The roughness of the asteroid Vesta is controlled in part by ground-ice, reports a new study published in Nature Communications this week. The presence of ground-ice on asteroids is significant for understanding their formation and evolution.

The asteroid Vesta is the second biggest object in the asteroid belt between Mars and Jupiter after the dwarf planet Ceres. The NASA Dawn spacecraft first visited Vesta in 2011-2012 to understand the dynamics and characteristics of this large asteroid and what this information could tell us about the history of the solar system. Any variations in surface roughness were expected to be produced by cratering caused by impacts from other asteroids. However, new observations from the Dawn spacecraft suggest that these variations cannot be explained by cratering alone. Essam Heggy and colleagues discover large smoother terrains that correlate with heightened hydrogen concentrations - together these hint at the possible presence of ground-ice, which may have contributed to the formation of Vesta’s current surface texture.

The team note that knowledge of the surface roughness of asteroids will be crucial for landing future missions on these bodies.