Leonard David's INSIDE OUTER SPACE

Image credit: CCTV/Inside Outer Space screengrab

Those samples rocketed from the Moon to Earth in 2020 by China’s Chang’e-5 lunar return mission keep on giving new insights about resource extraction.

Researchers from the Institute of Physics of the Chinese Academy of Sciences (CAS) and scholars from several Chinese universities, discovered ULM-1 (Unknown Lunar Mineral-1), a mineral crystal found to be enriched with water molecules and ammonium in the Chang’e-5 lunar samples.

Image credit: CCTV/Inside Outer Space screengrab

Brought to Earth in December 2020, Chang’e-5’s cache of roughly 1,731 grams (61.1 oz) of lunar samples has been found to contain water molecules. The discovery of a hydrated mineral, (NH₄)MgCl₃·6H₂O, in returned lunar soil samples contains water molecules that weigh approximately 41 percent of the total mass.

Chang’e-5’s landing and lob-to-Earth site was Northern Oceanus Procellarum, near a huge volcanic complex, Mons Rümker, located in the northwest lunar near side.

Map of Rümker region, target of Chang’E-5 sample return mission. Credit: Y. Qian, et al.

The research findings have been published online in the academic journal Nature Astronomy.

Preserved mineral

In an interview with China Central Television (CCTV), Jin Shifeng, associate researcher, Institute of Physics, Chinese Academy of Sciences, explained that Chang’e-5 landed at a relatively high latitude on the Moon where the temperature dropped, so this mineral was able to be preserved.

Photo taking during Chang’e-5 surface sampling.
Credit: CCTV/Inside Outer Space screengrab

“Like the ice we see in daily life, these substances are very volatile,” Jin said. “We found that the hydrated mineral decomposed at a relatively high temperature of about 100 degrees Celsius on Earth, which is why it can be preserved in such a harsh environment on the Moon for billions of years.”

First direct detection

According to CCTV, the researchers said “this discovery signifies the first direct detection of molecular water within the lunar regolith, shedding light on an actual form of water molecules and ammonium on the Moon’s surface.”

Chang’e-5 return capsule holding lunar specimens.
Credit: National Astronomical Observatories, CAS

The origin and chemical form of lunar water had remained elusive, CCTV adds, “despite extensive laboratory research on lunar samples collected by NASA’s Apollo mission dating from the 1960s and 1970s.”

The mineral’s structure and composition bear a striking resemblance to a mineral found near volcanoes on Earth. Terrestrial contamination or the Chang’e-5’s lander exhaust has been ruled out as the origin of this hydrate, according to the study.

The researchers said the finding opens up new possibilities for the future development and utilization of lunar water resources.

Lunar crop fertilizer

Chen Xiaolong, a researcher at the CAS Institute of Physics, also told CCTV: “We know ammonium is a nitrogen fertilizer. We use ammonium bicarbonate on Earth as a kind of nitrogen fertilizer. In addition, this mineral contains a small amount of potassium, which is a kind of potash fertilizers. This discovery means there is a good chance for humans to survive and grow crops on the moon in the future.”

Wu Weiren, chief designer of China’s lunar exploration program.
Image credit: CCTV/Inside Outer Space screengrab

According to the paper – “Evidence of a hydrated mineral enriched in water and ammonium molecules in the Chang’e-5 lunar sample” — the presence of ammonium indicates “a more complex lunar degassing history and highlights its potential as a resource for lunar habitation.”

Long-term lunar station

The findings also suggest that water molecules can persist in sunlit areas of the Moon as hydrated salts, providing crucial constraints on the “fugacity” of water and ammonia vapor in lunar volcanic gases,” the paper notes. A definition of fugacity is measuring the tendency of a component of a liquid mixture to escape, or vaporize, from the mixture.

Utilizing on-the-spot resources on the Moon is to play a major role in establishing a long-term lunar station. China is eyeing the establishment of the basic model of an international lunar research station by 2035.

To access the Nature Astronomy paper, go to: https://doi.org/10.1038/s41550-024-02306-8