Veggy Look-alike

I think the texture makes this look like vegetation. What is this really caused by?

Posted October 25, 2013 12:53 PM

Got to admit that I can't answer your question. There's been a few of these images lately and they're quite difficult to get a handle on, for me at least. Hopefully somebody will have a few ideas for you.

Have you had a look at the full HiRise image? That might tell you something. Good luck. 😉

Posted October 25, 2013 1:56 PM

by p.titchin in response to PaulMetcalfe's comment.

There is a filter colour glitch at the top of the RGB col strip showing a red band..Could this give a green tinge effect to the strip? The 'gold' effect lit up boulders are nice.~Pete

Posted October 25, 2013 2:57 PM

by Kitharode moderator

The HiRise image tells us it's the 'Ithaca Region Defrosted', so we're not looking at fans. It's a strangely textured area and the colours are unusual. Don't think the red glitch at the top has anything to do with it, because you see the same 'glitch' in many a HiRise image, with no hint of green present.

I've not had chance to look closely at Ithaca yet, but it looks fascinating.

Posted October 25, 2013 4:35 PM

by PaulMetcalfe

I have had a quick look at the HiRise and it does look fascinating. I will spend a little more time examining the maps. Any idea what the black plumes are comprised of (dust, gas etc.) as it may give a hint as to what is happening with regard the colour and texture.

Posted October 25, 2013 7:12 PM

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

In terms of the other images on the site, the black fans and blotches actually are the dust and dirt at the base of the ice sheet, so it's basically the same color as below the ice but with the ice there and the fact that's it's semitransparent you get the color contrast. In this image, the region is defrosted so there is no more carbon dioxide ice on the surface at this point

Cheers,

~Meg

Posted October 26, 2013 5:41 AM

by PaulMetcalfe in response to mschwamb's comment.

I would like to put forward a possibility that I am only basing on assumptions. I am not well-informed on the chemistry and physics of these phenomena so I am quite prepared to have this idea shot to pieces.
Assumptions
1/ The green texture is some sort of ice.
2/ The area is within a flat-bottomed valley. (I got this impression from the larger HiRise view)
3/ The gas or liquid at some stage becomes a viscous sludge as it freezes.
4/ If in a valley and dependent on other geographical features the wind may be very turbulent.

My thought is that as the sludge freezes in a turbulent wind, it may freeze with a very rough texture (what I will call a crystalline forest) instead of being allowed to smooth as might happen on an area where the wind blows constantly in one direction. The green colour (whether the correct colour or not) would be wind-blown dust etc. mixing into the sludge as it freezes.
I wanted to air this thought, even if completely potty, to see if there is any merit at all in it.

Posted October 26, 2013 11:15 AM

by Kitharode moderator

Hi Paul. I think it's safe to say that no matter how 'potty' your ideas are, I've already put something up here that's even pottier !! (I'll let the others speak for themselves). 😃

You may already have seen this, but if not you'll find it useful. When you visit a HiRise image you'll see the 'observation toolbox' just down the page. Here you can check the time of year from Solar Longitude (Ls) and this blog entry explains Ls: http://blog.planetfour.org/2013/02/11/martian-timekeeping/

Your image above was taken at Ls = 184deg just past perihelion, so just after high summer in the south. This does not mean that there will be no ice in the area, but it does suggest we're looking at martian surface rather than ice-cover. It's probably safe to discount any ideas about liquid in these present day images, but maybe a dense mass of gas/dust/ice might constitute a sludge. I'm not keen on that idea myself.

The winds play a large part in many of the images we see, but we know so little about them. Perhaps when we've classified another 10 million images the science team will be able to tell us something definate from the results of our work, but your observation about the difference between the effects of smooth or turbulent wind is a good one.

I'm a firm believer (with no evidence at all) in the idea that the South Polar Layered Deposits (SPLD's) play a major role in what can/cannot be found in one area or another. This is another useful image to keep to hand: http://www.nasa.gov/images/content/171411main_pia09224-thick-annot-516.jpg

Hope you'll throw in some more ideas of your own. Cheers.

Posted October 26, 2013 3:24 PM

by PaulMetcalfe in response to Kitharode's comment.

You may already know of other pictures from the Ithaca region. Anyway, I have just viewed one APF0001j1e that has the same texture but is brown. It has the same gold/brown 'boulder' like objects as well. It is beginning to look as though the region may be the same texture and that the colour may vary from spot to spot. I will hopefully get more from Ithaca to examine and see how common or not the texture is.

Thanks

Posted October 26, 2013 4:20 PM

by Kitharode moderator

Yes, I've seen some other Ithaca stuff (there's a few options at the bottom of the HiRise page) but I've only had a glance at them and not put any thought into 'how things work at Ithaca'.

I'm still working on a bigger picture, what lives where sort of thing, and I'm taking an interest in the similarities/differences between landscapes on either side of the pole. Pete (p.titchin) is well into boulders. Angi60 seems to be moving towards an interest in 'Angular Hills'. Wassock is into everything, but to see his strongest focus visit his 'Heart of the Matter' discussion on the HiRise board (recommended).

The science team have Ithaca on their 'hit list' of observations for fans/blotches, but I don't know of anyone here who's investigating Ithaca in particular. If you dig around and find anything interesting we'd love to hear about it.

Posted October 26, 2013 6:55 PM

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

As my name cropped up, Ill add my threepenceworth. I get worried about colour arguements. I don' have access to the science, but I well remember the radical change in colours because an orange tube on a lander was noticed to be the wrong colour. I gather the colour given to us is based on an assumption that that it is what the colour should be! 😃. ie the sky was blue, whereas it is in fact pink! This image is quite old (2007) and the full HiRise col strip does not look so broccoli like. I now use greyscale more than I used to. I do like these 2007 images though, because my beloved boulders look so nice in gold!!~pete

Posted October 26, 2013 7:40 PM

by wassock moderator

Don't have time to chop these up and post as seperate images This is the HiRise page for this image - look at the map projectyed greyscale and the obvious dog leg feature which looks like a gully of some kind - this image from 26 July 2007 and non-iced

http://hirise.lpl.arizona.edu/PSP_004666_0945

Now the same thing from earlier the same year, 16 Feb, most of the surface features seen in the first (later) image are obscured but there is a clear correlation between the fans and the features beneath the ice which can be seen in the first, non-ice, image - 'specially the edge of the dog leg feature

http://hirise.lpl.arizona.edu/PSP_002622_0945

Posted October 26, 2013 9:52 PM

by PaulMetcalfe in response to p.titchin's comment.

I agree that assumptions about true colour can be misleading and that colour cannot really be used as scientific evidence unless there is categorical proof that a colour is true. However, I will always refer to a colour portrayed in an image, otherwise it would be confusing not to. My interest in these Ithaca pictures is mainly with the texture (that may possibly turn out at a future date to be a very mundane Martian feature). There are as you know some very diverse and interesting features in all the views we now see from Mars. As much as they interest me, I can in my own mind imagine the geological and atmospheric conditions that cause them (I am not saying I can satisfactorily explain them) but this texture intrigues me regardless of what colour it appears to be. I would love the colours to be true as that would make the detective work even more appealing.

Paul

Posted October 26, 2013 11:08 PM

by PaulMetcalfe in response to wassock's comment.

Thanks for the links. I had viewed the HiRise and found the pictures useful in getting a wider view of the local terrain.

Paul

Posted October 26, 2013 11:11 PM

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

Pete. Have you seen the HiRise camera science paper? You might make some 'colour sense' out of it. The techie camera stuff is over my head I'm afraid, so I only read the orbital stuff. https://wiki.umn.edu/pub/ShackeltonCraterProject/CameraInfo/HiRISE_Manual.pdf

This link is also in 'Science of the HiRise Camera' on the HiRise board. Cheers.

Posted October 27, 2013 3:52 PM

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

All I will comment is that this is 2007, the lit boulders show up as golden. Still feel that this is due to colour variations in the image. Similar terraine and boulders in later images where the bright boulders were called 'snowballs', beautifully lit and white,and the image was not tinged green.

Posted October 28, 2013 6:30 PM