Granular Asteroid

Understanding the physical and mechanical properties of small planetary bodies (comets, asteroids, small satellites) is essential not only for the study of the solar system and its origins, but also as a basis for future space exploration and mining missions. Until very recently, it was assumed that the smallest of asteroids were monolithic rocks with a bare surface. But recent space missions and observations have established that not only their surfaces are covered by regolith, but that their internal structure is not monolithic either. From these observations, the concept of a “granular asteroid” has progressively emerged.

Granular asteroids are naturally occurring gravitational aggregates (rubble piles) bound together by gravitational and possibly cohesive forces. They have large interior voids which allow them to support large plastic deformations. Their macroscopic behavior and internal structure are still not well known and how to predict their mechanical strength, based on their microstructure and dynamics, is still an open question. However, in view of their discrete nature, it is reasonable to use the theoretical concepts and numerical tools developed for granular media to study them. A first major result we obtained was to define a coherent framework by extending the inertial number paradigm by incorporating gravitational and cohesive inter-particle forces in an extended inertial number.

Rotational disruption of self-gravitational cohesive granular asteroid. Simulations made with the LMGC90 software


Main articles

[1] E. Azéma,  P. Sanchez and D. Scheeres, Scaling Behavior of cohesive self-gravitating aggregates, Phys. Rev. E (Rapid Communication), 98, 030901(R) (2018)
[2] P. Sanchez, M. Renouf, E. Azéma, R. Mozul and F. Dubois, A contact dynamics code implementation for the simulation of asteroid evolution and regolith in the asteroid environment, ICARUS, 363, 114441 (2021).