Probe the regolith characteristics of asteroids from multi-epoch infrared light curves

Regolith, materials of mixture of dusts and boulders, are believed to widely exist on asteroidal surface. However, evidences from recent asteroidal space missions show that regolith on different asteroids can be quite different. There are asteroids that have regolith dominated by fine dust, for example, 433 Eros. There are also asteroids with regolith dominated by porous boulders, for example Ryugu and Bennu. Besides, there exist asteroids, where part of the surface are covered by fine dust, and the other regions are boulders with different size and porosity, for example Itokawa.The physical status of asteroidal regolith can tell us inforation about the origin and evolution of the asteoids. Here we report a method to probe the regolith characteristics of asteroids from multi-epoch infrared light curves, from which the surface albedo, roughness, thermal inertia or mean grain size or boulder porosity can be investigated. Besides, through analysis of multi-epoch infrared light curves, surface heterogeneity can be also evaluated. These physical characteristics of regolith can be helpful for study about the origin and evlution of asteroids.