Earth’s Plasma Sheet Helps Make Water on the Moon

University of Hawaiʻi at Mānoa planetary scientist Shuai Li, led research that high energy electrons in Earth’s plasma sheet (part of the magnetosphere) are contributing to weathering processes on the Moon’s surface and the electrons may have aided the formation of water on the lunar surface.

“To my surprise, the remote sensing observations showed that the water formation in Earth’s magnetotail is almost identical to the time when the Moon was outside of the Earth’s magnetotail,” said Li. “This indicates that, in the magnetotail, there may be additional formation processes or new sources of water not directly associated with the implantation of solar wind protons. In particular, radiation by high energy electrons exhibits similar effects as the solar wind protons.”

“Altogether, this finding and my previous findings of rusty lunar poles indicate that the mother Earth is strongly tied with its Moon in many unrecognized aspects,” said Li.

In future research, Li aims to work on a lunar mission through NASA’s Artemis programs to monitor the plasma environment and water content on the lunar polar surface when the Moon is at different phases during the traverse of the Earth’s magnetotail.

Nature Astronomy – Formation of lunar surface water associated with high-energy electrons in Earth’s magnetotail

Solar wind implantation is thought to be one of the primary mechanisms in the formation of water (OH/H2O) on the surface of the Moon and possibly on the surface of other airless bodies. The lunar nearside spends ~27% of its daytime in Earth’s magnetotail where the solar wind flux is reduced by as much as ~99%. However, no correlated decrease in surficial water content has yet been seen on the lunar nearside. Here we report abundance observations of lunar surficial water on the nearside at different stages during the Moon’s passage through Earth’s magnetotail. We find that the water abundance at lunar mid-latitudes substantially increases in the dusk and dawn magnetosheath when the solar wind flux increases, yet remains nearly constant across the central magnetotail. We suggest that although we have confirmed the importance of the solar wind as a major source of fast water production on the Moon, hitherto unobserved properties of the plasma sheet properties may also play an important role.