ATS-III resistojet thruster system performance.

An ammonia-fueled resistojet engine was developed, qualified, and subsequently tested on the ATS-III spacecraft. The experimental objectives of the test were to demonstrate the operation and function of the resistojet and to obtain micropound thrust measurements in space. Except for problems encountered with the solenoid valves, the first objective was met. The liquid ammonia storage tank and feed system designed for operation in a zero-g environment and the resistance-heated thrusters operated successfully. The second objective was successfully met. Measurements of micropound thrust performance were obtained for both cold flow and electrically heated flow. The measurements compared well with ground measurements. System description, ground characterization, and flight test results are discussed.