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Released July 16, 2003

INTERNATIONAL SPACE STATION TO TEST
Southern Miss CHEMISTRY PROFESSOR'S 'SWEET SCIENCE'

HATTIESBURG - With his upcoming experiment aboard the International Space Station, chemistry professor Dr. John Pojman of The University of Southern Mississippi is proving the old adage about necessity being the mother of invention.

After the recent Columbia Space Shuttle disaster left NASA without a means of bringing up new experiments to the Space Station, the agency decided to continue its research by using items already on board.

"It has been an orbital scavenger hunt," said Pojman, who has worked extensively with NASA during the last 10 years, studying polymer processing and how miscible fluids interact in weightlessness.

"We finally decided on Russian honey, which the astronauts use with their tea, and water as our two fluids."

The Miscible Fluid in Microgravity (MFMG) experiment will test how miscible fluids - those that completely dissolver in each other - interact without the interference of gravity. The test, which will be performed this September by astronauts using unused urine collection syringes and Zip-lock bags, can only be performed 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. "The results of the experiment could help us develop improved understanding of processes ranging from the dissolving of plastics to protein crystal growth."

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. Pojman said his test will determine if the same breakup occurs with two miscible fluids by injecting honey into water and observing if the honey stream breaks into drops.

"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.

A veteran of more than 800 microgravity parabolas aboard NASA's KC-135 research aircraft, also known as the "Vomit Comet," Pojman has traveled to NASA's Marshall Space Flight Center several times to develop the actual crew procedures for the test. The NASA operations team documented each step of the procedure and has prepared a file with digital pictures to upload to the Space Station.

Several students and visitors have also worked on the project, including graduate students Brian Zoltowski and William Ainsworth, postdoctoral researcher Dr. Victor Wyatt, and two visitors, Boon Teo of Singapore and Birsen Varisli of Bolivia.

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April 20, 2004 4:09 PM

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