Physics Van 3-site Navigational Menu

Physics Van Navigational Menu

Q & A: water in space

Learn more physics!

Most recent answer: 10/22/2007
Q:
On the sci-fi program Battleshp Galactica was a scene of water pouring out of ruptured tanks into deep space. I contend that water being exposed to the intense cold would have frozen on contact and the resulting ice would have closed off the holes saving the water in the tanks. Others contend that the water would have vaporized on contact because there is no air or pressure in space. Still the question remains, if there is no air or pressure, can the water vaporize and if yes, what happens to the ensuing steam (mist) if it cannot be absorbed by the air as it does on earth. Matter can’t be lost according to Newton, so where is it? Not an earth shattering question, but I’d love to know the answer. Thanks.
- Evelyn Palmeri (age 70)
Flagler Beach FL
A:
You raise a few questions.
One is simple- can water vaporize in space, without air? The answer is yes. The water vapor in the atmosphere isn't stuck to air molecules, but exists as water molecules bouncing around independently. You can easily have a gas with only water and no air. In fact, when you boil water the bubbles that form under water are almost pure water vapor, without air.

Now the nearly empty space that the vapor would go into may be intensely cold, but it has almost nothing in it to get warmed up. In other words, it has a very low heat capacity. It wouldn't cool the water down significantly. However, the water would get cold for another reason. Exposed to a vacuum, it would boil away. Conversion to the vapor soaks up a lot of energy, the latent heat of vaporization. All the surroundings would cool down, including the water that had not yet boiled off.

You can actually freeze water by putting it in a vaccum using this effect. Some vaporizes and the rest is cooled enough to freeze. I really can't calculate whether in your story you should expect ice plugs to block up the holes or not. In the long run, the water would evaporate (sublimate) from the ice also, leaving nothing.

Mike W.

(published on 10/22/2007)

Follow-up on this answer.