Understanding the sources of lunar water is crucial for studying the history of lunar evolution, as well as the interaction of solar wind with the Moon and other airless bodies. Recent orbital spectral observations revealed that the solar wind is a significant exogenous driver of lunar surficial hydration. However, the solar wind is shielded over a period of 3–5 days per month as the Moon passes through the Earth’s magnetosphere, during which a significant loss of hydration is expected. Here we report the temporal and spatial distribution of polar surficial OH/H₂O abundance, using Chandrayaan-1 Moon Mineralogy Mapper (M ³) data, which covers the regions inside/outside the Earth’s magnetosphere. The data shows that polar surficial OH/H₂O abundance increases with latitude, and that the probability of polar surficial OH/H₂O abundance remains at the same level when in the solar wind and in the magnetosphere by controlling latitude, composition, and lunar local time. This indicates that the OH/H₂O abundance in the polar regions may be saturated, or supplemented from other possible sources, such as Earth wind (particles from the magnetosphere, distinct from the solar wind), which may compensate for thermal diffusion losses while the Moon lies within the Earth’s magnetosphere. This work provides some clues for studies of planet–moon systems, whereby the planetary wind serves as a bridge connecting the planet with its moons.

了解月球水的来源对于研究月球演变的历史以及太阳风与月球和其他无空气物体的相互作用至关重要。最近的轨道光谱观测表明，太阳风是月球表面水化的重要外生驱动力。但是，当月球穿过地球的磁层时，太阳风将被屏蔽，每个月的时间为3-5天，在此期间，预计水分会大量流失。在这里，我们使用Chandrayaan-1 Moon Mineralogy Mapper（M ³）数据报告了极性表面OH / H ₂ O丰度的时空分布，该数据涵盖了地球磁层内部/外部的区域。数据显示极性表面OH / H ₂ O含量随纬度增加，并且在太阳风和磁层中，通过控制纬度，成分和月球局部时间，极性表面OH / H ₂ O的丰度概率保持在同一水平。这表明极性区域中的OH / H ₂ O丰度可能是饱和的，或者是由其他可能的来源补充的，例如地风（来自磁层的粒子，不同于太阳风），这可以补偿热扩散损失，而月亮位于地球的磁层之内。这项工作为行星-月球系统的研究提供了一些线索，由此，行星风充当了连接行星与卫星的桥梁。