posted 01-07-2011 06:24 PM               

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."

posted 04-13-2012 06:34 AM               

Researchers crunched raw data collected during runs of the Labeled Release experiment, which looked for signs of microbial metabolism in soil samples scooped up and processed by the two Viking landers. General consensus of scientists has been that the experiment found geological, not biological, activity.

The new study took a different approach. Researchers distilled the Viking Labeled Release data, provided as hard copies by the original researchers, into sets of numbers and analyzed the results for complexity. Since living systems are more complicated than non-biological processes, the idea was to look at the experiment results from a purely numerical perspective.

They found close correlations between the Viking experiment results' complexity and those of terrestrial biological data sets. They say the high degree of order is more characteristic of biological, rather than purely physical processes.

posted 07-12-2018 12:21 PM               

The variety of organic molecules that Curiosity recently discovered on the Red Planet included chlorobenzene. This molecule is created when carbon molecules burn with perchlorate, so scientists suspect that it could have been created when the soil samples were burnt, according to New Scientist.

Researchers were inspired by this indirect evidence to dig a little deeper and find more evidence that the Viking landers could have found and then destroyed organics. In a new study, published in June in the Journal of Geophysical Research: Planets, Melissa Guzman of the LATMOS research center in France, McKay and a handful of collaborators revisited the Viking lander data to see if anything was missed.

This team found that the Viking landers also detected chlorobenzene, which the researchers said could have formed from burning organic material in the soil samples.

Still, this is not proof that the Viking landers found organic molecules and then accidentally burned them, the researchers told New Scientist. Even the scientists who completed this investigation are divided.