Overview

• Recent papers in the International Journal of Astrobiology provide evidence that cosmic rays penetrating subsurface water or ice on Europa, Enceladus, and Mars can drive radiolysis reactions energetic enough to sustain microbial metabolism.
• Computer simulations led by NYU Abu Dhabi’s Center for Astrophysics and Space Science quantify how varying cosmic-ray intensities trigger radiolysis across these cold worlds, building on laboratory results from single-ice-grain experiments.
• Europa and Enceladus emerge as prime radiolytic habitats due to their thick ice shells and underlying oceans, while Martian subsurface ice also shows potential as an energy source in the absence of sunlight.
• The radiolysis process splits water molecules and releases electrons that could fuel microbial life, offering an alternative to sunlight or geothermal heat in environments formerly deemed uninhabitable.
• Authors advocate redefining the traditional Goldilocks Zone to include cold, irradiated subsurface reservoirs under a Radiolytic Habitable Zone concept and recommend that future mission designs target chemical byproducts of cosmic-ray interactions beneath planetary ice.