There is a debate raging right now among NASA and other space agency scientists about the risks of bringing Martian soil samples back to Earth – that debate was started by the Perseverance rover landing on Mars, digging soil samples and hermetically sealing them in airtight containers to be picked up by another space mission and returned to Earth for study. How will we be protected from potential life forms or viruses that could contaminate and even destroy life on our planet as so many science fiction novels and movies have predicted? That mission hasn’t been scheduled but it has already been proven feasible by China’s Chang’e-5 mission which brought lunar samples back to Earth in December 2020. While past experience supported the idea that this was safe -- there appears to be no life on the Moon -- a new discovery has proven that lunar soil can perform photosynthesis – a key process for plant life on Earth to convert sunlight, water, CO2 and nutrients into oxygen. Could this have once supported life on the Moon. Is this an “Uh-oh” moment?
“Lunar in situ resource utilization offers a great opportunity to provide the material basis of life support for lunar habitation and traveling. Based on the analysis of the structure and composition, Chang’E-5 lunar soil sample has the potential for lunar solar energy conversion, i.e., extraterrestrial photosynthetic catalysts.”
In a study published in the journal Joule, lead author Yingfang Yao, a scientist at Nanjing University, explains that the purpose of conducting his experiments on lunar regolith – the dust and broken rocks on the lunar surface -- was to help future space travelers reduce the amount of materials needed to establish and live in a space colony … with the ultimate goal of a “zero-energy consumption’’ life support system. That means creating an energy cycle which is powered by sunlight (already on the Moon) and utilizes lunar materials (soil, water) and materials the astronauts create (carbon dioxide (CO2)) to completely support breathing (creating oxygen), subsistence (creating water) and fuel (creating methane to power equipment and spaceships). (A graphic drawing of the entire process can be seen here.)
“Compared with catalysts on the Earth, lunar soil or components extracted from lunar soil, as the photocatalysts for splitting water on the Moon, can greatly reduce the load and cost of spacecraft.”
Yao explains in Sci News that his team achieved its goal of proving that lunar soil can create extraterrestrial photosynthesis and provide the energy and materials to support human life on the Moon. There is some bad news – the natural process of lunar photosynthesis is slow and not very efficient. Yao proposes that this can be greatly improved by “melting the lunar soil into a nanostructured high-entropy material.” That would make it a better photosynthetic catalyst but requires bringing more fuel and materials. But … it can be done.
Which brings us back to the concerns about bringing alien life forms, viruses, Earth-destructive diseases and other dangerous carry-ons from the Moon, Mars, asteroids and beyond. The cat (catalyst?) is already out of the bag with samples of lunar and asteroid soil already on Earth and under study. While no life has been found and no harm done (that we know of), does this discovery of lunar photosynthesis mean we may have to look closer at extraterrestrial samples for hidden abilities to create zero energy consumption life support systems for alien life forms? Could life form on other planets without the need for growing plants for food or converting CO2 into oxygen? On the other hand, what does this say about the search for extraterrestrial intelligence by looking for evidence of methane? Can a planet create methane without organic life via extraterrestrial photosynthesis?
The search for life on other worlds – like life itself – is complicated.