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Looking at Density Differently in Microgravity
We learn in elementary school about the three phases of matter -- solids, liquids, gases -- and how they behave. These forms of matter, particularly liquids and gases, have a tendency to act differently in the microgravity environment of the International Space Station, regardless of their density, or mass.

The Binary Colloidal Alloy Test-6 - Phase Separation, or BCAT-6, investigation looks at how liquids and gases separate and come together in microgravity. This helps researchers to understand the fundamental questions about what happens when gases and liquids separate from each other, along with resulting patterns in the way solids are suspended in liquids. The results of this physics investigation may be used in the creation of better formulas and stabilizers to extend shelf life for products, foods, and medicines; and advances in propellant research for future rocket engines.

In an interview, Peter Lu, co-investigator for the BCAT-6, said, "The nice thing about going to microgravity is that those density differences don’t matter...you have the liquids and gasses separating from each other, but one doesn't always float to the top over the other and we can actually look at the structure of that process."

During the interview, Lu discussed previous investigations of this nature, why the station is a great place for this type of research, and what types of results researchers are looking for exactly. Learn more about BCAT-6 in the feature “It's All in the Mix With Fluid Physics in Space.”

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Lori Keith
Public Affairs Office
NASA's Johnson Space Center