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The physics of the sands of Mars

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  • derhexer@aol.com
    URL to an article from NASA http://science.nasa.gov/headlines/y2005/31jan_sandsofmars.htm?list1051868 First few paragraphs January 31, 2005: Imagine this
    Message 1 of 2 , Jan 31, 2005
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      URL to an article from NASA
      http://science.nasa.gov/headlines/y2005/31jan_sandsofmars.htm?list1051868

      First few paragraphs
      "January 31, 2005: Imagine this scenario. The year is 2030 or thereabouts.
      After voyaging six months from Earth, you and several other astronauts are the
      first humans on Mars. You're standing on an alien world, dusty red dirt beneath
      your feet, looking around at a bunch of mining equipment deposited by
      previous robotic landers.

      Echoing in your ears are the final words from mission control: "Your mission,
      should you care to accept it, is to return to Earth--if possible using fuel
      and oxygen you mine from the sands of Mars. Good luck!"

      It sounds simple enough, mining raw materials from a rocky, sandy planet. We
      do it here on Earth, why not on Mars, too? But it's not as simple as it
      sounds. Nothing about granular physics ever is.

      Granular physics is the science of grains, everything from kernels of corn to
      grains of sand to grounds of coffee. These are common everyday substances,
      but they can be vexingly difficult to predict. One moment they behave like
      solids, the next like liquids. Consider a dump truck full of gravel. When the truck
      begins to tilt, the gravel remains in a solid pile, until at a certain angle
      it suddenly becomes a thundering river of rock.

      Understanding granular physics is essential for designing industrial
      machinery to handle vast quantities of small solids--like fine Martian sand.

      The problem is, even here on Earth "industrial plants don't work very well
      because we don't understand equations for granular materials as well as we
      understand the equations for liquids and gases," says James T. Jenkins, professor
      of theoretical and applied mechanics at Cornell University in Ithaca, N.Y.
      "That's why coal-fired power plants operate at low efficiencies and have higher
      failure rates compared to liquid-fuel or gas-fired power plants."

      So "do we understand granular processing well enough to do it on Mars?" he
      asks.

      Let's start with excavation: "If you dig a trench on Mars, how steep can the
      sides be and remain stable without caving in?" wonders Stein Sture, professor
      of civil, environmental, and architectural engineering and associate dean at
      the University of Colorado in Boulder. There's no definite answer, not yet. The
      layering of dusty soils and rock on Mars isn't well enough known.






      [Non-text portions of this message have been removed]
    • raybell_scot
      ... steep can the ... Sture, professor ... associate dean at ... not yet. The ... Surely it s actually EASIER than on Earth... after all, the gravity is lower
      Message 2 of 2 , Feb 2, 2005
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        --- In sciencefictionclassics@yahoogroups.com, derhexer@a... wrote:
        > Let's start with excavation: "If you dig a trench on Mars, how
        steep can the
        > sides be and remain stable without caving in?" wonders Stein
        Sture, professor
        > of civil, environmental, and architectural engineering and
        associate dean at
        > the University of Colorado in Boulder. There's no definite answer,
        not yet. The
        > layering of dusty soils and rock on Mars isn't well enough known.

        Surely it's actually EASIER than on Earth... after all, the gravity
        is lower (less risk of cave-ins), and there is considerably less
        moisture about (though this might not be the case deep underground
        of course), meaning less risk of landslides.
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