A scientist has found a strange underground bug that opens the possibility of alien life thriving elsewhere in the universe.

The rod-shaped bacterium called Desulforudis audaxviator was found 2.8 kilometers beneath a gold mine in South Africa. A scientist has found that the microbe survives on byproducts of radioactive uranium, thorium, and potassium in the depths of the mine since it doesn't have access to light, oxygen, and carbon.

The discovery led to the theory that alien life might be living in uninhabitable environments in the universe, feeding on cosmic radiation to survive.

"It really grabbed my attention because it's completely powered by radioactive substances," Dimitra Atri, an astrobiologist and computational physicist from the Blue Marble Space Institute of Science in Seattle, Washington and author of the study, said in a report by Science.com.

On Earth, plants get energy from sunlight through a process called photosynthesis. Light converts water and carbon dioxide into hydrocarbons and the molecules are broken down through oxidation. Humans, animals, and other organisms feed on the plants and absorb the energy stored in them.

D. audaxviator, on the other hand, gets energy from radioactive uranium in the rocks. The radiation breaks up the sulfur and water molecules in the rocks, which the microbes easily take in as food. According to Atri, extraterrestrial life forms are likely to adopt the same system. Instead of radioactive materials beneath the planet, the microbes feed on galactic cosmic rays (GCR), which are high-energy particles that are thrown across the universe from a supernova.

After simulations based on existing data about cosmic rays, Atri found that there are enough cosmic rays to supply energy to a simple underground life on the moon, Mars, Pluto, the outer shell of Europa, and comets. However, the hypothetical alien life form should still require water, food and heat source. Atri considered Mars to have the biggest potential to host life thriving on GCR, as the planet is rocky and could likely hold liquid water.

But according to NASA astrobiologist Chris McKay, who wasn't involved in the study, such an ecosystem would find it difficult to evolve into complex, multicellular life. "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," McKay said in a report by Popular Science.

Atri aims to conduct further studies on the gold mine microbe to determine how it would respond to cosmic radiation levels similar to those on Mars and in other celestial bodies.

The research is published in the Journal of the Royal Society Interface.