An analytical model for a transient vapor plume on the Moon

Naturally occurring lunar transients have been observed for many centuries. Artificially induced impacts on airless near-Earth objects are now being used as a test bed to study a wide range of geomorphic phenomena. In this paper an analytical theory is used to predict the flash event that signals the initial phase of a surface impact. The model predicts the wave form, duration, and radiated energy content of the vapor plume starting only with the mass and kinetic energy of the impactor. The theory is applied to the planned 2009 LCROSS lunar impact where the impact flash event is predicted. The transient radiation emitted by the impact can be used to obtain some relevant impact parameters, and it is predicted to be energetic enough to possibly be captured by terrestrial observers.