Here's a flicker between sol 21 and 24 showing change (or, rather, lack of):


Ignore the color of the brightest part of the white stuff, it's overexposed. The small white chunk in sol 21 image appears to disappear in sol 24 (inset).

Are you referring to the chunk that appeared on sol 19 and the was smeared into smaller bits on sol 20? Hard to say in the shadow, but those chunks may have indeed disappeared.

Yes, that one. It's in the shadow in sol 24 image, but other darker bits are subtly visible and yet this one isn't.

Nice animation!

There is another tiny chunk in the far right of the images (below the furthest right white streak) that is in full sunlight in both images that went away in the second image of the sequence.

-Mike

yes exactly
hortonheardawho from marsroverblog.com found this for sure now .

IT is ice

http://www.flickr.com/photos/hortonheardaw...881091/sizes/o/

Here's my take on the sol 20 - sol 24 changes using the 5 filter (R1ABC2) set from each for comparison. Ugordon's warnings about the brightest features absolutely apply. There might be legitimate changes, but they might also just be overexposure / time-of-day / stretching differences.

The "bright stuff" under the shadow I feel much more confident about: it's there on sol 20, gone by sol 24.

good point to obserwation is in this place also



http://www.flickr.com/photos/hortonheardaw...881091/sizes/o/

Beautiful stuff, guys. I agree about the disappearing light bits in the shadow. But the lighting in the latest gifs (slinted, horton) is very similar on sols 20 and 24, as you can see by the shadows. We are again clearly seeing a darkening over time of the larger exposed substrate areas.

How does this sound: White substrate is mostly white ice, plus some dark dust/sand impurities. As the ice sublimates, the impurities are left behind. Eventually, the surface of the substrate is essentially completely covered by the dark impurities. That stage has almost been reached on the leftmost large exposed substrate area - there's very little white left by sol 24.

Awesome animation, slinted. That went straight to the blog.

--Emily

slinted and all...

awesome indeed ... Peter Smith agrees...

http://phoenix.lpl.arizona.edu/06_19_pr.php

MUST BE ICE!!!!

Craig

"It must be ice," said Phoenix Principal Investigator Peter Smith of the University of Arizona, Tucson. "These little clumps completely disappearing over the course of a few days, that is perfect evidence that it's ice. There had been some question whether the bright material was salt. Salt can't do that."

There is also an animation at the UA Phoenix page clearly showing the changes at lower left of Dodo-Goldilocks. Images from Sols 20 and 24 (June 15 and 18, 2008). "These images show sublimation of ice in the trench informally called "Dodo-Goldilocks" over the course of four days".


Pay Dirt !!

ken

So as far as those disappearing chunks, how did they sublimate so fast? I thought we were talking microns per day of sublimation...

That was for ice attached to a large body. A relatively small piece sitting on regolith would behave quite differently.

It also crosses my mind that those "chunks" might be more like shavings than solid blocks.

I so could not resist this!

Ice, Ice Baby!



EDIT: poignant lyric for today:
"If there was a problem yo I'll solve it
Check out the hook while my DJ revolves it "

Media Update

NASA and the University of Arizona, Tucson, will hold a media teleconference at 10 a.m. PDT (1 p.m. EDT) (5 p.m. UTC) on Friday, June 20, to report on the latest news from NASA's Phoenix Mars Lander mission.

I wonder what the major topic will be?

Jack

Note This conference is only posted on the Arizona web page as of 11:00 p.m. EDT. I hope it will be announced on NASA's audio streaming page soon

Streaming Page
http://www.nasa.gov/news/media/newsaudio/index.htm

Whoa! I've just read an AP summary of the press conference in which it is stated that, yes, it IS ice under the thin, insulating layer of Martian dust. And I'm going to go out on a limb and agree with the exogeologists who have been surmising that this is not just a polar region phenomenon, but global, ie, Mars may have as much water. relatively speaking, as Earth, only it is locked away as ice under a relatively thin layer of Martian regolith. And thus volcanic activity can unleash the torrents of water in evidence all over the planet. And this perhaps also accounts for the "seepages" that we see in the sides of many craters. And thus it is likely as well that there are pockets -- perhaps huge pockets -- of liquid water at many, many places under the surface.

Ice on Mars! Now you see it, now you don’t
Scientists say they know white stuff was frozen water because it vanished

http://www.msnbc.msn.com/id/25274243/

The AP story had at least one quote that was copied verbatim from the press release; the press conference hasn't happened yet. It does contain some news from Barry Goldstein saying that they now understand the sol 22 anomaly and have developed a software patch. Glennwsmith, there probably is lots of ice underneath the surface but it is not as close to the surface elsewhere on Mars (where it is warmer) as it is near the poles.

I hope to be able to listen in to tomorrow's press conference but I've got the baby on Fridays and I don't know what her plans are for me yet...

--Emily

How do we know this is water and not CO2 ice already? We all suspect this of course but the media is reporting it as fact. TEGA hasn't found any water yet so is there some IR spectral measurement I don't know about?

Too low pressure and high temperature for CO2 ice. We know the temperature at the landing site -- on sol 22, for instance, it was a high of -22 and a low of -80. And the pressure is very low, on the order of 8 millibars. If you look at a phase diagram for carbon dioxide, you'll see it's always a gas under all these conditions -- it has to get really, really cold to make carbon dioxide ice, and you don't get that cold at the low elevations near Mars' north pole during the summer.
Click to view attachment
I took this phase diagram from an interesting article, "Why You Can't Have a Snowball Fight on Mars"

This may make you wonder, okay, if you read that diagram it looks like water should be stable as a solid under these conditions, so why did the chunks vaporize? The problem is that the diagrams assume equilibrium conditions. But Mars is a big system and there's heating during the day and cooling at night and dry or wet air masses moving in and wind doing stuff, so at any moment things aren't in equilibrium. I understand that there could be some conditions prevailing at the Phoenix landing site that might even lead to net deposition of water ice, but they've always seemed fairly sure that excavated chunks would sublimate during the day. (I wonder if any water ice deposition happens in cold traps overnight.) Large bodies of ice like what's exposed under the lander might show little change, sublimating a tiny bit during the day and getting deposited on a bit overnight. But if you sublimate much of a chunk during the day, it's gone for good; it's not like a chunk is going to reappear from nothing overnight, so chunks that are sufficiently small should go away as a result of cyclic sublimation and deposition.

--Emily

m! case closed. forgot about the relatively high temps right now at the landing site.

Water being stable as a solid at 8 millibars as indicated on a phase diagram would require a partial pressure of water vapor of 8 millibar not a total atmospheric pressure of 8 millibar. A layer of dirt on top of the ice could prevent the water vapor sublimated from the ice from diffusing away to the atmosphere so the vapor pressure of water vapor below the soil could remain near atmospheric pressure. Removing the dirt layer protecting it would allow the water vapor to disperse. Then the ice would then be exposed the the atmosphere which is mostly CO2 with little water vapor. Ice at the surface would be unstable and would sublimate unless the temperature was low enough to be at equilibrium with the partial pressure of water vapor in the atmosphere.

Not to toss out the water too soon, but ....

There is also the possibility that this loss of bright stuff in the trenches could be water of hydration evaporating from a salt newly exposed to the open dry atmosphere. (water of hydration of a salt is NOT ice.) This would change the crystal morphology of the salt. This would then be expected to change the brightness/reflectivity of the salts. Frankly, I am surprised to see that everyone is proclaiming this ice without eliminating this possibility.

For example, magnesium sulfate exists as MgSO4.7H2O. The waters of hydration are lost in a very dry atmosphere over about 3-4 days. The hydrated form is bright and crystalline and reflective. The annhydrous form is dull and non-reflective. I remember doing this experiment as a freshman in college!

I want to see analytical proof of water. I really do hope this is water !

p.s. I found this very nice paper, discussion exactly these phase transitions in mag sulfate under martian temperature/pressure conditions, and expected physical appearance: CONVERSION OF CRYSTALLINE MgSO4.XH2O TO THE HYDRATED AMORPHOUS PHASE – A
RAMAN, NIR, AND XRD STUDY. http://www.lpi.usra.edu/meetings/lpsc2006/pdf/2168.pdf

Evidence of water ice now being reported on CNN:
http://www.cnn.com/2008/TECH/space/06/20/p...s.ap/index.html

(I have a minor issue with this sentence in the article: "However, an initial soil sample heated in a science instrument failed to yield evidence of water". - Couldn't they have said "did not determine evidence for water" instead of using the f-word?)

-Mike

Even if this could explain change in brightness of a surface, what about the entire disappearance of small, dislodged chunks?

It's probably time to start looking for evidence of rust on the footpads...

Yeah, Phoenix' price as used hardware might be going down. Nothing a good paint job can't fix, though!

CNN TV also running the story, including a sidebar with Miles O'Brien that featured an animated before & after GIF very much like those seen here...is anybody at UMSF now a credited TV star, perhaps...?

( briefly dropping out of lurking mode...)

As much as I hate to do so, I have to agree with silylene: the case for water-ice -- at least in the Goldilocks trench -- is "not proven".

Here is a sol 20-24 3D animation of the shadowed area in the trench.

I created it to see if I could see how much of the clumps remained after the "sublimation". Unfortunately even the NASA gif image drops out in the darkest part of the shadow -- where the most interesting clumps were. But if you look closely at the bright clumps that fade nearest the shadow edges I think you can see that the clumps do not completely disappear.

Even in the darkest shadow there appears to be "something" where the white clumps were -- so, yes, there may have been a dramatic change in the white clumps -- but perhaps no more so than the reductiion in the brightness parts of the top of the trench.

Yeah, I believe that it's water-ice but it's not yet scientifically proven.

I am still puzzled why the infrared spectrum from the left SSI camera has not been cited as supporting evidence for water-ice.

( jumping back into cyber-space...)

Also unlurking briefly....

If the lumps were dirty ice, then surely you wouldn't expect them to completely disappear.

Chris

Teleconference on right now...

Big day for Mark and the rest of the team. Congratulations!

Indeed! It's awesome that an imaging instrument was able to beat other ones to the discovery and practically nail this as ice.

ICE - wow that sure is COOL !

Very early after landing Phoenix took a look under the craft,
showing exposed bright material where the landing jets had blown
the sand away.

It would be interesting to revisit this area and see if there have
been any visible changes. This 'bright stuff' has been exposed
for much longer than any in the trenches.

ce

I agree that this doesn't prove the case for water, and that hydrated salts are a possibility, but I just don't see what you do on the animation: There are a lot of changes that could be due to different shadowing or image artefacts, but I don't see any consistent outlines between the two frames, and the shadowing around the lumps looks to change as well. Is there any chance you could draw me some outlines to make it a bit clearer?

Go on drop out of cyberspace, the view from here is just as interesting!

Edit; ICE, I meant doesn't prove the case for ICE, please oh great god of woo don't strike me down!

Well the whole world knows now about the water ice

It's the main headline on the Drudge Report website

points to a Bloomberg article:

http://www.bloomberg.com/apps/news?pid=206...refer=worldwide

Sure looks like ice in this blinker
Click to view attachment

Exactly. If the disappearing lumps were composed of sedimentary particles cemented by ice, the lumps would disintegrate when the ice sublimed, but not completely disappear.

Man, I really think this discovery, or rather confirmation, demands a new thread, something entitled "it IS ice"... Done - J

We now know for sure that Mars is full of rocket fuel and water to drink. Fantastic news.

I think we've been pretty confident of that for several years now based on orbiter data, but it is indeed nice to see it at a "human" scale of reference...and at an easily accessible depth.

Now there's the problem of getting ice-laden samples into the ovens before it sublimates. CNN reported yesterday that a fresh dig had only about 30 min for delivery before ice crystals small enough to filter through the screens would sublimate off; is this accurate?

That's probably based on the telecon yesterday (Miles O'Brien was 'there'), when they said they wanted the whole process to take 30 minutes. That does not necessarily mean the ice would sublimate that fast.

Thanks, Gordan! Had to miss the telecon; I'm in Texas attending a work-related class.

I would be curious to know just how rapidly suitably small ice crystals would sublimate during the daytime at the site, though. Presumably the team has a model for this; they'd need it to estimate the actual water content of the sample prior to acquisition.

Sorry for barging in, just a quick comment then I'll slink away to lurk-mode again.

These mission scientists are circumspect and they won't state things until they have absolute proof, and that's good. But:

As soon as we saw what got exposed by the rockets it was instantly obvious that anywhere they dug they would find more ice. By the flat heterogeneous landscape it's true for miles around. Phoenix is sitting on a frozen f'ing lake bed. Orbital data already says there is a vast amount of water ice underneath.

Other things that strike me as just 'obvious:'

They are digging these trenches side by side to make a clean workspace for going as deep as they can reach without surface material cascading into it, so as to get purer ice samples.

At this latitude the 'surface,' the depth to which sublimation happens at this time of year, is ideal. It's an awesome location for this experiment. They nailed it, absolutely perfectly.

But the real shock is yet to come, if it does: That will be if/when they detect amino acids in the ice makeup. On that discovery, they will be very, very circumspect - as they should be.

Very exciting times, it's truly historic. Water ice up close is unprecedented.

Thanks for this forum and to all who post, it's a terrific read. You do a superb job of getting down to details, which is why someone 'stating the obvious' is just a bandwidth-waster on one level, but is hopefully also perspective provoking and encouraging. Cheers

BTW have we had a look at Snow Queen lately? Ten bucks and my left (elbow) says it is going to sublimate away, albeit slower than the fresh samples.

The feature reminds me of those dirty ice chunks that build up under the wheel wells of a car and then drop on the street.

Been wondering about that myself, actually; it's been awhile, but guess that the arm's been a bit busy. Seems like an important observation, though.

Re car wheelwell ice chunks, here's a quick story. When I first read about meteorites when I was little in the middle of a Montana winter there were apparently all kinds of things that looked like them on the road- black, sooty torn up 'rocks'. Spent an entire afternoon collecting & dragging these things into my backyard, convinced that I was doing important sample collection...my parents were a bit displeased later on after discovering a sizeable mound of crappy road ice back there!

Um, I was not a particularly bright kid...

Aminoacids ??? I would not bet on it.
Phoenix is not equipped to detect organics, let alone find their structure.
The wet chemistry lab experiments will look for inorganics and oxidants, if I remember well.

This is one of the prime objectives of Phoenix. I don't know how specific they can get in the identities though.
If organics are found, chances are they would be the same types as already found in comets and meteorites... including amino acids.

"The mass spectrometer is sensitive to detection levels down to 10 parts per billion, a level that may detect minute quantities of organic molecules potentially existing in the ice and soil." (Let's hope they get those darn doors working!)

A number that's relevant to this discussion is what the maximum mass capability of the mass spec in TEGA is -- I can't seem to get that to turn up on a quick Google search. My guess is that amino acids are too large to be detectable -- that they're looking for smaller stuff, simpler carbon chains -- but that's just a guess, and it'd be helpful if someone could turn up a reference on this. IIRC, the mass spec instrument on Cassini can only detect the very smallest amino acid, whichever one that is.

--Emily

Hmm. Thanks, Emily.

So, basically, the most wildly optimistic and hoped-for outcome would be to detect a plethora of simple products of thermal decomposition, which might hint at the existence of more complex molecules.

What are the design limitations of mass spectrometers with respect to identifying organics, anyhow? If I understand their operation correctly, they'll provide gross elemental composition with sort of a hint at relative abundances, but there's really no way to infer chemical structures except by comparison with standard "pure" spectra of a given substance.