Water on Mars - Page 10

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LWS


Posts: 3062

Reply: 181



PostPosted: February 16, 2012 9:11 AM 

Barsoomer; He is never wrong even when he is wrong. Didn't he claim it was dust?

Winston

Serpens


Posts: xxx

Reply: 182



PostPosted: February 16, 2012 9:45 PM 

LWS I referenced work such as this.
http://ashimaresearch.com/wp-content/uploads/papers/InadaEtAl08.pdf
In that example pure dust with no ice content at all.

But dust would provide a nucleation site and in a cold trap then some ice fog could form. Note ice fog - not water fog. But the water vapour content of the atmosphere is miniscule.

Barsoomer


Posts: 344

Reply: 183



PostPosted: February 20, 2012 9:28 PM 

Regarding the MARSIS result of extensive sediment deposit remnants from two former Northern Oceans, the paper suggests two possibilities for where the water went, (1) stayed in place, (2) sublimed and was cold-trapped elsewhere. Since there is no known "elsewhere" that seems to contain all that water ice, option (1) seems more likely.

The paper also mentions that three lobes or branches of the sediment deposit/ocean remnants extend far southward. The 3 branches are in Chryse Planitia, Utopia Planitia, and Amazonis Planitia. That suggests there may be something special about these regions, with possibly surviving large underground ice deposits. Rampart craters provide some evidence that deposits remain.

Of course, many will recognize Chryse Planitia and These Utopia Planitia as being the sites of the two Viking Landers that conducted biology experiments in the 1970s. In hindsight, they may have been exactly in the most fortuitous locations. The deposits are far enough south that they would be unstable over the long term, which means remnants, if they exist, would still be exuding vapor to some degree.

John Henry Dough


Posts: xxx

Reply: 184



PostPosted: February 22, 2012 4:20 PM 

Yes and this shows there will always be a need for more/faster Rovers.And Satellites.
We need some Leadership with $$$$$$$$$$
The Tech is present. (Mama's got the know-how)
jhd

Serpens


Posts: xxx

Reply: 185



PostPosted: February 22, 2012 5:32 PM 

Barsoomer. There is option 3 - that the bulk of atmospheric gas and water vapour was lost through the solar wind effect. ASPERA-3 on Mars Express confirmed the extensive penetraoon of the solar wind into Mars' atmosphere. But probably a combination of all three. A lot of groundwater was frozen , and the lowlands would seem a logical place for this to have concentrated. Meridiani in the other hand, where we know extensive and long lasting water existed dried out completely, possibly because tyhe topography drains NNW.

Surface water/ice and such ground water/ice that could sublimate did so over time. Some was cold trapped perhaps and then covered with protective dust (indications of small glacial effects etc in highlands)but the majority was removed from Mars by 'sputtering'.

Isn't it possible that the the Tharsis bulge formed during, or more likely after the Northern Ocean? So the something special about Amazonian and Chryse Planitia is simply that they are the remains of a big bay separated by the creation of the Tharsis Bulge.

Barsoomer


Posts: 344

Reply: 186



PostPosted: February 22, 2012 6:17 PM 

[link]

It seems that less water may have been lost to space than generally thought. The upcoming MAVEN mission may clarify this issue.

Serpens


Posts: xxx

Reply: 187



PostPosted: February 23, 2012 2:47 AM 

Barsoomer. Leshin's hypothesis was interesting - but was published in 2000 and has not really stood the test of time, although she herself has had a brilliant career. In her paper she mentioned that the deuterium enrichment that was the basis for her hypothesis had previously been proposed to be due to shock devolitization (Minnitti and Rutherford)but dismissed this. The problem I had when I first read the paper was that ther was no real knowledge of the provenance of the material investigated. Yes it came from a Martian meterorite probably millions of years old, but before the impact?

The basic process is that the heavier deuterium isotope will tend to stay lower and the lighter hydrogen isotope will be lost to space, resulting in enrichment. With the seasonal transit of atmosphere and entrained water between poles the volume of water influenced is constrained by the the cyclical events, rather than having a planet wide crustal resevoir a she implied, being available for atmospheric exchange.

MPJ


Posts: 250

Reply: 188



PostPosted: February 28, 2012 7:00 AM 

Salty Soil Can Suck Water Out of Atmosphere: Could It Happen on Mars?
[link]

LWS


Posts: 3062

Reply: 189



PostPosted: February 28, 2012 10:55 AM 

MPJ; Thanks for that reference. It almost totally explains those damp appearing channels in meridiani.

There are also many other clues that the same mechanism is at work on Mars. The crude spectra seems to make that same kind of suggestion but needs refinement. There is also the established finding on terran spectroscopy from experiments comparing the spectra of ground minerals at different water contents, that the percentage reflectance is shifted downwards in the Vis-NIR bands as water content increases. Even though those bands may not have a significant absorbance peak there is a possibility that the actual presence of small amounts of water could be gauged from the downward shift of the graphs.

The other aspect of reflectance spectroscopy that does not seem to have been appreciated is that our eyes can, on their own tell the difference between a damp soil and a wet one, Spectroscopy is only finding a mathematically reproducible method for doing the same thing remotely. Where actual images are available we should not throw out the visual evidence of what is actually on the ground and replace it with incomplete spectroscopic evidence in a system where water is present at an infinitesmilly smaller level than it can be anywhere on Earth.

MPJ, once again, an excellent find.

Winston

John Henry Dough


Posts: xxx

Reply: 190



PostPosted: February 28, 2012 1:39 PM 

Very good find,,,MPJ,,this would seem to open
other avenues of thought,no?
First thing I think of,,,Is there a way to reverse the processes(s) ?
For the soil to give back to the dry atmosphere?
Hard questions.
j.

John Henry Dough


Posts: xxx

Reply: 191



PostPosted: February 28, 2012 2:18 PM 

And does it get wetter with depth?
Obviously that would be ,,Yes,,but
I wish the MSL would have carried a drill,
One meter,,perhaps would have in-disputable evidence.
jd

Barsoomer


Posts: 344

Reply: 192



PostPosted: February 28, 2012 3:14 PM 

> our eyes can, on their own tell the difference between a damp soil and a wet one

Good point, Winston. Our eyes have a lifetime of experience distinguishing damp soil from dry, based on multiple cues that go beyond reflectance.

Another point is that as frost or ice is warmed, it loiters a while at the 0 degree point until it re-acquires the latent heat of fusion of ice. So as long as the pressure is even slightly above the triple point pressure, there should be at least a brief liquid phase, perhaps enough time to form a brine with any salt that is present.

Serpens


Posts: xxx

Reply: 193



PostPosted: February 28, 2012 6:11 PM 

I am a little confused as this principle has been used for a heck of a long time to calibrate humidity sensors and even to keep the humidity in packaged products low? In fact I remember a magnesium chloride plus water in a glass in a sealed container experiment from high school. It just needs lots of water. But hold on...Spirit's observations revealed that on Mars the atmosphere not the soil was the dessicant.

Damp soil? I love the distant sound of steam trains. Very Happy

Ben


Posts: 2270

Reply: 194



PostPosted: February 28, 2012 6:14 PM 

Just a thought: If the "wet' soil contains a brine, wouldn't there be signs of corrosion on Oppy after 8 years ?

LWS


Posts: 3062

Reply: 195



PostPosted: February 28, 2012 6:52 PM 

Ben; Since it is likely that for Oppy and Spirit no effort nor expense would have been spared to ensure that they could withstand whatever environmental conditions were thrown at them on Mars (albiet for 3 months only), the materials used should be expected to be rust resistant.

Also, it seems you haven't been following the "stains" discussion. There does appear to be some corrosion, slight though it may be.

Winston

MPJ


Posts: 250

Reply: 196



PostPosted: February 29, 2012 3:36 AM 

Serpens, the principle is rather mundane as you stated in re193. What i find interesting is those mysterious wet patches of ground in the totally dessicated antarctic DRY valleys where there is virtually no precipitation:

"Levy said the science team discovered the process as part of "walking around geology" - a result of observing the mysterious patches of wet soil in Antarctica, and then exploring their causes. "

They wonder if such wet patches of soil could develop due to the same principle on Mars and those explain certain more intuitive observations as described by Winston and Barsoomer. It is also something to ponder in regards to the newly discovered reoccurring slope linae features i think.

[link]

Serpens


Posts: xxx

Reply: 197



PostPosted: February 29, 2012 9:30 AM 

MPJ. You may note the comment the McMurdo Dry Valleys weather stations had reported several days of high humidity earlier in the spring, leading them to their discovery of the vapor transfer.
Mars is totally dessicated. In comparison the atmosphere of the dry valleys is wet with precipitation of some 10mm to 100mm water equivalent depending on the Valley.

Barsoomer


Posts: 344

Reply: 198



PostPosted: February 29, 2012 11:25 AM 

cardiffcentreforastrobiology.com/marswater.pdf

Recent (Aug 11, 2011) short note by Levin on the subject of liquid water.

It has been noted in several places that the pricipitable water on Mars is variable and exceeds at least 100 microns in some places at some times, especially during the Northern summer when water is transferring from the north polar cap to the south polar cap. When that water vapor pulse reaches the Mars dichotomy where the land elevation sharply increases, one might surmise some kind of meteorological consequence.

MPJ


Posts: 250

Reply: 199



PostPosted: February 29, 2012 3:05 PM 

Serpens, here is another quote from the universetoday news adressing the same finding:

"Though Mars, in general, has lower humidity than most places on Earth, studies have shown that it is sufficient to reach the thresholds that Levy and his colleagues have documented in Antarctica."

http://www.universetoday.com/93848/salty-soil-on-mars-could-be-slurping-water-from-the-atmosphere/

Science is an agile process with lots of changes while we progress - nothing is written in stone yet Wink

Serpens


Posts: xxx

Reply: 200



PostPosted: February 29, 2012 4:56 PM 

MPJ. Again I would take you back to mundane physics rather than catchy titles. Absolute humidity...NOT relative humidity is the measure. There is miniscule water in the Martian atmosphere and (as on Earth by the way) almost all of it is high in the troposphere. More germane, Spirit showed that the atmosphere is the dessicant as salts lost moisture once the protective regolith was breached.

We have seen no indication whatsoever of moisture at Meridiniani (ice frost is not moisture and it sublimates direct from solid to gas).

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