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The Ion Auxiliary Propulsion System project and other preflight technology work took place in the 1974 to 1983 timeframe. Flight test objectives were to verify in space the thrust duration, cycling, and dual thruster operations required for stationkeeping, drag makeup, station change, and attitude control. This implied demonstration of overall thrusting times of 7,000 hours and 2500 on/off cycles. The 8 cm diameter, mercury ion engine input power was 0.13 kW, and the thrust was 5.1 mN at a specific impulse of 2500 s. The masses of the flight thruster-gimbal-beamshield unit, the PPU, and the digital controller were 3.77 kg, 6.85 kg, and 4.31 kg, respectively.63 The system stored 8.63 kg of mercury, and the propellant storage and feed system weighed 1.56 kg. The IAPS successfully completed all flight qualification tests and was installed on an Air Force technology satellite. The flight of the Teal Ruby spacecraft was canceled by the Air Force due to lack of funding.

During the course of the technology and preflight programs there were a number of endurance tests performed. A laboratory-type 8-cm engine was tested for 15,040 hours and 460 cycles at the 0.14 kW level. An engineering model IAPS engine and PPU were successfully tested for 9,489 hours and 652 cycles. The thruster and PPU were located in the same vacuum chamber during this test. A third endurance test was conducted using another engineering model thruster and PPU. This hardware was operated at full-thrust for 7112 hours and had 2571 restarts. No major changes in thruster performance, and no life-limiting degradation effects were observed in this test.

The preceding was an excerpt from:
Sovey, J. S., Rawlin, V. K., and Patterson, M. J.: "Ion Propulsion Development Projects in U. S.: Space Electric Rocket Test 1 to Deep Space 1." Journal of Propulsion and Power, Vol. 17, No. 3, May-June 2001, pp. 517-526.

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Last Updated: 04/21/2009 1:43 PM