Properties of Asteroidal Regoliths: In Situ Missions, Light Scattering Observations, and Simulations

Recent space missions to asteroids are providing new insights on regolith layers, which seem to be ubiquitous on their surfaces. They result from successive meteoritic impacts and present a huge variety of properties, corresponding to the huge variety in gravity, structure, composition and impact history on these atmosphere-less bodies. Complementary remote observations of the light scattering properties of numerous asteroids (which depend only upon the phase angle and the wavelength of observations, and upon the properties of their surface and sub-surface), give clues to regoliths' average composition and size through experimental simulations, including measurements on samples of selected powdered meteorites. The preparation of missions to near-Earth asteroids, together with experiments on board the ISS, should provide a better understanding in the coming years.