As Mars’s atmosphere thinned and its surface became cold, dry and irradiated billions of years ago, any surviving microbial life may have found its last refuge underground. Yet the environments most c

A recent scientific review suggests that if microbial life ever existed on Mars, it likely retreated underground to escape the planet's harsh, irradiated surface. Researchers are now evaluating how different depths and geological environments might have served as potential refuges for ancient life.