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To El Dorado...
ustrax
post Dec 28 2005, 01:49 PM
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I see it like this, winds coming from SE, bringing lighter particles and volcanic sand, climbing the slope.
In the place where now we see the dark sand, there is a wall on the western side keeping the volcanic sand imprisioned but letting the lighter particles follow their way, following the direction of the winds, quoting Steve Squyres, an 'eolian cul-de-sac'.
So, if analyzing that El Dorado dark deposits, it wouldn't surprise that Spirit would find mainly micro basaltic pieces, crystals and lots of olivine, the composition of volcanic sand.
Well, just a guess... wink.gif


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djellison
post Dec 28 2005, 01:51 PM
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The prevailing wind is from the NNW however, look at all the DD tracks crossing Gusev Crater

http://www.msss.com/mars_images/moc/2004/0...02.R1101577.jpg

Doug
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ustrax
post Dec 28 2005, 02:05 PM
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QUOTE (djellison @ Dec 28 2005, 01:51 PM)
The prevailing wind is from the NNW however, look at all the DD tracks crossing Gusev Crater

http://www.msss.com/mars_images/moc/2004/0...02.R1101577.jpg

Doug
*


Yes Doug I know...But I find strange that if the sand was being brought from NNW then we would see dark material in a wider area right under the summits...And we see it only in that hill corner...
And Steve Squyres, on a question I made, answered that the El Dorado material had 'probably just climbed a hill slope'...
Soon we'll have more answers...


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ustrax
post Dec 28 2005, 02:08 PM
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Just forgot this, talking about volcanic sand patterns:

http://www.edgypix.com/pages/torf0706.shtml

Have some similarities, doesn't it?


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helvick
post Dec 28 2005, 02:22 PM
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QUOTE (ustrax @ Dec 28 2005, 03:05 PM)
Yes Doug I know...But I find strange that if the sand was being brought from NNW then we would see dark material in a wider area right under the summits...And we see it only in that hill corner...
*

I think we are talking about two different seasonal wind systems. I know nothing about the prevailing winds in Gusev but I'm pretty sure there are global changes in the average wind direction between Southern Hemisphere Summer (DD Season, NNW tracks) and winter (SSW would make sense but the local geography might seriously change that and the overall impact of the martian global weather system most certainly creates trade wind bands which might reverse these).
This is just my gut feel for the thing, SH Winter, polar regions cool substantially and pressure rises leading to predominantly Southerly wind (source) directions and this would reverse in NH winter. The global imbalance in Martian seasons would play an important role as the SH Winter effects are less extreme and shorter.
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ustrax
post Dec 28 2005, 02:26 PM
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QUOTE (ustrax @ Dec 28 2005, 02:08 PM)
Just forgot this, talking about volcanic sand patterns:

http://www.edgypix.com/pages/torf0706.shtml

Have some similarities, doesn't it?
*


Let's see if you can understand what I'm trying to say...
I think that the volcanic sand was trapped in a depression (not-an-abyss!) existing between the western wall and where now lays the boundary between the light and dark material (in reddish tone), brought from winds (direction indicated by the arrows) from the floor of the basin...
The area covered by light material (in brownish tones) worked as a road to perdition to that poor dark sand.

http://img.photobucket.com/albums/v352/ustrax/pw.jpg


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RNeuhaus
post Dec 28 2005, 02:36 PM
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QUOTE (ustrax @ Dec 28 2005, 09:05 AM)
Yes Doug I know...But I find strange that if the sand was being brought from NNW then we would see dark material in a wider area right under the summits...And we see it only in that hill corner...
And Steve Squyres, on a question I made, answered that the El Dorado material had 'probably just climbed a hill slope'...
Soon we'll have more answers...
*

Hello, the answer will be by looking the formation of dunes. The dunes always forms in perpendicular angle to the prevailing winds. Very soon we are going to confirm about this whenever Sprit takes a much better view and angle picture. Up to now, there are still no good pictures to see about this.

Rodolfo
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Bill Harris
post Dec 28 2005, 02:53 PM
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QUOTE
The dunes always forms in perpendicular angle to the prevailing winds.


Not always. This is true with transverse dunes, but not with longitudinal or reversing dunes.

I think that the answer will be complex. Is this area the result of selective winnowing or deposition of the dark sand because of a unique wind pattern caused by orographic effects, or is it caused because the source material for the sand is _at_ this location, or both? We need MIs of the sand, and minerology.

Note other "dark sand" examples in the Northeast Basin and another spot to the south of the Inner Basin. Start picking up clues: from the current route, what is the local wind direction?


--Bill


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Bob Shaw
post Dec 28 2005, 03:33 PM
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QUOTE (DFinfrock @ Dec 28 2005, 03:44 AM)
It looks to me that there is such a sharp edge to the dune/ripple field, that it should be no problem to drive right up to the first ripple, extend the arm, and examine it closely, without actually placing a wheel into the sand itself.

David
*


David:

Very true!

And, returning to the subject of the holes which Opportunity has seen, it'd be an ideal way for that counting exercise. I've also had another bright idea - this time, perhaps in the Ted Stryk / Phil Stooke Department of Old Data: Viking 1 saw some drifts, which Ted has turned into super-res images on his website. I can't see any, but has anyone else spotted any holes? If they're not visible at Gusev when we see El Dorado up close, possibly not visible at Chryse in old images BUT visible at Meridiani then we're seeing either a 'special' impact event (which I'd be leery of, though obviously it might happen) or something inherent in the Meridiani environment...

Ted's website is at: http://pages.preferred.com/~tedstryk/

Bob Shaw


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antoniseb
post Dec 28 2005, 04:09 PM
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QUOTE (Bob Shaw @ Dec 28 2005, 10:33 AM)
If they're not visible at Gusev when we see El Dorado up close, possibly not visible at Chryse in old images BUT visible at Meridiani then we're seeing either a 'special' impact event (which I'd be leery of, though obviously it might happen) or something inherent in the Meridiani environment...
*


It's worth trying to count them per square meter. We've seen images of a lot of square meters of dust-piles at Meridiani, and not nearly so many at Gusev, no mater whether we look at ALL of El Dorado or not. If the images from Chryse show even one, it will be a lucky chance.
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ustrax
post Dec 28 2005, 04:23 PM
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New maps up:

http://marsrovers.jpl.nasa.gov/mission/tm-spirit/index.html


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ustrax
post Dec 28 2005, 04:41 PM
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Ladies & Gentlemen...
We have arrived!:

http://qt.exploratorium.edu/mars/spirit/na...00P0775L0M1.JPG

biggrin.gif


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dot.dk
post Dec 28 2005, 04:50 PM
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WOW!!! blink.gif

That IS amazing!! Looks greeeeeat!

This is a great end to 2005! Happy New Year! biggrin.gif


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dot.dk
post Dec 28 2005, 04:51 PM
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LOOK at that! ohmy.gif





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ustrax
post Dec 28 2005, 04:54 PM
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QUOTE (dot.dk @ Dec 28 2005, 04:51 PM)
LOOK at that!  ohmy.gif

*


Wasn't it supposed to stay just at the 'shore'?
Spirit just couldn't resist to refresh her wheels... smile.gif

http://qt.exploratorium.edu/mars/spirit/na...00P0775L0M1.JPG

Don't swim to far away honey! huh.gif


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