Microbes could be a key partner in humanity’s quest to extend its footprint beyond Earth.
The bacteria have successfully extracted resources from rocks in microgravity and simulated Martian gravity, suggesting that “biomining” has real potential to help settlement outside the Earth, a new study reports.
Biomining is an established practice here on Earth; microbes help catalyze the extraction of copper and gold from rocks, for example. But it is unclear how well such organisms could function on Mars, the moon or an asteroid, given the very different gravity conditions of these cosmic locations.
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The new study sheds light on the issue. It reports the results of BioRock, a European Space Agency experiment that operated for three weeks on the International Space Station in the summer of 2019.
BioRock tested the ability of three bacterial species – Sphingomonas desiccabilis, Bacillus subtilis and Cupriavidus metallidurans – to filter rare earth elements (REEs) from rocks under conditions of microgravity and gravity on Mars.
REEs (which initially seemed scarce here on Earth, hence the misleading name) are a set of 17 elements that are key components in many electronic devices and important in the production of a variety of metal alloys, thanks to their unique catalytic and magnetic properties .
In the BioRock experiment, which flew to the space station aboard a SpaceX Dragon cargo capsule, the researchers measured the efficiency with which the three bacterial species leached 14 different REEs from the basaltic rock into small “bioreactors” customized. This type of rock was consciously chosen; Basalt, which forms from cooled lava, is common on the Moon, Mars, and Earth.
B. subtilis (a resistant species commonly used in space experiments) showed a reduced ability to bioleach under low gravity conditions and C. metallidurans did no better than the non-biological controls on the ground. But S. desiccabilis was able to extract REEs well in all three gravity conditions, the scientists found.
“We were surprised that there was no significant effect of the different gravity on biomining, as microgravity is known to affect fluid behavior,” study co-lead author Charles Cockell, of the Kingdom’s Center for Astrobiology Kingdom at the University of Edinburgh in Scotland, he told Space.com via email.
“However, we think it could be because the microbes have had enough time to interact with the rocks,” Cockell said. “It also shows that biomination can be performed in different gravities, such as on asteroids, the moon or Mars.”
And meaningful and operational biomining could likely be done in space with an enlarged version of the reactor used by the BioRock team, he added.
“You would probably want to modify it, such as mixing the fluid and crushing the rock to improve its accessibility to microbes, but the basic idea would be the same,” Cockell said.
Establishing permanent and sustainable human settlements on the Moon, Mars and beyond will require “living off the earth” to the greatest extent possible, experts point out. The new study suggests that microbes could help make that vision a reality, but not quite yet, as there is still work to be done.
“I think we should continue to explore the types of microbes that would give us the best results in extracting useful elements from materials found in space, such as asteroids, the moon and Mars, and we should continue to develop the technology for the optimizing these types of biologically enhanced industrial processes in space, “Cockell said.
The potential applications of the new findings are not limited to space settlements either.
After all, S. desiccabilis showed up in the simulation of Mars gravity, “indicating the production of a potential biological signature under altered gravity, with implications, for example, for additional methods for testing the hypothesis of life on Mars”, Cockell , co-lead author Rosa Santomartino (also of the British Center for Astrobiology) and their colleagues wrote in the new study, which was published online today (10 November) in the journal Nature Communications.
Mike Wall is the author of “Out There” (Grand Central Publishing, 2018; illustrated by Karl Tate), a book about the search for alien life. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or Facebook.