Planet Four Talk

Boulders and fans

  • wassock by wassock moderator

    This image (from HiRise) is from inca city March 2007 http://hirise.lpl.arizona.edu/PSP_002868_0985

    Lots of boulders with associated fans

    enter image description here

    This one from May 2011 http://www.uahirise.org/ESP_022607_0985 same group of boulders ice free this time, sun appears to be on the left (or the boulders are pits). Whlst the fans are clearly related to the boulders they dont seem to have much to do with the channels/ridges.
    Note the neat rows of boulders in the 2 near hoizontal channels near the top, and in other places, how did they come to be?

    enter image description here

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  • Kitharode by Kitharode moderator

    Which image did you take these from? The Greyscale map-projected has sun on the left-ish, the non-map has sun on the right.

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  • wassock by wassock moderator

    Hi kith, the HiRise refs for both are given, both are from the HiRise jp2 greyscale images. The one with fans is timed at 5:09 Pm (sl196.2), the other at 3:16 PM (sl 298.1)

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  • wassock by wassock moderator

    Hi Kith are the two post we put on this thread missing at your end as well?

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  • Kitharode by Kitharode moderator

    Hi Wassock. I removed my last post because I realised I was asking a question about jpeg images, but then reread your post above pointing out that you were using jp2 images.

    Haven't noticed anything of yours gone missing.

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

    Could be a bug in how the delete works. Can you guys try and recreate it? If it does I'll submit as a support ticket.

    Cheers,

    ~Meg

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  • Kitharode by Kitharode moderator

    Wassock: In your first image, it definately looks like boulders lit up on the left and the fans are definately associated with them. In your second image the boulders are less clear, but they still appear to have light on the left. My problem is with the background. For the life of me I cannot see channels with light coming from the left. What I see is a 'rippled' surface lit up from the right. Obviously this cannot be correct if the boulders are boulders (which they appear to be).

    Meg: We do know that if you post something and then delete it later, the discussion board still displays your original as the 'last post' for about 24hrs or so. Then it clears it's throat and your 'last post' disappears. However, if wassock posted something that has disappeared without him deleting it I've no idea what's going on there.

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  • wassock by wassock moderator in response to Kitharode's comment.

    I have trouble seeing the channels as channels too, but viewing them as ridges makes the boulders into pits so I can acept that they are ridges, but my eyes are not convinced

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  • Kitharode by Kitharode moderator

    Hence the need to confirm for sure that the light is coming from the left. If not, you've got a major find here.

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  • wassock by wassock moderator

    Kith they are both afternoon shots, the summer one 2 hours later than the spring one, do the sun will be on the same side in both (ish)

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  • angi60 by angi60 in response to wassock's comment.

    Hi Wassock. Forgive me for putting a fly in the ointment, but my eyes don't convince me that the lines of objects are boulders (though obviously if you've looked at this at higher magnification, you have an advantage over me!) Certainly, on the bottom image they look more like boulders, but looking at the top image, the surface looks 'knobbly'. Therefore, in the top image I'm more convinced to see them as knobbly protuberances (assuming of course that the sun IS coming from the left, and that I'm actually looking at the right objects!) But that's just my interpretation of course (probably misguided)!

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  • Kitharode by Kitharode moderator

    Wassock: Thanks for that. So is the light from the left or the right? ** 😛 **

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  • wassock by wassock moderator

    Neither, I think, as I read it looking at the map projected images, which these are North is at 205 degrees starting trom 3 o clock which would put the afternoon sun somewhere down the bottom.

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