If you shake a plastic bag filled with water, a few tiny air bubbles will race to the top in seconds. However, if you launch that same bag into space, those bubbles will look and act a lot different.
A recent video from Canadian Space Agency (CSA) astronaut David Saint-Jacques shows different-size air bubbles gurgling their way around a bag of what appears to be a gel-like substance but is actually water.
The reason water takes on this unfamiliar form has to do with gravity, or rather, the lack thereof. On Earth, air is lighter than water, and its added buoyancy compared to water makes it float upward and quickly burst through water droplets. In space, however, air bubbles linger in the liquid rather than floating to the top, because gravity isn't pulling the liquid down.
"Scientists are trying to better understand the behavior of bubbles in microgravity," Perry Green, senior program scientist at CSA, told Space.com.
On Earth, the buoyancy of the air bubbles causes them to rise to the top together, creating a segregation between air and water. However, in microgravity, nothing forces the air bubbles to interact and thus rise together, Green said.
Previous research has looked at boiling water in space, examining how those bubbles formed in different sizes than bubbles in boiling water on Earth. In space, one large air bubble forms in the boiling water and traps heat energy inside.
"You don't have a lot of precise answers [for the effects of microgravity on liquids,]" Green said. "In microgravity, it's difficult to predict."
However, if better understood, bubbles' behavior in space could help engineers build more-efficient cooling systems for space exploration.
Saint-Jacques has been at the International Space Station for 183 days now, conducting different experiments. He has previously demonstrated the effects of microgravity on honey, showing that it pours out of a jar and turns into an elastic-like substance.
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