Searching for life on Mars in the snow and ice

The surface of Mars is extremely cold, irradiated, and desiccated. But at one time, the planet was much warmer and wetter, with flowing water, lakes, and even an ocean covering most of its northern hemisphere. Because of this, scientists speculate that life may have emerged on Mars billions of years ago and could still be there today. Ever since the Viking 1 and 2 missions landed on the surface in 1976, the search for evidence of past (and maybe present) life has been ongoing.