April 15, 2003click on either of these
images to view the complete 4 Mb Quicktime movie
Blowing Bubbles
Credit: Don Pettit, ISS Expedition
6 Science Officer, NASA
Explanation: Not long ago International Space Station
science officer Don
Pettit discovered the amazing properties of watery
thin films in space: They’re remarkably tough. You can shake
them, spin them, even paint on them.
Now he’s learned how to blow
them up, too.
It’s done using Alka SeltzerTM.
Don describes the procedure: "Here we have a liquid film
made of very little water stretched across a wire loop. We simply
drop an effervescent tablet into the middle. You can see that
the volume expansion is quite significant as chemicals
in the tablet (baking soda and citric acid) dissolve in water
and then react
to form carbon dioxide gas. The resultant bubbles inflate the
film."
"The fate of bubbles in
a liquid is an important topic for operations in low gravity.
Whether you’re designing a
science experiment or a piece of engineering equipment that
is supposed to work in this environment, it’s really important
to understand what happens to gas in liquid and vice versa. I’m
hoping this demonstration will give [designers] some ideas about
what might happen to their systems up here and maybe inspire
some new experiments."
The full-length
video of his demonstration shows how tiny bubbles swirl (hypnotically)
in a stirred film, how small bubbles combine to form bigger and
bigger pockets of gas, and how unwanted bubbles can be removed
from gas-contaminated fluids using a syringe.
"These thin films really
are a wonderful tool for experimentation." So what’s next? "The best is still
ahead," he says. Stay tuned….
Editor’s note: Don Pettit has done similar experiments
involving effervescent tablets and spheres of water (rather than
films of water). See the entire series: Reel
1 (2Mb); Reel 2 (4Mb);
Reel 3 (2Mb); Reel
4 (4Mb) | 
