The regolith, the layer of dust commonly observed on the surface of certain planets, satellites, and asteroids, provides vital information on the formation and evolution of celestial bodies. However, the formation of these layers is still enigmatic. In collaboration with astrophysicist colleagues (M. Delbo and P. Michel, Cassiopeia, UMR 6202, Nice), we will study the relative roles of thermal cycling and shocks resulting from impacts on the formation of fine particles. We will also study the role of regolithisation as a source of dust in the Solar System. We will combine the observations at different scales (from the ground, space, and on meteorites) with new, original experiments on thermal fatigue (CRPG) and impact energy (Kobe, Japan), and these processes will be simulated with numerical codes developed in Nice. This study will allow us to better understand the process of the formation and evolution of fine particles, which is essential knowledge required for the preparation and interpretation of data from the space missions dedicated to the study of asteroids (such as Dawn, OSIRIS-Rex, Hayabusa, and MarcoPolo-R).
The formation and evolution of regoliths. Thermal fatigue experiment in a climatic chamber simulating the diurnal and nocturnal temperature changes on the surfaces of asteroids. Example of regoliths observed on the surfaces of asteroids : On the left, a thin regolith on (433) Eros ; on the right, a regolith composed of gravel and pebbles on the surface of Itokawa (25143).