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Water's odd behavior in weightlessness comes under scrutiny in a new European Space Agency video, which shows an astronaut spinning small jars of liquid for science.

Astronaut Thomas Pesquet recorded the video in the International Space Station's Kibo laboratory as part of a "voluntary science" experiment that astronauts do outside of normal working hours. The French astronaut spins in circles with first one, then two jars; close-ups show the water slowly sloshing inside, and bubbles forming.

"Here I recorded some video of water in these tanks as it moves about inside; the technical term is sloshing," Pesquet said in a statement accompanying the video. [Fun in Zero-G: Weightless Photos from Earth and Space]

"How fluids behave is hard to model in computers and predict ... but we need this information to build better spacecraft tanks to use every last drop and increase their working life," he added.

The experiment, called SPHERES-Slosh, was previously performed on the space station using volleyball-size autonomous robots that can fly in formation. Pesquet did the experiment again after the researchers saw some "surprising results," European Space Agency officials said in the statement, although they did not specify what those results were.

Pesquet, a member of the Expedition 51 crew, has been on board the International Space Station since November. He has performed one spacewalk, and regularly posts updates on his spaceflight on his Twitter account.

Follow Elizabeth Howell @howellspace, or Space.com @Spacedotcom. We're also on Facebookand Google+.Original article on Space.com.