Water doesn’t compress. It would just freeze assuming it wasn’t already.

The loss of pressure would initially cause the water to boil. As the water boils to vapor, it cools the remaining water. Eventually the water would be cooled to the point it would freeze. After that the ice would sublimate to vapor.

I thought everything can be compressed.

What if the breach was on the side not facing the sun? Would it still sublimate due to the pressure difference, or would it remain as a solid until exposed to light?

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Liquids are broadly referred to as incompressible because density changes from temperature and pressure are minimal.

Sublimation of ice cools the ice left behind. Eventually the remaining ice will reach the temperature point in the ice/water/vapor pressure vs. temperature phase diagram at which ice is the equilibrium state. Below that temperature (somewhere below -100°C.) sublimation effectively stops.

This is why moons of the outer planets can have long-lived ice crusts exposed directly to the hard vacuum of space.

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The process was used in the Apollo missions to cool the LM and the EVA suits. Water ran through a porous metal block exposed to the vacuum. Water first sublimated, then an ice crust. Turning water into vapor needs a lot of energy, thus the method is very effective.

The method is still used with EVA suits.

I think the discussion is about decompression, not compression. In the vacuum of space, water would decompress, freeze, and eventually sublimate into vapor.

Explain how you decompress something that wasn’t compressed to begin with.

You're being compressed right now. Atmospheric pressure applies 1 bar (~14.7 pounds per square inch - PSI) on your body externally at sea-level. That means you are currently being compressed with 41,160 pounds of force given an average of 2,800 square inches of skin surface. In a vacuum, that compression is released to nearly zero. You would be quite effectively decompressed.

Just because pressure is applied to something doesn’t mean it compresses. Water does not compress.

Take a science class on the state of fluids, gasses, and solids, it will answer your questions. I'm not here to tutor.

This process occurs because of the vacuum of space, not as the result of energy absorbed from the sun. The heat we feel from the Sun here on the Earth's surface is the result of the energy from the sunlight being absorbed and retained by the atmosphere. In space, the only energy you "see" is what strikes you in a "line-of-sight" sense. The amount of energy involved in this situation would be very small and would have a relatively small impact on the evaporation and sublimation processes.

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At very low pressures water is only stable as a gas or solid. Initially water will boil off rapidly, causing the temperature to drop, and eventually causing parts to freeze. If the ice is able to block the breach (breach is small compared to volume, and an ice dam is able to form), then the water boiling will cause the pressure to rise until liquid water is again stable, or the ice dam blows out and we're back at the start.

You should be able to get a fairly wide range of equilibrium states depending on initial conditions.