On second thought, there may be life on Mars after all.
A new analysis by an international team of scientists revealed that soil samples collected 36 years ago contained properties which indicate extraterestial microbes were indeed present. The samples were initally collected by NASA's Viking rovers and put through a series of tests called the Labeled Release experiments to see if certain byproducts of life processes, such as respiration, can be detected. The results at that time, while promising, were complicated by a number of problematic factors, mainly the possibility of contamination.
For instance, while those experiments turned up a pair of organic chlorine compounds known as chloromethane and dichloromethane, the molecules also happened to be common in earthly chemicals such as the cleaning fluid used by the Mars rovers. And with even the mere off-chance that they were introduced into the samples by an earthly source was enough to render the results inconclusive.
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But the authors of the new study, published online in the International Journal of Aeronautical and Space Sciences, used an entirely different approach known as complexity analysis. Instead of trying to make an assessment based solely on the presence of native compounds, they translated the data into sets of numbers to determine if whatever was present in the samples exhibited the same high degree of complexity that's typically found with living systems on earth. If the numerical data matched up, then, as the reasoning goes, it's safe to conclude that there's a very high statistical likelihood that some kind of living form was residing in that patch of dirt.
"Control responses that exhibit relatively low initial order rapidly devolve into near-random noise, while the active experiments exhibit higher initial order which decays only slowly," the paper states. "This suggests a robust biological response."
Although the logic makes intuitive sense, some detractors have argued that the technique still hasn't proved to be reliable even when it comes to comparing living and non-living systems on Earth.
"Ideally, to use a technique on data from Mars, one would want to show that the technique has been well-calibrated and well-established on Earth. The need to do so is clear; on Mars we have no way to test the method, while on Earth we can," planetary scientist and astrobiologist Christopher McKay, with NASA's Ames Research Center in Moffett Field, Calif., told Discovery News.
Still, Joseph Miller, a neuropharmacologist at the University of Southern California's Keck School of Medicine and one of the authors of the study, feels pretty confident in the team's conclusions.
He tells Discovery News: "On the basis of what we've done so far, I'd say I'm 99 percent sure there's life there."
(via Discovery News)
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