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Mars Space Science

Water Ice On Mars 364

cathector sends along a story from on the discovery of water ice on Mars. "Scientists have figured out the mysterious white substance unearthed by NASA's Phoenix lander on Mars. It's frozen water. The breakthrough came last week when Phoenix's stereo camera caught the substance in the act of disappearing. Bathed in martian sunlight for four days, the white substance sublimated — i.e., it transformed from solid to gas without passing through the liquid state. This is how water behaves on Mars.... Some readers have asked, how do we know the white substance is not frozen CO2 (dry ice) instead of frozen water? Answer: Phoenix's landing site is too warm for dry ice. The average daily temperature is about -70 F while dry ice requires temperatures lower than about -109 F." The animated GIF showing the ice sublimating is pretty nice too.
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Water Ice On Mars

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  • by Anonymous Coward on Sunday June 22, 2008 @07:11PM (#23898015)

    Now we just need a little global warming.

  • So, if we sent a bunch of robot tractors to Mars and uncovered the dirty ice caps, wouldn't they all sublimate and all that water vapor would warm the planet? Are we looking at a cheap way to terraform the planet?

    • by CDMA_Demo ( 841347 ) on Sunday June 22, 2008 @07:24PM (#23898105) Homepage
      escape velocity on mars is 5.027 km/s, and water vapor will slowly move out of mars because of its high rms velocity. So, the answer is "no"
      • Re: (Score:3, Interesting)

        by Bob(TM) ( 104510 )

        Actually, that argument can be made for any atmospheric gas constituent, not just water vapor.

        There is less water in the Martian atmosphere oxygen while the water is more massive, so the oxygen would leave at a proportionally greater rate (assuming we are observing a long term steady state). One theory of the rapid loss has more to do with disassociation of H and O by UV radiation. H would quickly leave by your molecular motion argument leaving a relatively larger amount of O.

        If that's the case, we'd be m

        • Re: (Score:3, Informative)

          by WalksOnDirt ( 704461 )

          There is less water in the Martian atmosphere oxygen while the water is more massive...
          Really? I see the atomic mass of an oxygen molecule as 16 + 16 = 32, while water is 16 + 1 + 1 = 18.

          But you're right, either way the dissociated hydrogen is way lighter.

        • Personally (Score:3, Insightful)

          by WindBourne ( 631190 )
          I would rather use the nukes to bring a few asteroids to impact mars. Some of those contain a load of ammonia. Ammonia is a great great house gas. Of course, that would disassociate over time, leaving N2 in the atmosphere.
      • Re: (Score:3, Funny)

        by Fizzl ( 209397 )

        You leave Mr. Stallman out of this!

  • by ecklesweb ( 713901 ) on Sunday June 22, 2008 @07:14PM (#23898037)

    In other news, NASA announced today that a manned mission to Mars is planned to retreive the newly found ice in time for the 2012 Kentucky Derby. NASA plans to upstage Woodford Reserve's famous $1000 Mint Julep at the race with its own $3,000,000 version of the traditional cocktail. While plans are still being firmed up, the beverage will reportedly come in a limited edition collector's glass.

  • Snow (Score:5, Interesting)

    by Joe Tie. ( 567096 ) on Sunday June 22, 2008 @07:15PM (#23898043)
    Pardon my total ignorance of the subject, but does this mean that it might occasionally snow on mars? Or would the environment be too different to allow it?
    • Re:Snow (Score:5, Interesting)

      by Mr2cents ( 323101 ) on Sunday June 22, 2008 @07:36PM (#23898197)

      No, martian air is way too dry to form snow. There is water in the athmosphere, but IIRC it is something like a layer 1mm thick if all the water would condense on the ground. What happens is that some of that water freezes to/in the ground if it gets cold enough.

      What I learned from following the press conferences online, is that since mars doesn't have a large moon, the axis of rotation changes much more than earth does, so if it is directed towards the sun, the ice could actually melt.

      • Re: (Score:3, Interesting)

        by Fluffeh ( 1273756 )
        I recall reading/seeing somewhere that Jupiter can pull Mars off axis causing it to buckle over to around 60 degrees before it works itself back to it's 23 degrees.
      • Re: (Score:3, Funny)

        by Anonymous Coward

        we should wisely remember that all these claims of ice or dry ice and so many other speculations are based on our earthly experience and so are limited to our sense perception. the fact is that every planet, all those millions that you can and cannot see in the sky are fully habitable and many many people are living there. this is the knowledge coming from the topmost intelligent people who have ever appeared on this planet and given fully scientific information about other planets. spending billions on

    • Re:Snow (Score:5, Interesting)

      by MichaelSmith ( 789609 ) on Sunday June 22, 2008 @07:41PM (#23898227) Homepage Journal

      Pardon my total ignorance of the subject, but does this mean that it might occasionally snow on mars? Or would the environment be too different to allow it?
      The area the lander in is covered by ice during the winter so we are going to find the answer to your question quite soon.
  • Water sublimating (Score:5, Interesting)

    by NoobixCube ( 1133473 ) on Sunday June 22, 2008 @07:16PM (#23898053) Journal
    If I remember my chemistry classes correctly (there is a high chance I don't), water would do this under lower air pressure, I think. Correct me if I'm wrong, I just thought some kind of explanation would be better than "because it's on Mars".
    • Re:Water sublimating (Score:5, Interesting)

      by Rob Kaper ( 5960 ) on Sunday June 22, 2008 @07:24PM (#23898111) Homepage

      Is water the only material that can sublimate? If not, why should we be so sure this has to be water just because we want it to be?

      • Re: (Score:2, Informative)

        by jberryman ( 1175517 )

        CO2 sublimes on earth of course, and many other substances do under different conditions. Per the summary, we know it could not be frozen CO2.

      • by PieSquared ( 867490 ) <isosceles2006@gma i l .com> on Sunday June 22, 2008 @07:57PM (#23898339)
        Pretty much anything can sublimate under the proper conditions. But when you say "a white solid that sublimates at -70 degrees F and martian surface pressure and is found in macroscopic quantities naturally" you narrow down the field quite a bit. In this case, to exactly one reasonable possibility.
        • I know (Score:5, Funny)

          by Anonymous Coward on Sunday June 22, 2008 @08:43PM (#23898635)

          Pretty much anything can sublimate under the proper conditions. But when you say "a white solid that sublimates at -70 degrees F and martian surface pressure and is found in macroscopic quantities naturally" you narrow down the field quite a bit. In this case, to exactly one reasonable possibility.

          Yep, Vodka.

      • Re:Water sublimating (Score:5, Informative)

        by mrbluze ( 1034940 ) on Sunday June 22, 2008 @08:50PM (#23898689) Journal

        Is water the only material that can sublimate?

        To quote wikipedia: This can occur if the atmospheric pressure exerted on the substance is too low to stop the molecules from escaping from the solid state.

        Atmospheric pressure is not as important as the partial pressure of the substance at its surface. That is, in this case, the vapour pressure of water which is practically zero on Mars. Therefore water, if it is not locked down in crystalline form, cannot exist in liquid form because it cannot form an equilibrium with its surroundings to form a 'triple point' (solid/liquid/vapour phase temperature).

        It also depends, as far as I understand, on the interaction between molecules of the substance. If it is too weak, the range of temperatures at which the substance can be liquid is narrow (or practically zero). It's a fairly wide range for water, though.

        I didn't study the topic beyond that and it was years ago.

        PS. Iodine is another substance that sublimates.

      • Re:Water sublimating (Score:4, Informative)

        by KKlaus ( 1012919 ) on Sunday June 22, 2008 @11:36PM (#23899699)

        All materials sublimate. The liquid phase doesn't exist beneath a substance's triple point, so at pressures beneath that level temperature increases cause the material to go directly from solid to gaseous (sublimate). [] has a good picture of what we're thinking about.

        • Re: (Score:3, Interesting)

          by locofungus ( 179280 )

          All materials sublimate

          Not sure about helium. If it can sublimate then it's going to be way up the phase diagram at enormous pressure at or close to the critical temperature. But it can definitely go straight from the superfluid state to the vapour state.

          It's quite bizarre when you watch He4 transition to superfluid as you reduce the pressure. It's boiling away vigourously and then suddenly all the boiling stops (and it becomes quite difficult to see because it's refractive index is so close to 1)


    • Re:Water sublimating (Score:5, Informative)

      by Breakfast Pants ( 323698 ) on Sunday June 22, 2008 @07:25PM (#23898117) Journal

      Doesn't really need to be under low air pressure, if ice is in the presence of low vapor-pressure it will sublimate (see icecube tray in your freezer).

    • Re:Water sublimating (Score:4, Informative)

      by cyklo ( 795952 ) on Sunday June 22, 2008 @07:27PM (#23898133)

      Indeed it does, and it's probably better explained using a triple point diagram: []

      On earth (at higher pressures), increasing temperature goes from the solid, to liquid, and then to gas phases (the triple-point in the middle is at zero degress celcius)

      The lower atmospheric pressure on Mars (~1% of sea-level earth pressure) means that you go straight from solid to gas. In fact, the liquid part is actually impossible (IANAChemist) unless you increase the pressure sufficiently.

    • Re:Water sublimating (Score:5, Informative)

      by cathector ( 972646 ) on Sunday June 22, 2008 @07:53PM (#23898319)

      water sublimation doesn't need to be exotic; it happens in your freezer all the time.
      you know how ice cubes gradually lose their sharp edges and finally become just little puddle-shaped lumps in the bottom of the ice try ? that's sublimation too.

    • phase diagram (Score:3, Informative)

      Here []

      How to read them []

      I feel that a great disservice was done to a lot of us early on with a simplistic view of the usual three phases of matter.

      And yes, you're right. That is part of the explanation.

  • Better picture (Score:5, Informative)

    by Jade E. 2 ( 313290 ) <slashdot@perls[ ] ['tor' in gap]> on Sunday June 22, 2008 @07:17PM (#23898055) Homepage
    That animation is actually cut off. The main sublimation that was observed is below the frame of that picture. There's a better one here [], where you can actually see the small chunks farther down disappearing completely.
  • by commodoresloat ( 172735 ) * on Sunday June 22, 2008 @07:19PM (#23898069)
    It means we finally have a suitable accompaniment for Martian scotch.
  • A first glance, it doesn't look to me like ice "melting" any more than salt or some other finely-grained material blowing away (no, I'm not saying it's salt -- just something that could move). Is there no wind in that area or something?

    • Re: (Score:2, Informative)

      by Anonymous Coward
      There is wind, however it apparently didn't move anything else in the pictures. Also, the wind wouldn't be very strong since the atmosphere is so thin.
    • Re: (Score:3, Informative)

      If I understand correctly, the water is blowing away.. just not as crystals. It is blowing away as discreet water molecules much like evaporation. The crystals gain energy from the sun and a little from the impact of the atmospheric gases and then the water molecules lift from the crystal lattice and suspend in the atmospheric gas matrix.

      If you visualize everything as tiny versions of the colored balls in a child's play pit, you will notice that each type of ball (atom) has a different weight and tends to

  • by Anonymous Coward

    dry ice requires temperatures lower than about -109 F.

    But what about pressure? A look at the phase diagram [] shows that carbon dioxide can be a solid (dry ice) at 25 C (room temperature), but at 10000 bar. I dunno what the pressure is on the surface of Mars, but temperature isn't the only thing that dictates if dry ice exists. Pressure is just as important. I doubt that Mars has that kind of pressure though.

    And why are we using F? This is a science article, posted on a web site for nerds.

  • by Gavin Scott ( 15916 ) * on Sunday June 22, 2008 @07:23PM (#23898095)

    I've noticed that almost all of the news headlines covering this are qualified statements like "Lander finds water on Mars, according to scientists". As if they're afraid to actually say something straightforward like "Water found on Mars" and they have to make it clear that they're just reporting what someone else is saying (with the implication that maybe they don't really believe it). At the same time they seem to have no problem with other headlines like "Celebrity Arrested Drunk" without the need to qualify it as "Celebrity Arrested Drunk According To Police" etc.

    Maybe it's just me, but I mind it a bit irksome that so many big news outlets seem so detached from any sort of science reporting these days.


    • Although I agree with you in principle, I think it might be due to the anticipation of NASA's announcement, which could do away with the "according to scientists [working on the project]" caveat.
    • by CaptainPatent ( 1087643 ) on Sunday June 22, 2008 @07:37PM (#23898207) Journal
      News fails to take responsibility according to one internet poster.

      More at 8.
    • I've noticed that almost all of the news headlines covering this are qualified statements like "Lander finds water on Mars, according to scientists". As if they're afraid to actually say something straightforward like "Water found on Mars"

      I think the reason is that the scientists technically have no proof it is actually water - what they have instead is a substance that looks like water, behaves like water and quacks like water. Whether it makes said something water, you be the judge.

      On the other account, I totally agree - the media don't always seem so scrupulous in other areas :)

    • Re: (Score:3, Funny)

      by Jafafa Hots ( 580169 )
      Well, those scientists, all they have are "theories," doncha know. You can't trust them. Their stories are always changing, unlike the Word of our Lord And Savior which has been true for millennia.

      All hail Zeus.

  • by Swampash ( 1131503 ) on Sunday June 22, 2008 @07:23PM (#23898103)

    Could we have this important information in units used by, I don't know, the rest of the world?

    • Re: (Score:3, Insightful)

      Well, as soon as a country from a part of that world, then you'll get your pronouncements to the public in metric. You have to remember that NASA is publicly funded. They need the public engaged in their discoveries, in order to maintain their funding. So, it only makes sense that they report their public findings to the media in units that average ( and the not so average members of congress) understand. I'm sure there are those a NASA that thinks they should be trying to convince the American public to us
    • by belg4mit ( 152620 ) on Sunday June 22, 2008 @08:27PM (#23898549) Homepage

      Send your own fucking probe if you can't be bothered to subtract 32 and multiply by 4/9.

    • by Solandri ( 704621 ) on Sunday June 22, 2008 @11:11PM (#23899563)

      Could we have this important information in units used by, I don't know, the rest of the world?
      Hah! With this announcement, NASA has predicated that Fahrenheit is now used on the surface of two worlds, thus re-establishing its dominance over that other temperature unit which is only used in part of one world. We will wrest control of this universe back from you metric heathens, even if we have to do it one planet at a time!
  • One Problem: (Score:5, Informative)

    by grasshoppa ( 657393 ) <skennedy@tpn o - c o .org> on Sunday June 22, 2008 @07:32PM (#23898171) Homepage

    Here's the problem: We still don't know conclusively. Yes, we have observations which are highly suggestive, but we don't have a chemical composition of the substance, so we don't know for sure.

    Science is a hard mistress; she demands proof before making such claims.

    • Correct, and further experiments will be undertaken to confirm that it is indeed water ice.

      In the mean time, though, it's pretty safe to act under the assumption that there is indeed water on mars.

    • Re: (Score:3, Funny)

      by Anonymous Coward

      >> Science is a hard mistress; she demands proof before making such claims.

      I shall have this woman.

  • by speedtux ( 1307149 ) on Sunday June 22, 2008 @07:45PM (#23898263)

    Finding water was one of the key goals of the Phoenix mission.

    That is a bizarre statement. Large quantities of ice have been observed in numerous ways already. Even the Viking lander observed water frost directly in the 1970's: [] []

    That frost sublimated just like this ice did.

    Here are other observations: []

    Here you can see a frozen crater lake: [] []

    Not only is that ice, it may actually be an outflow.

    What makes the results from Phoenix exciting is that the actual experiments that Phoenix is supposed to perform depend on having landed on ice. But finding ice somewhere on Mars is not a surprise.

    • by TennilleGuy ( 1312411 ) on Sunday June 22, 2008 @09:06PM (#23898799)
      Yes, water ice on Mars is nothing new. That's why they went there. They could not have another failed mission, could they? Before Phoenix there was Opportunity. Why? The NASA-funded mineralogical neophytes spent our money looking for liquid water where they saw widespread hematite...coarse grained grey hematite. water in its structure! On Earth, in the banded iron formations that are BILLIONS of years old, that is a metamorphic mineral. It did not form in liquid water! Its PRECURSOR minerals (goethite; ferrihydrite; lepidocrocite) did form in water. Using hematite as a "beacon" for liquid water would be like using anthracite coal as a beacon for a coal swamp or a piece of chinaware as a beacon for a kaolin mine. Now we have a mission that is the equivalent of finding sand in the Sahara Desert? They KNEW that there was water ice there...for years. Big deal? Unbelievable spin! If they actually find anything relevant to life on Mars one needs to inquire... Why didn't they go there in the first place? Why did they waste our money landing in a billion year old metamorphic landscape? Even the face-saving hematite "blueberries" are a joke when placed into context with the remote data used to select that landing site...platy coarse-grained hematite.
  • Anybody else see Dan Quayle running around with his chest puffed up saying, "I Told You So".

    Good for him :)

  • by viking80 ( 697716 ) on Sunday June 22, 2008 @08:42PM (#23898627) Journal

    First, I think the best evidence so far that this is water is not this picture, but the fact that the Mars Orbiter's spectrometer determined that that is was a lot of hydrogen in the ground near the poles.

    That some white stuff vanishes is poor evidence. They need to get the white stuff in an oven and test it.

    Let's assume it is water.
    What really puzzles me is how clean the water is. It is covered with what would make a dirty mud if it ever melted together. Also on earth, you never have clean water if you have flash floods like what you see as a result of a volcanic eruption or meteroid impact. You only have clean water/ice in snow and still lakes/oceans.
    This implies:
    1. The ice has not melted after the dust blew over it.(A long time)
    2. It used to be a lake/ocean or snow

    So the purity of the ice might be a bigger discovery than the fact that it is ice there.

    • there's a number of geological processes that can concentrate water like this

      in areas on earth where a lot of freezing and thawing occurs on earth, rocks get concentrated neatly in rings according to size, as if someone sorted them

      i'm not saying this process is anything like why the ice is so pure on mars, what i am saying is that there are plenty of natural processes out there that concentrate materials in orders that, contraintuitively, seem like it took intelligent concentration, but are in fact totally natural

      i won't even begin to speculate what processes on mars could do this, but i wouldn't be surprised if someone more knowledgeable than me could describe such a natural mechanism for ice purification on mars

  • Four days apart (Score:4, Insightful)

    by Trogre ( 513942 ) on Sunday June 22, 2008 @09:05PM (#23898785) Homepage

    So these two frames [] were taken four days apart while the sublimation was taking place. My question would be - where are the rest of the frames? Does this lander really only "look around" every few days?

    It would be nice to see it at even a 1-day resolution and get a 4-frame animation of the process. Those lumps should be seen to get smaller and vanish.

    Not that I'm complaining, this is still very cool (no pun intended).

  • Standards.... (Score:5, Informative)

    by jonfr ( 888673 ) * on Sunday June 22, 2008 @09:12PM (#23898823) Homepage

    U.S needs to upgrade it's standards. A good start would to move from Fahrenheit to Celsius. After that you can move over to the metric system.

    -70 F is -56 C
    -109 F is -78 C

    Conversion done with Google.

  • Seems to me... (Score:3, Informative)

    by nexuspal ( 720736 ) on Sunday June 22, 2008 @09:33PM (#23898971)
    That a lot of the people here see dry ice, white and solid like the stuff found on mars, and the fact that dry ice subliminates in our atmosphere, and come up with the idea that the white stuff must be solid CO2 and not water. Of course this is completely fallacious logic, as the pressure and temp in the area make it physicaly impossible for CO2 to be a solid (if temp/pressure data is correct)....
  • by jollyreaper ( 513215 ) on Sunday June 22, 2008 @10:50PM (#23899415)

    You say you think it's sublimation
    Well you know
    that'd be out of this world
    What else could explain the diminution
    Well you know
    that'd be out of this world
    But when you talk about reduction
    Don't you know ice ain't the only thing
    Don't you know other substances are white [x3]

    You say you got an aqueous solution
    Well you know
    We'd all want to see the proof
    Martians might be liliputian
    Well you know
    Look for them if you can can
    But if you want money for space probes that crater
    All I can tell you is brother maybe later
    Learn how to use metrics first, alright? [x4]

Things are not as simple as they seems at first. - Edward Thorp