NASA has conducted the first test of a high-power ion engine that could propel the Jupiter Icy Moons Orbiter (JIMO) planned under the Project Prometheus nuclear-powered spacecraft initiative. The high-power electric propulsion (HiPEP) ion engine is one of several candidates under study for the JIMO.

The HiPEP microwave ion thruster was tested in a vacuum chamber at NASA Glenn Research Center, operating at power levels up to 12kW and over equivalent exhaust velocities of 60,000-80,000m/s. Tests are scheduled to culminate with runs at the full power level of 25kW.

The thruster is being designed to provide a seven- to 10-year lifetime at specific impulses (fuel efficiencies) exceeding 6,000s - which compares with 460s for the Space Shuttle main engines. Xenon gas is ionised with microwaves and a pair of rectangular grids at the rear of the engine, charged with 6,000V of electric potential, accelerates the ions, producing thrust. Use of microwaves should provide longer life, says NASA.

Compared with the ion thruster used in the Deep Space 1 probe, the HiPEP engine should increase power by a factor of 10 or more; fuel efficiency by two to three; grid voltage by four to five; and lifetime by five to eight. Overall thruster efficiency should be increased by 30%, NASA says. The rectangular shape allows power to be increased by stretching the engine.

Source: Flight International