Search for Life on Mars a Top Priority for Robot Probes, Scientists Say (Charles Q. Choi)

Nov. 11, 2010 (Space.com) -- The first and only attempts to search for life on Mars were the Viking missions launched in 1975. Now scientists are suggesting the next decade of robotic probes sent to the Red Planet should make the search for life the highest priority.

After the Viking missions, the general consensus was that cold, radiation, hyper-aridity and other environmental factors ruled out the chances for microbial activity on or near the surface of Mars. This assumption -- based largely on how Viking's instruments did not detect organic compounds that would have indicated Martian life -- has been reinforced by each follow-up mission since then.

The Mars Science Laboratory, scheduled for launch in 2011, is dedicated to searching for evidence that the Martian environment was once capable of supporting life on the Red Planet. However, some scientists argue the strategy for Mars exploration should center on the search for life itself -- "extant" life that is either active today or is dormant but still alive.