Engine Model: MR-502. Other Designations: Improved Electrothermal Hydrazine Thruster. Designer: Rocket Research. Application: Communications satellite N-S stationkeeping, MMAS 5000. Propellants: Hydrazine. Thrust(vac): 0.50 N (0.11 lbf). Isp: 304 sec. Burn time: 7,200 sec. Mass Engine: 0.85 kg (1.87 lb). Diameter: 0.0884 m (0.2900 ft). Length: 0.19 m (0.64 ft). Chambers: 1. Chamber Pressure: 6.60 bar. Area Ratio: 100.00. Thrust to Weight Ratio: 0.0600. Country: USA. Status: In Production. First Flight: 1991. Last Flight: 1995. First Flown: Astra 1B (March 1991). Flown: 16 (32 produced) planned to end-1995. Dry Mass: 848 gm. Length: 19.4 cm. Max Diameter: 8.84 cm. Mounting Method: bolted four places. Propellant: hydrazine at 0.119-0.167 gm/sec over Shell 405 catalyst and 610-839.6. W electric heater. Feed Method: GN2 or Ghe at 21.8-23.8 atm through Wright Components 9 W dual seat. solenoid valve. Thrust: 0.36-0.50 N. Isp: 280-304 sec vacuum. Expansion Ratio: 100:1. Nozzle Length: 0.879 cm. Nozzle Cooling Method: radiative. Combustion Chamber Pressure: 3.4-6.5 atm. Combustion Chamber Temperature: 800 Celsius. Combustion Chamber Cooling Method: radiative. Duty Cycle: 300 sec minimum to 2 hr maximum. 430,000 pulses. Itotal: 525 kNs.
