Numerical simulations of the landing of Mascot deployed by Hayabusa2 on a regolith bed for a big boulder

Abstract

JAXA’s asteroid sample return mis- sion Hayabusa2 was launched on December 3, 2014 and reached its target, the C-type near-Earth asteroid (162173) Ryugu on June 27, 2018. It will bring back samples from Ryugu’s surface to Earth in 2020. DLR/CNES lander MASCOT (Mobile Asteroid SCOuT) [1] on board Hayabusa2 reached the surface of Ryugu on October 3, 2018. It first bounced on or near a large boulder, and then bounced several times on the surface to finally settle upside down. It was then relo- cated to allow camera observations and in-situ measure- ments. Thanks to MASCOT’s onboard measurements and observations from Hayabusa2 optical navigation cam- era (ONC) system, the lander’s trajectory can be at least partly reconstructed. A better understanding of the in- teractions between the lander and a low-g asteroid sur- face, applied to MASCOT’s case, can therefore provide essential hints about Ryugu’s surface properties. For this purpose and because MASCOT possibly bounced on a boulder, we conducted several sets of sim- ulations of MASCOT impacting a regolith bed repre- senting Ryugu’s surface, with and without a boulder