Impact and stick-slip dynamics in the soft-landing on minor celestial bodies

Abstract

The soft-landing on the surface of minor celestial bodies has been investigated with considering the impact and stick-slip effect. The polyhedron model is used to analyze the irregular shape and topography and geomorphology of minor celestial bodies. The soft-sphere discrete element method is used to fill the irregular minor celestial body’s polyhedron model and cover the surface of the body; and then the irregular shape, the gravitational environment, as well as the impact and hopping with the surface can be calculated precisely. The dynamical parameters of failed soft-landing and successful soft-landing are calculated and analyzed. In the cases of successful soft-landing, there are two obviously different kinds: firstly, the final position of the lander is near the target position; secondly, the final position of the lander is far from the target position. The difference of these two kinds of results is discussed. This research shows the major dynamical behavior of soft-landing on minor celestial bodies includes impact, hopping, as well as stick-slip effect. If the initial positions of soft-landing are improper chosen, the lander may become orbital motion around minor celestial body after one or more impact and hopping, or turn to quasi-periodic motion around equilibrium points without impact, or perhaps be static far from the initial position after several times of impact and hopping and leads to the failure of the deep space mission. For the successful soft-landing process, after several times of landings on the surface during the soft-landing process, the lander will finally settle on the surface of the minor celestial body. The results show that the soft-landing region should be selected as a flat area or concave region, which is far from the equatorial plane of the minor celestial bodies.