  There is growing evidence suggesting the presence of aqueous environment on
ancient Mars, raising the question of the possibility of life in such an
environment. Subsequently, with the erosion of the Martian atmosphere resulting
in drastic changes in its climate, surface water disappeared, shrinking
habitable spaces on the planet, with only a limited amount of water remaining
near the surface in form of brines and water-ice deposits. Life, if it ever
existed, would have had to adapt to harsh modern conditions, which includes low
temperatures and surface pressure, and high radiation dose. Presently, there is
no evidence of any biological activity on the planet's surface, however, the
subsurface environment, which is yet to be explored, is less harsh, has traces
of water in form of water-ice and brines, and undergoes radiation-driven redox
chemistry. I hypothesize that Galactic Cosmic Ray (GCR)-induced
radiation-driven chemical disequilibrium can be used for metabolic energy by
extant life, and host organisms using mechanisms seen in similar chemical and
radiation environments on Earth. I propose a GCR-induced radiolytic zone, and
discuss the prospects of finding such life with Rosalind Franklin rover of the
ExoMars mission.
