Investigating Asteroid Surface Geophysics with an Ultra-Low-Gravity Centrifuge in Low-Earth Orbit

Abstract

Near-Earth small-body mission targets 162173 Ryugu, 101955 Bennu, and 25143 Itokawa produce gravity fields around 4 orders of magnitude below that of Earth and their irregular shapes, combined with rotational effects produce varying surface potentials. Still, we observe familiar geologic textures and landforms that are the result of the granular physical processes that take place on their surfaces. The nature of these landforms, however, their origins, and how these surfaces react to interrogation by probes, landers, rovers, and penetrators, remain largely unknown, and therefore landing on an asteroid and manipulating its surface material remains a daunting challenge. The AOSAT+ design is a 12U CubeSat that will be in Low-Earth Orbit (LEO) and that will operate as a spinning on-orbit centrifuge. Part of this 12U CubeSat will contain a laboratory that will recreate asteroid surface conditions using crushed meteorite as a regolith proxy. The spinning of the laboratory will simulate the surface gravity of asteroids 2 km and smaller. The result is a bed of realistic regolith, the environment that landers and diggers and maybe astronauts will interact with. A crucial component of this mission involves the reproduction of the experimental results in numerical simulation in order to extract the material parameters of the regolith and its behavior in a sustained, very low but nonzero-gravity environment.