Cosmic Rays May Hold the Key to Life on Harsh Alien Worlds

For decades, the search for alien life has focused on the so-called “Goldilocks zone” — the region around a star where conditions are just right for liquid water to exist. But a new study suggests that life may not be limited to these warm, sunlit regions. Instead, it could also thrive in what scientists call the “radiolytic habitable zone” — environments where cosmic rays provide the energy needed to sustain life.

Cosmic rays are streams of highly energetic particles traveling through space at nearly the speed of light, produced by stars, supernovae, and even black holes. While Earth’s thick atmosphere shields us from most of them, worlds with thinner atmospheres, like Mars, are directly exposed. On icy moons such as Europa (Jupiter) and Enceladus (Saturn), cosmic rays could penetrate beneath the frozen surface into subsurface oceans, sparking life-sustaining chemical reactions.

According to the study, published July 28 in the International Journal of Astrobiology, cosmic rays can split water molecules underground through a process called electrolysis, releasing electrons that could fuel chemical reactions. This energy might support microbial life deep in the ice or water — hidden from the harsh, frozen surfaces above.

“Life might be able to survive in more places than we ever imagined,” said Dimitra Atri, astrophysicist at New York University Abu Dhabi and co-author of the study. “Instead of searching only for warm planets with sunlight, we can now consider cold, dark worlds with water beneath the surface — as long as they are exposed to cosmic rays.”

This groundbreaking idea expands the search for extraterrestrial life far beyond the traditional habitable zone. It suggests that even worlds considered too cold or dark could host ecosystems powered not by sunlight, but by cosmic radiation itself.