The cratering dynamics of granular soil induced by an impinging jet

The interactions between an impinging jet and a regolith bed, often referred to as Plume-Surface Interactions (PSI), occur during takeoffs and the entry, descent, and landing sequences of spaceflights. Here, we present the results of an experimental campaign to characterize regolith erosion and cratering dynamics from impinging jets under a range of environmental and flow conditions. For these experiments, a nozzle was placed over the transparent front edge of a regolith bin to create a half-crater and expose the crater profile. A high-speed camera was used to image the evolution of the exposed crater profile and the complex interactions between regolith particles and the impinging flow throughout the jet impingement process. The role of the jet flow Mach number, the normalized nozzle height, and the ambient pressure on the measured cratering and erosion dynamics were investigated in this work. In helping to unveil the underlying physics governing Plume-Surface Interaction erosion processes, this study constitutes a valuable resource for future spaceflight missions to the Moon and Mars.