Water on Mars - Page 2

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Barsoomer


Posts: 344

Reply: 21



PostPosted: April 7, 2011 1:34 AM 

If the dark material was blowing up from below, wouldn't the outer surface of the rock be blackened? The darkness seems mostly underneath light-topped rocks.

Rather than dark material being blown up from below, I can't help believing the dark material below came from on top. In Kye's last image, it looks to me that the light-topped rocks have partially collapsed down, revealing a massive smooth dark layer of soil underneath, below the thin rock layer.

MPJ


Posts: 250

Reply: 22



PostPosted: April 7, 2011 3:29 AM 

IMO there is no single explanation of slope streaks on Mars. The typical rather dull streaks in dust laden areas of Mars are what they are thought to be: dust/sand i guess Smile

In other areas, eg the streaks orginating just from rocky outcrops are another class and i suspect they are the product of some kind of weathering (chemical,physical or biology of some kind - who knows?).

Yet another class I consider from observations are those streaks which also seems to originate only from descrete sources (rocky outcrops or holes?) which soon fades to bright white color (like in the image of re4) - evaporate residue of brines or other volatiles?

Kye Goodwin


Posts: 1166

Reply: 23



PostPosted: April 7, 2011 1:15 PM 

Ben, Yes, maybe Namib at Endurance is a bedrock outcrop. Here's an oblique view again (far right, center):

The rocks above the northwest wall structure at Santa Maria are not bedrock. In this way then, the two fine-grained wall structures maybe occupy slightly different geologic settings, which for you suggests that they don't share an origin. I don't understand how either formed, so I'm less impressed with the bedrock/breccia distinction. You suggest that material has blown up the slope, but what was the LAST thing to happen to the fine material in this image?

Maybe there is a landform I've never heard of in that photo of Arizona you're missing, but I thought that climbing dunes, for example, would be transverse to the wind and run across the slope. Are you saying that the sand blew up this slope at Santa Maria in some earlier time but is now mostly sliding back down? If the sand has been placed on the slope by wind, how do we explain the west end of the structure that doesn't have any sand below it? It is hard to imagine the sand blowing across the slope, to create transverse ripples running up and down the slope, without sand also spilling downward.

To me, it really doesn't look like wind was the last process to reorganize the fine material on the north-west wall of Santa Maria. At Namib we would never suspect wind to be the agent, because there are no ripples below, and because the structure has what look like elongated colluvial fans running up and down the slope. I think that the north-west wall structure in Santa Maria is related to the one under Namib.

The dark wall trickles and their relationship to the deeper dark wall deposits is a separate issue, though both appear to be gravity-shaped. If the dark trickles are one source of the deeper dark deposits then I would have to guess that they are the primary source, just by Occam's Razor. It is extraordinary enough to have one source of uniform fine-grained dark sand accumulating there. It is too much complexity for me to expect two entirely unrelated sources of dark sand to contribute.

MPJ, Yes, there are many kinds of slope streaks on Mars and in my opinion none have been well explained. Occam's Razor again makes me wonder if the variety of streaks might be related in some way. The streaks that Oppy has imaged do not appear to involve water, not in an obvious way at least, but there is also plenty of evidence that they are not dust avalanches. I think that Oppy's streaks, which are the only ones ever imaged close-up, might have something important to tell us about all the slope streaks. They are collectively the most active features on the surface. I suspect that they are related, quite possibly by descent.


mann


Posts: 161

Reply: 24



PostPosted: April 7, 2011 1:26 PM 

ok, all the geologists, rock guys, say everything we see is made up of basalt.

they say the dark sandy material is basalt.
they say that the dark streaks are coming from the basalt rocks in the cliff. Why when we drill into the rocks, they are not grey?
MPJ, is correct, when he says grey soil, comes out of holes. grey soil, out of buff colored sandstones.

Stan


Posts: 14

Reply: 25



PostPosted: April 7, 2011 3:43 PM 

Anyone have any ideas how liquid water could be on a comet? It would seem the lack of air pressure would cause instant evaporation.

[link]

Stan

Stan


Posts: 14

Reply: 26



PostPosted: April 7, 2011 9:14 PM 

Help, my post did not seem to go through.

I'll try another.

Does anyone no how liquid water can exist on a comet, when the air pressure would seem to be non existent?

[link]

dx


Posts: 1661

Reply: 27



PostPosted: April 8, 2011 1:07 AM 

folks>>>

I don't see the effects of water uphill or down hill in any of these pics, but I do see a lighter soil under the top layer of the Martian surface, and then a further darker soil under that lighter layer. Look at Oppy's wheels as it treks across the soil, they displace the original surface layer with the layer directly underneath, hence a lighter trial displays its track.

In my mind and several years ago with many discussions on what the streaks on the soil might be, we settled the cause with 'dust devils' lifting and separating the various soil layers giving the impression of water filtering through the Martian sands. One can actually see these streaks randomly all over Mars. IMO the location of these streaks is important because of the various ground elevations that would gather winds of varying speeds and intensities as seen in 4 above. There must be a big reason for a lot of wind to be generated at those 2 particular spots and it seems to be a high ridge. Does anyone know which way the wind blows in that pic?

We know that exposed ice, re: Phoenix site, sublimates quickly, and when it did no dark soils were noticed in the holes dug.

Besides all that, wouldn't the 'water' simply pool itself into an irregular shape instead of a linear shape in one direction?

Just my thoughts.

yt
dx


Kevin Author Profile Page



Posts: no

Reply: 28



PostPosted: April 8, 2011 4:32 AM 

Comets roam around the coldest parts of Space but latest findings from the Stardust samples suggest liquid water exists in Wild 2 Surprised So Mars being in a lesser frigid zone must surely have every possibilty of holding some liquid water beneath its surface.

[link]

Kye Goodwin


Posts: 1166

Reply: 29



PostPosted: April 8, 2011 12:56 PM 

Ben, I wrote a long response to your reply 20 yesterday morning but it hasn't appeared yet, so I'll try a short response. I agree that there may be a difference between the context of the structure under Namib (far right, center)

and the context of the structure on the north-west wall of Santa Maria (bottom half of the image).

Namib may be bedrock and the rock at the top of the north-west wall is breccia. I don't think I understand the relationship between the outcrops and the sands below. What force LAST affected the surface in the second image above? I haven't been able to make an argument yet but I better check if this posts before I bother writing any more.

Ben


Posts: 2270

Reply: 30



PostPosted: April 9, 2011 12:35 PM 

Kye; It appears that the last force that affected that slope is wind blowing upward out of the crater.
I just noticed something else that supports this.
The jumbled rocks have "rounded" wind abraided ends facing into the crater and angular ends pointing up out of the crater.

Kye Goodwin


Posts: 1166

Reply: 31



PostPosted: April 10, 2011 12:58 AM 

Ben, Re your reply 30, yes, It has to be wind alone or the story gets really strange. The structures on the floor of Santa Maria are interpreted as wind ripples, and those structures are seamlessly connected to the structure on the wall, so the wall structure must also be shaped, at least lastly, by the wind. I don't think that this is wind acting alone and so I think that the story has indeed gotten very strange. Mars has pulled a science-fiction ending.

Mann, re your 24, No mainstream rock guy would accept that anything at all is coming from the sub-surface in the making of these streaks that Oppy has imaged. I don't know if a scientist has ever mentioned the Meridiani streaks in a paper. Anyone, Please? I think that, as with the wall structure at Santa Maria, a strictly wind-powered explanation is the only choice, if this phenomenon is going to stay boring. Even where there are close-ups of material emerging from fractures, in the mainstream view, wind must be solely responsible for placing the sand where it flows down into the fractures from somewhere higher up:

I'm thinking that these trickles of stuff may actually be coming from the sub-surface and be connected to the mysteriously rapid crater erosion, that the mainstream recognizes but cannot explain. Looking again at the big streaks in the image linked in MPJ's reply 4: The astounding thing about that image is that it looks like something has been emerging from the sub-surface. The start zones are tiny and look like they have contributed to multiple events, but, in the end, a strictly aeolian-loaded-avalanche explanation that does not involve the subsurface is possible, if not plausible. My point is that it gets really, really interesting at the point where we think that the subsurface is involved, not at the point where we think liquid water is involved. If Mars science were to notice Oppy's dry slope streaks and come to explain them as material originating underground, then that would be revolutionary.

Ben


Posts: 2270

Reply: 32



PostPosted: April 10, 2011 1:39 PM 

Kye; Excellent example in your # 31.
When I look at thse trickles I am reminded of a large hour glasses in which the very dry sand finds the lowest point that will support it , then cascades down the slope.

As sand continues to accumulate above,( which I believe is from the top of the cliff) the flow is rejuvenated and actually behaves a bit like water the way it follows the diagonal cracks until it encounters a break and spills downward vertically.

I can't coceive of any mechanism that would
create the very dry sand , below the surface, and move it against gravity to the surface so it could trickle downward.

In MPJ's # 4, I doubt this is sand because of its color change and the small source area compared to the size of the streaks.

I believe it is some other substance (probably liquid) that is being periodically expelled from the subsurface.

This may even be a substance we haven't yet considered ,but whatever, it is common .

What are the localities it has been observed; crater walls, dune slopes ??

MPJ


Posts: 250

Reply: 33



PostPosted: April 12, 2011 4:30 AM 

This guy found liquid brine flow on Mars:

"The most existing thing is that these features are only forming in the southern hemisphere and during the summer. We have not found any evidence of these features in the northern hemisphere or during any other season," Ojha said.

"Regardless of any hypothesis, it is very important because we are understanding more about what is happening on Mars," he said. "When NASA looks for the most important feature for life, it is flowing water. If it is true, there could be tremendous implications for astrobiology and future exploration."

http://uanews.org/node/39118

Ben


Posts: 2270

Reply: 34



PostPosted: April 12, 2011 1:08 PM 

Now we need to see some good images which show where itis originating.

Kye Goodwin


Posts: 1166

Reply: 35



PostPosted: April 12, 2011 2:40 PM 

Ben, re your reply 32, There are some significant differences between what we see in that image from Erebus (linked in 31) and your hourglass analogy. The Erebus "flow" system, unlike an hourglass, doesn't have a particularly large reservoir of material above, though I agree that the fractures above and behind the escarpment are likely full of the same "active" material as what we see trickling out the front. The Erebus "flow" system doesn't have a single short narrow "bottle-neck" like an hourglass but instead seems to require passage of the sand through a fairly long narrow fracture, or more surprisingly, it has somehow found SEVERAL fractures and moved through them in the same way. A very similar situation seems to have arisen with several fractures at Endurance, and hundreds at Victoria. Here's Endurance:

Here's an image adjacent to the one above to get a better idea where the "streams" are originating:

And here's just one of several images that show multiple streaks in Victoria.

For most of the streaks in the third image it is not clear that the material emerges from fractures, but for a few streaks it appears to come from fractures. Several other examples of apparent transport through fractures appear in the many other images of Victoria streaks.

There is no way to prove that these multiple flow systems at multiple craters are not entirely a wind-related phenomenon, but I for one no longer find the aeolian explanation convincing. Clearly, though some sort of downslope gravity movement is involved, these streaks cannot be described as dust or sand avalanches. Material trickling through fractures is almost the opposite of an avalanche. A true avalanche would likely plug the fractures. So what sort of motion is involved? I can't think of a plausible boring explanation. Lately I'm thinking that the whole system is a manifestation of Life, and in some way "purposeful".

I can quibble about the plausibility of simple sub-surface gravity flow through fractures, which now you, Ben, seem to have accepted, but somehow that's not the nub of the issue. Somehow there's a much bigger problem for the aeolian-loading theory in the timing of all this, but I'm having trouble articulating it. We see this happening NOW in multiple places. This seems to be the most active process Oppy has imaged. If it represents material flowing into the craters delivered by the wind from an outside source, why has so little sand accumulated in the craters over millions of years? I don't like the idea that we've arrived at a special time, unless it is a special time that re-occurs over and over in some kind of cycle.

I think that it makes quite a bit of sense to think of the trickling sand as material being eroded from the sub-surface and then accumulating locally. Clearly there has been a great deal of material removed from the bays of Victoria and from all those wide "fractures" in the cliffs. My simple theory is that some of this missing material is the trickling sand. I've been investigating patches of uniform fine sand at Meridiani, which include a number of structures: microchannels, sand-tails, sharp little trenches, smooth little ripples and various slope flow features including the streaks. I've found these phenomena to be highly clustered at Meridiani, occurring in association with each other at particular types of location. The best generalization that I've come up with yet is that these special sand patches are correlated with erosion of the bright rock. Generally this means at craters, but also includes the Anatolia trenches, which appear to be eroded into the plain and also various nameless little escarpments not associated with craters:

That's just south of Victoria's annulus and not at a crater. It seems that the bright rock here has been eroded more than most places on the plains, and deep microchannels containing patches of uniform fine sand are associated with the erosion as usual. Erosion on Mars is a huge mystery. Lately I've been thinking that Life is responsible for most of it, and it mostly takes place while the rock is covered with soil.

Ben


Posts: 2270

Reply: 36



PostPosted: April 12, 2011 6:35 PM 

Kye; Let me clarify my position on subsurface gravity flow features.
Specifically MPJ's #4 image.

I believe this particular flow is liquid of some type (not sand) that is being expelled periodically from the subsurface of the clifff face.

My hour-glass analogy only refers to the selective movement and channeling of dry dust through multiple fractures and gaps that allow it to flow downward in the manner that sand flows out of the hour glass.

This process is probably sporadic and depends on uphill wind replenishment of the sand.

As a side note the horizontal fractures act as riffles and may trap some of the heavier particles.

Thanks for the last image. I remember seeing it and concluded it is a local "facies" of Meridiani rock which geologically means a different depositional environment.

I particularly like the idea of layers of sediment associated with an intermittant spring.
The softer layers are easily eroded (by wind) and provide the dust accumulations.

Other than creatures like moles, termites ,ants etc. I don't see anything that can cause suburface erosion and bring the material to the surface. Wink

Kye Goodwin


Posts: 1166

Reply: 37



PostPosted: April 12, 2011 9:10 PM 

Ben, re your 36, Here's the first paragraph of your 32:

" Kye; Excellent example in your # 31.
When I look at thse trickles I am reminded of a large hour glasses in which the very dry sand finds the lowest point that will support it , then cascades down the slope."

And here's that image from Erebus again:

Regardless of the origin of the sand, it seems to be emerging from narrow fractures in some cases here, and therefore probably moving through narrow fractures, and I think that we agree on this. I find this movement surprising.

In 36 you write "This process is probably sporadic and depends on uphill wind replenishment of the sand." Yes, It would have to depend on the wind in your scenario, but why uphill movement of the sand? If the sand can be lifted up the escarpment why wouldn't it disperse across the plain even more easily? I think that if we have to have an ongoing aeolian cycle of some kind, and we do, or it gets too unlikely that we would catch it happening, then it has to involve movement of sand across the plain. Local sand couldn't be cycled up and down the escarpment by wind without being part of a larger system. This gets me back to asking why the sand would be blowing around the plain generally but end up running through these fractures over and over again? If there were a bowl-shaped slope above the fractures, loaded with sand, I would be reassured that this is boring. Then there are all the examples of crusted soil that we have seen at Meridiani. We wouldn't guess that soil would trickle through fractures, even if there were an aeolian cycle to deliver it.

You write in 32, "I can't conceive of any mechanism that would create the very dry sand , below the surface, and move it against gravity to the surface so it could trickle downward."

Me either Ben, except One, and I find just the "flow" through tight spaces in itself pretty remarkable. We wouldn't expect "moles, termites, ants etc." because these organisms' ancestors had already been evolving on Earth for billions of years when these groups were new, but I wouldn't rule out the work of something with a much more ancient common ancestor of Earth life.

MPJ


Posts: 250

Reply: 38



PostPosted: April 13, 2011 5:38 AM 

Ben, re34: here is a nice snapshot of the observed Asimov Crater and those newly discovered TSL (100% zoom systhetic nomap RGB - illumination from lower right, south is up):

The source (waypoint 2 and 3) appears to be rocky outcrops with bright bluish taint (which is usualy connected to some kind of ice in HiRISE synthetic RGBs). Also if this is realy a brine it appears to be pooling at waypoint 1 Smile

Another shot a little further north of the same image strip:

If I were to send a rover there to check it out i would equip it with some big rubber tires in case it gets a little muddy...

Link to the according abstracts

Ben


Posts: 2270

Reply: 39



PostPosted: April 13, 2011 1:00 PM 

Kye; I meant replenishment from uphill sand.
(bad) Embarassed

Kye Goodwin


Posts: 1166

Reply: 40



PostPosted: April 13, 2011 2:31 PM 

MPJ, re your 38, Thanks for the images and that link to an abstract that is a good read. You wrote, "The source (waypoint 2 and 3) appears to be rocky outcrops with bright bluish taint...". Oppy's slope streaks almost always have a rocky outcrop as their apparent source, like so many in Hirise images. I'm amazed that no one is making this connection. Slope streaks of various kinds are the most active features on Mars as a whole, and at Meridiani, where they are numerous and widespread.

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