April 7, 2003click on either of these
images to view the complete 1.4 Mb Quicktime movie
High Tea
Credit: Don Pettit, ISS Expedition
6 Science Officer, NASA
Explanation: It’s a competition: surface tension
vs. gravity. Surface
tension holds droplets of water together. Gravity pulls them
apart. On Earth, gravity usually wins. Only small droplets have
enough surface tension per unit mass to remain intact. Onboard
the International Space Station (ISS), however, surface
tension rules. Weightless water can form big
floating drops, large enough to quench your thirst and tough
enough to handle using chopsticks.
ISS science officer Don Pettit
paused for afternoon tea–above–and showed us how it’s done:
"It’s easy," says Pettit. "You just take your
chopsticks, pick up a blob of tea, and pop it in your mouth.
This is a practical demonstration of all the surface chemistry
we learned about in college."
Because fluid droplets onboard
the space station are undisturbed by their own weight, they make
marvelous research tools for investigations in basic
fluid physics. The applications are many: Firefighters are
interested because water mists can be used to extinguish
flames. Weather forecasters are interested because rain clouds
are made of water droplets. Automakers are interested because
internal combustion engines burn tiny drops of fuel. And so on….
Plus, they’re fun–and the entertainment
value shouldn’t be underestimated. One day, perhaps, luxury space
hotels will offer their guests afternoon tea 300 miles above
Earth . No cups or plates. Just chopsticks and droplets. Now
that’s high
tea!
Editor’s note: Don Pettit has filmed a series of afternoon
tea demonstrations. The movies show how honey, peanut butter
and tea behave in low gravity, and how astronauts clean up after
snack time: Reel
1 (4.9 Mb), Reel
2 (1.4 Mb), Reel
3 (2.5 Mb), Reel
4 (2.6 Mb). |
