Mapping Lunar Lander Plume Ejecta Trajectories to Lunar Surface Elevations

It is necessary to determine fallout locations of regolith ejecta from descent engine plume-surface interactions due to the risks such particles present to lunar surface operations. Models of ejecta trajectories demonstrate that regolith fallout could reach anywhere on the lunar surface. However, these models have yet to consider the topography of the lunar surface that can modify trajectories to either extend or reduce the range of ejecta. Here we couple orbital-based trajectory modeling with the lunar digital elevation models from LRO/LOLA to determine fallout locations around potential landing sites in the region of the lunar south pole. Limited particle trajectories have been matched to the lunar topography at a spatial resolution of 5-m. We demonstrate lunar topography can both prevent ejecta leaving landing site locations and vary impact locations by over 100%. Thus, lunar topography must play a role in quantifying the risks of ejecta from a chosen landing site.