Light flashes caused by impacts against the moon

Impacts of meteoroids on airless cosmic bodies (asteroids, comets, Moon) result not only in cratering and fragmentation of a target, but cause a formation of radiating vapor plumes. Though the duration of the flash is rather short and the coefficient of the kinetic energy conversion into the radiation impulse is rather small (in comparison to the impacts onto the planets having atmospheres), it may be sufficient for detection of such impacts. Radiation efficiency of the impact is determined by many factors: mechanical and chemical composition of the target and projectile, optical properties of the eject material, impact parameters (velocity, trajectory inclination, event scale, etc.). An estimate of the light impulse created by a 1m-in-radius silica body impacting the lunar surface with the velocity of 50km/s has been made by Melosh et al.(1). In view of some impending experimental work (2) it appeared important to review and refine the estimates of luminous efficiencies and other characteristics of impac...