Imagine you're sitting in a pub with a pint
of real ale. Gravity keeps the beer in the glass
and the bubbles rise through it. Now imagine
that you have a globule of beer floating in a
spacecraft in zero gravity. What happens to the
bubbles? What direction do they move in--if
they move at all? Are they the same size as on
Earth? Would the beer have a frothy head?
Are there likely to be any other unusual
In microgravity (zero gravity), surface tension tends to be
the driving force behind fluid behaviour. Once
released from whatever container it was in, your
blob of beer would just float there. However, if
you opened a can of beer in orbit, you'd create a nifty little beer cannon that cover the wall with
several globs of beer.
Bubbles would still form in your beer globule,
because the carbon dioxide would still come out
of solution under room temperature and pressure,
but they wouldn't move in any direction. Not
only that, but the larger bubbles (and head) in
Earth beer form because the bubbles float to the
top of the glass and bump into each other on the
way. Space beer would have a number of bubbles
throughout, so you'd just get a foamy mass.
Bubbles are likely to be fewer and larger in
microgravity because as they form, they remain
at the nucleation sites instead of drifting
However, their growth may be slower because it
would depend more on diffusion through the
liquid and less on circulation. On Earth, the
behaviour of beer depends largely on gravity. In
free fall, surface tension, momentum, vapor
pressure and diffusion dominate, so small bubbles
are less likely to meet and fuse, but big bubbles
are less likely to reach the surface and burst.
Forces hardly noticeable on Earth have weird
effects in microgravity and complicate working in
space. Localised drying and the lack of
convection cause differences in viscosity, vapour
pressure and surface tension, which make fluids
creep, drift and distort unexpectedly.
Astronauts aren't allowed to drink carbonated
drinks in orbit, because the body relies on gravity
to burp excess gas. No beer is one of the many
sacrifices one must make for space exploration.
Source: Edited from the responses of Todd Dark-Fox and Jon Richfeild in the NewScientist.