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Thread: Lake in a crater?

  1. #1
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    Lake in a crater?

    An interesting image at:


    http://themis.asu.edu/zoom-20040422a.html

    We chose this area because of the presence of craters in the vicinity, which we hope will help with our thesis about the presence of craters that contain lobates as use for evidence that there might once have been water in this area.

    This image is causing us considerable difficulty due to the presence of a structure that resembles a lake located in the center of the crater.
    Could this indeed be a lake?

    Patrick

  2. #2
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    That's a very interesting image. Not only does it look like a lake, but it looks as if there's a stream feeding into it. Do any of the Mars orbiters have the equipment to determine if that really is water?
    Everything I need to know I learned through Googling.

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    Isn't the atmospheric pressure on Mars too low to allow liquid water on the surface? It was always my understanding that it would boil away almost instantly at that pressure.

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    Perhaps if there is a continious stream of water, it might hold enough to form a lake. (also, perhaps there could be a thin layer of ice on top)

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    Quote Originally Posted by cuboctahedron
    Perhaps if there is a continious stream of water, it might hold enough to form a lake.
    That's possible, I guess, but it would have to be replenishing the water in the basin at the same rate that it was boiling away from the surface. Given the amount of surface area shown in the image that I would think you'd need a lot of water flowing in.

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    Well, it looks like it could be some sort of dark sedimentary deposit instead of liquid water, but either way, it's pretty cool. It definitely doesn't look like it was just shaped by wind.

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    A brighter closeup of something that appears to be a sort of a spring, creating a stream.


  8. #8
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    definitely worth a shot with the high resolution MOC camera
    (about 2 to 4 times better resolution than the THEMIS image)
    maybe we could suggest this area for the MOC "public target"
    program at
    http://<br /> <a href="http://www.m...lts/</a><br />
    however, I'm afraid it's not a lake but some dark sand/deposit stuff
    forming yet another "dark single dune"
    like there are so many inside the craters ...
    Also, for a lake, the "shoreline" does not look "rugged" enough ... it rather looks "smooth" like the shilouette of a large dune ...

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    I am inclined to say it's a pool/little lake.

    IF it was a hill or sand pit, it would have had at least some faint surface features.
    About water in general: streaks have been detected on Mars elsewhere, that had been formed by recent water flows.(it has been discussed many times already, I believe)

    Also, for a lake, the "shoreline" does not look "rugged" enough ... it rather looks "smooth" like the shilouette of a large dune ...
    Lakes, pools can have various shorelines, depending on the environment, that can range from flat beach-like shores to steep (vulcanic) trenches. It's hard to validate if it's a lake based on shoreline characteristics.

    Anyhow, I hope Mars Express drops a visit soon over the region too.

    PS,
    another image, that *might* indicate a lake:


    (strip available at http://www.msss.com/moc_gallery/m07_.../M0902042.html)

  10. #10
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    If you see the "pond" as black without detail, maybe you should adjust your monitor a bit

  11. #11
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    Very interesting. That first one does look like water, or wet dirt. It does follow the contour and look like an equipotential surface. This deserves a closer look.

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    Martian sweet crude

    It's oil!

    Quick! Call Haliburton!

    We might just get a manned mission to Mars yet!

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    Increasing the brightness and contrast brings out some textures that makes it look less like a lake and more like something geological:

    Everything I need to know I learned through Googling.

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    Quote Originally Posted by ToSeek
    That's a very interesting image. Not only does it look like a lake, but it looks as if there's a stream feeding into it. Do any of the Mars orbiters have the equipment to determine if that really is water?
    What's the resolution of the laser altimeter? It seems like that would go a long way towards determining if this was a lake.

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    Of course! the old oil in a crater trick! doh!

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    Quote Originally Posted by ToSeek
    Increasing the brightness and contrast brings out some textures that makes it look less like a lake and more like something geological:
    I have to disagree; water has a degree of transparancy, so what you might see are the features of the lake-floor. If it were crude-oil for example than it would remain black. You can clearly see a basin now.

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    I find it curious that the margins of the dark region extending from the crater edge to the "lake" seem to be parallel to many of the numerous dust-devil tracks. That makes me think the dark material was moved by the prevailing winds -- though from or to the crater edge, I cannot tell. Which way do the winds blow there?

    There sure seems to be a channel entering on the left end of the lake-like area. That could ell be ancient, though, and perhaps we are now see dark dust filling in a low spot in a former lake.

    I'd sure like it to be a lake, though. Or at least a big hunk of ice.
    0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 1 0 0 1 0 1 1 0 0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 0 1 1 0 1 0 0 1 0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 ...
    Skepticism enables us to distinguish fancy from fact, to test our speculations. --Carl Sagan

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    Quote Originally Posted by 01101001
    we are now see dark dust filling in a low spot in a former lake.
    If it were dark dust,wouldn't wind at least spread some of the material in it's surroundings? The boundary is to sharp.

  19. #19
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    cuboctahedron, you have an interesting point amount ToSeek's analysis. I was going to suggest it could be a Lunar style mare.

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    Theres the darker line following the "coastline" in the bottom of the "pond"... bottom detail caused by older coastline?
    Fo for a lake it couldnt be very deep, and from the darkness of the bottom it looks like its shallower in the middle areas...

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    Where's the steam plume from the boiling pool of water?
    Now ice, that's a possibility.

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    I did a histogram stretch and brought out what looks like some uneven terrain:



    But it would be nice to get a better image to be able to decide for sure.
    Everything I need to know I learned through Googling.

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    If the ribbed rim on the lower side is of a steep face it could either be a large black sand dune or a lobe of black lava. I would prefer the dune myself.

    Jon

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    How are those photographic strips put together?

    Do the original photo edges happen to butt up exactly to one another or did the originals overlap one another as I would think is the case at one point? If they overlap then the actual overlap sections would form a stereo pair as the satellite shot while continuing to orbit.

    That stereo pair section then might show whether the feature is concave (like a lake you can see into) or convex (like a dune, which I think I am seeing).

    Might it be possible to create an intentional stereo pair with the same satellite on another pass?

    RBG

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    Oliver Morton discusses this crater on his blog.

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    There are many indications of current surface-water on Mars(see example links provided below).

    "MOC Images Suggest Recent Sources of Liquid Water on Mars"
    http://www.msss.com/mars_images/moc/june2000/


    "NASA unveils evidence of liquid water on Mars"
    http://www.cnn.com/2000/TECH/space/0....01/index.html
    "Report: Water springs found on Mars"
    http://www.cnn.com/2000/TECH/space/06/21/mars.water/


    Also:last fall a study about water evaporation on mars done by Arkansas-Oklahoma Center for Space and Planetary Sciences states:
    ...suggest that even under worst case scenarios, where wind is maximizing evaporation, evaporation rates on Mars are quite low." This implies that surface water could indeed exist, or have existed recently, under the given conditions on Mars
    http://www.uark.edu/misc/csaps/News/

    I understand that one has te be careful when claiming issues regarding surface water, however I can't comprehend that subjects about liquid water tends to be categorized as 'against the mainstream' and that it is saver to say that any occurance related to possible water must ressemble something like "hey, that must be dust or some unknown natural process; water is surely unlikely", making one less vulnerable in debate.
    I am not saying such conservatism is right/wrong, but I think it is incorrect when some thesis (e.g. 'no current liquid water on Mars') transforms itself over time into a sort of doctrine, making it more difficult for new perceptions or proposals to alter the initial thesis.

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    cuboctahedron,

    From the phase diagram of water:

    http://www.lsbu.ac.uk/water/phase.html

    It can be seen that liquid water cannot exist at the pressure found on Mars. It either boils or freezes, depending on the temperature.

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    Quote Originally Posted by Kaptain K
    It can be seen that liquid water cannot exist at the pressure found on Mars. It either boils or freezes, depending on the temperature.
    If so, The Arkansas-Oklahoma Center for Space and Planetary Sciences must have it all wrong.

    I have to read through your link first though ., but for a quick response:

    I think there are two occasions in which fluid water can form lakes, with respect to the graph mentioned:

    - water coming from the soil might be a hot-spring
    - temperatures on Mars itself are sometimes not as cold as one might think: http://emma.la.asu.edu/tdaydaily.gif .(note that temperatures here are in Celcius)

    In both occassions liquid water on Mars, will probably get coated with an ice layer on top thus preventing severe vapor. Since the ice coat would than vaporize it would yet protect the liquid water lying below, and at the same time vapored ice would get refreshed from the liquid water, replacing the vapored icelayer.

    As long as the supply of water exceeds the vaporization, it will remain a lake.

  29. #29
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    Quote Originally Posted by cuboctahedron
    Quote Originally Posted by Kaptain K
    It can be seen that liquid water cannot exist at the pressure found on Mars. It either boils or freezes, depending on the temperature.
    If so, The Arkansas-Oklahoma Center for Space and Planetary Sciences must have it all wrong.

    I have to read through your link first though ., but for a quick response:

    I think there are two occasions in which fluid water can form lakes, with respect to the graph mentioned:

    - water coming from the soil might be a hot-spring
    - temperatures on Mars itself are sometimes not as cold as one might think: http://emma.la.asu.edu/tdaydaily.gif .(note that temperatures here are in Celcius)
    3. It's not pure water but salt water (brine), which has a different phase diagram from pure water that is more tolerant of cold temperatures.
    Everything I need to know I learned through Googling.

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    I must say Capt K's phase diagram is very odd. I have never seen the triple point of water given as a decimal of megapascals before.

    There is a lot of mythology about the stability of water on the surface of Large areas of Mars are above the triple point of water at least briefly for much of the year. The triple point of water is (with a little bit of rounding) 6 millbars and 0.01 degrees. the average surface pressure of mars is 7 millbars and the equitorial regions ground reach 20 degrees. The problem is that at this pressure the stablity field eith respect to temperature is very narrow.

    However, dissolved acids and salts will greatly widen the stability field. with respect to temperature. Surafce water in analogous environments on earth, cold or high deserts, is almpost always quite saline.

    Jon

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