Oblique impact cratering: A comparison of low-velocity experiments to high-velocity experiments

Abstract

Previous impact cratering experiments performed by Gault and Wedekind (1978), used high-velocity impactors (~1 km/s to 7 km/s) to quantify how impact angle affects crater morphology and ejecta pattern. Low velocity (144 m/s to 260 m/s) impact experiments were conducted in a vacuum chamber with a basaltic sand target material and impact angles ranging from 0.5° to 90° (vertical) at the Impact Cratering Laboratory at the University of Tokyo Kashiwa. The crater morphology and ejecta distribution from low velocity impacts are then compared to results from the higher velocity projectiles. When adjustments are made to the low-velocity measurements to account for differences in velocity, the displaced mass ratio follows a sinθ distribution, as is seen in the high- velocity experiments. In the low-velocity experiments, asymmetric ejecta is present at slightly higher impact angles. The presence of an uprange forbidden zone occurs at the same impact angle (20°) in both sets of experiments. The most striking difference between the two sets of experiments is the complete lack of a downrange forbidden zone in all of the low-velocity experiments. With the exception of the very lowest impact angles, these low-velocity oblique impact experiments yield similar changes in crater characteristics with varying impact angles to the previous high-velocity experiments.