A Chinese lunar lander has detected traces of local water on Earth's satellite. A team of scientists has now determined where this "most important liquid in the universe" comes from on the Moon.
Scientists first learned about the discovery of traces of water on Earth's natural satellite back in 2020, when the Chang'e-5 landing module used an on-board spectrometer to identify water-bearing rocks in the lunar soil. Laboratory analysis of soil samples delivered to our planet a year later confirmed the initial findings. Now the research team has finally determined where water comes from on the Moon in the first place.
Naturally, "lunar water" was not found in the form of liquids or at least ice crystals: there are no open bodies of water, and although the place where Chang'e 5 conducted research is called the Ocean of Storms, it has nothing to do with Earth's oceans.
In fact, the Chang'e 5 only discovered hydroxyl-bearing rocks formed by interaction with water. Nevertheless, the hydroxyl group in lunar rocks is the same for lunar water as smoke is for fire: it is proof of existence.
Multi-step laboratory analyses have shown that the hydroxyl groups in the lunar rocks come from two different sources. A small fraction came from the influence of the solar wind on the surface of the satellite (Apollo 11 delivered soil samples to Earth with similar results). Most of the hydroxyl groups are in the form of apatites, which are quite common rocks both on the Moon and on Earth.
Such a large number of hydroxyl groups could not have been formed by the solar wind alone, scientists say: water must have been on the Moon from the start and played a role in its formation. Moreover, the presence of water there could be important for potential colonization of the satellite and the construction of the first human settlements on its surface.
The Chang'e-6 and Chang'e-7 landers are expected to continue studying the Moon as they evaluate the satellite's water resources, including polar ice, and their main objective.