Will water or lava freeze in space, or would it be a gas?

  1. This not only goes for water, but any hot, melted substance suddenly exposed to the near vacuum of space.

    For example, suppose I have a stream of water leaking out of a space ship. Does the water freeze because space is at 50-100 K (in our solar system), or does it evaoprate because the air pressure of space is so low? Or, is it more complicated than that where some of the water will freeze on the outside of the spaceship, and some will escape through the solar system as gas?

    This also applies to super-hot lava erupting on moons of Jupiter or Saturn. The lava is very hot ~1000-2000 K. The temperature of such moons is ~50-100 K. So, by this reasoning, the lava would freeze into rock. But, these moons also do not have any atmosphere, thus they have very low pressure. Low pressure makes almost the phase of everything a gas, so by the second line of logic, the lava should outgas into space.

    I can't see which is which, so I ask for help here.
     
  2. jcsd
  3. Bandersnatch

    Bandersnatch 1,258
    Gold Member

    Water will first boil, then freeze. Boiling takes away the energy from the liquid, see, so it cools down rapidly.
    Somebody posted a really well-made educational video here once, ilustrating just this process:
    https://www.physicsforums.com/showthread.php?t=658014

    As for the lava, molten rock outgasses the volatile components of the flow, the rest solidifies. There might be some parts of the lava flow that will hapily exist in gaseous form, and these will escape into space cooling the rest a bit, but the bulk of the flow will just lose energy via conduction(contact with the surrounding ground) and radiation.
     
  4. Depends where in space, right?

    Think of comets as they come in from the Oort cloud. They're chunks of rock and frozen water. As they float in towards the Sun, the water and other chemicals begin to heat up and outgas, creating a tail.
     
  5. It depends on viscosity, dissolved gasses, and things like that. Lava is very viscous so I'd expect it to usually hold together. "Room temperature" water I would expect to blow itself apart by vigorous boiling.
     
  6. marcus

    marcus 24,129
    Science Advisor
    Gold Member
    2014 Award

    I've seen liquid water boil and freeze at the same time. At low pressure under a bell jar.
    As someone said, the room temperature water cools itself by letting part of itself boil away, so that the rest can freeze.
     
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