Arthur J. Villasanta – Fourth Estate Contributor
Washington, DC, United States (4E) – There might have been some form of living microorganisms on Mars billions of years ago and the descendants of these things might still be alive.
NASA last week announced its Curiosity Mars rover had found new evidence preserved in rocks that suggests Mars might have supported ancient life. It also said it had found new evidence in the Martian atmosphere that relates to the search for current life on the Red Planet. These findings are a good sign for future missions exploring the planet’s surface and subsurface but aren’t necessarily evidence of life itself.
The new findings consists of the discovery of “tough” organic molecules in three-billion year-old sedimentary rocks near the surface, as well as seasonal variations in the levels of methane in the atmosphere.
Organic molecules contain carbon and hydrogen, and might also include oxygen, nitrogen and other elements. While commonly associated with life, organic molecules also can be created by non-biological processes and are not necessarily indicators of life.
“With these new findings, Mars is telling us to stay the course and keep searching for evidence of life,” said Thomas Zurbuchen, associate administrator for the Science Mission Directorate at NASA Headquarters, in Washington. “I’m confident that our ongoing and planned missions will unlock even more breathtaking discoveries on the Red Planet.”
“Curiosity has not determined the source of the organic molecules,” said Jen Eigenbrode of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who is lead author of one of the two new papers published in the journal, Science. “Whether it holds a record of ancient life, was food for life, or has existed in the absence of life, organic matter in Martian materials holds chemical clues to planetary conditions and processes.”
There is clear evidence that Mars’ climate in the distant past allowed liquid water — an essential ingredient for life as we know it — to pool at the surface. Data from Curiosity reveal that billions of years ago, a water lake inside Gale Crater held all the ingredients necessary for life, including chemical building blocks and energy sources.
“The Martian surface is exposed to radiation from space. Both radiation and harsh chemicals break down organic matter,” said Eigenbrode. “Finding ancient organic molecules in the top five centimeters of rock that was deposited when Mars may have been habitable, bodes well for us to learn the story of organic molecules on Mars with future missions that will drill deeper.”
In the second paper, scientists describe the discovery of seasonal variations in methane in the Martian atmosphere over the course of nearly three Martian years, or almost six Earth years. This variation was detected by Curiosity’s Sample Analysis at Mars (SAM) instrument suite.
Water-rock chemistry might have generated the methane, but scientists cannot rule out the possibility of biological origins. Methane previously had been detected in Mars’ atmosphere in large, unpredictable plumes. This new result shows that low levels of methane within Gale Crater repeatedly peak in warm, summer months and drop in the winter every year.
“This is the first time we’ve seen something repeatable in the methane story, so it offers us a handle in understanding it,” said Chris Webster of NASA’s Jet Propulsion Laboratory, lead author of the second paper.
Finding methane in the atmosphere and ancient carbon preserved on the surface gives scientists confidence that NASA’s Mars 2020 rover and ESA’s (European Space Agency’s) ExoMars rover will find even more organics, both on the surface and in the shallow subsurface.
“Are there signs of life on Mars?” said Michael Meyer, lead scientist for NASA’s Mars Exploration Program, at NASA Headquarters. “We don’t know, but these results tell us we are on the right track.”
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