Blue?

• by wassock moderator

  This image was taken on the 18th December 2010, as were APF0000wzs,wyc,wyf,wyw and more all showing this distictive fan type. Far as I can tell all of these striking blue fans, leastways those tagged as #blue, were taken the same day. the only image I've come across which comes close to these is http://hirise.lpl.arizona.edu/ESP_029387_0950 which is from November 2012. There are quite a lot of other 'blues' from December 2010 but comparatively few from other years. Anyone got one of these distinctive narrow dark fans with a blue surround that's not from 2010?

  Posted June 27, 2013 12:24 AM

• by Kitharode moderator

  What you say appears to be true. I'll keep it mind and keep my eyes open. Are you theorising, or just interested?

  Posted June 27, 2013 2:57 AM

• by wassock moderator

  Been trying to look at the chronology of how the fans form and where the blue fits in. Turns out that there's not that much blue about which I'm thinking may be a camera issue, or those images from other years have just not been released.

  Posted June 27, 2013 7:42 AM

• by wassock moderator

  And if you look at the IRB colour images on HiRise all the blue fans are purple!

  Posted July 2, 2013 10:19 PM

• by angi60

  Ready for a song guys? 'When the deep purple falls over misty Martian soils,
  And the stars begin to twinkle in the sky.....'

  All together now......
  (Just a bit of doctoring to a real song, in case you don't know it!) I'm in a silly mood, so couldn't resist 😄

  Posted July 2, 2013 11:15 PM

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

  All data is released on the HiRISE website, there's a pretty set release schedule for HiRISE data. So Martian years 1-4 on the HiRISE website and on the links to the those pages from Talk at the bottom it links to the images taken in the surrounding area close to the image. So it should all be there.
  Cheers,
  ~Meg

  Posted July 3, 2013 4:31 AM

• by wassock moderator

  Wasn't Seriously suggesting that all the good pics had been hidden Meg, It just seems odd that there are no more examples of the really good blue fans other than from one day in December 2010, that I can find leastways.

  Posted July 3, 2013 7:27 AM

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

  I know. I just wanted to let you know what data was available on the HiRISE pages. Also possible that other images weren't commented on in Talk so that would make them harder to find. We have a lot of season 1 still to go through, so definitely keep an eye out.
  Cheers,
  ~Meg

  Posted July 3, 2013 4:58 PM

• by wassock moderator

  All the ones tagged blue with the blues fans are the same day, blues from other times are just nowhere near as good/the same. Were the camera settings in someway different on that day? Or are we seeing something very rare and/or fleeting so that only one HiRise image has captured it?

  Posted July 3, 2013 10:52 PM

• by mschwamb scientist, translator

  Well again, different processes perhaps. Originally the thought was all the blue was carbon dioxide frost (at least when in grad school) and in the past few year that has changed when you see those images where there we dark fans and now they have grey/blue halos where there was dark material before. This could be actual carbon dioxide frost condensing whereas the others are the particulates from the fans sinking into the ice and the carbon dioxide ice recrystallizing.

  So in that case, it might be that the images were taken at a chance timing where there was frost coming out or had been recently deposited.

  ~Meg

  Posted July 4, 2013 3:28 PM

• by wassock moderator

  so is the blue essentially the same as the bright/white halos?

  Posted July 4, 2013 10:50 PM

• by mschwamb scientist, translator

  I believe so. I think using color alone is hard to say much about as Anya and Michael wrote about in the blog. But I believe the white and blue is thought to be fresher carbon dioxide ice or frost and that likely both the mechanisms the deposition of frost/particles sinking through+ice recrystalizing are occurring on the south pole. I think there is more of a lean now towards the particulates sinking in for the halos especially. This cutout (APF0000ptt) has a bluish tint in the halos but others don't as you've pointed out.

  Cheers,
  ~Meg

  Posted July 7, 2013 4:20 PM

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

  Hi Meg, this is starting to cross with the other current thread on HiRise, need to go find and reread the paper on the ice cleaning itself of particulate but I seem to remember somewhere that for the initial clean of particles entrained during the winter they are all gone in a couple of days? But the particles in the fans take longer?

  why/how do we get the purty blue colour? is it real, as in caused by light interacting with the surface, or just a camera effect

  Posted July 7, 2013 11:08 PM

• by angi60

  Wassock - In case you're interested, here are more bright blue fans dated November 29th 2010.

  

  Posted July 9, 2013 1:11 AM

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

  Michael wrote a nice explanation on the blue and ice crystalization here.

  Cheers,

  ~Meg

  Posted July 11, 2013 4:14 PM

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

  Thanks angi thats a greeny blue and there seems to be a fair amount of that from all years. What I'm looking for is the brilliant sky blue fans which all seem to be from 2010 and most of the "best" ones from the same day/HiRise image

  Posted July 12, 2013 12:51 AM

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

  Thanks for pointing back to that Meg, still doesnt clarify why we see blue, or if what we are looking at really is blue. And he's also calling airborne crystallised (in the vent plume) CO2, frost instead of snow, which confuses things (for me least ways).

  Posted July 12, 2013 12:59 AM

• by angi60 in response to wassock's comment.

  Ah, sorry! I'll watch out for brilliant blue then. At least you know I can insert images into text now!!

  Posted July 12, 2013 1:18 AM

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

  Well the crystaline structure of the ice changes, and so the light reflection and refraction is different which I believe is what creates the color. I don't know if it's really blue because of the way the HiRISE filters are. Yes I think people are kinda referring to the same thing when they say frost or now.

  Hopes this helps,

  ~Meg

  Posted July 12, 2013 2:21 PM

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

  wrt the frost/snow thing it seems to me important to make a distinction between the 2. Snow will, initially, be a layer of particulate CO2 on top of the solid transparent ice, or on top of a dusty fan. Frost will be deposited from air as a fresh layer of ice either direct to the existing layer or as a coating on the dust fans. If co2 frost is anything like water frost, on grass say, the the range of visual effects could be considerable. Whichever, each combination, frost/ice, solid ice/dust fan , will be different. thus it's important to get the definitions tied down so we all know what we're talking about (ses me)

  Posted July 12, 2013 10:31 PM