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Probable Water Ice Sighted On Mars

Posted by timothy on from the pronounced-wooder-ice-in-philly dept.

CraftyJack writes "Bright white chunks in the trenches dug by the Phoenix Lander have disappeared, leading Peter Smith & co. to believe that the chunks were ice that has since sublimated."

3 of 393 comments (clear)

  1. Re:Dry ice? by MichaelSmith · · Score: 5, Informative

    In such a carbon dioxide rich atmosphere, how do we know it is water ice and not frozen CO2? What do we know of the Martian surface and subsurface temperatures? Its too warm for solid CO2. Even at night the temperature is barely cold enough for carbon dioxide to solidify.
    --
    http://michaelsmith.id.au
  2. Re:The real question is... by GeffDE · · Score: 5, Informative

    H2O ice does sublimate. Here's an easy way to prove it. All you need is a freezer and an ice cube tray.

    1. Fill ice cube tray with water (liquid, H2O water) and put it in freezer.
    2. Go back in a day and mark the level of the ice in the tray.
    3. Return later (preferably at least a week) and marvel at how the ice is below the level marked.
    4. ???
    5. Profit.

    The ice was in the freezer the whole time, so it didn't melt (assuming the freezer was set correctly and continuously powered). Therefore, the solid water lost must have changed to water vapor.

    --
    It has been a nervous year, with people beginning to feel like Christian Scientists with appendicitis.
  3. Re:The real question is... by Ihlosi · · Score: 5, Informative

    H2O ice does sublimate. Here's an easy way to prove it.

    There is absolutely no need to prove that.

    Just pull up a phase diagram of water (google is your friend), look at the lower-left
    corner (i.e. low pressure and low temperature), and what do you see ?

    A line where the solid phase borders on the vapor phase.

    And what's a phase transition from solid phase to vapor phase called ?

    Bingo. Sublimation.