Dusty plasmas in the lunar exosphere: Effects of meteoroids

Abstract

A possibility of the formation in the lunar exosphere of dust cloud due to meteoroid impacts onto the lunar surface is studied. The main attention is paid to the high altitudes over the lunar surface including the range of the altitudes between 30 and 110 km where the measurements of dust were performed within the NASA LADEE mission. From the viewpoint of the formation of dust cloud at high altitudes over the Moon, the most important zone formed by the meteoroid impact is the zone of melting of substance. Only the droplets originated from this zone have the speeds between the first and second astronautical velocities (for the Moon). Correspondingly, only such droplets can perform finite movement around the Moon. The liquid droplets harden when rising over the lunar surface. Furthermore, they aquire electric charges due to the action, in particular, of the solar wind electrons and ions, as well as of the solar radiation. Thus dusty plasmas exist in the lunar exosphere with the characteristic number density ≲ 10−2 m−3 of dust particles with the sizes from 300 nm to 1 μm which is in accordance with the results of measurements performed by LADEE.