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VASIMR technology, which uses radio waves to ionize propellant, such as argon, xenon or hydrogen, and heat the resulting plasma to temperatures 20 times hotter than the surface of the sun creating thrust. In place of metal nozzles to control the direction of the exhaust, VASIMR uses magnetic fields.
Houston-based Ad Astra Rocket Co., which has raised millions of dollars from private investors, reached a significant milestone last year when it successfully operated a demonstrator VASIMR at full power in a vacuum chamber.
Ad Astra plans to launch its flight version VASIMR to the space station in 2014. As a backup, they intend to manufacture two engines in case a launch accident or other major problem prevents the first from reaching the outpost.
Once the engine is safely installed outside the station, the spare could be tapped for a new missions.
Much more at DiscoveryNews