Planet Four Talk

Manhattan

  • wassock by wassock moderator

    Sorry to keep flogging this one folks.

    I think these are from the Manhattan region. Strikes me that each of these images show many fans in a number of different orientations. Each comes from a similar time of year from each of the 4 Martian years so far monitored. What is striking to me is the similarity of the pattern of fans year on year. For a single image multidirectional fans explained in terms of separate eruption events with changing wind directions works well. But does that model stand up when needed to explain the same pattern happening year on year?

    5 May 2007 SL 232
    http://hirise-pds.lpl.arizona.edu/PDS/EXTRAS/RDR/PSP/ORB_003600_003699/PSP_003614_0945/PSP_003614_0945_RED.abrowse.jpg

    11 March 2009 SL 225
    http://hirise-pds.lpl.arizona.edu/PDS/EXTRAS/RDR/ESP/ORB_012200_012299/ESP_012290_0945/ESP_012290_0945_RED.abrowse.jpg

    13 January 2011 SL 216
    http://hirise-pds.lpl.arizona.edu/PDS/EXTRAS/RDR/ESP/ORB_020900_020999/ESP_020927_0945/ESP_020927_0945_RED.abrowse.jpg

    12 December 2012 SL 224
    http://hirise-pds.lpl.arizona.edu/PDS/EXTRAS/RDR/ESP/ORB_029900_029999/ESP_029907_0945/ESP_029907_0945_RED.abrowse.jpg

    Posted

  • wassock by wassock moderator

    NB the 'northward' fans form first every year!

    Posted

  • Kitharode by Kitharode moderator

    Keep flogging - There's still life in this 'horse' for sure 😉

    A single image, showing multidirectional fans, tells us that the wind has changed direction. It doesn't tell us which fans formed first; It doesn't tell us whether the same thing happened the year before. To find out, we'd need a series of images. You have a series of images with 'the same' multidirectional fans in them. Do they not imply that the winds in this area are the same each year?

    What other options might explain this series of images?

    Posted

  • wassock by wassock moderator

    There's a lot of images for each year - as can be seen from the ones above the pattern is pretty much the same each year. And the order that they form is also the same - particularly the northward (ish) pointing ones appear first.

    There's also a suggestion that the other fans 'develop' as the year progresses - they get darker/larger with time but in the same (varying) orientations that they started

    Posted

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

    Well I think if there is a dominant prevailing wind direction in that region at a given time where the vent is, you may likely see the same direction for fans year to year. So I think it does hold up. There may be changes in wind but if there is more prevalent or stronger wind direction for a given time of the year than that would explain seeing the fan directions repeat from year to year.

    Cheers,

    ~Meg

    Posted