Water on Mars - Page 8

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Posts: xxx

Reply: 141

PostPosted: January 11, 2012 5:44 PM 



Posts: 250

Reply: 142

PostPosted: January 25, 2012 4:22 AM 

Lots of clouds visible in Rosetta probe Mars imaging during the fly-by and the bright white southern polar cap during the northern autumn equinox :



Posts: 344

Reply: 143

PostPosted: January 28, 2012 2:07 AM 


More evidence for a Northern Ocean on Mars, apparently as recently as 3 billion years ago.


Posts: 250

Reply: 144

PostPosted: January 28, 2012 1:29 PM 

Another example of things that "shouldn't been there" but turns out to be there anyway:

Large Amounts of Water Ice Found Underground on Mars


Posts: 344

Reply: 145

PostPosted: January 31, 2012 8:03 PM 

The left image is the frosted gnomon on Sol 257. The right is a later image after it thawed.

I used a ruler to measure the diameter on my screen of both images. The diameter of the sphere in the left image is slightly more than 3% larger than that of the right image.

According to this reference:


the gnomon sphere is 2cm in diameter. This implies that the frost covering is about one third of a millimeter, or about 300 microns.


Posts: 3062

Reply: 146

PostPosted: January 31, 2012 8:49 PM 

Barsoomer; Great outside the box thinking! Should the calculated frost thickness be about 600 rather than 300 microns?

btw. I think imageJ might be able to do a more accurate job of measurement.

In any case, it suggests that the frost cover here is very substantial and significantly more than the guesstimates made in the Viking frost images.



Posts: 3062

Reply: 147

PostPosted: January 31, 2012 9:16 PM 

Barsoomer; Oops! You're right. The thickness is about 300 microns indeed.

I used your images to get a diameter of 214 pixels for the dark, uncovered gnomon and 221 pixels for frosty the gnomon. i.e 3.16 % cover which roughly translates to about a 300 microns frost cover, not 600 as I suggested above.



Posts: 344

Reply: 148

PostPosted: January 31, 2012 11:00 PM 

Winston, thanks for that confirmation.


This experimental study (Figure 7) shows that frost older than 1 hour has a density of about 0.3 times that of water.

If the same holds true for Mars, then 300 microns of frost is equivalent to about 100 microns of water.


Posts: xxx

Reply: 149

PostPosted: February 1, 2012 8:08 PM 

One of the keys to the scientific principle is that outcomes must be repeatable. I tried to duplicate your measurements. With an out of focus gnomen and bleeding of pixels I think your results are wishful thinking and a self fulfilling prophesy.


Posts: 344

Reply: 150

PostPosted: February 1, 2012 9:49 PM 

Serpens, are you saying you were unable to do the measurement, or you did the measurement and got a different result?

If the latter, what result did you get, and what points did you measure between?

If the former, can you make a best effort? Poor focus and bleeding of pixels should affect both images equally.


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Reply: 151

PostPosted: February 3, 2012 12:46 PM 

This says no water on Mars surface for a lonnng time



Posts: 250

Reply: 152

PostPosted: February 3, 2012 2:17 PM 

Ben, just read the paper ( https://fileexchange.imperial.ac.uk/files/aafc223436/2011GL049896.pdf )

I don't think this could be used for generally characterizing global Martian soil(?). Actually the authors came to a conclusion which would restrict the usage of the term soil so they somewhat contradict themselves if you ask me.

But i wonder if they have seen particles like this while analyzing the micro images for tiny particles: Shocked

from Sol 09: http://i54.tinypic.com/2qmno6q.gif
Sol 21:

This timelaps animations are not related to the magnetic properties experiment and where shown to me while talking about the above paper with one of my astrobiology peers. Smile


Posts: 344

Reply: 153

PostPosted: February 3, 2012 3:05 PM 

Interesting report, Ben. Thanks for the pdf reference, MPG; I look forward to reading it.

Six hundred million years of aridity is an improvement over the previous estimate of 3 billion years.

I assume the 5000 years of liquid water alteration is averaged over the whole planet and over the whole 600 million years. That would not rule out, for example, 100 years of surface warm wet conditions during each of, say, 60 high-obliquity periods.

It also does not rule out more frequent wet conditions for a very small fraction of the Martian landscape, for example, some of the micro-channels or the very few apparent small pond remnants we may have seen on the trek of Oppy.

Another point is it obviously does not rule out large amounts of frozen H2O, which may possibly be mobilized by microbes in protected areas like in the pore spaces of rocks ejected from the sub-surface.


Posts: 2270

Reply: 154

PostPosted: February 3, 2012 5:23 PM 

MPJ & Barsoomer; Just read the paper and believe effort involved was well done.

Although it may not represent global Martian soil, I think it is representative of the widespread, cold, arid, aeolian environment in Mars late history.

I have long been an advocate that Mars surface water period was brief and generally catastrophic being associated with a short period when the planet warmed up , water was quickly released and it then returned to its earlier and current (cold-dry)conditions.

I am confused by the comment that the clay content is restricted to .05% by volume.
How then are they able to obtain the high clay we were supposed to find at CY?

One final comment.
I have always objected to the term "micro-channel" because it suggests surface flow where there is no evidence for such.
Why don't we call them what they are (cracks accentuated by wind erosion).


Posts: xxx

Reply: 155

PostPosted: February 3, 2012 6:00 PM 

Ben /MPJ Nice find. It is difficult to keep up with papers and the popular (science) press provides a very helpful guide.

MPJ. The movement of particles over time has been discussed at length previously of the Phoenix forum. Such would be expected given the sample loading process. You may like to point your astrobiological peer to the discussion.

Barsoomer. The 600 million years refers to the period since the time of the Heimdal impact, estimated at 600 Mya and does not set a milestone for water interaction. Phoenix landed on the Heimdal ejecta blanket and they cannot make determonations as to what happened before that time. They identify 11 um size as the probable divider between local impact origin and aeolian deposition from remote sources. The larger particles could thus have been subjected to alteration in the impact plume and the aeolian deposits could have been altered billions of years before.

This analysis aligns to the total lack of any water transport in the soil determined by the TECP. Hopefully this analysis of soil immediately above ice will confirm for you that underground ice does not translate in any way to surface moisture.

I agree with you that the use of the word soil is probably incorrect but this is no big deal. The soil Science Society of America definition of soil includes the unconsolidated mineral or organic matter on the immediate surface..... The or. While regolith would be more appropriate for Mars I don't think the use of the word soil, which for most people is intuitively the surface particle layer, detracts from the paper or dilutes the facts.


Posts: xxx

Reply: 156

PostPosted: February 3, 2012 6:05 PM 

Ben. Croas post. The small clay content would be aeolian deposits. While large clay deposits have been located they are in the main exposed as buried layers (Gale, Mwarth Vallis) exposed by channels rather than removal of overlying (non clay) sediment. So the small percentage composition is consistent.


Posts: 250

Reply: 157

PostPosted: February 4, 2012 6:08 AM 

Serpens, not wanting to dig deeper into that but the apparent movements and grow like motions of the linked gifs are related to a quite short time period (1 Sol max). Its peculiar but i understand that nobody would openly trust there eyes and acknowledge such. There are more such examples shown to me by the way but Phoenix research is dead here i guess. There cant be life on Mars so lets put such things to the bin. Smile


Posts: 3062

Reply: 158

PostPosted: February 4, 2012 6:11 PM 

MPJ, Barsoomer;

Seems to me there are some inconsistencies in the work that makes their overall conclusion that there has been no significant water alteration of soil on Mars entire surface over the past 500 million years and linking that with the possibility of finding life at or near the surface anywhere on Mars, somewhat suspect.

First of all, they essentially use Earth as a model to determine Particle Size Distribution (PSDs) of Phoenix soils (even though they used the lowest rates found on Earth) and then infer that the small PSD values of the Phoenix soil samples, related to clays, are mainly due to relative lack of water interaction on the soil particles and then make the jump to correlating the low PSD, in relation to clays, with long measurable periods without appreciable water (Apparently using an earth Model). In addition, they seem to have totally ignored the effect that multicelled life would have had in contributing to PSDs on Earth, even in the most arid zones.

There seems to be a lot of steps there that would merit greater justification than I found or recognized in the paper.

Of course, it is quite likely that Mars has had the kind of low water environment for perhaps 500,000 years that it now exhibits. But who really knows how long for sure given the methodology used for estimating ages on mars? But that low water environment is apparently characterized by quite appreciable water ice or bound water content in the near subsurface of some soils and by atmospheric supersaturation. It doesn't take an Einstein to recognize that these conditions will of themselves lead to very little clay development that could be in any way comparable to a water rich Earth. Yet they use Earth as a model even while suggesting that the Moon would be a better entity for comparison.

In spite of mentioning the seeps that NASA has suggested is evidence of surface water periodically breaching the surface and saying that their study does not invalidate the NASA conclusions re. the seeps, they still maintained in the paper that their conclusions are likely relevant to all of Mars.

The finding that the surface soil on mars is generally uniform needs ground truthing before it can be taken as gospel. Ground truthing has only been done on a very limited scale by the landers and rovers and they could only merely scratch the surface. It seems to be quite risky for a scientific study to extrapolate from the known results to a conclusion for all of Mars.

If they had restricted their conclusions to the Phoenix area that was sampled it might be OK but to jump from their Phoenix data to their grand conclusions for all of Mars seems to be a bit of an overreach.



Posts: 344

Reply: 159

PostPosted: February 4, 2012 7:02 PM 

Ben, "micro-channel" is a neutral term that describes the morphology without implying a particular interpretation.

Calling them "cracks accentuated by wind erosion" would completely prejudge what they are--all of them.


Posts: 3062

Reply: 160

PostPosted: February 4, 2012 7:57 PM 

Serpens; Re. your 149 and Barsoomer's 150. I'm adding my voice to barsoomers' request that you let the board know what measurements you got for the naked glomon and frosty the gnomon.

I would also invite some other posters to do their own measurements and post them here.

Serpens, your post where you didn't even deign to let us know your measurements but tried to give the impression that even an attempt to measure the gnomon was of no value and antiscientific is disingenuous at the best and totally unworthy of someone who quotes "a key of the scientific principle".


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