Multiple sources of water preserved in impact glasses from Chang’e-5 lunar soil | Science Advances

The existence of molecular H ₂ O and evolution of solar wind–derived water on the lunar surface remain controversial. We report that large amounts of OH and molecular H ₂ O related to solar wind and other multiple sources are preserved in impact glasses from Chang’e-5 (CE5) lunar soil based on reflectance infrared spectroscopy and nanoscale secondary ion mass spectrometry analyses. The estimated water content contributed by impact glasses to CE5 lunar soil was ~72 ppm, including molecular H ₂ O of up to 15 to 25 ppm. Our studies revealed that impact glasses are the main carrier of molecular H ₂ O in lunar soils. Moreover, water in CE5 impact glasses provides a record of complex formation processes and multiple water sources, including water derived from solar wind, deposited by water-bearing meteorites/micrometeorites, and inherited from lunar indigenous water. Our study provides a better understanding of the evolution of surficial water on airless bodies and identifies potential source and storage pathways for water in the terrestrial planets.