In a recent opinion piece in Scientific American, former Viking Mars investigator Gil Levin fired up anew the argument over whether that mission did in fact discover Martian life in the 1970s, and whether we can now say there’s a conclusive case for life on the Red Planet.
He bases his case primarily on the results of Viking’s Labeled Release Experiment, for which he was the principal investigator. The experiment was designed to detect carbon dioxide in the Martian soil as a result of microbial metabolism. After Viking collected the soil, it was “spiked” with a set of organic nutrients, including amino acids. The measurements observed on Mars were roughly consistent what you would expect if life were present. However, most scientists later concluded that the released carbon dioxide was more likely due to inorganic reactions of the chemically reactive Martian soil.
Mars is drier than the driest desert on Earth, so any Martian microbe would have to be adapted to those conditions. I suspect that too much water was added during the life detection experiments, possibly putting the Martians under osmotic shock and practically “drowning” them in their first encounter with humankind!
Read full, original post: The Debate Over Whether We’ve Already Found Life on Mars, Continued