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Released January 14, 2004


HATTIESBURG -- Astronaut Dr. Michael Foale will begin testing an experiment developed by Dr. John A. Pojman, a professor in the Department of Chemistry and Biochemistry, aboard the international space station on Jan. 20.

The Miscible Fluid in Microgravity (MFMG) experiment will test how miscible fluids - those that completely dissolve in each other - interact without the interference of gravity. The test, conducted with unused urine collection syringes and Zip-lock bags, can be performed only in weightlessness. However, it does have some down-to-earth implications, Pojman said.

"The models used to simulate the experiment provide information on the fundamental interactions between molecules," he said.

Immiscible fluids, like oil and water, exhibit something called "interfacial tension" because of the different ways that each type of molecule pulls on each other. "This interfacial (surface) tension is what allows a water skeeter to walk on water," Pojman explained. The experiment, accepted by NASA in April, will test a time-worn but unsupported theory. "One hundred years ago, a scientist named Korteweg predicted that miscible fluids could act like immiscible fluids until they had diffused and become uniform," Pojman said.

"Although there has been much theory and some provocative experiments during the intervening century, no definitive experiments have been performed. This simple experiment will be a step toward a complete test of Korteweg's hypothesis."

If a stream of one immiscible fluid is injected into another in weightlessness, the stream will break into drops - a phenomenon called the Rayleigh-Tomotika instability. By injecting honey into water and observing if the honey stream breaks into drops, Foale will test to see if the same breakup occurs with two miscible fluids, Pojman said.

"Because the honey is denser than water," he said, "the stream sinks in the water when we try to do the experiment on earth."

Pojman added, "A drop of immiscible fluid in another fluid will always become spherical in weightlessness. We will test if an irregular drop of water injected into honey does the same. To prevent the drop from floating to the top of the honey, the experiment must be performed in weightlessness."

Both experiments will also be performed while heating the fluids to test if miscible fluids migrate - something that is seen with immiscible drops and streams.

Pojman is a veteran of more than 800 flights aboard NASA's KC-135 research aircraft, also known as the "Vomit Comet." He has also traveled to NASA's Marshall Space Flight Center several times to develop the actual crew procedures for the test.

On Dec. 29, Russian cosmonaut Alexander Kaleri heated a can of Russian honey to make sure it would not be crystallized when Foale begins performing the experiment on Jan. 20. On that day, Professor Pojman will be present at the NASA MSFC control room to discuss the experiment with Foale, who will then perform the heating experiments over the next four days. "This is tremendously exciting," Pojman said. "My students, collaborators and I have been working on this research since 1998, and we are eager to see how our fluids will behave."

Pojman will be in Lyon, France until Jan. 18 working with Dr. Vitaly Volpert and Dr. Nick Bessonov, of the Université Lyon I, who have performed the computer simulations for the MFMG experiment. Pojman is also an invited speaker at a workshop on diffuse interfaces during his visit. He just returned from a conference in Reno, Nev., where he also talked about his work.

The other set of experiments have yet to be scheduled.


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April 20, 2004 4:09 PM