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Thread: Big Dunes On Mars

  1. #1
    Big Dunes on Mars

    Mars is kind of like Texas: things are just bigger there. In addition to the biggest canyon and biggest volcano in the solar system, Mars has now been found to have sand ripples twice as tall as they would be on Earth.

    Initial measurements of some of the Red Planet's dunes and ripples using stereo-images from the Mars Orbiter Camera onboard the Mars Global Surveyor have revealed ripple features reaching almost 20 feet high and dunes towering at 300 feet.

    One way to imagine the taller dimension of ripples on Mars is to visualize sand ripples on Earth, then stretch out the vertical dimension to double height, without changing the horizontal dimension.

    "They do seem higher in relation to ripples on Earth," said Kevin Williams of the Smithsonian National Air and Space Museum. Williams will be presenting this latest insight into the otherworldly scale of Marscapes on Monday, Nov. 3 at the annual meeting of the Geological Society of America in Seattle, WA.

    Ripples are common on Mars and usually found in low-lying areas and inside craters, says Williams. On Earth they tend to form in long parallel lines from sand grains being pushed by water or air at right angles to the ripple lines. Dunes, on the other hand, are formed when grains of sand actually get airborne and "saltate" (a word based on the Latin verb "to jump"). That leads to cusp-shaped, star-shaped, and other dune arrangements that allow materials to pile sand much higher.

    How exactly Martian dunes and ripples form is still unknown, says Williams, since the images from space give us no clues to the grain sizes or whether they are migrating or moving in any way. Though there are Viking spacecraft images from almost 30 years ago to compare with, the images do not have the resolution to confirm whether ripples have moved much in that time. For now, the dimensions of ripple-forms on Mars are the only indications of whether they are large ripples or small dunes. Williams' results came about from the advantageous combination of image parameters to get the first height measurements of these ripple-like features at the limit of image resolution.

    According to Williams, it's likely the doubled heights of Mars ripples relative to their spacing is made possible by the same thing that makes Mars' volcanoes so tall: lower gravity. With about one-third the gravity of Earth, sand, silt, and dust can theoretically stack up higher before gravity causes a slope failure.

    However, other differences could play roles in making these large piles of sand as well. "It could also be from different wind speeds, air densities or other factors," said Williams. Mars has a perennially subfreezing, very thin atmosphere in which global dust storms have been known to obscure the surface from view.

    The study of Mars dunes and ripples has been underway since Viking spacecraft images of Mars first revealed such features in the late 1970s and early 1980s, says Williams. The primary difficulty of the work continues to be in discerning the close-up details, like the exact heights of features and grain sizes. As with dunes and ripples on Earth, these wind-blown features could reveal a lot about local and regional weather and wind currents — if more was known about ripple and dune building under the very un-Earthlike conditions of Mars.

    So far the only close-encounters humans have ever had with Martian dunes were with the Viking Landers and the Pathfinder mission, which sent the Sojourner rover trundling among Martian boulders. "There were some small dunes in the area of Pathfinder," Williams said.

    There are also likely to be ripples or small dunes within range of the far more mobile Mars Exploration Rovers now enroute to the Red Planet, Williams said. The Mars Exploration Rovers, Spirit and Opportunity, are larger and will be able to travel much further than Sojourner, making it more likely they will be taking a closer look at ripples as well as other geological features of Mars.

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  2. The Drawing Room   -   #2
    Barbarossa's Avatar mostly harmless
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    why have you posted this?

  3. The Drawing Room   -   #3
    Its interresting.
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  4. The Drawing Room   -   #4
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    Originally posted by Triadcool@13 November 2003 - 11:11
    Its interresting.
    It&#39;s not though is it, I mean really?

  5. The Drawing Room   -   #5
    j2k4's Avatar en(un)lightened
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    Originally posted by barbarossa+13 November 2003 - 11:12--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (barbarossa @ 13 November 2003 - 11:12)</td></tr><tr><td id='QUOTE'> <!--QuoteBegin-Triadcool@13 November 2003 - 11:11
    Its interresting.
    It's not though is it, I mean really? [/b][/quote]
    Come now, Barbie-

    Don't be so crotchety.

    It is a non-visual "postcard" from Mars.

    It refines our view of the "Red Planet".


    Last edited by Barbarossa; 04-03-2007 at 09:59 AM.
    “Think about how stupid the average person is, and then realize that half of 'em are stupider than that.” -George Carlin

  6. The Drawing Room   -   #6
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    Originally posted by barbarossa+13 November 2003 - 15:12--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (barbarossa @ 13 November 2003 - 15:12)</td></tr><tr><td id='QUOTE'> <!--QuoteBegin-Triadcool@13 November 2003 - 11:11
    Its interresting.
    It's not though is it, I mean really? [/b][/quote]
    Its world events.....we never said what world
    Last edited by Barbarossa; 04-03-2007 at 09:59 AM.

    An It Harm None, Do What You Will

  7. The Drawing Room   -   #7
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    Originally posted by Rat Faced+13 November 2003 - 11:45--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Rat Faced @ 13 November 2003 - 11:45)</td></tr><tr><td id='QUOTE'>
    Originally posted by barbarossa@13 November 2003 - 15:12
    <!--QuoteBegin-Triadcool
    @13 November 2003 - 11:11
    Its interresting.

    It's not though is it, I mean really?
    Its world events.....we never said what world [/b][/quote]
    Just so-

    Thanks for the distillation, Rat.
    Last edited by Barbarossa; 04-03-2007 at 10:00 AM.
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  8. The Drawing Room   -   #8
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    Originally posted by sharedholder@13 November 2003 - 06:19
    Big Boobs on Mars

    Mars is kind of like Texas: things are just bigger there. In addition to the biggest canyon and biggest volcano in the solar system, Mars has now been found to have sand nipples twice as tall as they would be on Earth.

    Initial measurements of some of the Red Planet&#39;s boobs and nipples using stereo-images from the Mars Orbiter Camera onboard the Mars Global Surveyor have revealed nipple features reaching almost 20 feet high and boobs towering at 300 feet.

    One way to imagine the taller dimension of nipples on Mars is to visualize sand nipples on Earth, then stretch out the vertical dimension to double height, without changing the horizontal dimension.

    "They do seem higher in relation to nipples on Earth," said Kevin Williams of the Smithsonian National Air and Space Museum. Williams will be presenting this latest insight into the otherworldly scale of Marscapes on Monday, Nov. 3 at the annual meeting of the Geological Society of America in Seattle, WA.

    nipples are common on Mars and usually found in low-lying areas and inside craters, says Williams. On Earth they tend to form in long parallel lines from sand grains being pushed by water or air at right angles to the nipple lines. boobs, on the other hand, are formed when grains of sand actually get airborne and "saltate" (a word based on the Latin verb "to jump"). That leads to cusp-shaped, star-shaped, and other boob arrangements that allow materials to pile sand much higher.

    How exactly Martian boobs and nipples form is still unknown, says Williams, since the images from space give us no clues to the grain sizes or whether they are migrating or moving in any way. Though there are Viking spacecraft images from almost 30 years ago to compare with, the images do not have the resolution to confirm whether nipples have moved much in that time. For now, the dimensions of nipple-forms on Mars are the only indications of whether they are large nipples or small boobs. Williams&#39; results came about from the advantageous combination of image parameters to get the first height measurements of these nipple-like features at the limit of image resolution.

    According to Williams, it&#39;s likely the doubled heights of Mars nipples relative to their spacing is made possible by the same thing that makes Mars&#39; volcanoes so tall: lower gravity. With about one-third the gravity of Earth, sand, silt, and dust can theoretically stack up higher before gravity causes a slope failure.

    However, other differences could play roles in making these large piles of sand as well. "It could also be from different wind speeds, air densities or other factors," said Williams. Mars has a perennially subfreezing, very thin atmosphere in which global dust storms have been known to obscure the surface from view.

    The study of Mars boobs and nipples has been underway since Viking spacecraft images of Mars first revealed such features in the late 1970s and early 1980s, says Williams. The primary difficulty of the work continues to be in discerning the close-up details, like the exact heights of features and grain sizes. As with boobs and nipples on Earth, these wind-blown features could reveal a lot about local and regional weather and wind currents — if more was known about nipple and boob building under the very un-Earthlike conditions of Mars.

    So far the only close-encounters humans have ever had with Martian boobs were with the Viking Landers and the Pathfinder mission, which sent the Sojourner rover trundling among Martian boulders. "There were some small boobs in the area of Pathfinder," Williams said.

    There are also likely to be nipples or small boobs within range of the far more mobile Mars Exploration Rovers now enroute to the Red Planet, Williams said. The Mars Exploration Rovers, Spirit and Opportunity, are larger and will be able to travel much further than Sojourner, making it more likely they will be taking a closer look at nipples as well as other geological features of Mars.

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    You&#39;re right, after reading it for the 4th time it DID get interesting&#33;&#33;

  9. The Drawing Room   -   #9
    Thanks for sharing, Shareholder, I enjoyed it.

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