Mount Sharp - Extended Mission 1 - Page 61

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LWS


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Reply: 1201



PostPosted: January 24, 2016 5:30 PM 

Barsoomer;

Look at this one.

[link]

To me this is a strong indication of liquid flows from under the surface of ripples. In this case the flow is not from under a rock and appears to be occasioned by the vigorous nearby movement of Curi.

Hope they recognize the import of this image and quickly do some indepth science of the very typical debris flows.

Barsoomer


Posts: 344

Reply: 1202



PostPosted: January 25, 2016 1:00 AM 

I can't see them driving on the dune, but maybe they can do some remote sensing.

AZ-Dave


Posts: xxx

Reply: 1203



PostPosted: January 25, 2016 11:34 AM 

On that image - Nasa has actually seen those slides and commented on them.
They happen when Curi (weighing in at 2000lbs) rolls by and the vibrations cause sand that is at steep angles to slide, this happens on dunes on Earth also, so there is probably good explanation for that.

I think we are seeing different types of activity in different areas. They are also doing a lot of images to look for movement/change over several days, and supposedly some wind-detection measurements - Im very interested to see what they come up with. Ive already seen some of the animated GIF's and there appears to be white flecks that move, or appear and disappear.

AZ-Dave


Posts: xxx

Reply: 1204



PostPosted: January 25, 2016 11:47 AM 

Here is a good stitches, extremely high res image selfie. There are several slides on the slipe-face of the dune, some further away, and some that appear to be right at its wheels.

The left wheel - appears to be partially buried in the sand as well.

https://www.flickr.com/photos/105796482@N04/24571234586/sizes/o/

Faceless


Posts: xxx

Reply: 1205



PostPosted: February 1, 2016 3:04 AM 

Ooids found at Namib Dune:
[link]

Kye Goodwin


Posts: 1166

Reply: 1206



PostPosted: February 1, 2016 3:10 PM 

AZ-Dave, re your 1204, That's a beautiful panorama you linked, with many avalanches visible, but it doesn't include any part of "the slip face of the dune". This is the most interesting discovery about Namib, in my opinion. What we were calling the slip face before Curi's arrival was imaged from sols 1194 to 1210 but then Curi returned to a position where the slip face isn't visible. The big surprise is that these smaller structures that we've been calling ripples have their own "slip faces", a phenomenon that DOES NOT OCCUR ON EARTH. So these "dunelets" or "rippunes" are going to force, at the least, a change to the aeolian terminology we use for Mars to a system that does not correspond to the terminology we use for Earth. YAY!

The weird thing is that we've seen lots of ripples at all three rover sites but none have shown avalanching until now. The activity on the big slip face and the activity on these dunelets must be connected in some way. Is it special sand, or special wind or what?

I sure hope that some of the native soil movements get studied, not just the rover induced movements, which might turn out to be really different.

They're sure spending a lot of time at this location beside the dune. I don't know what the research plan includes besides chemical analysis of the sand. Hopefully Curi will trench one of the dunelets that shows native movement and we will get to see any internal structure. Hopefully Curi will return to the big slip face and re-image to look for changes.

AZ-Dave


Posts: xxx

Reply: 1207



PostPosted: February 1, 2016 3:47 PM 

Very good points indeed. Part of the problem we might all be facing, is that if pressure on Mars is indeed much higher than officially stated, then the actions of wind/moisture etc will be significantly different than expected.

I will note...looking at the up-close images of the sand, a lot of it appears to be much smaller than 1mm, in the 1/10th range...so this stuff is small...there are also the perfect Ooid-spheres present all over, and the sand has many different types of grains...its not a homogeneous substance.

Im also postulating that the Dunes may have a frozen or partially frozen interior...which would beg the question...where all the moisture coming from? More to be determined on that.

LWS


Posts: xxx

Reply: 1208



PostPosted: February 1, 2016 4:31 PM 

AZ-Dave

Just to confuse the issue a bit more.

Here's a 3D anaglyph of two sol 1236 navcam releases from today.

Curi's wheel movements caused 2 major slippages from higher up the slope. The first one (the highest one) resulted in the classic "debris flow" phenomenon where the surface crust was broken and darker material flowed in characteristic patterns from under the crust.

Below that layer the crust merely separated showing the dark structureless subsurface.

Below that is the pattern left by the wheel churning and then below that is dark churned material emanating from the churned up soil.

The same process, probably involving water, is at work here as is seen on most of the slopes that Curi has imaged.

Winston

LWS


Posts: xxx

Reply: 1209



PostPosted: February 1, 2016 4:33 PM 

Here's the x-eyed 3D for the image shown in reply 1208.

Winston

LWS


Posts: xxx

Reply: 1210



PostPosted: February 1, 2016 9:46 PM 

Here's a comparison, by montage, of the sol 1221 and sol 1236 images of the area of the "debris flows"

Note that it seems that the flows have enlarged a bit between the two dates. The middle crack has widened. The flows below the middle crack are smoother and the surficial "salt deposit" that was evident in the sol 1221 image has gone.

Winston

AZ-Dave


Posts: xxx

Reply: 1211



PostPosted: February 2, 2016 3:29 PM 

I indeed saw these, and other people (aka NASA) are noticing the crust...I believe they are taking interest in it...because the crust infers more moisture present at least in air, than would be expected.

On the debris under the crust, Im 99.9% sure its very fine very dry..the "darkness" vs Lightness is caused a lot because the NAVCAm's see in mid and near I.R. and not what the human eye will see...so the darkness of any NAVCAM images needs to be considered and compared with MAHLI and MAST whenever possible.

I dont think we are seeing liquid flows (temps too low), but Im still thinking there could be significant Ice under the dunes somewhere, and surely in the crust (though it would take very little frost/ice to make the crust adhere)

Im very interested in what the sand movement data will show...so far, I havnt see much to show the dunes moved much...which means when they do move they move faster...where does the air resistance come from at less than 1% ATM?

LWS


Posts: xxx

Reply: 1212



PostPosted: February 2, 2016 4:23 PM 

AZ-Dave;

It seems as if it is now respectable to consider that the RSL's or slope streaks might be powered by liquid brines.

So why should it be unlikely that the "debris" flows are similarly powered?

Indeed, the first images of the flows we are now discussing showed what might be traces of salt from a putative brine left on the surface. Why should these "dry" very fine particles leave those deposits in a characteristic pattern of evaporation from the surface?

Re, the darkness of the "flows" in the navcam images as compared with the Mastcam and MAHLI ones, You have evidently not yet seen the numerous MAHLI and Mastcam images of the " debris flows" that are characteristically very much darker than the surface crusts of the typical martian dust.

The RSL's form in low or lower temperatures than the "debris flows".

If there is significant ice under the surface is'nt it also likely that there could be brines there as well that could ensure that such brines would escape almost instantly if the crust is removed thereby producing the debris flows? The pockmarked appearance of the Marathon "extruded blob" is a characteristic of escaping water vapour from sandy material through interstices in the sand coloumn.

What we therefore see and what the rover's instruments would be analysing for sublimed water would be the fine debris left. The water has gone by the time curi is ready to analyse it!

So yes! I don't agree with you that water was not involved in the "debris flow process" even though water might not be found in the flows at the stage analyses for such water is done.

Its simple!

Winston

ffff


Posts: xxx

Reply: 1213



PostPosted: February 2, 2016 11:56 PM 

It isn't too cold. Gales gets up to 90f in summer. We need to stop repeating this line from the 1970s..Mars is not cold. Spirit rover had three weeks of 90 degree temps before it but the bullet. Equator areas on mars are not going to be much different than deserts on earth. Cold nights and hot days

greenmars


Posts: xxx

Reply: 1214



PostPosted: February 2, 2016 11:58 PM 

It gets that warm on mars? Interesting

Faceless


Posts: xxx

Reply: 1215



PostPosted: February 3, 2016 3:36 AM 

Really great science at Namib Dune, reported in
http://astrogeology.usgs.gov/news/astrogeology/sol-1242-last-analyses-of-the-dump-piles

Kye Goodwin


Posts: 1166

Reply: 1216



PostPosted: February 4, 2016 6:45 PM 

ffff, and greenmars, "It gets that warm on Mars ?" No it doesn't, but I think I may know where that rumour comes from. I remember reading years ago that heat sensors that measured the temperature of parts of the Spirit rover itself sometimes reached the +30's C heating in the sun. The air temperature would never have gotten anywhere near that high. Surfaces heated by the sun on Mars could get a lot warmer than we might expect because the air is so thin that it doesn't cool surfaces very well. Its the same principle as those solar water heaters that use a vacuum as a thermal insulator. For the same reason the surface of the ground on Mars often gets well above the air temperature a few centimeters above. Both can get well above freezing at midday but neither ever gets hot.

Barsoomer


Posts: 344

Reply: 1217



PostPosted: February 4, 2016 10:46 PM 

We don't have to guess the temperatures, we can get them from the official sites:

[link]

[link]

Festus


Posts: xxx

Reply: 1218



PostPosted: February 5, 2016 10:34 AM 


That's cold air, but surface temps do get above 0C. I believe Spirit was trapping surface heat. But hey, heat is heat.

Faceless


Posts: xxx

Reply: 1219



PostPosted: February 8, 2016 5:00 AM 

NASA scientists saw no ooids at High Dune in Bagnold Dunes:
http://www.hou.usra.edu/meetings/lpsc2016/pdf/2298.pdf

LWS


Posts: xxx

Reply: 1220



PostPosted: March 1, 2016 5:36 PM 

Trying to retrieve this thread

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