astroengine writes "Almost every month we see news dispatches from the Mars where the nuclear-powered rover Curiosity finds water-bearing minerals in rocks and other circumstantial clues that the Red Planet could have once supported life. But in terms of finding direct evidence of past or present Martians, the rover barely scratches the surface, says geochemist Jan Amend of the University of Southern California. Using Earth life as an example, some species of microbes live miles below the surface, without sunlight or oxygen, metabolizing chemicals that are the result of radioactive decay. Most intriguing of all is the microbe Desulforudis Audaxviator that dwells nearly two miles down, a life form that would feel right at home inside Mars' crust. 'This organism has had to figure out everything on its own,' says Amend, 'it splits water into hydrogen and oxygen for metabolism.' Amend hopes to drop probes deep underground in some of the world's most inhospitable locations over the next few years, creating a possible analog for future Mars subsurface studies."