John Priscu knows that microbes can live in the toughest environments, including two miles below the Antarctic ice in one of the coldest, deepest and darkest points on Earth. If life can thrive down there, Priscu believes, then chances are good that it can also thrive on the dry, cold surface of Mars. Priscu’s ongoing study of the Vostok ice in Antarctica has earned him a spot on a National Research Council that is looking for ways to prevent the contamination of Mars due to human exploration.