Household appliance in space.

Astronauts may someday microwave more than just the tasty rations NASA provides-they may cook their fuel as well. A prototype space thruster now undergoing tests uses scavenged parts from a conventional microwave oven to burn fuel more efficiently.

"We've been using the magnetrons, the tubes the microwaves come from, out of conventional microwave ovens," says engineering professor Michael M. Micci of Pennsylvania State University in State College. "They're inexpensive." Micci and his students bombard a gaseous fuel in their prototype's combustion cham- ber with microwaves to create a superheated cloud called a plasma. The plasma ignites incoming fuel, which then shoots out of an ordinary rocket nozzle. Burning the fuel at a higher temperature increases combustion efficiency, says Micci. This thruster design could reduce by 50 percent the amount of propel- lant needed to keep satellites from drifting.

As spacecraft generate more electric power, propulsion devices like the micro- wave thruster are gaining popularity. Micci claims his microwave thruster exceeds other electric devices in lifetime and efficiency.

"The concept has merit," says James Sovey, an aerospace engineer at NASA's Lewis Research Center in Cleveland. The real problem with developing a new thruster today is not technology, he adds, but funding.