International Space Station Crew 27

Crew 27 will be on the International Space Station March 2011-September 2011

The Expedition 27 crew members, from right, are Commander Dmitry Kondratyev and Flight Engineers Andrey Borisenko, Catherine Coleman, Alexander Samokutyaev, Paolo Nespoli and Ron Garan. Photo credit: NASA

So what are they doing up there? Here's one thing they're researching:

The Marangoni Effect:

A Fluid Phenom03.10.11 Video still of
Marangoni experiment. (JAXA)

Ever heard someone say their wine has "legs" or "tears of wine?"

 Wine legs or tears of wine is a phenomenon manifested as a ring of clear liquid that forms near the top of a glass above the surface of wine. The drops continuously form and fall in rivulets back into the liquid. One factor in the way fluid moves is called Marangoni convection, or flow, and Japan Aerospace Exploration Agency researchers are very interested in studying it in a gravity-free environment.

You can see the wine legs
in the shadow

Marangoni convection is the tendency for heat and mass to travel to areas of higher surface tension within a liquid. Surface tension is a property of a liquid that causes the surface portion of liquid to be attracted to another surface, such as a drop of mercury that forms a cohesive ball in a thermometer or droplets of water on a well-waxed car. This phenomenon is named after Italian physicist Carlo Marangoni who first studied the phenomenon in the 19th century.

"We are clarifying an unknown phenomenon and that’s very exciting," said Satoshi Matsumoto, a Marangoni science coordinator from the Japan Aerospace Exploration Agency. "Marangoni negatively affects the quality of crystal growth such as semiconductors, optical materials or bio technology materials. The convection also occurs in a heat pipe for heat radiation devices in personal computers, and degrades the radiation performance. Therefore, increased understanding of Marangoni convection not only expands our knowledge of fluid behavior, but also has great significance for production of semiconductor materials and equipment development for both space and ground use."

JAXA has been promoting four Marangoni experiments to fully understand a surface-tension-driven flow in microgravity. It will complete in 2015.

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