Abstract: Impact sampling is a sampling method applicable to the microgravity environment on the surface of asteroids and has been successfully applied to the Hayabusa 1 and Hayabusa 2 asteroid exploration missions. In this paper, an asteroid microgravity
impact sampling model is developed based on the domestic high-performance discrete element software MatDEM. The effects of initial impact velocity and projectile shape on the interior regolith features and ejecta after impact are investigated. The results show that increasing initial impact velocity can increase the stress and dense degree inside the same region of the regolith, and increase the number of ejecta particles and the number of ejecta particles from the deep part of the regolith. Within the same area of the regolith, the cone-headed projectile produces the highest stress peaks and the flat-headed projectile produces the lowest stress peaks. Round and flat-headed projectiles produce the highest number of ejecta particles and have the best deep sampling capability. Cone-headed projectile produces the lowest number of ejecta particles and has the weakest deep sampling capability. The conclusions help to understand the internal mechanism of the impact process and provide a reference for the design of impact sampling schemes in deep space exploration.

Key words: discrete element method, deep space exploration, asteroid, impact sampling, MatDEM