China’s lunar lander has found evidence of water.

On December 1, 2021, technicians at the Beijing Aerospace Flight Control Center monitored the status of the Chang’e-5 probe. [Photo/Xinhua]

According to a study published Friday in the journal Science Advances, China’s Chang’e‑5 lunar lander has detected the first in situ evidence of water molecules on the Moon’s surface, bringing an end to a long-standing scientific debate about the satellite’s humidity.

Since the mid-20th century, scientists have believed that the Moon is completely dry. However, in 2020, NASA confirmed through remote observations that water molecules are likely distributed across the lunar surface, although it lacked direct on-site evidence to substantiate this claim.

In December 2020, lunar samples returned by the Chang’e‑5 mission revealed that the soil at its landing site in the Oceanus Procellarum contains less than 120 parts per million of water—equivalent to 120 grams of water per metric ton. A rock from the same region was found to contain 180 ppm of water, making it significantly drier than any material ever analyzed on Earth.

Scientists believe that most of the water in lunar soil is delivered by solar wind, which bombards the Moon’s surface with hydrogen atoms. These hydrogen atoms then react with oxygen in surface minerals, forming water molecules and hydroxyl groups—chemical moieties consisting of one hydrogen atom bonded to one oxygen atom.

Interestingly, because this rock is somewhat wetter than the surrounding soil, it suggests that there may be additional water sources on the Moon—perhaps originating from its interior—since there is evidence that the rock could have been ejected from the lunar surface.

Lin Honglei, the first author of the study and an associate researcher at the Institute of Geology and Geophysics, Chinese Academy of Sciences, stated that detecting water signals such as water molecules and hydroxyl groups is distinct from searching for actual liquid water.

He said that scientists need to heat rocks and soil to extract water molecules and hydroxyl groups, then convert them into liquid water.

Lin Yangting, one of the study’s co-authors, stated that China’s next two lunar missions—Chang’e‑6 and Chang’e‑7—aim to conduct a more detailed examination of the abundance and distribution of lunar surface water at the same site.

He said the latest findings could serve as a foundation for achieving the scientific objectives of two upcoming missions.

(From ChinaDaily)