Water Freezing in Space: Debunking the Myth of Instant Boiling and Freezing

[mcstatz5829]

There's no thermodynamics forum, so I'll post this here.



Things "freezing" in space has always bothered me ever since Tim Robbins removed his helmet while in orbit around Mars. https://www.google.com/url?sa=i&rct...aw3EDjIXfRDkD56iV0A3X5gK&ust=1563459254378535

While I understand space is cold, less than 10 Kelvin cold, what always seems to be left out is heat transfer. Conduction and convection require physical contact to transfer heat, which doesn't apply in space.

That just leaves radiation.

Using the Stefan-Boltzmann law, a 20 cm sphere of water at 300 Kelvin should radiate 221 watts (using 0.96 emissivity), which means less than 1 K temperature drop per second. I'm assuming the sphere retains it's shape though. I'm not sure what the surface area becomes when it boils, but taking the volume of the sphere and making it a cylinder 1E-5 meters thick gives me over 300 square meters and 600 million watts of radiation. That should freeze quick!

So, is it fair to say water will boil and freeze, but Tim Robbins just suffocates?

 

[.Scott]

It will evaporate and freeze - both at the same time.
The evaporation is due to the vacuum - and the freezing is due to the evaporation.
Both will happen very rapidly. A 20cm sphere of water should build up a frozen shell in less than a minute.

Video of water in vacuum.

 

[berkeman]

Video of water in vacuum.

Cool video! Thanks

 

[OmCheeto]

So, is it fair to say water will boil and freeze

I'm kind of glad I didn't just google that, and find the source of your image: Does water freeze or boil in space?

Because at the end of the article, they gave the answer to your question: Yes. [boil and freeze]

Which would have misdirected me from a morning filled with learning all manner of strange and wonderful things:

08:47​

PF: Water Freezing in Space​

Let me just google that for the OP

08:59​

http://coolcosmos.ipac.caltech.edu/ask/244-What-would-happen-if-you-pour-water-into-space-​

Q; What would happen if you pour water into space?​

A; Water poured into space (outside of a spacecraft ) would rapidly vaporize or boil away.​

Why don't you mention freezing, caltech?
So I google some more stuff:

8:54​

Lunar water - Wiki​

​

09:01​

water phase diagram​

Well, those two are a bust. Ignoring lunar water, try and figure out why the phase diagram for water always seems to bottom out at 0°C:

09:58​

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2002GL016183​

Vapor pressure above ice at temperatures below 170 K​

Konrad Mauersberger Dieter Krankowsky​

2003​

​

​

https://www.researchgate.net/publication/23814668_A_survey_and_new_measurements_of_ice_vapor_pressure_at_temperatures_between_170_and_250K​

James Marti, University of Minnesota Twin Cities​

Konrad Mauersberger​

1993​

​

A survey and new measurements of ice vapor pressure at temperatures between 170 and 250K​

​

log10(P, Pa) = -2663.5/T + 12.537​

Lots of fascinating stuff. For me anyways.
The 2003 paper covered only a 4.5°C range. Does that mean there's something special going on at around 170 Kelvin?
The 1993 paper pointed out that in 1928, someone knew the vapor pressure of water down to 183 Kelvin. I do not know why that would be a thing to know, almost 100 years ago, but, it was.

Then, after some more googling and math and stuff, I found your link:

13:22​

​

Does water freeze or boil in space?​

Hence, the above.

 

[OmCheeto]

Another thing I learned, just by making the above post:

Your Medium^Medium notjustanimage contains a link.

 

[anorlunda]

I agree, cool video.

I would expect zero gravity to also have an effect. In zero g, bubbles don't rise to the surface and separate. So a boiling dollop of liquid may disperse into vapor which greatly increases the surface area.

On the other hand, we have reports of frozen H2O on the Moon, Mars, and the surface of Europa is primarily water ice.

 

[russ_watters]

While I understand space is cold, less than 10 Kelvin cold, what always seems to be left out is heat transfer. Conduction and convection require physical contact to transfer heat, which doesn't apply in space.

That just leaves radiation.

There are more, but they are mixtures of different mechanisms. The most important for water in space is evaporative phase transition/mass transfer. The water that boils/evaporates away carries heat with it and that drops the temperature of the water that is left. It's most commonly associated with convection, where instead of the fluid being external (air against a window, for example), the water provides the heat transfer fluid.
https://en.wikipedia.org/wiki/Heat_transfer#Phase_transition
This also discussed in the video.

 

[russ_watters]

I would expect zero gravity to also have an effect. In zero g, bubbles don't rise to the surface and separate. So a boiling dollop of liquid may disperse into vapor which greatly increases the surface area.

Consider what might happen if you try to constrain that water in some sort of tough, flexible bag...

 

[JT Smith]

It will evaporate and freeze - both at the same time.

And then what? In "space" will it ever gain enough energy to sublimate or will it remain frozen?

 

[.Scott]

If exposed to sunlight as close as Mars, it will sublimate.
On Mars, the atmospheric water vapor pressure is about 0.18Pa (0.03% of the total atmospheric pressure of 610Pa). Wiki: Water Vapor pressure

According to this site: H2O Vapor Pressure Calculator
That corresponds to about -75C. So, if you can keep you water below that temperature on Mars, it will be safe from being lost to sublimation.

 

[jbriggs444]

And then what? In "space" will it ever gain enough energy to sublimate or will it remain frozen?

In deep space, far from any stars, it is still exposed to the cosmic microwave background radiation at about four degrees Kelvin. That is enough to ensure complete sublimation.

 

[Heikki Tuuri]

https://en.m.wikipedia.org/wiki/Armstrong_limit
https://en.m.wikipedia.org/wiki/Vapour_pressure_of_water

The pressure of blood in a human is 14 kPa or more. Your blood in the major vessels will not boil at 37 C, because the water vapor pressure is only 6 kPa.

Water in less pressurized parts of the body will boil.

When the body has cooled down to 0 C, the vapor pressure is only 0.6 kPa. I guess human tissues will be able to keep at least that pressure, and the boiling will stop.

I recall reading somewhere that there will be no visible injuries because of the boiling. A human in zero pressure will die of the lack of oxygen in a few minutes. The Mars movie Mission to Mars was not realistic about removing the pressurized spacesuit helmet. The movie got negative reviews from critics (not because of bad physics, but because the plot was very shallow).

 

[Heikki Tuuri]

https://space.stackexchange.com/que...ctual-ice-on-the-moon-why-hasnt-it-sublimated

According to the discussion in the link, the ice sublimation rate per 1 billion years is negligible if the temperature is 100 kelvins. The rings of Saturn are at 100 kelvins. Sublimation will not destroy them until the Sun turns into a red giant.

The ice in the astronaut is enclosed into tissues which can hold some water vapor pressure. The sublimation process at the distance of Earth will take very long, at least thousands of years.

 

[OmCheeto]

https://space.stackexchange.com/que...ctual-ice-on-the-moon-why-hasnt-it-sublimated

According to the discussion in the link, the ice sublimation rate per 1 billion years is negligible if the temperature is 100 kelvins.

Yay!

"The extremely low sublimation rate of an exposed block of water ice at ~100 kelvins would result in that ice thinning by a millimeter per billion years."​

​

According to my interpolations, ice thinning @ 100 Kelvin is 0.6 mm per billion years.

The rings of Saturn are at 100 kelvins. Sublimation will not destroy them until the Sun turns into a red giant.

According to the ESA, the rings range in temperature is 40 °C.
The upper temperature is interesting.

The ice in the astronaut is enclosed into tissues which can hold some water vapor pressure. The sublimation process at the distance of Earth will take very long, at least thousands of years.

I will take your word for it.

ps. I found this comment interesting; "...the evaporation ceases to be limited by pressure and depends only on temperature. This happens at about 1 Pa...". [ref]