Space Propulsi Prof. Manuel martinez-Sanchez Lecture 1a: Mission Requirements for Space Propulsion Missions Requiring High Thrust(chemical thrusters) Planetary takeoff (launch rockets) Ing Apogee kick(GTO-GEO transfer motors) Perigee kick(GTo to Rapid maneuvering(proximity ops. spacecraft attitude control) Fast plane char Missions Requiring High Isp(EP) - Deep space missions(△V≥2-3km/ s typically) Long-term drag cancellation Long-term formation flight Planetary non-Keplerian orbits(e. g, parallel to Saturn's rings) Missions where High Isp(EP) is Beneficial(but could be done otherwise too) Propulsion for high-power satellites( Comsats, radar sats.) Orbit raising(LEO-high LEO, LEO-GEO End-of-Life deorbiting Orbit re-positioning Plane change(slow) Orbit corrections(NSSK,. Existing space Thrusters Two broad categories Chemical(high F/M, low Isp) ctrical(low F/M, high Isp) Chemical (1a) Monopropellant(N2H4) 230 F from 0.1 Ib(450 mN) to 10,000lb(Viking) High reliability, large experience base. Capable of pulsing(210ms), up to 10 pulses Needs strict handling processors, fuel warming systems Limited to sma‖l△v"s Moderate cost (1b) Bipropellant (usually hydrazine or MMH, plus N204) Isp305-325: 16.522, Space P pessan Lecture 1a Prof. Manuel martinez Page 1 of 316.522, Space Propulsion Lecture 1a Prof. Manuel Martinez-Sanchez Page 1 of 3 16.522, Space Propulsion Prof. Manuel Martinez-Sanchez Lecture 1a: Mission Requirements for Space Propulsion Missions Requiring High Thrust (chemical thrusters) − Planetary takeoff (launch rockets) − Planetary landing (Viking, Lunar Lander…) − Apogee kick (GTO-GEO transfer motors) − Perigee kick (GTO to escape) − Rapid maneuvering (proximity ops., spacecraft attitude control) − Fast plane change Missions Requiring High Isp (EP) − Deep space missions ( ∆ ≥ V km s 2 - 3 / typically) − Long-term drag cancellation − Long-term formation flight − Planetary non-Keplerian orbits (e.g., parallel to Saturn’s rings) Missions where High Isp (EP) is Beneficial (but could be done otherwise too) − Propulsion for high-power satellites (Comsats, radar sats…): ƒ Orbit raising (LEO-high LEO, LEO-GEO…) ƒ End-of-Life deorbiting ƒ Orbit re-positioning ƒ Plane change (slow) ƒ Orbit corrections (NSSK, …) Existing Space Thrusters Two broad categories: Chemical (high F/M, low Isp) Electrical (low F/M, high Isp) Chemical (1a) Monopropellant (N2H4) Isp ≅ 230 s. F from 0.1 lb (450 mN) to 10,000lb (Viking) High reliability, large experience base. Simple system Capable of pulsing (≥10ms), up to 106 pulses Needs strict handling processors, fuel warming systems Limited to small ∆V’ s Moderate cost (1b) Bipropellants (usually hydrazine or MMH, plus N2O4) Isp ≅ 305 - 325sec