Starts With A Bang

Water In Space: Does It Freeze Or Boil? (Synopsis)

Water drops can exist inside the pressurized environment of the International Space Station, but send them outside the cabin into the vacuum of space, and they can be liquid no longer. Image credit: ESA/NASA, of Andre Kuipers.

“You can’t cross the sea merely by standing and staring at the water.” –Rabindranath Tagore

You can’t answer a hypothetical question for certain, at least in science, without doing the experiment for yourself. Here on Earth, liquid water is plentiful; our planet has the stable temperatures and pressures that water needs to exist in its liquid state. Other planets aren’t so lucky: with a thin or negligible atmosphere, you can only have solid ice or gaseous water vapor.

The gravitational pull on the gases in our atmosphere cause a substantial surface pressure, giving rise to liquid oceans. Image credit: NASA Goddard Space Flight Center Image by Reto Stöckli, Terra Satellite / MODIS instrument.

So what happens if you take the Earth’s liquid water to space? By keeping it at Earth-like conditions and then rapidly exposing it to the conditions outside of your spacecraft, you can find out. In the vacuum of space, the temperatures are much too low for liquid water; everything should freeze. But the pressures are much to low for liquid water as well; everything should boil.

The formation and growth of a snowflake, a particular configuration of ice crystal. Image credit: Vyacheslav Ivanov, from his video at Vimeo:

Which one wins? Does water freeze or boil in space? The answer is first one, then the other! Get the science today.