The Moon is a unique natural laboratory for the study of the deep space plasma and energetic particles environment. During more than 3/4 of its orbit around the Earth it is exposed to the solar wind. Being an unmagnetized body and lacking a substantial atmosphere, solar wind and solar energetic particles bombard the Moon's surface, interacting with the lunar regolith and the tenuous lunar exosphere. Energetic particles arriving at the Moon's surface can be absorbed, or scattered, or can remove another particle from the lunar regolith by sputtering or desorption. A similar phenomenon occurs also with the galactic cosmic rays, which have fluxes and energy spectra representative of interplanetary space. During the remaining part of its orbit the Moon crosses the tail of the terrestrial magnetosphere. It then provides the opportunity to study in-situ the terrestrial magnetotail plasma environment as well as atmospheric escape from the Earth's ionosphere, in the form of heavy ions accelerated and streaming downtail. The lunar environment is thus a unique natural laboratory for analysing the interaction of the solar wind, the cosmic rays and the Earth's magnetosphere with the surface, the immediate subsurface, and the surface-bounded exosphere of an unmagnetized planetary body.

This article is part of a discussion meeting issue ‘Astronomy from the Moon: the next decades (part 2)’.

月球是研究深空等离子体和高能粒子环境的独特天然实验室。在其绕地球运行的超过 3/4 的轨道上，它暴露在太阳风中。作为一个未磁化的物体，缺乏大气层，太阳风和太阳高能粒子轰击月球表面，与月球风化层和脆弱的月球外逸层相互作用。到达月球表面的高能粒子可以被吸收或散射，或者可以通过溅射或解吸从月球风化层中去除另一种粒子。类似的现象也发生在银河宇宙射线上，其通量和能谱代表行星际空间。在其轨道的剩余部分，月球穿过地球磁层的尾部。然后，它提供了现场研究陆地磁尾等离子体环境以及以重离子加速和流下尾部形式从地球电离层大气逃逸的机会。因此，月球环境是一个独特的自然实验室，用于分析太阳风、宇宙射线和地球磁层与非磁化行星体的表面、直接地下和表面束缚的外逸层的相互作用。

本文是“月球天文学：未来几十年（第 2 部分）”讨论会议的一部分。