The Sun-Earth-Moon Connection: II--Solar Wind and Lunar Surface Interaction

TL;DR

This study uses kinetic simulations to analyze how Earth's magnetotail influences solar wind interactions with the lunar surface, revealing that space weathering continues despite magnetic shielding, impacting lunar exploration and habitability.

Contribution

It demonstrates through modeling that Earth's magnetotail does not block solar wind ions from reaching the Moon, affecting lunar surface weathering and charging.

Findings

Magnetotail does not prevent solar wind ion influx.

Lunar surface charging occurs even in Earth's magnetotail.

Space weathering of lunar regolith continues in these conditions.

Abstract

In the pursuit of lunar exploration and the investigation of water presence on the lunar surface, a comprehensive understanding of plasma-surface interactions is crucial since the regolith's space weathering can create H$_2$O. However, the Moon is in the Earth's magnetotail for nearly 20\% of its orbit, which could affect this water creation on the side facing the Earth if this condition shields it from the solar wind. The objective of this study is to understand how the passage of the Moon in the Earth's magnetotail affects the plasma delivery near the lunar surface. The Particle-In-Cell Electromagnetic (EM) Relativistic Global Model, known as IAPIC, is employed to kinetically simulate the Solar Wind-Magnetosphere-Ionosphere-Moon Coupling. The Earth's magnetotail does not prevent the influx of solar wind ions and ionospheric ions into the solar environment; therefore the space weathering of the regolith is not stopped in these conditions. In addition, the charge separation of solar wind ions and electrons happens is modeled, leading to electric fields and charging of the lunar surface that can be validated by observations. The study of the Sun-Earth-Moon system provides insight into the lunar environment while in the magnetotail, which is essential to better interpret the results of future Lunar missions. It also provides insights in the Lunar charging in different conditions that could affect the human presence on the Moon.