How Chinese Researchers Plan to Harvest Water on the Moon

Chinese researchers have developed an innovative method for extracting water on the Moon using lunar regolith and endogenous hydrogen. This process, driven by focused sunlight, could provide a sustainable source of water for future lunar bases, reducing the need for costly resupply missions from Earth.

Summary

• China and Roscosmos are planning the International Lunar Research Station (ILRSP), set to be completed by 2040.
• Chinese researchers have discovered a method to extract water from lunar regolith using a reaction with hydrogen.
• The process could yield 50 liters of water per ton of regolith.
• This method offers a sustainable water supply for lunar bases, essential for long-term habitation.
• The technology could be adapted for use on other celestial bodies, such as Mars.

Chinese Lunar Exploration: An Overview

In the coming years, China and Roscosmos plan to create the International Lunar Research Station (ILRSP), a permanent base in the Moon’s southern polar region. Construction of the base will begin with the delivery of the first surface elements by 2030 and is expected to last until about 2040. This base will rival NASA’s Artemis Program, which includes the creation of the Lunar Gateway and various surface elements that make up the Artemis Base Camp. However, several challenges must be addressed before establishing a sustainable lunar base.

Crews operating on the lunar surface for extended periods will require regular shipments of supplies. Unlike the International Space Station, which can be resupplied in a matter of hours, sending resupply spacecraft to the Moon will take about three days. As a result, NASA, China, and other space agencies are developing methods to harvest resources directly from the lunar environment – a process known as In-Situ Resource Utilization (ISRU). In a recent paper, a research team with the Chinese Academy of Sciences (CAS) announced a new method for producing massive amounts of water through a reaction between lunar regolith and endogenous hydrogen.

The Innovation: Water Production from Lunar Regolith

The research was conducted by Prof. Wang Junqiang and his team at the CAS Ningbo Institute of Materials Technology and Engineering‘s Key Laboratory of Magnetic Materials and Devices. They were joined by colleagues from the Center of Materials Science and Optoelectronics Engineering at the University of Chinese Academy of Sciences in Beijing. Their paper, titled “Massive Water Production from Lunar Ilmenite through Reaction with Endogenous Hydrogen,” recently appeared in the Chinese journal The Innovation.

Ever since the Apollo missions brought samples of lunar rocks and soil back to Earth for analysis, scientists have known that there is abundant water on the Moon. These findings were confirmed by several subsequent robotic sample-return missions, including China’s Chang’e-5 mission. However, much of this water consists of hydroxyl (OH) created through the interaction of solar wind (ionized hydrogen) and elemental oxygen in the regolith. There is also plenty of water in the form of ice that can be found in permanently shadowed regions (PSRs), such as the craters that cover the South Pole-Aitken Basin.

Unfortunately, lunar regolith contains very little hydroxyl that can be converted into water, ranging from 0.0001% to 0.02%. Moreover, the icy patches found in cratered regions are mixed with regolith, forming layers that extend beneath the surface. After examining the samples returned by the Chang’e-5 mission, Wang’s team determined that the highest concentrations of water were contained in ilmenite (FeTiO3), a titanium-iron oxide mineral found in lunar regolith.

How It Works

According to the research team, the water extraction potential of ilmenite is due to “its unique lattice structure with sub-nanometer tunnels.” The team conducted a series of in-situ heating experiments that revealed how hydrogen in lunar minerals could be used to produce water on the Moon. The process consists of heating lunar regolith to temperatures exceeding 1,200 K (~930° C; 1700° F) with concave mirrors. This leads to the formation of iron crystals and water bubbles in the material, which are then released as water vapor. The chemical process can be expressed as:

FeO/Fe2O3 + H –> Fe + H2O

The resulting water vapor is reclaimed at a rate of 51-76 mg of water for every gram of lunar soil. This works out to 50 liters (13.2 gallons) of water for every ton of processed regolith, enough to sustain 50 people daily. The team noted in their paper that “[t]his amount is ~10,000 times the naturally occurring hydroxyl (OH) and H2O on the Moon.” In addition to drinking water, this process could provide necessary irrigation water for growing crops, a critical requirement for future lunar settlements to lessen their dependence on Earth.

Potential Applications

This method could also be used to chemically separate hydrogen and oxygen gas from regolith, which could then be fashioned into propellant – liquid hydrogen (LH2) and liquid oxygen (LOX) – or used as fuel and to maintain supplies of breathable oxygen. “Our findings suggest that the hydrogen retained in [lunar regolith] is a significant resource for obtaining H2O on the Moon, which is helpful for establishing scientific research stations on the Moon,” the researchers concluded.

Another benefit is that the process is driven almost entirely by focused sunlight, while solar arrays can provide the additional power needed for the retention process. The one limiting factor is that this process will only be possible during a lunar day in the southern polar region (where China, NASA, and the ESA plan to build their bases). This means the facility could run for two weeks straight, followed by a two-week lull.

This can be mitigated by stationing processing facilities away from the polar regions or by creating a network of solar mirrors or satellites to direct light toward the southern polar region. In any case, this method presents a potential means of harvesting water on the Moon that is cost-effective compared to heating regolith in industrial furnaces and could be paired with ice extraction and processing to ensure future settlements have plenty of water.

Table 1: Water Extraction Process Steps

Table 2: Key Benefits of Solar-Powered Water Extraction

Future Implications

The ability to produce water on the Moon using local resources is a significant step toward achieving long-term human presence on the Moon. This breakthrough not only reduces the need for costly resupply missions but also enables the development of a self-sustaining lunar economy. By 2040, when the International Lunar Research Station (ILRSP) is expected to be fully operational, this technology could be the foundation for a thriving human settlement on the Moon.

Moreover, the methods developed for lunar water extraction could be adapted for other celestial bodies, such as Mars. As humanity pushes further into space, the ability to utilize local resources will be crucial for the success of long-duration missions.

China’s innovative approach to water extraction on the Moon marks a significant milestone in lunar exploration. By harnessing the power of the Sun and leveraging the unique properties of lunar regolith, Chinese researchers have developed a method that could make sustainable lunar habitation a reality. As the International Lunar Research Station (ILRSP) takes shape over the next two decades, this technology will play a critical role in ensuring the success of human missions to the Moon and beyond.

References

• NIMTE
• The Innovation
• Planetary Society – Chang’e-5 Mission
• NASA – ISRU
• NASA – Artemis Base Camp
• NASA – Lunar Gateway
• UNOOSA – ILRS Presentation

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