Chinese rover finds lunar soil could make oxygen and fuel on the moon

Lunar soil collected by the Chang’e 5 rover has been analysed, revealing it could be used to help generate oxygen and fuel on the moon

By Alex Wilkins

The landing site of the return capsule from the Chang’e-5 probe in Inner Mongolia

Ma Jianbing/VCG via Getty Images

Lunar soil could be used to make oxygen and other products from chemical reactions that mimic photosynthesis, according to an analysis of samples brought back to Earth by the Chang’e 5 rover. Reliable supplies of such substances are necessary for any future lunar base.

It is expensive to blast goods into space, so any material that can be found on the moon and that doesn’t have to be brought from Earth can save a lot of money.

Yingfang Yao at Nanjing University, China, and his colleagues examined a lunar soil sample to see if it could be used as a catalyst for a system that would convert carbon dioxide and water released by astronauts’ bodies into oxygen, hydrogen and other useful by-products like methane that could be used to power a lunar base.

“The question they are really asking is: ‘Is there something weird about lunar “soil” that will prevent us from doing things that we can do with Earth soil?’ Their answer is no,” says Michael Hecht at the Massachusetts Institute of Technology, who wasn’t involved in the research.

Yao and his colleagues first analysed their sample using techniques such as electron microscopy and X-ray diffraction to identify catalytically active components of the soil. They found high levels of iron and magnesium-based compounds that could be useful in a reaction mimicking the photosynthesis that occurs in green plants.

The researchers then tested the soil as a catalyst in various chemical reactions that would form part of a photosynthesis-like process to produce hydrogen and oxygen from CO2 and water. They found that the soil’s efficiency wasn’t as good as catalysts we have on Earth and isn’t currently good enough to generate products in sufficient quantities to support human life on the moon, but that tweaks to the structure and composition of the lunar soil sample might see significant improvements.

Hecht sees other potential problems to overcome. For instance, the reaction Yao and his team suggest performing requires liquifying the CO2, which they think could be performed simply using the moon’s cool atmosphere – but Hecht isn’t convinced that will work. “On the moon, cold temperature doesn’t mean you can condense CO2, you have to shed heat to do that.”

Journal reference: Joule, DOI: 10.1016/j.joule.2022.04.011

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