Scientists have developed a technology to extract water from lunar soil and use it to convert carbon dioxide (CO₂) into oxygen and chemicals for fuel.

The team from the Chinese University of Hong Kong believes the technique could make a manned base on the Moon a more viable option while potentially making it easier to conduct future deep space exploration using the lunar surface as a launchpad.

“We never fully imagined the ‘magic’ that the lunar soil possessed,” said researcher Lu Wang. “The biggest surprise for us was the tangible success of this integrated approach. The one-step integration of lunar H₂O extraction and photothermal CO₂ catalysis could enhance energy utilisation efficiency and decrease the cost and complexity of infrastructure development.” 

Currently, the cost of transporting a single gallon of water using a rocket into space costs around $83,000 (£62,000). This makes a liveable Moon habitat a very expensive proposition, with each astronaut using around four gallons per day.

Soil samples analysed from China’s Chang’E-5 mission found evidence of water on the lunar surface using spectral reflectance measurements of soil and rocks.

If human explorers on the Moon could harness resources already present, it could avoid many of the logistical challenges of transporting resources, as well as the cost. However, previously developed strategies for extracting water from lunar soil involved multiple energy-intensive steps and didn’t break down CO₂ for fuel and other essential uses.

The new technique both extracts water from lunar soil and directly uses it to convert the CO₂ exhaled by astronauts into carbon monoxide and hydrogen gas, which could then be used to make fuels and oxygen for the astronauts to breathe. The technology accomplishes this feat through a photothermal strategy, which converts light from the Sun into heat. 

The scientists tested the technology using lunar soil samples gathered during the Chang’E mission, as well as simulated lunar samples and a batch reactor filled with CO₂ gas that used a light-concentrating system to drive the photothermal process. The team used ilmenite, a heavy black mineral and one of several reported water reservoirs in lunar soil, to measure photothermal activity and analyse the mechanisms of the process. 

Despite the technology’s success in the lab, the extreme lunar environment still poses challenges that will complicate its usage on the Moon, according to the authors, including drastic temperature fluctuations, intense radiation and low gravity. 

Additionally, lunar soil in its natural environment does not have a uniform composition, which leads to it having inconsistent properties, while CO₂ from astronauts’ exhalations might not be enough to offer a basis for all the water, fuel and oxygen they need. Technological limitations also continue to present a barrier, with current catalytic performance still insufficient to fully support human life in environments beyond Earth, said Wang. 

“Overcoming these technical hurdles and significant associated costs in development, deployment and operation will be crucial to realising sustainable lunar water utilisation and space exploration,” the authors write.

Last year, Italy’s national space agency ASI kicked off a new project, which aims to develop small nuclear fission reactors to provide power on the lunar surface.