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Researchers in the School of Aerospace Engineering have developed a more fuel-efficient satellite engine that could allow unmanned missions to travel deeper into space at a much lower cost.
The research team, funded by an Air Force grant, made modifications to a satellite engine donated by aircraft engine manufacturer Pratt & Whitney to create the new engine.
"Traditionally, after a satellite separates from the launch vehicle, a chemical rocket engine running at maximum power pushed the satellite into orbit," said assistant professor Mitchell Walker. "Our engine uses ion propulsion — a technology that involves ionizing a gas, in this case xenon. Xenon atoms are injected into a discharge chamber and electrically charged, stripping the atom of electrons and forming light electrons and heavy ions. When the ions are exhausted from the spacecraft, they push it in the opposite direction at speeds much faster than chemical propulsion."
Although capable of pushing the satellite to very high speed, the exhaust velocity is controlled from the ground by adjusting the engine's power output. At separation from the launch vehicle — when the need for maximum acceleration is highest — the engine operates like an automobile in first gear then shifts to a fuel-conserving fifth gear until the satellite reaches low Earth orbit, about 185 miles. But to effectively relay microwave communication signals from one part of the globe to another, the satellite must be moved to a geosynchronous orbit — almost 22,000 miles higher — so that it remains in the same position relative to the ground all the time. To reach that altitude, Tech's engine shifts to solar power to move the satellite, using almost 40 percent less fuel than the traditional engine.
"The solar-powered engine adds much more energy than is possible with chemical rocket engines," Walker said. "The combined savings allow missions to launch using much smaller rockets or carry heavier payloads into space.
"The fuel savings also allows a satellite to be more maneuverable, allowing it to serve in towing or refueling capacities," he said.
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