecraft landing sites, including Gale crater and Jezero crater. Images acquired during Perseverance’s ongoing activities at Skinner Ridge rock and at future sampling stops will be used to further characterize the aeolian environment in Jezero and will provide new insight into enigmatic Martian winds.

Written by Mariah Baker, Planetary Scientist at Smithsonian National Air & Space Museum