The lunar plasma environment when the Moon is in the terrestrial magnetotail

The Moon during 5 – 6 days every orbit crosses the tail of the terrestrial magnetosphere. During these periods it is not exposed to the solar wind but to the terrestrial magnetotail plasma environment, providing the opportunity to study in-situ, from the Moon or from an observational platform in lunar orbit, the dynamics of the magnetotail and its dependence on drivers such as the solar and geomagnetic activity conditions. Phenomena as for instance plasmoids released from the near-Earth magnetotail and propagating anti-Sunward, hot plasma flows, energetic particle bursts, magnetic reconnection and plasma sheet dynamics can then be observed in-situ. The Moon during these periods is also very well placed to monitor atmospheric escape from the Earth into space, in the form of energetic heavy ions outflowing from the terrestrial ionosphere and transported into the deep magnetotail. Terrestrial heavy ions, transported to the Moon, may have preserved samples of the Earth’s ancient atmosphere by their implantation in the lunar regolith.