[thedoc (OP)]

Rory asked the Naked Scientists:
   I wonder if you can help with something. As a PR stunt for a commercial we are doing, we would like to send an ice bucket of water with a bottle of spirits into the atmosphere in order to chill the spirits and turn the water to ice. We would then need to bring it back to earth.

From online research I have done, it appears possible to get an object up and down using a weather balloon, but what are your thoughts on turning water to ice using the atmosphere (are there physics problems to consider) and what sort of height would be necessary?

Any feedback, advice or suggestions would be much appreciated.
Thanks
rory
What do you think?

[A.Carter]

I don't see any glaring problems. All you'll have to worry about is the temperature in the layer of atmosphere you are shooting for. By the time the pressure is low enough to cause your ice to sublimate, the temperature will surely be low enough to prevent it. Also you'd have to be rather close to space before the pressure becomes a problem anyway. I don't know how to insert graphics, so I will direct you to the wikipedia page for phase diagrams, which has a very nice one for water. 

[evan_au]

At the altitude of commercial jets (around 10km), the temperature is a chilly -40C to -60C.

Even at these temperatures, it can take water a while to freeze. I suggest putting it in something thin (so it can cool down quickly) with a large surface area, like ice-cube freezer bags.

Weather balloons can reach these altitudes - so it would be good to talk to meteorologists who regularly launch weather balloons to see what regulations and processes apply. The last thing you want is to christen a jetliner traveling at Mach 0.85 with your bottle of spirits! This may exceed the budget for your stunt.

You also have the difficulty of getting your ice and spirits down again. Presumably a parachute would help, along with some padding on the bottle.

...and then, after it lands, you have to reach it before the ice melts again!

Redundancy is an important principle in aeronautics. Have an insulated box with some ice cubes and a spare bottle ready on the ground. Some footage of the balloon going up, the parachute coming down, delete the part where you clear away the broken glass, and cut to pouring your triumphant glass....   

[William McC]

I would put ionized boiling water into a thin wall spherical shaped tank, so the tank was 1/4 filled with water, and seal it while water is hot and the tank purged of air. The next day after it cools down send it up. This way only water vapor and almost no air is present. When the sphere reaches the cold air, the water vapor will liquify reducing pressure in the vessel, causing a vacuum to form, and boil and freeze the rest of the water rather quickly.

You can boil and freeze water like this using a pump.

Sincerely,

William McCormick