New minerals, we do not discover them every day and even less on the Moon. This is nevertheless what a Chinese team has just done thanks to the samples brought back in 2020 by the Chang’e 5 probe. The researchers have also determined the concentration of helium 3 in lunar dust and identified the morphological characteristics of the particles of the moon. lunar ground.
Chang’e is originally the goddess of Mooning Chinese mythology, but today it is mostly the name of the Chinese Lunar Exploration Program (CLEP). As part of this program, the Chang’e 5 probe was launched on November 23, 2020, the purpose of which was to bring back samples of the celestial body, a first since the Soviet probe Luna 24 in 1976. This objective has been successfully achieved since, on December 16, 2020, the return capsule landed on Earth with 1,731 grams of matter lunar, making China the third country after the United States and the Soviet Union to bring lunar samples back to Earth.
A new mineral straight from the Moon
The news was announced on September 9, the eve of the Mid-Autumn Festival, by the China National Space Administration (CNSA, China’s space agency) and the China Space Authority.energyatomic (CAEA). This new mineral, named the “change site-(Y)”, was discovered by scientists from the Institute for Research on geology Beijing Uranium Company (BRIUG), a subsidiary of China National Nuclear Company (CNNC).
Change site-(Y) is a phosphate from the merrillite group. According to the Xinhua News Agency, this new mineral is a columnar crystal transparent and colorless. When the research team obtained the first 50 milligrams of lunar samples in July 2021 to conduct mineralogical research, they found traces of a new mineral. However, she failed to obtain the ideal data to determine the mineral, because the lunar soil particles were extremely small. The team then requested a second batch of lunar samples, weighing around 15 milligrams.
Among more than 140,000 particles, the researchers isolated a pure single-crystal particle, with a size of 10 by 7 by 4 micrometers, then decoded its crystal structure and verified that it is a new mineral. This first lunar mineral discovered by China was finally approved as a new mineral by the Commission on New minerals, the nomenclature and classification (CNMNC) of the International Association of Mineralogy (IAM), making the people’s republic the third country to have discovered a new lunar mineral, after the two superpowers of the Cold War.
From helium-3 to the morphological characteristics of lunar soil particles
Two other major results obtained by the CNNC from the samples brought back by Chang’e 5 were announced in the press release.
The first is that China has for the first time determined the concentration of helium-3 in lunar dust. This type of analysis is not a first for the country since, in 1978, the Chinese Institute of Atomic Energy (CIAE), a subsidiary of the CNNC, had determined the concentrations of 36 elements from the sample of one-gram lunar soil supplied by the United States. Furthermore, since the launch of CLEP, the CNNC has conducted activation analysis experiments on lunar soil simulants and meteorites in order to prepare for the analysis of lunar soil samples. The interest of helium-3 lies however in the fact that it is a potential fuel for the nuclear fusion. Researchers deduced the extraction parameters needed to harvest this isotope from returned samples, providing fundamental scientific data for lunar resource assessment and exploration.
The second is that the morphological characteristics of lunar soil particles have been identified through extensive and systematic studies, providing the scientific basis for studying how lunar soil formed.
Finally, the CNSA announced full approval for its next three lunar missions. Chang’e 6, 7 and 8, which correspond to phase 4 of China’s lunar exploration program and are expected to start launching as early as 2024, will explore the South Pole of the Moon and start building a basic structure for the International Station. lunar research, according to Shine.
Is helium-3 really worth it?
Helium-3 – the only known stable isotope containing more protons than neutrons (2:1) – is considered a promising potential fuel for nuclear fusion. In theory, a deuterium/helium-3 fusion reaction could release 164.3 megawatts of energy per gram of helium-3, all without producing radioactivity. On Earth, the helium-3 approach nevertheless poses a number of problems.
On the one hand, because a fusion involving this element could only take place at much higher temperatures than those necessary in a tritium reactor for example (several hundred million degrees). On the other hand, helium-3 is extremely rare and difficult to isolate on Earth. The main way to obtain it is to wait for the tritium from nuclear warheads and other associated stockpiles to decay, then collect it in small quantities. It does occur naturally in the Earth’s atmosphere, but in tiny concentrations (7.2 parts per trillion).
The surface of the Moon, on the other hand, could contain up to 1.1 million metric tons of helium-3. However, the costs associated with operating it would be astronomical. Indeed, the highest estimated concentrations of helium-3 in the lunar soil would be around fifty parts per billion. So, you would probably have to process 150 tons of regolith to harvest just one gram. You would then need to bring it back to Earth. Nevertheless, the extraction of lunar helium remains an option for China.
Finally, in addition to the Change site-(Y) and Helium-3 announcements, the National Space Administration of China also announced full state approval for the next three Phase 4 lunar missions. Chang ‘e 6, 7 and 8 will therefore lay the foundations of the future Chinese Lunar Research Station.
