Did Viking missions see life on Mars? New Scientist

A claim that NASA overlooked evidence of life on Mars in data collected by the Viking missions 25 years ago has been met with interest and scepticism. Joseph Miller, a visiting professor at the University of Southern California, re-analysed data collected by probes sent to the Martian surface by the Viking 1 and 2 spacecraft in 1976. He believes tests performed on soil samples reveal a cycle of chemical activity similar to the daily rhythms seen in living organisms on Earth.