Planet Four Talk

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  • p.titchin by p.titchin

    This image shows fuzzy emissions like 'ghosts'outlining the polygonal ice fracture lines. On the associated HiRISE RGB strip they cover the top third of the strip. The image is quite magical. I wondered at what stage in the evolution of this surface these formed. They were presumably originally nice clear linear venting. Have they and their associated fracture lines been covered by more ice? Have they just 'faded' ? Are they ? etc etc! The HiRise image will certainly go in my 'favourites'.

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  • mschwamb by mschwamb scientist, translator

    I don't these are polygonal ice fractures if you mean fractures in the ice. I think these are polygonal cracks in the ground (like this) and there may be some carbon dioxide on top we're seeing through. I don't think they were ever linear venting. The cracks form from the expansion and contraction of water ice in the ground near the surface (or at least it does on Earth) and scientists think it's the case for Mars as well. This page gives some more detail and other images of polyongal cracks/patterned ground.

    Cheers,
    ~Meg

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  • mschwamb by mschwamb scientist, translator

    I should also note that there is also been cracking in the ice observed as well, but I don't think this is what we're seeing here.

    Cheers,

    ~Meg

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

    Thanks as always for the links Meg, Cracked ground makes sense, but if you look at the image with the magnifying tool, the broad dark markings appear to be under ice, which then appears to have very fine crack fractures overlying the darker outlines.Also, in places the dark outlines are a pinky brown to one side of a thin crack, and black on the other side of the crack.."I love to lose myself in a mystery;" (Sir Thomas Browne). 😃

    Pete

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  • Kitharode by Kitharode moderator

    The HiRise image is part of my collection too. Mystery indeed. Looks like you've got another project here. Good Luck!

    "I love to find myself after being lost in a mystery" (Kitharode). 😛

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