In the search for life on Mars, are robots nearing their limits?

March 1, 2017 --Is there – or was there ever – life on Mars? NASA has spent decades investigating the question with orbiters and rovers, including its upcoming Mars 2020 rover, but at least one scientist suspects he already knows the answer. According to Gibert Levin, NASA probably detected microbial life on Mars in 1976. Dr. Levin was one of the scientists involved with the Viking lander, whose biological experiments gave conflicting results when samples tested positive for metabolism but negative for organic molecules. The unreliable organic molecule experiment was the one that failed, and the metabolism detection succeeded.