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As warm as the word vapor may sound it is actually really cold. Europa's oceans, if they exist, are -50°C and lower.
by deletes 13y ago
As warm as the word vapor may sound it is actually really cold. Europa's oceans, if they exist, are -50°C and lower.
- trekky1700 13y agoDoesn't water freeze and become ice at 0°C?
- Fargren 13y agoOnly at one atmoshpere of pressure.
- trekky1700 13y agoThe difference is negligible: http://i.stack.imgur.com/n6LXj.gif http://i.stack.imgur.com/n6LXj.gif
- Fargren 13y agoAccording to this[1] the pressure on Europa is "one hundred billionth that of the Earth". Your graph uses a log scale, so maybe I'm measuring this wrong, but I'm pretty sure under so little pressure, water can be vapor at -50ºC. So the pressure is hardly negligible in this case. [1]http://hubblesite.org/newscenter/archive/releases/1995/12/text/ http://hubblesite.org/newscenter/archive/releases/1995/12/te...
- deletes 13y agoYou can make supercooled water in your freezer. http://en.wikipedia.org/wiki/Supercooling http://en.wikipedia.org/wiki/Supercooling
- ceejayoz 13y ago> The process of supercooling requires that water be pure and free of nucleation sites Good luck finding distilled water with no contact with rocks/ice on Europa...
- trekky1700 13y agoThat requires very difficult circumstances that almost certainly can't occur at the planetary scale.
- mturmon 13y agoHmm. I did not think that the temperature of Europa's oceans (below their probable icy crust) has been well-constrained. To the extent that it has, I think the subsurface temperature is expected to be much greater than -50C in many places (the mechanism is tidal heating). There is a general belief that Europa is likely to have significant liquid water below its icy surface. The phase diagram for water (first image at http://www1.lsbu.ac.uk/water/phase.html http://www1.lsbu.ac.uk/water/phase.html) does not allow liquid water at -50C = 223K, no matter what the pressure. Atmospheric pressure on Earth is about 0.1 MPa, and gravity on Europa is about 1/6 of Earth. The highest pressure in Earth's oceans is about 1000x atmospheric pressure (100 MPa). Across this range (3 orders of magnitude), the melting point of H2O is pretty constant, 0C or a little below (see the linked phase diagram). My conclusion: liquid water implies temperatures of at least 0C in the relevant pressure range.
- deletes 13y agoNot really. https://www.youtube.com/watch?v=Fot3m7kyLn4 https://www.youtube.com/watch?v=Fot3m7kyLn4 Also. http://en.wikipedia.org/wiki/Supercooling http://en.wikipedia.org/wiki/Supercooling
- yongjik 13y agoFrom your link: A liquid below its standard freezing point will crystallize in the presence of a seed crystal or nucleus around which a crystal structure can form creating a solid. Europa's ocean is surrounded by a vast sheet of actual ice. You can't keep such an ocean at supercooled state.
- deleted 13y ago[deleted]
- Thrymr 13y agoIt's not likely that an entire large planetary body will maintain a state out of equilibrium for geological periods of time. Supercooling is unstable.
- trekky1700 13y agoUpon further research, where are you getting this number from? http://www.lpi.usra.edu/meetings/lpsc2002/pdf/1824.pdf http://www.lpi.usra.edu/meetings/lpsc2002/pdf/1824.pdf
- mturmon 13y agoThanks for turning up some real info. The paper you found is speculative, but the options they consider all have a temperature range within a few degrees of zero C. They entertain some scenarios whereby stratification could allow the deep temperature to get as high as ~4C without breaching the icy surface.