Chinese scientists have made a groundbreaking discovery in lunar soil samples returned by the country’s Chang’e-5 mission to the Moon, revealing the presence of water and ammonium in the form of a hydrated mineral, China Central Television reported Wednesday.

The findings mark the first time molecular water has been found in lunar soil, shedding light on the true form of water molecules and ammonium on the Moon.

The hydrated mineral, which has the chemical formula (NH4)MgCl3·6H2O, was discovered in samples returned by Chang’e-5 in December 2020. Its structure and composition bear resemblance to novograblenovite, first found on Earth in samples of basaltic lava taken from a fissure eruption that occurred on Russia’s far eastern Kamchatka Peninsula in 2012.

The mineral is formed when hot basalt reacts with water-rich volcanic gases and carnallite, an Earth evaporite mineral. Its existence on the Moon may help scientists determine the origin of such water sources as well as better understand the Earth-Moon relationship.

The study, published in the academic journal Nature Astronomy on July 16, was a collaborative effort by researchers from various prestigious institutions, including Beijing National Laboratory for Condensed Matter Physics, Beijing University of Science and Technology, Tianjin University, Qinghai Institute of Salt Lakes of the Chinese Academy of Sciences, and Zhengzhou University.

Researchers conducted a thorough analysis of the mineral’s chemical composition and formation conditions to rule out the possibility of terrestrial contamination or rocket exhaust as the source of the hydrate.

Moreover, this discovery suggests the potential presence of water molecules in sunlit regions of the Moon in the form of hydrated salts, opening up possibilities for lunar resource utilization and exploration. Unlike water ice, this hydrate demonstrates remarkable stability in the Moon’s challenging environment, according to the study.

The existence of water on the Moon holds great significance for the study of lunar evolution and resource development. Previous research on Apollo samples collected between 1969 and 1972 indicated the absence of water-bearing minerals in lunar soil, leading to the widespread assumption in lunar science that the Moon lacked water sources.

In the returned Apollo lunar sample, scientists employed high-sensitivity characterization techniques to identify minute traces of “water” (H+, OH-, or H2O) at a level of one millionth in certain glasses and minerals. The studies concluded without definitive proof of the presence of water molecules.

In comparison, the latest mineral samples from Chang’e-5 feature water molecules that comprise up to 41% of the sample’s mass.

In 1994, researchers observed the lunar poles and postulated the existence of water ice within permanently shadowed regions of the Moon. Subsequent observation via a sensing satellite in one such region in 2009 revealed water signals in lunar dust. More recently, other remote sensing data has indicated the presence of water molecules in sunlit regions of the Moon.

China’s Chang’e-6 mission made history late last month when it returned to Earth with the first samples collected from the far side of the Moon. Meanwhile, Chang’e-7, due to launch in 2026, will search the lunar South Pole for traces of ice — considered key to supporting a long-term presence on the Moon.

Editor: Tom Arnstein.

(Header image: IC)