Cross-Sectional Observation of Craters Formed by High-Velocity Impacts Under Low-Gravity

Abstract It is important to understand impact phenomenon under low gravity to estimate the surface properties and the evolutionary processes of small bodies such as asteroids. In the previous studies which investigate the effect of gravity on crater size from impact experiments, the crater formation process was mainly observed from above the target surface, and little information on the crater depth was obtained. In this study, we developed a measurement system that enables cross-sectional observation of the crater formation process under low gravity, and conducted high-velocity impact experiments with granular targets. The final crater depth-diameter ratios for the sand target with a particle size of 425 μm were about 0.2 and had similar values under different gravitational condition. On the other hand, the ratios for the fused alumina target with a particle size of 40 μm varied depending on the gravity. The ratio for the fused alumina target at 0.04 G were much higher than 0.2. The difference in crater shape may be due to the effect of cohesion of the fused alumina particles.