Planet Four Talk

Developing spider networks

  • p.titchin by p.titchin

    Nice image of fanfield with icy spider channels that seem > becoming a network. Part of an extensive area of similar terrain which is termed in the HiRISE caption 'Caterpillar dune evolution ' territory.

    Posted

  • wassock by wassock moderator

    It's also very early in the season - the hirise image is tagged 'Northern Summer' with the sun only 2 degrees above the horizon. Any idea what the caterpillar dunes are?

    Posted

  • Kitharode by Kitharode moderator

    Best I can make of them is that they are large structures, much longer than they are wide, with a rounded shape, somewhat like caterpillars. The blue-black 'hairy' fans help to give this impression (to me at least). I'm guessing that the caterpillers in this HiRise image are at the top running left to right, with the head and tail being outside the image. I'm guessing again when I suggest that the evolution is from bottom (spiders on flattish land) to top of image and formation of dunes.

    One more guess would be that there are a variety of shapes and sizes, but the 'caterpillar effect' would be the same in all of them. It has been suggested that to take up this shape there needs to be some 'cementing' of the material. Here's a paragraph and image of caterpillars in a nearby(ish) crater. http://archive.org/details/PLAN-PIA06332

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  • p.titchin by p.titchin in response to Kitharode's comment.

    thanks for the link Kith, have to admit I couldn't find any reason for calling for caterpillars in the images I sourced. The one in your link shows the reason for the name , but I haven't found similar in the images associated with my image. I put it up on the board for two reasons !1- Why caterpillars, 2/ much more important, it is a great image of developing spiders, (if they are developing) and--- hell! it's a great image with lots to admire and question.
    ~Pete

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  • mschwamb by mschwamb scientist, translator

    I believe these are what are meant by caterpillar dunes. The image linked is from a lower resolution camera MOC (Mars Orbiter Camera) on the Mars Global Surveyor. I'm not an expert in geology or planetary surfaces, so I'm speculating here, but I think with HiRISE's resolution the bean-shaped feature dune feature in the top of this grey-scale map-projected image is a caterpillar dune. Have to remember that HiRISE is showing a pretty zoomed in view of the surface, the smallest features resolved are about the size of a coffee table. Sometimes zooming out helps, that's one of the reasons there's actually the Context Camera (CTX) on MRO that images larger area to give context and targets for HIRISE.

    Cheers,

    ~Meg

    Posted

  • mschwamb by mschwamb scientist, translator in response to Kitharode's comment.

    We found the same image! The 'caterpillar' I think is for the shape not for anything to do with the fans, and come from the MGS/MOC days rather than HIRISE.

    Cheers,

    ~Meg

    Posted