1. AAE450 Spring 2009 More Attitude Control Thruster Options Brittany Waletzko Translunar/OTV Phase Week 7 Brittany Waletzko - ATT

2. AAE450 Spring 2009 The Scenario  Need thrusters to despin/desaturate reaction wheels during TLI  Must be capable of impulsive ΔV ~50 m/s  Already using Electric Propulsion for main engine  utilize power for attitude control? Brittany Waletzko - ATT

3. AAE450 Spring 2009 Bottom-Line Figures Brittany Waletzko - ATT (hydrazine monopropellant system uses <1W)  Bottom line: Neither of these options is likely to be the best option based on cost, power consumption, and complexity Future Work: Solidifying supporting hardware mass/power/cost figures, OTV integration work Electrothermal HydrazineResistojetArcjet Vacuum Thrust (N)0.5-10.1-0.23 Input Power (W)500/thruster300/thruster System Mass, 4 thrusters + PPU (kg)6.51.22 Max Exhaust Velocity (km/s)104 to 5 Max Isp (s)300500 Life Span (hrs)~3801000-1500 Cost ~ $150,000 for either

4. AAE450 Spring 2009 Questions? Brittany Waletzko - ATT

5. AAE450 Spring 2009 Brittany Waletzko - ATT Thruster Locations and Thrust Direction Vectors Thruster placement planned with assistance from Brian Erson

6. AAE450 Spring 2009 How They Work Brittany Waletzko - ATT Source: TU Delft website

7. AAE450 Spring 2009 Further Comments Brittany Waletzko - ATT Arcjets Electrode erosion in 1000-1500hrs (62 days) 90% efficient --> 267 W in means 30W heat dissipated Needs PPU 0.3 kW, 0.5kg Constrictor diameter 0.25mm, length.13mm Cathode diameter 1.6mm Thruster mass 0.18 kg Resistojets 35-40% better performance than no heating Heating configuration is crucial--indirect heating of prop has longer life Steady or pulsed INTELSAT used 0.55 kW per thruster N2H4, stationkeeping Iridium 0.5 kW per thruster N2H4, orbit adjustment Mass ~ 0.36 kg ~500 W for heating systems

8. AAE450 Spring 2009 Updated System Estimates Brittany Waletzko - ATT 8 thrusters may be too redundant; 4 already allows for the loss of one thruster, 8 makes the entire system redundant  reliability analysis needed

9. AAE450 Spring 2009 Primary References  Monopropellant Hydrazine Thrusters. Astrium Space Propulsion. 21 Jan 2009.  Rocket Research Corporation. "Final Report for Monopropellant Hydrazine Thruster System," 1965. http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19670030394_1967030394.pdf  Eric Wernimont, Ph.D. General Kinetics, Inc.: Huntington Beach, CA. Email Correspondence 7 Feb - 10 Feb 2009.   “Electrothermal Hydrazine Data” and many other links  Sellers, “Investigation Into Cost-Effective Propulsion System Options for Small Satellites.” Journal of Reducing Space Mission Cost, 1998.  Pinero and Bowers. “Power Electronics for a Miniaturized Arcjet.” 32 nd Joint Propulsion Conference and Exhibit,” 1996. Brittany Waletzko - ATT