Could it really have been mud seen earlier by Spirit?

[exoscientist]

The problem is we don't know how many layers there are of these monolayers of liquid water. The authors say "multiple" but don't quantify this: hundreds, thousands, millions? We don't know. It is possible for example that every single micron-sized particle is covered by it's own monolayer of liquid water. This clearly would result in quite a bit of water. This is something that should and can be simulated in the laboratory under Martian conditions. <br /> The phenomenon of "surface melting" is an manifestation of such thin liquid films. Most importantly this can occur on the ice between the <b>individual grains</b> in soil. This is the cause of such macroscopic phenomena as frost heave that results in ground being raised several feet in ice-filled ground. <br /><br />Some references on surface melting:<br /><br />FAQ - Melting Below Zero <br />"After a fall freeze, farmers in rock-ribbed regions such as New Hampshire may awaken to an upheaval of their previously cleared fields: stones stand on pedestals of ice needles, and soil bulges up around larger rocks. This occurrence (called frost heave) ranges from an agricultural annoyance to an industrial nightmare. Despite its dramatic effects, frost heave owes its strength to microscopic liquid films on the surface of ice. <br />"Frost heave begins when chilly air cools the soil and freezes some of the water near the top of the ground, but the real damage is wrought after this initial freeze. Molecular forces and impurities on the ice surfaces can prevent the moisture from freezing solid until the temperature drops several tens of degrees below zero Celsius. Until then, a microscopic film of water coats the ice crystals, which grow between the tiny fragments of rock and clay that make up the soil." <br />http://www.bushwalking.org.au/FAQ/FAQ_MeltBelowZero.htm<br /><br />CAPILLARY EFFECTS ON THE STABILITY OF ICE IN MARTIAN CRUST, Paul C. Hess1 and J <div class="Discussion_UserSignature"> </div>

 

[alpha_taur1]

Bob, <br /><br />There is one way of resoving this issue. Ask NASA. At the Daily updates pages on the NASA Mars site, there is an email link for questions. <br /><br />Ask the question about whether some of the features we saw at Gusev could be due to mud. I think you posted a similar question at another forum.<br /><br />I'd be interested in the answer you get.

 

[claywoman]

I've seen this picture in another thread and finally got brave enough to say this looks like muc. I got a bunch of answers as to why this isn't mud, but I have a hard time getting that idea out of my mind.<br /><br />If you look at the picture, you will notice the rover tracks, and the rocks. It looks like freshly made mud, and the tracks turn over the soil and that is even darker mud...So I know now that pictures are decieving...much to my embarrassment... <img src="/images/icons/blush.gif" /><br /><br />

 

[exoscientist]

This abstract to the upcoming LPSC conference reports on experiments <br />that show the evaporation rate of liquid water on Mars might be as low <br />as 1 mm per hour: <br /><br /><br />STABILITY OF WATER AND GULLY FORMATION ON MARS. <br />Lunar and Planetary Science XXXVI (2005) 1496.pdf <br />"We measured evaporation rates at 7 mb under <br />conditions much closer to martian than previous <br />work and eight determinations yielded a value of <br />1.04 ± 0.14 mm/h [7]." <br />http://www.lpi.usra.edu/meetin­gs/lpsc2005/pdf/1496.pdf <br /><br /><br />Bob Clark <br /><br /> <div class="Discussion_UserSignature"> </div>

 

[alpha_taur1]

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[exoscientist]

You can see the abstract on the second page of the session "MARTIAN FLUVIAL LANDFORMS AND PROCESSES":<br /><br />Sears D. * Roe L. Moore S. <br />"Stability of Water and Gully Formation on Mars [#1496] Experimental work, theory, the size and frequency of gullies and sand dune characteristics in a region of Nirgal Vallis, suggests that the major factor in determining the stability of water on Mars is the presence of wind."<br />MARTIAN FLUVIAL LANDFORMS AND PROCESSES, p. 2.<br />Lunar and Planetary Science XXXVI (2005) sess69.pdf<br />http://www.lpi.usra.edu/meetings/lpsc2005/pdf/sess69.pdf<br /><br /> The authors take into the account the effects of wind on evaporation rate. Interestingly they found some correlations of length of the Malin/Edgett gullies to the presumed wind direction that suggest, though not conclusively, that such a wind effect does occur on Mars.<br /><br /><br /> Bob Clark <div class="Discussion_UserSignature"> </div>