Impacts of fast meteoroids and a plasma-dust cloud over the lunar surface

The possibility of the formation of a plasma-dust cloud in the exosphere of the Moon owing to impacts of meteoroids on the lunar surface is discussed. Attention is focused on dust particles at large altitudes of ${\sim}\,10{-}100$ km at which measurements were performed within the NASA LADEE mission. It has been shown that a melted material ejected from the lunar surface owing to the impacts of meteoroids plays an important role in the formation of the plasma-dust cloud. Drops of the melted material acquire velocities in the range between the first and second cosmic velocities for the Moon and can undergo finite motion around it. Rising over the lunar surface, liquid drops are solidified and acquire electric charges, in particular, owing to their interaction with electrons and ions of the solar wind, as well as with solar radiation. It has been shown that the number density of dust particles in the plasma-dust cloud present in the exosphere of the Moon is ${\lesssim}\,10^{-8}$ cm$^{-3}$, which is in agreement with the LADEE measurements.