One bug with a complicated name has a very simple diet - just radioactive uranium and cosmic rays, not light, oxygen and carbon that build up life on Earth.
Meet the bacterium Desulforudis audaxviator. It was discovered 2.8kms beneath a gold mine in South Africa, without a shred of the requirements for photosynthesis. Once they found it, scientists wondered what really created that life, according to a study published by the Royal Society.
"It really grabbed my attention because it's completely powered by radioactive substances," publisher of the findings, Dimitra Atri, told Science Alert. "Who's to say life on other worlds doesn't do the same thing?", Atri adds.
The Desulforudis audaxviator survives on the sulfur and water molecules around it, through rocks broken up by radiation. Not radioactive materials but galactic cosmic rays from supernovas keep it alive.
"The great thing about environmental genomics is that it has made it possible to form a much more complete picture of microscopic life everywhere on Earth, instead of being limited to the very small proportion of bugs" - microorganisms, that is - "that can be cultured in the lab," says Dylan Chivian of Berkeley Lab's Physical Biosciences Division (PBD), lead author of the Science paper. "Almost all organisms live in communities with subdivided roles within their ecosystems. By extracting DNA from environmental samples, the various players in these microbial communities and the abilities of their dominant members can be identified, even if complete genomes of most of them are impossible to sort out."
What does that portend for life in the universe? If the bacterium can live on radioactive byproducts then why can't alien life live on cosmic radiation?
Even lunar life might be able to live on cosmic rays, if water and a heat are made available. Cosmic radiation levels rather like those on Mars would impact Desulforudis audaxviator.
However, the theory was debunked by NASA astrobiologist Chris McKay. He said: "The energy itself is so small, and because of the high radiation, the organism would have to spend a lot of energy repairing damage from radiation. It uses a lot of its energy in this process".
