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| Dormant desert life hints at possibilities on Mars | |
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| Tweet Topic Started: 27 Feb 2018, 02:54 AM (84 Views) | |
| skibboy | 27 Feb 2018, 02:54 AM Post #1 |
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26 February 2018 Dormant desert life hints at possibilities on Mars ![]() © NATURE PUBLISHING GROUP/AFP/File | Current Mars, red, dead and dry on the left contrasts with the same landscape covered in water, early in the planet's history, more than three billion years ago MIAMI (AFP) - It may rain once a decade or less in South America's Atacama Desert, but tiny bacteria and microorganisms survive there, hinting at the possibility of similar life on Mars, researchers said Monday. The desert, which spans parts of Chile and Peru, is the driest non-polar desert on Earth and may contain the environment most like that of the Red Planet, said the report in the Proceedings of the National Academy of Sciences. Lead researcher Dirk Schulze-Makuch, a professor and planetary scientist at the Technical University of Berlin, and colleagues took a trip to the desert in 2015 to learn more about what kind of life might exist there. Then, unexpectedly, it rained. Scientists detected an explosion of biological activity in the soil, and quickly began using sterile spoons to scoop up samples. Genomic analyses helped identify the several apparently indigenous species of microbial life -- mostly bacteria -- that had somehow adapted to live in the harsh environment by lying dormant for years, then re-animating and reproducing once it rained. - Water, source of life - "In the past, researchers have found dying organisms near the surface and remnants of DNA, but this is really the first time that anyone has been able to identify a persistent form of life living in the soil of the Atacama Desert," Schulze-Makuch said. "We believe these microbial communities can lay dormant for hundreds or even thousands of years in conditions very similar to what you would find on a planet like Mars and then come back to life when it rains." Scientists returned to the Atacama in 2016 and 2017 for follow-up visits, and discovered that the same microbial communities in the soil were gradually reverting to their dormant state. But they did not completely die off. Single-celled organisms, found mainly in the deeper layers of the desert, "have formed active communities for millions of years and have evolved to cope with the harsh conditions," said the PNAS report. Since Mars had oceans and lakes billions of years ago, researchers say early life forms may have thrived there, too. The world's space agencies are sending robotic vehicles to Mars in a bid to uncover signs of life, but any attempt to return samples to Earth will be costly and complicated. Schulze-Makuch said the research may help scientists home in on ways to study Martian microbes, which might have evolved to the planet's colder, drier climate over time, much like the Atacama microbes. "We know there is water frozen in the Martian soil and recent research strongly suggests nightly snowfalls and other increased moisture events near the surface," he said. "If life ever evolved on Mars, our research suggests it could have found a subsurface niche beneath today's severely hyper-arid surface." Source: .com
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| skibboy | 28 Feb 2018, 01:31 AM Post #2 |
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Atacama's lessons about life on Mars By Jonathan Amos BBC Science Correspondent 8 hours ago ![]() The Atacama has been in a hyperarid state for millions of years Even in the driest places on Earth there is life eking out an existence, it seems. Scientists have examined the soils in those parts of the Atacama desert that may not see any rains for decades. Still, the team led from the Technical University of Berlin, Germany, found evidence of microbes that have adapted to the extreme conditions. These hardy organisms are of interest because they may serve as a template for how life could survive on Mars. "All the stresses you have in the Atacama, you have on Mars, too - just a little tick more," TU Berlin's Dr Dirk Schulze-Makuch told BBC News. So, as well as super-aridity that means even higher levels of ultraviolet radiation and soils that are loaded with salts. Dr Schulze-Makuch's team sampled a range of sites in the South American desert - from those places that get a regular wetting from fogs to those where precipitation of any form is extremely rare. ![]() The Atacama's similarities to Mars mean it is used as a location to film sci-fi movies As luck would have it, the scientists turned up in 2015 just a month after one of the celebrated freak rain events. Perhaps not surprisingly given the presence of water, the team detected metabolising microbes in the heart of the Atacama. And then, equally unsurprisingly, the researchers saw the level of that activity decline sharply in the following two years as conditions dried out. "Some have argued that what you're seeing is simply organisms that have blown in on the wind - that what you're seeing is just the remnants of cells and DNA of these organisms as they are dying. "But what we found from our genomic analysis is that there are organisms in the ground that have adapted to high UV radiation, to high salt concentrations," Dr Schulze-Makuch explained. In other words, these microbes are indigenous. And when the water comes they become active; and when the water goes, many will obviously die but a good number will go into a dormant state to await the next precipitation event. ![]() Mars wasn't always so dry: Billions of years ago it had a lot of water This could be how life persists on Mars today - if ever it was there in the first place, said Dr Schulze-Makuch. "About four billion years ago, there was a lot of water on Mars; you even had oceans. And then it got drier and drier. "But even nowadays you have these moisture events. You get fog there; you have even nightly snow storms; and there are these 'recurring slope lineae', which are these briny flows near the surface. Water will also form around minerals. "Think about microbes - for them a little puddle is an ocean. So if they have only just a little bit of water, it may be enough for them." The team cannot say how long the dormant Atacama species can survive without coming into contact with water, but it could be hundreds or even thousands of years, the scientists think. Dr Schulze-Makuch's group is about to return to the desert to follow up on their sampling locations. Their study is published in the Proceedings of the National Academy of Sciences. Source: .com
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