Latest Martian Ice News: Scientists Investigate Water Ice on Red Planet

[lwymarie]

http://sciencenow.sciencemag.org/cgi/content/full/2008/620/2

This article is about Martian ice. Why can't it be dry ice? Why are the scientists so sure that it is water ice?

 

[Janus]

It lasts too long for dry ice under those conditions. Both water ice and dry ice will sublimate when exposed, dry ice will do so much more quickly than water ice.

 

[curiouschris]

If you watch the video of "disappearing ice" other changes also occur such as about 1/3 down a small lump appears to fall over and outside the trench small changes are noticed.

My question would by what made those other changes? other disappearing chunks of ice or action of the lander?

As for the time it takes for dry ice/water to sublimate how could one be sure they sublimate at different timescales on the Martian surface.

The conditions are vastly different to anything found here. So the assumption of timescales may be inaccurate. Also dry ice is less likely to contain impurities than water hence the puzzling lack of impure remains after the "water" evaporates.

The comment "the Phoenix lander has scraped a few centimeters down to an irrefutable layer of water ice in the martian arctic" seems a little too strong in its conviction.

 

[Janus]

If you watch the video of "disappearing ice" other changes also occur such as about 1/3 down a small lump appears to fall over and outside the trench small changes are noticed.

My question would by what made those other changes? other disappearing chunks of ice or action of the lander?

As for the time it takes for dry ice/water to sublimate how could one be sure they sublimate at different timescales on the Martian surface.

The conditions are vastly different to anything found here. So the assumption of timescales may be inaccurate. Also dry ice is less likely to contain impurities than water hence the puzzling lack of impure remains after the "water" evaporates.

The comment "the Phoenix lander has scraped a few centimeters down to an irrefutable layer of water ice in the martian arctic" seems a little too strong in its conviction.

They know the temp & pressure at the area of the lander. They know the physical properties of both dry ice and water ice (including those at the local temp and pressure). Thus they know how fast each would sublimate under those conditions, It is also obvious that the difference in sublimation times must be significant enough to remove doubt for then to make said claim.

 

[curiouschris]

Still the "known facts" relate to conditions on earth. Knowing the conditions on Mars doesn't automatically mean they know 'all conditions' that may be present and unless the replicate those conditions including unknowns and test it here the assumptions made are significant enough to warrant caution.

must be significant enough to remove doubt for then to make said claim

I remember plenty of unqualified claims such as the chunk of meteorite found in antarctica containing a fossil of an alien life form, turned out to be something totally different.

I didn't mention it but I should have, why haven't they taken the 'ice' on board I am sure they have the necessary equipment to run 1000's of tests under fully known conditions. rather than the subjective test they have performed.

That to me is a glaring omission.

Isn't the search for water one of primary objectives of the mission, one would think that either the announcement would wait or the testing would jump any already waiting.

 

[Janus]

Still the "known facts" relate to conditions on earth. Knowing the conditions on Mars doesn't automatically mean they know 'all conditions' that may be present and unless the replicate those conditions including unknowns and test it here the assumptions made are significant enough to warrant caution.

What other "conditions" other than temp and pressure would you suggest that were not taken into account? The physics on Mars is no different that that on Earth.

I remember plenty of unqualified claims such as the chunk of meteorite found in antarctica containing a fossil of an alien life form, turned out to be something totally different.

I remember that event, and at no time did anyone claim "with high confidence" that the meteorite contained extra-terrestrial fossils. Some scientists suspected and hoped that it might be the case, others were less than convinced, and a great number took a "wait and see" attitude. This was more akin to the attitude shown when they first noted the white area uncovered by the landing. They suspected that it could be ice, they hoped that was ice, but they weren't willing to claim yet that it was ice without further evidence.

 

[curiouschris]

I have no idea what conditions may be different. But to rely on a video recording when you have a lab at hand seems like folly. also they said that there was an oddity, why no sediment within the ice?

When something doesn't fit the alarm bells should be ringing.

lwymarie raised the possibility it could be another material. maybe,maybe not. but the limited information available to us certainly leaves the question wide open. and I have recently learned that fools and fanatics are so certain of themselves, the certainty in that article worries me. there is ample room for doubt ;)

 

[B. Elliott]

I have no idea what conditions may be different.

That's not the point Janus was making; There cannot possibly be any other conditions present, other than temperature and pressure. The Phoenix itself is equipped with an array of weather measuring equipment. As you input the data that's available, impossibilities are trimmed away which leaves possibilities. If enough is trimmed away, hopefully, your left with only one conclusion.

When something doesn't fit the alarm bells should be ringing.

And what is making anyone think that an alarm bell is ringing? What's not fitting?

 

[curiouschris]

That's not the point Janus was making; There cannot possibly be any other conditions present, other than temperature and pressure. The Phoenix itself is equipped with an array of weather measuring equipment. As you input the data that's available, impossibilities are trimmed away which leaves possibilities. If enough is trimmed away, hopefully, your left with only one conclusion.

And if those conditions were replicated here on Earth I am sure they are right but we aren't talking about Earth we are talking about another planet.

There cannot possibly be any other conditions present, other than temperature and pressure.

Whoa do I detect an extreme level of certainty there?

Can you be certain at what rate dry ice and frozen water sublimate on mars. its extremely cold and conditions are very different. perhaps the wind effects it perhaps the lower density air effects it, what constituents in the Martian atmosphere may be interacting with it. the shade from the bloody great spaceship next to it will effect it. The reflections from the lander will effect it and the landers internal heat will effect it.

Paige wonders, however, how the ice chunks disappeared so thoroughly, leaving no sign of any salt or dirt that they may have been carrying. "That's puzzling," he says

From the article if you did not read it. If its puzzling to them then something is missing from the puzzle.

I am not saying they are wrong I am just saying I agree with lwymarie there may well be another explanation. With a fully fitted lab why didn't they test it in there. any other test is subjective. that cannot be avoided.

 

[chroot]

And if those conditions were replicated here on Earth I am sure they are right but we aren't talking about Earth we are talking about another planet.

The physics of dry ice evaporation is the same everywhere in the universe, including Earth and Mars.

its extremely cold and conditions are very different. perhaps the wind effects it perhaps the lower density air effects it, what constituents in the Martian atmosphere may be interacting with it.

You can build a machine that produces a cavity with Mars-like conditions within it (low-pressure CO2 atmosphere, cold temperatures, winds) here on Earth relatively simply. I'm not a planetary geologists, so I can't cite any specific experiments, but I'm sure such basic measurements have been made made times. If any geologists can cite an experiment, that'd be great.

the shade from the bloody great spaceship next to it will effect it.
the reflections from the lander will effect it and its own internal heat will effect it.

If you can't say how significant these effects would be, you cannot really use them in an argument.

With a fully fitted lab why didn't they test it in there. any other test is subjective. that cannot be avoided.

They're going to "touch it" soon -- using other instruments to conclusively show it's water ice. If I'm not mistaken the lander has some kind of a mass spectrometer on it, which would be a truly definitive measurement.

- Warren

 

[DaveC426913]

And if those conditions were replicated here on Earth I am sure they are right but we aren't talking about Earth we are talking about another planet.

Whoa do I detect an extreme level of certainty there?

Can you be certain at what rate dry ice and frozen water sublimate on mars. its extremely cold and conditions are very different.

Much as you'd like it to be so, it's just not that different. Physics does not behave differently on other planets.

And by the way, I do believe it has occurred to them to make their tests in the appropriate temps and pressures.

Consider: scientists are able to "predict" conditions on Mars so well that the landing craft they've sent there are lasting 10 times longer than designed. If they didn't know their stuff pretty well, the craft would have gone belly up much sooner.

 

[B. Elliott]

And if those conditions were replicated here on Earth I am sure they are right but we aren't talking about Earth we are talking about another planet.

Another planet which follows the same laws of physics that we experience here on Earth.

Whoa do I detect an extreme level of certainty there?

Yes.

Can you be certain at what rate dry ice and frozen water sublimate on mars.its extremely cold and conditions are very different.

Considering that the two will sublimate at different temperatures and pressures, yes. If you expose a small chunk of solid CO2 to the temperatures and pressures which we are detecting in the area, it will sublimate MUCH quicker than a same-sized chunk of H2O.
Yes it's extremely cold, but that does not mean CO2 and H20 suddenly follows new laws. Trust me, we've experimented with CO2 and H20 here on Earth (in labs) at temperatures WELL below those at the Phoenix site.

perhaps the wind effects it

The phoenix lander is equipped with a wind speed indicator. Accounted for.

perhaps the lower density air effects it.

The Phoenix lander is equipped with a pressure sensor. Accounted for.

what constituents in the Martian atmosphere may be interacting with it.

That's what the Phoenix lander is! It's a weather station specifically built to measure what constituents in the Martian atmosphere are interacting with it.

the shade from the bloody great spaceship next to it will effect it.

It definitely will, and has. The shade helps preserve any ice that is exposed due to minimizing heating effects from the Sun. Accounted for. From the Phoenix home page...

Having the workspace north keeps it in the shade during midsol, optimal for working with ice that we do not want to go away after we uncover it.

http://phoenix.lpl.arizona.edu/blogsPost.php?bID=178

The reflections from the lander will effect it and the landers internal heat will effect it.

Reflections bouncing off of a lander which is located in a far North latitude, and which are coming from a faint, slowly fading Sun which will eventually disappear completely? Have you even been following the mission at all, or only trying to dissect specific bit of information that appears in the media from time to time?

The lander is not emitting enough heat to interact with the sol around it. The Phoenix lander is insulated to be able to survive in the extreme cold conditions.

 

[LowlyPion]

I think a more interesting question about the subsurface ice is the process by which it appears there under the surface.

Now we can see it sublimate in the low pressure atmosphere (6 millibars or so) when exposed. There is to a certain extent the presumption that it sublimates through the porous Martian soil even when Phoenix scrapers aren't scraping it up though.

So how did it get there in the first place?

At one time there was apparently free flowing water at lower latitudes at least and that implies a bit of a higher global temperature for that way back when.

Now if the water that is the ice we see today originally settled there as a result of water flow. That would suggest some melting at least of polar region ice accumulations at some point. (I trust we can say a river didn't run through the spot of the lander.)

Alternatively, the ice that is seen there may possibly be layered in over polar ice cycles that get subsequently covered by layers of insulating dust sweeping over the polar region. (My uninformed guess.)

Whatever the mechanism for it being there though suggests that it has a further story to tell about Martian climate history.

 

[curiouschris]

B. Elliot

Whoa do I detect an extreme level of certainty there?

Yes.

LOL read Janus's tagline then.

All I have done is support the original post. by saying how can they be "certain"

I am sure the physics of dry ice sublimation is universal. I am just not sure the effects of the environment is. My references to the lander its reflectivity, internal heat and shadow are just obvious ones which may or may not effect the sublimation of whatever the compound was.

Have they created the perfect insulator? must have missed that bulletin. The exterior of the craft can heat up (regardless of interior insulation) and that can then re-radiate to its surroundings.

I am not saying the assumptions are wrong or the science is faulty, I am just saying given the many variables and possible unknowns (hence I don't know them) and the very fact we screw up here on Earth often enough, there is room enough for doubt.

Of all the comments here no one commented on Paige's puzzle. which is in contrast to what they expect given all they know. Therefore they can't know everything.

If the teacher said it was midnight and your watch said it was midday would you accept what the teacher said or look out the window. I am looking out the window.

But sadly its a known fact most people would accept the teacher (person in authority scientist/politician/parent/priest/shaman/rabbi/etc) and adjust their watch to his/her time without so much as a glance out the window.

 

[B. Elliott]

If the teacher said it was midnight and your watch said it was midday would you accept what the teacher said or look out the window. I am looking out the window.

And so am I. Always. I'll pretty much make a safe bet that more than 90% of the people on this forum occasionally 'look out the window' also.

With that said, how are you suggesting that we get 'better evidence' other than the data which Phoenix is providing?

 

[B. Elliott]

Also, it's a bit funny for a non-specialist to be questioning the results from a group of people who are highly specialized in their respective fields.

Your not just doubting one teacher. Your doubting multitudes of teachers.

 

[LowlyPion]

Excellent picture of the lander at top with the solar panels deployed, with the heatshield to the right middle and the parachute at the bottom.

http://phoenix.lpl.arizona.edu/images/gallery/lg_647.jpg

Almost like being there - but with popcorn.

The terrain is certainly of interest as well. Aside from the natural texturing of the terrain looks like you can see the disturbances to the surface caused by landing.

 

[curiouschris]

As I said in the first place. Take the ice into the on board lab. test it using whatever means they have provided, I assume they have suitable mechanisms available to them, such as the mass spectrometer mentioned above.

I am not doubting anyone actually. I am just "agreeing" the method of determining what the frozen white stuff seems subjective rather than conclusive. Which was the point of the original post.

And as far as doubting a multitude of teachers, yes I do and I am proud of it. Its the doubters in history who have swum against the tide that make the real progress.

Otherwise we would all be worshipping the sun God and not straying too far from shore lest we fall from the edge of the world.

That is not a slight against anyone here. Its just to say sometimes we should be wary of what accept as the truth. Life is so busy that it is often easier to accept what we are told rather than wonder if there may be a different explanation. Often the reason we accept without question the 'teachings' of another authoritative person is because we *want* to believe it.
Look at all the UFO enthusiasts. I even had one friend who firmly believed crop circles were the method of communication employed by ET's. When I explained that a pair of old chaps actually started the craze and they even explained how they did it in such a way that it "defied explanation". This person simply moved to a new position of the ET's "adopted" it as their method of communication. I could only chuckle to myself and promise my wife never to raise the subject again.

If we look at the world around us we see the problems this unquestioning results in, especially when it reaches the level of fanaticism, and no-one is immune from it regardless of who they are and what they believe.

Oh and thanks Lowlypion I appreciate your efforts ;)

 

[B. Elliott]

As I said in the first place. Take the ice into the on board lab. test it using whatever means they have provided, I assume they have suitable mechanisms available to them, such as the mass spectrometer mentioned above.

I am not doubting anyone actually. I am just "agreeing" the method of determining what the frozen white stuff seems subjective rather than conclusive. Which was the point of the original post.

And as far as doubting a multitude of teachers, yes I do and I am proud of it. Its the doubters in history who have swum against the tide that make the real progress.

Otherwise we would all be worshipping the sun God and not straying too far from shore lest we fall from the edge of the world.

That is not a slight against anyone here. Its just to say sometimes we should be wary of what accept as the truth. Life is so busy that it is often easier to accept what we are told rather than wonder if there may be a different explanation. Often the reason we accept without question the 'teachings' of another authoritative person is because we *want* to believe it.
Look at all the UFO enthusiasts. I even had one friend who firmly believed crop circles were the method of communication employed by ET's. When I explained that a pair of old chaps actually started the craze and they even explained how they did it in such a way that it "defied explanation". This person simply moved to a new position of the ET's "adopted" it as their method of communication. I could only chuckle to myself and promise my wife never to raise the subject again.

If we look at the world around us we see the problems this unquestioning results in, especially when it reaches the level of fanaticism, and no-one is immune from it regardless of who they are and what they believe.

Oh and thanks Lowlypion I appreciate your efforts ;)

Following the lines of your proud doubters of history, they're doubts which changed history were testable and provided proof that the current accepted information is false. They didn't just make up theories and nor did they 'change history' based off pure untestable speculation. They had to provide cold, hard, observable, testable data to back up their claims. Otherwise, they're no closer to truly understanding than their sun god worshiping ancestors.

What data at hand makes you think it could be something other than H20?

 

[LowlyPion]

... I am just "agreeing" the method of determining what the frozen white stuff seems subjective rather than conclusive. Which was the point of the original post.

And as far as doubting a multitude of teachers, yes I do and I am proud of it. Its the doubters in history who have swum against the tide that make the real progress.

It's one thing of course to question authority and quite another to ignore facts that we have before us. Now while it may be that you haven't personally experienced the triple point of H2O, needless to say that point is known, just as the rest of the state behavior of water is over the P-V-T space. (A 3D plot of properties in Pressure-Volume-Temperature space.) Given the meteorological readings from the instrumentation on board we should have a pretty good idea then of just what point in the PVT space the lander is operating. It's a pretty safe bet then that with observed sublimation of the disrupted particulates and the exposed scrapings that what we are seeing there is behaving as we know water behaves. Additionally it is apparently not behaving as CO2 would at the same point in PVT space. That's a pretty strong case to be made for it being water and not CO2.

My sense of it in looking at the pictures - and in this regard looking at the color corrected pictures and not so much relying on the animated bw GIF that is the video you mention - is that the sublimation results in discernible voiding of some of the areas of the exposure and a lowering of the surface in the scraped areas. Also of interest are later photos of the trenches that show further sublimation. (See Sol 33 in particular.)

Moreover, drawing from personal experience and looking at the terrain that Phoenix finds itself in, I don't see anything that disagrees then with those observations, so much as really reminding me of pretty dirty snow pack that one sometimes sees roadside where the roads have been heavily sanded for travel. Now I realize that is not scientific and only anecdotal, but for me it does reinforce my agreement that what is seen in the pictures is water - sublimating - as one expects water to behave in such conditions.

As to using the TEGA spectrometry ovens those efforts are under way and I'm sure as soon as those results are available we will all know more.

 

[DaveC426913]

...it does reinforce my agreement that what is seen in the pictures is water - sublimating - as one expects water to behave in such conditions.

Well yes, but the point is one expects carbon dioxide to behave that way too. The crux here is what evidence is conclusive enough to say water and not CO2.

 

[LowlyPion]

Well yes, but the point is one expects carbon dioxide to behave that way too. The crux here is what evidence is conclusive enough to say water and not CO2.

Well no actually, one does not expect CO2 to behave in this manner at this point in the PVT space. If your choice is to ignore the hard evidence of what is observed and to anchor your skepticism in some stubborn demand to swim in the stuff or have a sip, then I'd say the technology looks a bit limited to afford you this opportunity.

However, the science of its observed properties, and the conclusions that can be drawn from the observable evidence, short of such satisfying experiential proof as you might demand, a reasonable expectation on which to operate is that it is in fact H2O.

Lest you forget the whole reason the landing site was chosen was because observational satellites detected spectra consistent with hydrogen in the polar region. To not find water here would even be a bit of surprise.

To see a polar map of their findings see:
http://mars.jpl.nasa.gov/odyssey/gallery/latestimages/PIA04254.html

To see estimates of historical water availability on the planet see:
http://www.sciencemag.org/cgi/content/abstract/294/5548/1914

30 meters high planet wide? 100 feet?

 

[LowlyPion]

30 meters high planet wide? 100 feet?

On a 40% g planet just think of the wave action there. Too bad its moons are such runts. But even with wind driven water, ... that would be exciting.

Surf's up.

 

[DaveC426913]

Well no actually, one does not expect CO2 to behave in this manner at this point in the PVT space. If your choice is to ignore the hard evidence of what is observed and to anchor your skepticism in some stubborn demand to swim in the stuff or

You misunderstand.

You said "it does reinforce my agreement that what is seen in the pictures is water - sublimating - as one expects water to behave in such conditions."

It seemed to me that you were basing your conclusion that it was water on the fact that it appears - in the pictures - to be behaving like water. I was simply arguing that this is not enough to draw a conclusion, since a visual analysis would not exclude CO2 i.e. it would look - in pictures - the same.

Anyway, no need to beat this up; I've reread your post and we're on the same page.

 

[LowlyPion]

... and we're on the same page.

Apparently not the same page, since you seem to persist in wanting to interpret the visual evidence, absent the additional facts relating to time, and pressure and temperature. Not to mention the gamma ray scattering data that chose this landing zone precisely because it was mid-region to the high hydrogen band scattering readings.

To be specific the melting point of CO2 at about 8 millibars is -125C. The weather at the site on Sol 33 showed a temperature range of -80C to a high of -34C with wind out of the SE at 11 to 14 km/h with atmospheric pressure at about 8.3 millibars. Welcome to the land of rapid boil-off CO2.

Now ice on the other hand at -34C - call it 240K has a vapor pressure of about .33 millibar. With the reported wind conditions contributing to accelerating sublimation and the naturally low percentage of water measured in the Martian atmosphere (low humidity) then the kind of shrinkage observed looks to be consistent with it being H2O.

Hence a visual inspection of two photos, showing sublimation over the time period reported should indeed exclude CO2. So much so are the weather conditions unfavorable that it's not clear to me that from the time the trench was dug by the scoop and retracted out of the way that a picture of solid CO2 could have been made exposed like that.

 

[DaveC426913]

Apparently not the same page, since you seem to persist in wanting to interpret the visual evidence, absent the additional facts relating to time, and pressure and temperature.

No, I do not. You are misreading me.

I thought that that's what you were doing. I was arguing against that.

Not to mention the gamma ray scattering data that chose this landing zone precisely because it was mid-region to the high hydrogen band scattering readings.

To be specific the melting point of CO2 at about 8 millibars is -125C. The weather at the site on Sol 33 showed a temperature range of -80C to a high of -34C with wind out of the SE at 11 to 14 km/h with atmospheric pressure at about 8.3 millibars. Welcome to the land of rapid boil-off CO2.

Now ice on the other hand at -34C - call it 240K has a vapor pressure of about .33 millibar. With the reported wind conditions contributing to accelerating sublimation and the naturally low percentage of water measured in the Martian atmosphere (low humidity) then the kind of shrinkage observed looks to be consistent with it being H2O.

Hence a visual inspection of two photos, showing sublimation over the time period reported should indeed exclude CO2. So much so are the weather conditions unfavorable that it's not clear to me that from the time the trench was dug by the scoop and retracted out of the way that a picture of solid CO2 could have been made exposed like that.

:grumpy: So, we both agree that CO2 is ruled out, right?

 

[LowlyPion]

So, we both agree that CO2 is ruled out, right?

Yes I would certainly say that CO2 is ruled out by the combination of factors including the pictures (and perhaps not necessarily by one picture alone) that would give clues about time lapse as well as other observations about temp and pressure.

Let me encourage you to be a little clearer in your qualified statements then because as you can see I am easily thrown off in thinking you were saying that CO2 was not in fact ruled out.

Cheers and good wishes.