“There is little doubt that most of the lunar surface hosts water in one form or another,” said a study signed by Chinese researchers and published in Nature Geoscience on Monday. They examined in detail around 100 tiny glass marbles, ranging in size from the thickness of a hair to a millimeter, that were brought back by the Chang’e 5 mission in 2020.
Up to two billion years old, these marbles were formed by the impact of meteorites — meteorites or asteroids — that melted lunar material. American lunar missions had brought back samples, but this is the first time they’ve been studied in detail.
They contain up to two millionths of a gram of water equivalent per gram of balls. Water derived from processes other than lunar volcanism or the fall of comets (which contain ice).
Also read: Meteorites bring water to the depths of the moon
The team led by researchers from the Chinese Academy of Sciences assumes that the glass balls formed when a meteorite hit them initially lost most of their water.
They would then have been bombarded by solar winds, which would have supplied them with hydrogen, which would then combine with the oxygen atoms contained in the spheres. This is how water molecules are formed.
The lunar soil consists of 3 to 5% glass beads, according to estimates based on examination of soil samples brought back from the American Apollo missions.
The study concludes that these glass beads could be the “dominant reservoir” involved in the lunar water cycle. And that this reservoir could be “usable in situ in future lunar exploration.” Especially since that water would be “pretty easy to extract.”
The American side, meanwhile, is focusing on water sources in the form of ice, which has been detected at the moon’s south pole and could be turned into fuel. NASA has planned a mission with a robot called VIPER for 2024 to study ice concentration there.
For further: How do you live on the moon?