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The power of HiRISE
Stu
post Oct 6 2010, 08:36 PM
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Hmmm. Good point about the deposition, hadn't thought of that... smile.gif Just thought it was a fascinating view.

Wow... just spotted this is my 4000th post. Doesn't time fly when you;re having fun? smile.gif


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ngunn
post Oct 6 2010, 09:54 PM
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'Dry water' has just been in the news: http://www.telegraph.co.uk/science/science...-dry-water.html

Apparently if you subject the powder to pressure you can squeeze the water out of it. What I don't know is whether this form of water is more resistant to sublimation under Martian conditions than ordinary ice. It does make me wonder though if something akin to 'dry water' could be present in Martian sediments. If so then the transient appearance of ice in avalanche debris might not be out of the question.
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vikingmars
post Oct 7 2010, 12:33 PM
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QUOTE (Phil Stooke @ Jul 29 2010, 04:21 PM) *
I did an experiment using pictures of the old Spirit lander. I tried finding images of other places at Meridiani - Beagle crater, Eagle crater...

Great work Phil ! You are really the leading landing sites imaging cartographer ! CONGRATULATIONS. wheel.gif wheel.gif wheel.gif wheel.gif wheel.gif
Although they are not of your quality work, I did also some tries in 2007 combining several HiRISE images together to get more details for Viking and MPF :
- VL1 : http://www.unmannedspaceflight.com/index.p...ost&p=97402
- VL2 : http://www.unmannedspaceflight.com/index.p...ost&p=97712
- MPF : http://www.unmannedspaceflight.com/index.p...ost&p=97572
Enjoy ! smile.gif
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fredk
post Oct 10 2010, 02:38 AM
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QUOTE (elakdawalla @ Oct 6 2010, 09:30 PM) *
that spot in the fan should be an area of deposition, not exposure

So maybe there were chunks of ice that came down with the avalanche, and those whitish areas are the remnants of the last of them as they sublimate away. That would mean it was a recent avalanche, but we have caught them in action before...
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Juramike
post Oct 10 2010, 04:44 AM
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QUOTE (ngunn @ Oct 6 2010, 04:54 PM) *
'Dry water'


..has been around since 1968. It is the "potential" application extensions that made news.

Official ACS press release here.

It is basically a hydrogel, except it is encapsulated in silica rather than in a polymer. (Think of it as teensy drops of water surrounded by a silica coating.) The silica prevents evaporation, but allows the diffusion in of gases through the silica barrier. (I'm guessing the strength of the water network prevents the individual water molecules from easily escaping.)

I'm not sure how easily this could be formed naturally on Mars....




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nprev
post Oct 10 2010, 05:10 AM
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Yeah, that looks like a pretty unlikely substance, all right.

Hmm. Why does it have to be ice? We've seen Spirit's bum wheel churn up all sorts of bright deposits, including white stuff. Maybe it's a big deposit of MgO, or even CaCO3. If so, dust deposition will gradually cover it up.


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lavaphile
post Oct 19 2010, 05:40 PM
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The blue color is typical of ice in HiRISE "enhanced" color images. These cliffs are along the margin of the polar cap and are composed of mostly ice (H2O) with coloring/coating by dust. So I think the blue is exposing clean ice from broken blocks that fell to the base of the cliff. What is really hard to appreciate from these images is just how steep and tall these cliffs are...
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sgendreau
post Oct 21 2010, 10:41 PM
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About 700m (2500 ft) and darn near vertical. blink.gif
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monitorlizard
post Oct 29 2010, 09:36 PM
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Don't really want to start a new topic, so I'll put this here. I've noticed that the weekly releases of new images on the uahirise.org website have only had one extended phase (ESP prefix) image per week, with the rest being primary science phase (i.e., older) images. I found something from the September 2010 MEPAG meeting in a presentation titled "Current Orbiter Capabilities for Future Landing Site Selection" that might help explain this:

"HIRISE: Team has used longer and more frequent warm-ups to compensate for increasing ADC (analog to digital converters) bit flip errors. Considering an onboard annealing sequence which ground testing indicates could reduce errors by breaking up and dispersing the ADC contamination."

Later in the presentation it says "need to use the capabilities conservatively where instrument and/or spacecraft limitations dictate." Also of interest is where it reports CRISM capabilities have decreased because of degradation of its gimbal (used for high resolution) and coolers (needed for IR observations). I don't think these degradations are reversable.

Hopefully, HiRISE can successfully do the annealing fix before maximum data transmission rates are reached again next year.
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nprev
post Oct 30 2010, 12:13 AM
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Rats. Nothing serious (yet), but it always hurts to see spacecraft begin to age.

At least the restart issue seems to have been cured, so hopefully the ADCs can be healed as well.


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monitorlizard
post Oct 30 2010, 06:33 PM
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I should add, for those who are interested in CRISM, that the same presentation said the following about future CRISM operations:

"Plan: Use full VNIR/IR capability for 2 weeks every other month in mini-campaigns focused on high priority items(especially during periods of higher data rate)
--VNIR-only mode can be used at other times (but avoid major dust events)
-----VNIR (0.4 to 1.1 micrometer) aqueous mineral signatures are limited to ferric minerals
Bottom Line: Full-resolution VNIR/IR targeting reserved for high priority targets"

It's sad to see the instrument in decline, but cryocoolers like CRISM's are hard working pieces of machinery that can't be expected to last forever. They sure did a good job until now, though.
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Stu
post Nov 17 2010, 08:20 PM
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Attached Image


Colourisation of 'rock bridge' seen on one of today's new HiRISE releases (seen before, but still cool!) http://hirise.lpl.arizona.edu/PSP_001420_2045


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vikingmars
post Dec 23 2010, 10:52 AM
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Some stunning pics of the interior of giant Mars pits...
Link : http://news.nationalgeographic.com/news/20...636_600x450.jpg
Attached Image

Enjoy ! smile.gif
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SteveM
post Dec 23 2010, 04:20 PM
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QUOTE (vikingmars @ Dec 23 2010, 05:52 AM) *
Some stunning pics of the interior of giant Mars pits...
Link : http://news.nationalgeographic.com/news/20...636_600x450.jpg
Enjoy ! smile.gif
Very nice detail. Any idea of the depth of those pits? A second image would give a stereo pair; or if we knew the illumination geometry, the shadows would do it.

Steve M
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Tesheiner
post Dec 23 2010, 04:41 PM
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Here's the page at the HiRISE site: http://hirise.lpl.arizona.edu/ESP_019997_1975
Look at the bottom for some geometry info.
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