New investigations spearheaded by New York University Abu Dhabi suggest that radiolysis, a process triggered by Galactic cosmic rays, could serve as a feasible energy source for sustaining microbial existence within the subterranean realms of terrestrial celestial bodies like Mars, Europa, and Enceladus.
NASA’s Cassini spacecraft captured this stunning mosaic of Enceladus on October 5, 2008 as the spacecraft sped away from this geologically active moon of Saturn. Image credit: NASA / JPL / Space Science Institute.
It is a well-established fact that ionizing radiation exerts a detrimental impact on biological systems, manifesting in DNA damage, cellular disruption, and the generation of reactive oxygen species, among other deleterious effects.
Although direct exposure to substantial doses of radiation is undeniably inimical to biological processes, ionizing radiation has the capacity, and in certain circumstances is known, to yield a variety of compounds beneficial to life.
One such pathway involves the generation of life-supporting substances through radiolysis initiated by charged particles.
“Our investigation centered on the ramifications of cosmic ray impacts on subterranean water or ice,” stated Dr. Dimitra Atri of New York University Abu Dhabi, collaborating with researchers from the University of Washington, the University of Tennessee, Rice University, and the Universidad Industrial de Santander.
“These impacts induce the dissociation of water molecules, liberating minute entities known as electrons.”
“On Earth, certain microbial species possess the ability to metabolize these electrons for energy, analogous to how flora harness solar energy.”
“This phenomenon, termed radiolysis, is capable of providing sustenance for life even in environments characterized by darkness and frigid temperatures, devoid of sunlight.”
The surface of Europa looms large in this newly-reprocessed color view; image scale is 1.6 km per pixel; north on Europa is at right. Image credit: NASA / JPL-Caltech / SETI Institute.
Employing computational simulations, the scientific team assessed the energy yield achievable through this process on Mars and the icy satellites orbiting Jupiter and Saturn.
These moons, enveloped by substantial ice mantles, are hypothesized to harbor liquid water beneath their exteriors.
The findings indicated that Enceladus presented the most substantial potential for supporting life via this mechanism, followed by Mars, and subsequently Europa.
“This revelation fundamentally alters our conceptualization of potential extraterrestrial habitats,” remarked Dr. Atri.
“Rather than exclusively focusing on exoplanets possessing warmth and sunlight, we can now broaden our considerations to include frigid and dark locales, provided they possess subsurface water reserves and are subjected to cosmic radiation flux.”
“The ramifications suggest that life may be viable in a far wider array of locales than hitherto contemplated.”
This image from Mars Express’ High Resolution Stereo Camera shows the globe of Mars set against a dark background. The disk of the planet features yellow, orange, blue and green patches, all with an overall muted grey hue, representing the varying composition of the surface. Image credit: ESA / DLR / FU Berlin / G. Michael / CC BY-SA 3.0 IGO.
Within the framework of their investigation, the authors also delineate a novel concept termed the radiolytic habitable zone.
Diverging from the conventional ‘Goldilocks zone’—defined as the orbital region around a star conducive to surface liquid water—this emergent zone directs attention towards locations featuring subsurface water reservoirs energized by cosmic radiation.
Given the ubiquity of cosmic rays throughout the cosmos, this implies a significantly expanded potential extraterrestrial biosphere.
“These findings furnish valuable directives for forthcoming space exploration endeavors,” stated the research group.
“Instead of solely scrutinizing planetary surfaces for biosignatures, scientific missions might also investigate the subsurface environments of Mars and its icy moons, equipped with instruments capable of detecting chemical energy generated by cosmic radiation.”
“This research inaugurates promising new avenues in the quest for life originating beyond Earth and posits that even the most somber, frigid regions of our Solar System may harbor conditions suitable for life’s perpetuation.”
The publication detailing this research is featured in the International Journal of Astrobiology.
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Dimitra Atri et al. 2025. Estimating the potential of ionizing radiation-induced radiolysis for microbial metabolism on terrestrial planets and satellites with rarefied atmospheres. International Journal of Astrobiology 24: e9; doi: 10.1017/S1473550425100025
