Earth wind as a possible source of lunar surface hydration

TL;DR

This study investigates lunar surface hydration sources, revealing that Earth's magnetospheric particles contribute to hydration and identifying optimal energy ranges for surface hydration formation, challenging previous solar wind-only models.

Contribution

It introduces the role of Earth's magnetospheric particles in lunar hydration and identifies new energy ranges influencing hydration formation, expanding understanding beyond solar wind effects.

Findings

Lunar hydration levels remain constant inside the magnetosphere.

Earth wind particles contribute to lunar surface hydration.

Optimal energy ranges for hydration formation are identified.

Abstract

Understanding the sources of lunar water is crucial for studying the history of lunar evolution, and also the solar wind interaction with the Moon and other airless bodies. Recent observations revealed lunar hydration is very likely a surficial dynamic process driven by solar wind. Solar wind is shielded over a period of 3-5 days as the Moon passes through the Earth's magnetosphere, during which a significant loss of hydration is expected from previous works.Here we study lunar hydration inside the magnetosphere using orbital spectral data, which unexpectedly found that the polar surficial OH/H2O abundance remains at the same level when in the solar wind and in the magnetosphere. We suggest that particles from the magnetosphere (Earth wind, naturally different from solar wind) contribute to lunar hydration. From lunar orbital plasma observations, we find the existence of optimal energy ranges, other than 1 keV as previously thought, for surface hydration formation. These optimal energy ranges deduced from space observations may provide strong implications for laboratory experiments simulating lunar hydration processes.