The detectives trying to unlock the mystery of whether life ever existed on Mars have uncovered a new clue that they believe will help solve the cold case.
For more than three decades, it's been widely accepted that the red planet is lifeless. That belief is largely based on results from two 1976 Viking landers which tested Mars soil samples and found no evidence for carbon-based molecules, the building blocks of life.
"That's the start if you think of it as a mystery story, something from the opening scenes of CSI," said Chris McKay, a research scientist with NASA's Ames Research Center in California.
"The first scene is Viking, 1976. NASA spends a lot of money to send an instrument to Mars to characterize organisms we're sure are there, and they aren't. It finds nothing."
Scientists were mystified and have continued to be for 35 years. Even if life had never existed on Mars there should still be some evidence of organic compounds -- even meteors that fall to Earth contain organic material, McKay told CTV.ca.
But it turns out Viking may have found something after all.
In 2008, the Phoenix Mars Lander reached its destination and began collecting and testing samples. Phoenix found perchlorate, a chemical that contains chlorine, in samples taken in the planet's so-called arctic region.
This was unexpected, and McKay and his colleagues became suspicious that maybe there was more to the original Viking findings than previously thought.
So they travelled to the Atacama Desert in Chile, a region with conditions thought to be similar to Mars, where McKay and others have been carrying out simulation tests for a decade.
They took soil samples from the desert, mixed them with perchlorate, and applied heat-- with fascinating results.
"We expected the perchlorate to destroy the organics, which it did, but something else came out, somewhat of a surprise," McKay said.
In addition to destroying the organic compounds, the experiment also formed methyl chloride -- an organic compound that contains chlorine and organics.
This gas was also detected when Viking cooked Martian soil samples in its oven back in the 70s but the result was attributed to contamination.
The scientists now had a "smoking gun."
"All of a sudden we had a clue to help us look back and solve the cold case of the missing organics on Mars," McKay said, suggesting the finding means that not only perchlorate, but also organics, were in place at both Viking landing sites.
"It's like when you find the missing piece of the jigsaw puzzle and then it all comes together," he said
McKay said the gas only showed up in tests conducted on Mars, with Martian soil sample in Viking's oven. It didn't show up in tests conducted en route to the red planet, casting doubt on the original theory that methyl chloride was the result of contamination from the probe itself.
McKay is clearly excited about the finding, but he cautioned that it represents more of a signpost for the future direction of the search for life on Mars, than evidence of life itself.
"(This) does not say that Mars has life or ever had life, but what it does mean is we now have a much better way of searching for evidence of life," he said.
Scientists typically search for evidence of life by looking for biological organic molecules such as DNA. Until now, they believed Mars had no organics, and were at a loss as to how to carry out further searches.
Now, with the launch of the next Mars probe set for 2011, scientists can search for organics with renewed expectations and more advanced techniques that will protect any organics from being destroyed, as they were with the Viking.
"I think the popular jargon is this is a game-changer and it means there's going to be a much bigger emphasis on organics detection on Mars," McKay said.
"We're going to stop taking pictures of rocks and start looking for organics."
McKay and his colleague, Rafael Navarro-Gonzalez of the National Autonomous University of Mexico, will be co-investigators of the 2011 probe.
Navarro Gonzales was the lead author of a study co-written with McKay on the results of the Chile experiments.
Author: Andy Johnson | Source: CTV News [September 12, 2010]