Interesting features in Hirise pic.

[h9c2]

No, I installed just openEV. The browser plugin works quite nicely, with easy zoom features and measurement features.<br />I'll do crops the old fashioned way (print screen).

 

[centsworth_II]

The "wrinkled surface" looks exactly like the dust/sand ripples<br />seen by the rovers Spirit and Opportunity. The top picture below<br />is El Dorado in the Columbia Hills as seen from orbit before Spirit <br />got there. There was much speculation (not by scientists) that it <br />was a deep hole. MRO shows it to be a "wrinkled surface" (center <br />image) and Spirit's ground level image shows it to be a field of<br />wind-blown sand/dust ripples.<br /> <div class="Discussion_UserSignature"> </div>

 

[h9c2]

very nice sequence.

 

[alkalin]

A series of good views you have given, but the darkness could be because of shadow in a depressed area. This one does not give me that impression. Many areas of sand pretty much look alike concerning contrast, and sand can look rippled like this, but why the darkness in this area and the well defined borders? I still think the photo given by H9C2 is a lava flow because from the right edge of the dark area there appears to be a lava vent. Maybe we need higher resolution to determine this. <br /><br />

 

[vandivx]

<font color="yellow">Crop of the "lake."<br /><br />There seems to be some detail in the shadow.</font><br /><br />nice how that 'detail in the shadow' got confirmed, it is educating to compare that to the next posted picture as well as series of the three pics from centsworth_II above here<br /><br /><br />anyway, looking at the best on the web version it looks like the whole area of those two location published here is darkish, perhaps the dark stuff underneath is getting exposed as the top cover gets blown away and those 'lakes' show fully what's underneath<br /><br />vanDivX <div class="Discussion_UserSignature"> </div>

 

[generic_man]

Apparently my own other throw-away idea was correct:<br /><br />"The only strong alternative explanation is of course the deeper Regolith is exposed and is very dark. But that seems very reaching. They ought to bounce some Radar off them to confirm a uniform surface, as they have at Titan. The equipment is online and available for that."

 

[generic_man]

"but why the darkness in this area and the well defined borders? "<br /><br />Maybe it was a "lake" at one time; a Lake of Fire. It has shorelines and entirely different morphology and regolith deposit than the areas outside of it. <br /><br />There seems to be little evidence of outflow, so it may have been a geological equivalent to an "abscess" ---an area of crustal softening due to a bubbling up of magma that never burst out and flowed, thus creating a literal Lake of Fire. As in Hell.

 

[vandivx]

I took some detail pics<br /><br />ftp://mir2.pointclark.net/PSP_002812_1855_RED_details.zip<br /><br />if some of you want to post these pictures on here, go ahead, I never posted any and not sure how to go about it<br />I suppose you use 'img' tags with http:// url inside them? and then you wait for approval?<br /><br />there are intriguing messas and what looks like volcanos but is probably just ejected boulders from impact cratering, sinking (or perhaps lifting) of whole large areas, probably prevailing winds from the left side as you look at the picture creating those bugaboos that throw dark shadow to the right... it is mind boggling for this Mars tourist <img src="/images/icons/crazy.gif" /><br /><br />vanDivX <div class="Discussion_UserSignature"> </div>

 

[h9c2]

After you compose your post, you mark "I want to preview my post and/or attach a file". Hit continue, and browse for your file.

 

[abq_farside]

I was able to download the J2000 plug-in. One problem I have seen is if you pan to quickly it was crash the browser.<br /><br />But it is great for viewing these large hi-res files. Great detail comes out. <br /><br />Take a look at the MRO thread in M&L <div class="Discussion_UserSignature"> <p> </p><p><em><font size="1" color="#000080">Don't let who you are keep you from becoming who you want to be!</font></em></p> </div>

 

[centsworth_II]

<font color="yellow">"if some of you want to post these pictures on here, go ahead"</font><br /><br />Thanks, I picked out the images showing dark sand ripples in the bottoms of craters:<br /> <div class="Discussion_UserSignature"> </div>

 

[centsworth_II]

How did that light-colored dune -- so straight -- get formed?<br />Did it form first, to be later surrounded by dark ripples or did it form<br />over top of the ripples? Did they both form at the same time? <div class="Discussion_UserSignature"> </div>

 

[centsworth_II]

<font color="yellow">"Maybe it was a 'lake' at one time; a Lake of Fire."</font><br /><br />Yeah. It doesn't have that round crater look. But well-defined borders of the<br />depression do explain the sharp edges of the dark sand field contained within.<br />Maybe it's the severly remnants of two conjoined craters? Or maybe there's <br />some other explaination, like you say. <div class="Discussion_UserSignature"> </div>

 

[centsworth_II]

<font color="yellow">"The only strong alternative explanation is of course the deeper Regolith <br />is exposed and is very dark."</font><br /><br />The non-alternative explaination is that the dark material is dark sand <br />which has collected in the bottoms of depressions (mostly craters).<br /> <div class="Discussion_UserSignature"> </div>

 

[silylene old]

A lot of these holes simply do not look like craters. I base this on shape, size distribution, and proximity to one another.<br /><br />A close look at the detailed picture also shows a lot of layering in the light colored rock.<br /><br />Could these be origainlly long ago water formed (potholes, sinkholes), or holes formed by an aelian process? And then later filled with dark sand? <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>

 

[centsworth_II]

Those dark sand patches are a lot less of a mystery to Mars scientists<br />than they may once have been, now that one -- El Dorado -- has been<br />visited on the ground by the MER, Spirit.<br /><br /><b>"Dark patches similar in some respects to El Dorado have <br />been observed from orbit at many locations on Mars... <br /><br />Objectives of Spirit’s visit to El Dorado were to <br />characterize this unusual unit ...and obtain data to help <br />calibrate and inform interpretations of orbital observations <br />of other, similar features elsewhere on the martian surface."</b><br />http://www.lpi.usra.edu/meetings/lpsc2006/pdf/1829.pdf<br /><br /><br />Comments by Steve Squyres -- MER lead scientist:<br /><b>"El Dorado is a spectacular dune field. We didn't know what it was <br />going to be until we got on top of it. We think that, in terms of how <br />this thing got here, because of the configuration of this terrain with <br />respect to the prevailing winds, it may be an aeolian cul-de-sac. ...<br />Mini-TES spectra of El Dorado look like the dark soils exposed by wheels <br />during traverses: pyroxene, plagioclase, olivine of Fo45 or so. What you <br />see in the Microscopic Imager is a sand that is very well sorted, very well <br />rounded, grain sizes a few hundred microns, chemistry very similar to <br />average Gusev soil though somewhat higher in olivine. This is very clean <br />stuff. Mössbauer mineralogy: lots of olivine, pyroxene, essentially <br />unaltered, low Fe3+, very clean.</b> <br />http://www.planetary.org/blog/article/00000497/<br /><br /><br /><b>El Dorado, Columbia Hills, Mars --- by Spirit, Mars Rover</b> <div class="Discussion_UserSignature"> </div>

 

[centsworth_II]

<font color="yellow">"A lot of these holes simply do not look like craters."</font><br /><br />Maybe not. The nature and origin of the depressions is a lot more <br />uncertain than the nature of the dark sands filling them. <div class="Discussion_UserSignature"> </div>

 

[vandivx]

<font color="orange">two conjoined craters? Or maybe there's<br />some other explaination</font><br /><br />the majority of those dark ripples are inside circular depressions and those are fairly obviously craters and I would think those irregular shaped 'lakes' will also be craters, multiple conjoined craters that is, in some places you get almost no cratering and then in one close area you have four, five craters fairly close together, probably the metorite broke up before hitting (one good example of that is inside that large humungous crater at the bottom of the overall picture of the area<br /><br />that said there is also evidence of sinking and cracking of the surface cover which seems to be just a shell cover for the dark stuff undernath, on the overall picture view at the top right is what looks like some muddy flats that were flowing at some time, you can see that place on the very first post on this thread by H9C2<br /><br />air turbulence is an amazing thing if it can form that one dune inside the crater but other such dunes cover even the whole crater's bottoms<br /><br />and of course 'black' sand doesn't have to be black, dark red color makes best black even on color photos when there is not quite enough light, perhaps that dark stuff is red and it is what makes Mars reddish as it gets flown about in fine dust all over the planet and in some areas you just see it concentrated like inside these craters, meteorites punched holes into surface cover and uncovered the red sand directly... could that be?<br /><br />BTW for those who still can't open the picture, its size should be 252 MB when properly downloaded and I used one of the recomended viewers on that site, the Kakadu viewer for windows http://www.kakadusoftware.com/ and it works fine although the controls take some getting used to<br /><br />vanDivX <div class="Discussion_UserSignature"> </div>

 

[vandivx]

"evidence of sinking and cracking of the surface cover which seems to be just a shell cover for the dark stuff undernath"<br /><br /><br /><br />vanDivX <div class="Discussion_UserSignature"> </div>

 

[exoscientist]

H9C2, I wanted to see an area imaged by MGS be imaged by HIRISE.<br /> How did you go through your request to see the blowup of that image above?<br /><br /><br /> Bob Clark <div class="Discussion_UserSignature"> </div>

 

[h9c2]

I just emailed the webmaster on the hiroc page.

 

[h9c2]

So, am I correct in understanding that this is an effect of some sort of aeolian centrifugation and sorting process? (particles get sorted according to size and specific density)<br /><br />Do we have examples of a Terran equivalent?<br />

 

[centsworth_II]

Steve Squyres' description of El Dorado as an "aeolian cul-de-sac" <br />seems to imply that dark basaltic sand has collected there. His <br />description of the sand as "clean" seems to say that the ubiquitous <br />light dust that covers (almost) everything on Mars has been blown <br />away from the area.<br /><br />Slinted, one of the great posters over at unmannedspaceflight.com,<br />made several movies that actually show El Dorado being swept clean in <br />this thread.<br /><br />See here in the thread (check the link to the movie), <br />and here.<br /><br /><br /> <br /> <div class="Discussion_UserSignature"> </div>