Prediction of regolith particle scattering considering adhesive force during spacecraft landing under low gravity

In recent years, there has been an increase in commercial lunar landing exploration, and in Japan, there are plans for the next exploration to be the return of samples from the surface of the Martian moon. Due to the fact that this is not a touch-and-go exploration to the surface, but rather a landing stay of several hours, it is necessary not only to land in consideration of the terrain, sunlight, and communication status, but also to overcome dynamic events that occur at the moment of landing. In such landing conditions, the primary concerns are the destruction of observation equipment due to the physical collision of scattered regolith particles and the deterioration of equipment characteristics due to particle adhesion; consequently, the prediction of particle behavior is of significant importance. This paper presents the findings through analyses that predict the behavior of regolith particles scattered in contact with a landing pad that has a kinetic energy of several hundred Joules. Subsequently, the most unfavorable conditions are identified, predicated on the disparity in the characteristics of the celestial surface layer; this analysis yields recommendations for regolith countermeasures, which are arduous to evaluate under the test constraints of low gravity and their actual dimensions.