A bizarre organism that lives nearly 2 miles underground and eats food produced through radioactive decay might just thrive through a nuclear holocaust-- and possibly survive on other worlds elsewhere in the universe, too.
The bacterium Desulforudis audaxviator was first discovered in 2008 in samples of groundwater from beneath the Mponeng gold mine in South Africa. It's like nothing else found anywhere on Earth. In fact, within it's ecosystem-- which is within 140 degree groundwater miles beneath the surface-- it lives alone. No other organism has been found there. For food, it consumes energy from the radioactive decay of uranium in the rocks around it.
"This very deep subterranean mine [in South Africa] has water leaking through cracks that contain radioactive uranium," explained principal investigator Douglas Galante, to the Brazilian news agency FAPESP. "The uranium breaks down the water molecules to produce free radicals. The free radicals attack the surrounding rocks, especially pyrite, producing sulfate. The bacteria use the sulfate to synthesise ATP [adenosine triphosphate], the nucleotide responsible for energy storage in cells."
"This is the first time an ecosystem has been found to survive directly on the basis of nuclear energy," he added.
This organism is so strange that researchers are now studying it as a possible model for extraterrestrial life, especially on worlds far away from the life-giving energy of a star.
One place where we might find aliens that are similar to Desulforudis audaxviator is right here in our own solar system: Jupiter's moon Europa. Previously, scientists have looked to organisms that live along hydrothermal vents as analogues to what we might find on Europa, which is an ocean world covered in a layer of ice that is also suspected of having hydrothermal vents. But there's a problem with this model; hydrothermal organisms here on Earth still rely on oxygen that is produced by other organisms closer to the surface.
Desulforudis audaxviator, however, lives in a far more isolated system. They get everything they need from the process of radioactive decay. Scientists also believe there is plenty of radioactive material on Europa to support this kind of life without having to posit a larger ecosystem.
Just the fact that life can survive on nuclear energy is pretty incredible. It proves that life, when given a foothold, can find a way to survive in even the harshest and most unlikely of places. The universe might be teeming with organisms like Desulforudis audaxviator. At the very least, these bacteria greatly expand our understanding of what is possible when it comes to habitable conditions for life throughout the cosmos.