For decades, scientists have believed that life—at least as we know it—requires a dependable energy source, whether from the Sun, chemical reactions, or geothermal activity.
But what if life on other planets doesn’t need any of these? What if some organisms could survive entirely on cosmic radiation?
A groundbreaking new study suggests just that: certain life forms might be able to sustain themselves using cosmic rays alone.
The idea, put forward by astrobiologist Dimitra Atri from the Blue Marble Space Institute of Science, proposes that radiation, which is often seen as a lethal force, could actually fuel alien microbes.
At first glance, it sounds like something out of science fiction.
But Earth already harbors an organism that hints at this possibility: Desulforudis audaxviator, a bacterium found 2.8 kilometers (1.74 miles) beneath South Africa’s surface.
This deep-dwelling microbe survives not on sunlight or organic matter, but on energy derived from the radioactive decay of uranium.
If something like this can exist on Earth, could similar microbes thrive on other planets, feeding on the high-energy particles constantly streaming through space?
A Counterintuitive Revelation
The idea that life can exist without sunlight is already well-established, thanks to discoveries of organisms living near hydrothermal vents in the deep ocean.
However, the notion that cosmic radiation could serve as a viable primary energy source turns a lot of conventional astrobiology on its head.
Atri’s hypothesis suggests that extraterrestrial microbes could utilize cosmic radiation in much the same way that plants use sunlight for photosynthesis.
This would mean that life might not need a thick atmosphere to shield it from radiation—in fact, a thinner atmosphere might be better, as it would allow more cosmic rays to reach the surface and sustain microbial life.
To test this idea, Atri conducted simulations of cosmic ray interactions with planetary environments such as Mars, Pluto, Europa, Enceladus, and comets.
His calculations showed that the impact of these rays on planetary surfaces could generate enough energy to power microbial life—assuming those microbes were highly specialized to tolerate radiation.
Cosmic Rays: A Lifeline or a Threat?
This is where things get tricky.
While cosmic radiation could theoretically supply energy, it is also highly destructive.
Radiation can break apart molecular bonds, causing extreme damage to biological tissues.
Any organism relying on cosmic rays would need to have an extremely slow metabolism and an efficient repair system to counteract cellular damage.
“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,” Atri told Popular Science. “
It uses a lot of its energy in this process.”
Moreover, life would require a delicate balance.
Too much radiation could overwhelm an organism’s repair mechanisms, while too little would not provide enough energy to sustain it.
Astrobiologist Duncan Forgan from the University of St Andrews agrees, noting that such life forms “want a steady flux of energy from cosmic rays, but not so much that it’s damaging.”
Implications for the Search for Alien Life
Atri’s research fundamentally shifts how we think about habitable worlds.
Until now, scientists have focused on planets with thick atmospheres, assuming that a protective shield is necessary for life.
But if organisms can thrive because of cosmic radiation, then the search for life should expand to include barren, airless environments—places we previously deemed inhospitable.
For instance, Mars, Europa, and Enceladus—all prime candidates for extraterrestrial life—have thin or nonexistent atmospheres.
Instead of searching for subsurface lakes or geothermal heat, scientists might need to look for signs of radiotrophic life in dry, rocky environments where cosmic rays freely penetrate.
A New Chapter in Astrobiology?
If Atri’s hypothesis proves correct, it could revolutionize our understanding of life’s resilience.
The idea that tiny microbes could survive on radiation alone forces us to reconsider what we mean by “habitable.”
This also opens up the possibility that life might be far more common in the universe than we ever imagined—just not in the way we expected.
“It’s funny,” Atri said in an interview with Science, “because when we look for planets that contain life currently, we look for a very thick atmosphere.
With these life forms, we’re looking for the opposite.”
If extraterrestrial microbes are indeed out there, thriving in the radiation-rich conditions of deep space, the implications would be staggering.
Not only would this expand our definition of habitable worlds, but it might also challenge the assumption that Earth’s life-supporting conditions are unique.
What’s Next?
As exciting as this theory is, it remains speculative for now.
More studies, including lab experiments and future space missions, will be needed to confirm whether cosmic rays truly can sustain life.
NASA’s upcoming missions to Europa and Mars could provide valuable insights, as they will be looking for biosignatures in extreme environments.
If confirmed, this discovery could fundamentally reshape our search for life beyond Earth.
Rather than focusing solely on worlds with liquid water and thick atmospheres, we might find that the most alien life forms of all are those that thrive in conditions we once thought were utterly uninhabitable.
