Dry moon theory challenged as China finds traces of water in moon's soil

The lunar soil brought back by China's Chang'e-5 mission in 2020 has led to the discovery of a hydrated mineral containing molecular water

The search for the absolute necessity of sustaining a lifesource on any celestial object, water, for decades has been fruitless. Moon, our planet’s closest ally, had also sent out disappointing signals in that regard, with early Apollo missions reporting no signs of water. 

However, in a recent groundbreaking discovery, Chinese scientists have uncovered water molecules in lunar soil, reshaping our understanding of the moon's composition and potential, according to a report by Hong-Kong daily South China Morning Post (SCMP), on Tuesday. 

The Chang’e-5 mission has turned this long-held belief on its head, revealing that our closest celestial neighbour may hold more secrets than previously imagined. This discovery not only opens new avenues for scientific inquiry but also opens the door for immeasurable possibilities of utilising lunar resources in the future.

Earlier, the American Apollo missions from decades ago had returned empty-handed on that front as they found no water in their lunar samples, leading Nasa to conclude that the moon’s soil was entirely dry.

However, the lunar soil brought back by the Chang’e-5 mission in 2020, when analysed by Chinese scientists, has led to the discovery of a hydrated mineral containing molecular water, as reported by the Chinese Academy of Sciences (CAS) on Tuesday.

“If this water-bearing mineral is present in the lunar samples, more than one piece should be found,” SCMP quoted a scientist.

Decades of search of water on moon

The quest for lunar water has spanned decades.

During the United States’ Apollo missions in the 1960s, scientists initially sought evidence of water on the moon. 

But the early analyses of Apollo soil samples had reinforced the belief in a "dry moon," quelling the possibility of lunar water for many years.

Technological advancements in microanalysis and remote sensing have recently challenged this notion, SCMP said, citing the journal Nature Astronomy.

For instance, in 2009, India's Chandrayaan-1 spacecraft detected signs of hydrated minerals—in the form of oxygen and hydrogen molecules—in the sunlit areas of the moon.

In 2020, Nasa announced the presence of water on the sunlit lunar surface, based on findings from the Stratospheric Observatory for Infrared Astronomy, which identified water molecules in the Clavius crater, one of the largest craters visible from Earth in the moon's southern hemisphere.

Unclear findings till now

Despite these findings, the absence of lunar samples from high latitude and polar regions has left the origin and chemical form of lunar hydrogen unclear, according to the Nature journal.

The Chang’e-5 mission’s 2020 retrieval of lunar samples from the moon’s near side provided researchers a fresh opportunity to explore lunar mysteries, including water presence, as these samples were younger and from a higher latitude than those collected by Apollo and Soviet Luna missions, SCMP said.

In 2022, the Chang’e-5 lunar lander delivered the first on-site evidence of water on the moon’s surface.

Further discoveries are anticipated with the upcoming return of China's Chang’e-6 mission in June, which aims to bring back up to 2 kg of material from the moon’s oldest basin on its far side.