Hmmm

• by wassock moderator

  Cant decide if this is a large field of tiny fans or just 'dirty' terrain. No idea about why there are clear paths unless they are caused by giant slugs and snails

  Posted January 27, 2013 8:50 PM

• by Paul_Johnson

  Clearly these are not sludg and snail trails, wassock.......Martain Wilderbeast, obviously.....moving across the dusky plains in search of 'Red Weed.'

  Where's a scientist when you need one....?

  Tchh...

  Posted January 27, 2013 9:24 PM

• by rowbumby

  Iv come across these images and asked about them in a diff post and this is what a scientist told me....
  by Portyankina scientist
  Report Right, these are not spiders. Most probably they are some kind of permafrost polygons.

  Anya

  Hope this helps

  Posted January 29, 2013 10:13 AM

• by JellyMonster

  I think the 'clear paths' are an optical illusion. The surface has the same unevenness all over, although I cannot imagine, how the dirt/dust has settled in the way that it has... any ideas (that's if I'm right of course)? The inverted picture link below, shows the 'paths' better. I also did a few histogram edits to enhance the surface texture.

  http://www.mediafire.com/view/?xb4bx8w50cabc04

  Posted January 29, 2013 4:28 PM

• by Kitharode moderator

  Do you think your image is related to this? http://planetfour.org/subjects/standard/50e742b85e2ed211dc002aad.jpg

  I'd always thought this was spidering (complex web of chains) so I read depressions. Not so?

  Posted January 29, 2013 6:11 PM

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

  I think that the whole area has the same sort of structure and it's just shaded like this- like a giraffe, or it was once all shaded and someone took a rubber to it (that's an eraser )

  Posted January 29, 2013 10:17 PM

• by rowbumby

  In regards to my other comment about it being permafrost polygons. Have a look at this image http://www.universetoday.com/40281/evidence-of-dry-lake-beds-on-mars/ its has similar shapes to this (which are permafrost)....Also Debate over polygons on Mars remains active, even after several decades of detailed observations. Similarity in geometric patterns on Mars and Earth's seafloor has long captured the imagination.Understanding these patterns may in turn support for the idea of ancient oceans on Mars.On Earth, polygon-shaped areas are common in fine-grained deep-sea sediments.Have a look at this deep sea polygons image https://www.dropbox.com/s/8xkdhpytlsr7i3n/deep ater marine polygons.jpg?m 😃

  Posted January 30, 2013 12:59 AM

• by wassock moderator

  The surface texture of the dark bits and the light bits is the same, one is dirty the other is clean. The white bits are clearly not cracks

  Posted January 31, 2013 12:42 AM

• by rowbumby

  Desiccation cracking of mud and silt offers one explanation for some polygons, but most polygons on mars are probably not of this type.Some polygons and other forms of patterned terrain may be due to freeze-thaw driven heaving, with or without thermal contraction cracking that can sort sand,silt and dust from pebbles.cobbles and boulders in polygonal patterns.
  Small polygons on mars are probably primarily permafrost ice features, although some may be mud desiccation features,Mud desiccation make most sense where the polygons are strictly limitied to deposits contained in depressions and having evident inlet channels and layered sedimentary deposits exhibiting onlapping relatuons (embayment) with higher ground,terraces or other indications that the site was where water once ponded,even these could be due to icy permafrost. 😃

  Posted January 31, 2013 8:42 PM

• by rowbumby

  Iv also come across more images of the same patterns (sort of same) APF00000gh APF00000lw APF00000ik APF00000j7 APF00000ed APF00000gz

  Posted January 31, 2013 8:47 PM

• by wassock moderator

  I may have found the slugs !
  https://www.dropbox.com/s/zof247tw1nagij4/Screenshot_2013-03-13-00-13-25.png

  Here for the full thing (RGB colour image) http://hirise.lpl.arizona.edu/PSP_006538_1035

  How weird are they? Not clear if these are the dunes in the commentary or not.

  Posted March 13, 2013 12:32 AM

• by Kitharode moderator

  Brilliant Find. The article says dunes, shifting dunes at that. It seems to me that that's what you're dealing with here. Let's assume that for now.

  Your screenshot helps here, because if it's dunes they should drift. The middle dune of your screenshot has a 'crater' on its left hand side that looks to be partly buried by the edge of the dune. Strong possibility, eh?

  The alignment of the slugs is interesting. Obviously wind related. Probably blowing bottom right to top left judging by the shape. Could be more right to left, but the top slug in the screenshot doesn't seem to be shielding its neighbour. Strong enough to 'sweep the floor' and shift the dune, but not strong enough to take the whole body.

  How old are these dune slugs? Were they once much bigger? Maybe a slug plateau worn down to this, soon to be no more (astronomically speaking)? Where have they come from and how far have they got?

  I agree with the title of this thread: Hmmm....

  Posted March 13, 2013 1:16 AM

• by wassock moderator

  The text calls the dunes 'crescent shaped', I would go more tear drop or lozenge for these, there are some things at the top which fit the description but they are not particularly in your face.

  Posted March 13, 2013 8:04 AM

• by wassock moderator

  Just followed the link in the text - the slugs are the dunes.
  Plus having had a look a bit closer, this is a north pole image, latitude 76 and is heaving with spiders.

  Posted March 13, 2013 8:07 AM

• by Kitharode moderator

  Teardrop / Lozenge for sure. Perhaps they can be crescents as well, or up to a certain size then change. Maybe 'frosty crescents' on the dunes were the first thing to be imaged and the name stuck. Latitude 76N, eh? So if there's spiders AND slugs in the north, will there be slugs in the south as well? I've not seen any so far.

  Thinking out loud: North polar surface material probably different from south. North pole region is 'lower' than the south region (so temp and pressure come into play?). Shorter winter up north and long summers (different sublime and settle cycle).

  On the assumption that the slugs are wind-driven objects, does the katabatic wind come in here? From what bit I know, the katabatic comes down slopes and is fast. It occurs in the south, I'm guessing it could in the north, but does the 'higher' southern region produce more slope hence more strength to the katabatic?

  Never really liked slugs - I do now.

  Posted March 13, 2013 6:10 PM

• by AUricle in response to Kitharode's comment.

  the katabatic comes down slopes and is fast. It occurs in the south, I'm guessing it could in the north

  Indeed it does,....but its effects come in unexpected ways. Check this out, it'll have you shaking your head.
  http://www.universetoday.com/65084/mars-polar-cap-mystery-solved/

  Posted March 13, 2013 7:39 PM

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

  Good input AUricle, thanks for that. Yes, my head is shaking. Gonna have to have another read and think about all that, but at least we've got wind, strong shaping wind. Good chance we might get a reasonable 'hypothesis' about these slugs before we find the science paper entitled 'Everything You Need to Know About Slugs'. (If you find said article, can you hold it back for a bit?)

  Posted March 13, 2013 7:58 PM