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.

If you had the choice between a product that you had to shake before use and one that came premixed, you'd probably buy the one that was easier to use and worked best. Industries are aware of this, and of the benefits of products with a reputation of functioning as promised, use after use.

In an effort to secure even better product formulas, Procter and Gamble Co., or P and G, decided to take their research to a higher level - aboard the orbiting laboratory of the International Space Station.

Working with NASA, P and G funded an investigation of how gas and liquid phases separate and come together in microgravity. The Binary Colloidal Alloy Test-6: Phase Separation, or BCAT-6-Phase Separation, study specifically looks at colloids, which are like tiny spheres evenly dispersed in a fluid, gas or solid to help stabilize the mixture. Over time, these colloids can move around - known as coarsening - causing changes in the concentrations and properties of the substance.

On Earth, gravity complicates this research by causing heavy components to sink and lighter ones to float. In space, however, these forces are minute, revealing the natural movement of the colloids. The on-orbit samples' aging process works more slowly and evenly, making it easier to study.

Principal Scientist Matthew Lynch, Ph.D., of P and G, explained the benefit of removing gravity from the equation when looking at colloid dispersions in fluids. "What we want to do is decouple that gravitational piece from the fundamental underpinnings of this motion of coarsening so that we can superimpose it later and understand the problem holistically," said Lynch.

To conduct these experiments, astronauts set up the hardware for the study and homogenize - blend - the samples. They then take a series of time-interval pictures as a sample ages over a period of weeks. Changes in the samples are analyzed to reveal the coarsening. The samples are stored for a period of six months on the station, before the crew retrieves them for more imaging and return to Earth.

This investigation builds on previous BCAT studies that contributed to the collective knowledge of fluid physics in microgravity. "What [the investigation] really helps us do is create theories that help define a lot of the physics in our products," said Lynch. "This helps us to make some decisions, both in terms of creating appropriate experiments and compositions, as well as intellectual property related to some of those findings."

According to Lynch, about two thirds of P and G's biggest brands are soft-matter systems - things like fabric softener, deodorant and detergent, to name a few - that could benefit from this study.

Armed with a better understanding of the nature of the fluids separation, researchers can work on creating better stabilizers and product formulations. Stabilizers are expensive and take up space in products, so improved formulas can contribute to reduced costs that lead to less expensive products. Greater stabilization can also increase shelf life.

Applying the fundamentals of fluid physics to formulas can translate into profit across the industry. In products such as fabric softeners, forgetting to shake can lead to product failure and annoyed consumers.

"If you go out to the store and buy something that's settled or something that's creamed on top, you pour it off out of the bottle and you're not going to want to buy it again. So we spend a lot of time trying to make products that stay well dispersed. It's a very big cost of time and money to try and to design products this way," commented Lynch.

The potential for BCAT research application in other areas is something that continues to grow. For instance, advanced colloidal formulas could also conceivably lead to improvements in items like liquid pharmaceuticals, which can be ineffective or even dangerous if not properly mixed when consumed. With better formulations, consumers could look forward to the certainly of a perfect product every time.

"I think the challenge is between how to connect up with the right people in the industry that will understand how to translate that high potential into practical sorts of things. So much of the success of station research is in being able to make those connections work well," said Lynch.