Apollo video photogrammetry estimation of plume impingement effects

Future missions to the Moon may require numerous landings at the same site. Since the top few centimeters are loosely packed regolith, plume impingement from the Lander ejects the granular material at high velocities. Much work is needed to understand the physics of plume impingement during landing to protect hardware surrounding the landing sites. While mostly qualitative in nature, the Apollo Lunar Module landing videos can provide a wealth of quantitative information using modern photogrammetry techniques. The authors have used the digitized videos to quantify plume impingement effects of the landing exhaust on the lunar surface. The dust ejection angle from the plume is estimated at 1°–3°. The lofted particle density is estimated at 108–1013 particles/m3. Additionally, evidence for ejection of large 10–15 cm sized objects and a dependence of ejection angle on thrust are presented. Further work is ongoing to continue quantitative analysis of the landing videos.

► Photogrammetry of the six Apollo Lunar landings has been performed to look at quantitative plume impingement effects.
► The authors estimate that the dust ejection angle derived from the exhaust plume was approximately 1°–3° on average.
► From the landing videos, the estimate for dust loading in the exhaust is approximately 108–1015 particles/m3.
► It is possible that 10–15 cm sized objects can be lofted in the exhaust plume.