Mining companies use microbes to recover metals such as gold, copper and uranium. Now researchers suggest bacteria could be enlisted for “biomining” in space, to extract oxygen, nutrients and minerals from the moon and Mars for use by future colonists.
More than a quarter of the world’s copper is harvested from ores using microorganisms, which separate the desired material from the rock to which it is chemically bound. Geomicrobiologists Karen Olsson-Francis and Charles S. Cockell of the Open University in Milton Keynes, England, reasoned that microbes could be drafted for use on other planets as well. “It would be a way of living off the land in space,” Cockell says.
The researchers experimented with a variety of cyanobacteria, often known as blue-green algae, on analogues of lunar and Martian regolith (loose surface rock). These photosynthetic bacteria have adapted to live in some of the most extreme environments on Earth, from the cold, hyperarid Antarctic McMurdo Dry Valleys to the hot, dry Atacama Desert in Chile, suggesting they might be capable of surviving the rigors of outer space.
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To test the microbes’ mettle, Olsson-Francis and Cockell launched several species 300 kilometers into low Earth orbit and exposed them in succession to vacuum, cold, heat and radiation. The bacteria were then grown with water on different rock types, including anorthosite from South Africa (analogous to lunar highland regolith) and basalt from an Icelandic volcano (similar to lunar and Martian regolith). The scientists detail their findings in a recent issue of Planetary and Space Science.
The microbes all extracted calcium, iron, potassium, magnesium, nickel, sodium, zinc and copper from the rocks. But Anabaena cylindrica, which is used as a fertilizer in rice paddies, grew the fastest, extracted the most elements, and could withstand both lunar and Martian conditions, potentially making it the best cyanobacterium to use in space.
Using microbes for biomining has many advantages, Cockell says. Although chemicals can extract minerals from extraterrestrial regolith, microbes catalyze this extraction at much faster rates. Purely chemical systems also require large amounts of energy, which early extraterrestrial outposts will likely lack. “We will not be able to colonize the moon or Mars without development of cyanobacterial biotechnologies,” says astrobiologist Igor Brown, who did not take part in the study. Space colonization is not just for humans anymore.