Blowing Bubbles in Space: Can You Create a Giant Bubble in the Vacuum of Space?

[mollwollfumble]

TL;DR Summary

How big a soap bubble, polymer bubble, or glass bubble could you blow in the vacuum of space? Rate of evaporation in vacuum. ISS.

This is an experiment I would have liked to do from the ISS, but an approximation could be done in a vacuum chamber on Earth. How big a soap bubble, polymer bubble, or glass bubble could you blow in the vacuum of space? How to calculate the evaporation rate in vacuum?

A liquid exposed to vacuum will boil then freeze. Delay boiling by using a cold liquid and delay freezing by inflating with a hot gas. This is a question of relative timescales, the timescale for inflating the bubble vs the timescale for evaporation. Can the timescale for inflation be shorter than the timescale for evaporation? Consider separately the following cases.

• Blowing a soap bubble
• Blowing a soap bubble containing a monomer that polymerizes by evaporation of water.
• Blowing a bubble in a thermoplastic such as PET.
• Blowing a bubble in glass, starting with really hot glass because there's no gravity in orbit to cause it to sag.

A typical PET bottle wall thickness is 250 μm. A typical soap bubble wall thickness is 1.2 μm. A typical soap bubble inflation speed is 7 cm/s. A typical soap bubble wand has a perimeter of 1.5 inches. From “How to make a giant bubble” in Phys. Rev. Fluids 5, 013304.

 

[anuttarasammyak]

I guess even tiny amount of gas inflate bubble without limit so we can make no bubbles.

 

[sophiecentaur]

If the pressure inside the bubble were the same as the local (outside) ambient pressure but the other conditions were kept the same, you could inflate the bubble to 10^-12Bar approx) and, if the liquid for the bubble was chosen to be a suitable HiVac oil, then I guess it would be a stable bubble.
A bubble machine would need a powerful fan - large and fast enough to actually move a significant some of those few molecules in 'space' and transfer some of their momentum to the film of oil and make it form a bubble. Probably not the best way when you think of the surface tension on a film of oil.
Alternatively, a tiny hole and a valve could admit a few air molecules into a drop of oil on the tip of a hypodermic needle. Perhaps foam has been observed around small leaks in the hull of spacecraft . HAHA - like finding a puncture in a bike tyre. Imagine an Astronaut crawling over the surface with a squeegee with oil in it and looking for bubbles.

 

[etotheipi]

I guess even tiny amount of gas inflate bubble without limit so we can make no bubbles.

I don't know much about the specifics, but won't the tension in the bubble material eventually balance the in internal pressure, so long as this pressure is not large enough so that "breaking stress" of the bubble material is exceeded?

 

[sophiecentaur]

so long as this pressure is not large enough

10^-12 Bar would be a bit difficult to measure out in practice. I imagine that the outgassing of the surface of a spacecraft would exceed that so the local 'vacuum' around a spacecraft would be higher than the pressure 10km away from it.
In practical terms, the problem would most likely be in finding a liquid with a low enough vapour pressure to allow a bubble to live any significant time. I guess astronauts have better things to do with they time than closely examining the outer skin of the craft to find some actual bubbles / foam. Things could be different if there were an actual use for such bubbles.

 

[DrStupid]

Things could be different if there were an actual use for such bubbles.

How about spray foam for constructions in space or on the Moon? That could be worth to be discussed.

etotheipi already pointed the basic problem: the components need to have a very low vapour pressure (in order to be balanced by the surface tension). Are there liquids with suitable properties and if yes could they be used for a spray foam (e.g. as solvent or even reactant for a polymerization)?

 

[sophiecentaur]

Are there liquids with suitable properties

High vacuum equipment uses some pretty suitable greases and oils. You could perhaps have to accept that the bubble would not last long.

 

[DrStupid]

You could perhaps have to accept that the bubble would not last long.

That doesn't need to be a problem. If the mechanical properties of the foam doesn't matter (e.g. if it is used for heat insulation) it just needs to remain intact until it gets solid (due to polymerisation or because it freezes). Than it may crack and release the gas. In this case it wouldn't even be necessary to reach a short-term equilibrium. It would be sufficient to slow down the expansion. That requires a high viscosity. Maybe a polymer at a temperature between melting point and glass-transition could do this job.

 

[anuttarasammyak]

I saw in some Sci-Fi movies astronauts repair their space suits breach applying gel-type chemicals outside. It should work under 300K temperature and 1 atm pressure difference between outside and inside. Similar factors with this thread should be considered for it.

 

[sophiecentaur]

gel-type chemicals outside.

This is less demanding that you would think. You can deal with a leak in a plumbing system with several Bar of internal pressure but wrapping tape round the leak and this can harden up to be as good as new. Thing about vacua is that it can never be more than 1Bar below the pressure at sea level!