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Flowing Water On Mars' Surface May Just Be Rolling Sand Instead (theverge.com)

Posted by BeauHD on from the anti-climatic dept.

Two years ago, NASA made a big splash when it announced the discovery of flowing water on the surface of Mars. Unfortunately, according to new research from the U.S. Geological Survey, the surface features that NASA thought were made up of liquid water may actually be flowing grains of sand instead. The Verge reports: The features in question are dark streaks that show up periodically on Martian hills, known as recurring slope lineae, or RSLs. When one of NASA's spacecraft, the Mars Reconnaissance Orbiter, studied these lines more closely, it found that the RSLs were made up of hydrated salts -- meaning they were mixed with water molecules. At the time, NASA thought that was significant evidence that flowing liquid water caused these bizarre streaks. But researchers at the USGS say these features look identical to certain types of slopes found on sand dunes here on Earth. Those slopes are caused by dry grains of sand flowing downhill, without the help of any water. It's possible the same thing is happening on Mars, too. Since liquid water is key for life here on Earth, many thought these strange lines of flowing water may help support life on the Martian surface. But now these RSLs may not be the best place to look for life anymore.

6 of 81 comments (clear)

  1. Flowing liquid water was never that plausible by drinkypoo · · Score: 4, Insightful

    Given the atmospheric pressure, and the temperature, it was highly unlikely that they had any flowing liquid water anyway.

    --
    "You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
    1. Re:Flowing liquid water was never that plausible by doctorvo · · Score: 5, Interesting

      Liquid brines are not only plausible under Martian conditions, they have been reproduced experimentally.

      Given the presence of large amounts of calcium perchlorate (eutectic point -74C), there are almost certainly liquid reservoirs of brine somewhere on Mars, the only question is how big they are and where/when they are exposed to the surface.

    2. Re:Flowing liquid water was never that plausible by phayes · · Score: 3, Informative

      This Ars Technica article was much more informative than the cited sources.

      Brines evaporating should have left detectable level of salt deposits which we are not seeing.

      That said, if it is sand, we should also be seeing a build-up of these darker sands at the bottom of the slopes which we are not seeing either.

      Clearly we are missing something that a visit would resolve.

      --
      Democracy is a sheep and two wolves deciding what to have for lunch. Freedom is a well armed sheep contesting the issue
    3. Re:Flowing liquid water was never that plausible by Mr+D+from+63 · · Score: 3, Insightful

      There is clearly (and understandably) a desire in the scientific community to find as much evidence of water on mars as possible. More water means higher chance of life and better chance of human colonization support. I think its possible the scientific community was biased toward a water flow explanation, or possibly that's just the one the media stuck to. Did they work as hard to prove other explanations? I'm not sure they did, but this story is evidence that they are doing just that.

  2. Re:That's science by Anonymous Coward · · Score: 5, Funny

    We've been going Antarctica for over a century now, and we have yet to set up a remotely self-sufficient Colony there. And it has things that Mars lacks, like Water, an Atmosphere, a warmer Climate, and Polar Bears... well... Penguins actually. What does Mars have? Lots of Sand, and no Magnetic Field to divert slightly greasy Solar Atoms.
    Which brings up the fact that Penguins are largely self-sufficient and happy there. They may not fly much, and their diet is limited, and on top of that, they have Penguin Breath. But we can learn a lot from them. They go for months without eating, they are warm enough, and they seem to quite enjoy Penguin Sex... even with all that Halitosis. Sociologically, Emperor Penguin Daddies babysit while the Girls have a Season Out. This is not as hedonistic as it would appear, since Emperor Penguins mate for life. They have fine Family Values.
    I do wish that the Space Nutters would stop reading crappy Science Fiction and dream of nailing Podkayne on Mars. Antarctica is perfect for them. In fact, it could be a Libertarian Paradise. Antarctica has no Taxes, no Police, and not even a Currency. They could have their own Monetary System, based on the Frostbitcoin.
    And it's White. Very, very White.

  3. this isn't news by doctorvo · · Score: 4, Interesting

    People already knew that sand/dust can cause similar features. They believed (and still believe) that this is indicative of flowing water because of seasonality, temperatures, and association with hydrated minerals. We won't know for certain until we observe flowing water more directly, of course.