By Irene Klotz
More than 30 years after NASA's Viking landers found no evidence for organic materials on Mars, scientists say a new experiment on Mars-like soil shows Viking did, in fact, hit pay dirt.
The new study was prompted by the August 2008 discovery of powerful oxygen-busting compounds known as perchlorates at the landing site of another Mars probe called Phoenix.
Scientists repeated a key Viking experiment using perchlorate-enhanced soil from Chile's Atacama Desert, which is considered one of the driest and most Mars-like places on Earth, and found telltale fingerprints of combusted organics -- the same chemicals Viking scientists dismissed as contaminants from Earth.
"Contrary to 30 years of perceived wisdom, Viking did detect organic materials on Mars," planetary scientist Christopher McKay, with NASA's Ames Research Center in California, told Discovery News. "It's like a 30-year-old cold case suddenly solved with new facts."
"If the Viking team had said 'Well, maybe there's perchlorate in the soil,' everybody would have said they're crazy -- why would there be perchlorates in the soil? It was only by having it pushed on us by Phoenix where we had no alternative but to conclude that there was perchlorate in the soil … Once you realize it's there, then everything makes sense," McKay added.
The Viking team's verdict that Mars lacked organics was the lynchpin argument against another Viking experiment that looked for signs of microbial life.