Tea - Mystery in a Cup of Tea

How different is teatime in orbit? Astronaut Don Pettit showed us in 2003 when he filmed himself taking tea onboard the International Space Station (ISS). Instead of sipping from a cup, Pettit used chopsticks to pluck grape-sized blobs of tea from mid-air, grinning each time he popped one in his mouth. Pojman remembers seeing the film. "I wanted to fly right up there and start experimenting," he says.

Understanding how fluids behave, singly or in mixtures, is important to the space program, especially now that NASA plans to send people back to the Moon and on to Mars.

"We're going to have to manufacture things in space," explains Pojman, "and that means dealing with fluids." As an example, he offers plastics - a key component of habitats, radiation shields, rovers, etc. Plastics are usually formed by combining dissimilar fluids or fluids and powders, then heating the mixture. "If you've ever used Bondo^TM to repair your car, you've done this yourself: you mix a resin together with peroxide to create a sticky plastic substance," adds Pojman.

Mixing is also necessary for certain types of medical space-research - "especially protein crystal growth in microgravity," notes Pojman. When two fluids are put together, do "Korteweg currents" flow? Do the fluids dissolve evenly? Do they break apart into droplets? These details actually make a difference.

Pojman himself couldn't go to the ISS to investigate such questions, so he devised an experiment that astronauts could do for him: the Miscible Fluids in Microgravity Experiment or MFMG for short. "MFMG is a very simple experiment," he says. "It involves two syringes, a drinking straw, honey and water. All of these things were already onboard the ISS."

One syringe is filled with honey or a honey-water solution, the other with pure water. The tips of the syringes are connected via a short tube (the straw). When all is ready, an astronaut gently squirts a blob of honey into the water, or vice versa, and films what happens. ISS science officer Mike Foale did the experiment last week, and transmitted the video to Earth.

"We've already learned something new," says Pojman.