《航天推进 Space Propulsion》（英文版）Lecture 1a: Mission Requirements for Space Propulsion

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 3

16.522, 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

F from 2.25 Ib(=10 N)to 26,000 lb( Shuttle RCS) arge experience base(but less than monop Relatively complex system Short Pulsing difficult but can do re-starts Toxic propellants Better Isp than monoprop High cost (1c) Solid Propellant(Aluminized HTPB/AP typically) Ip≈280-300sec F from 10/b to very large boosters Simple integration(no plumbing) Very light casing and inerts(=15-20%of propellant) Isp comparable to biprops Non-restartable 1-5% dispersion in impulse direction (requires trim engines for precise maneuvers) Moderate-to high cost (2)Electrical Broad range of power and Isp. Cost moderate to high(excluding power systems) IV (2a) Electrothermal(Heated hydrazine, heated H2 or heated waste gas) High n, low Isp Very simple, limited by material T Can raise monoprop. n Ha to Isp s 310sec (Intelsats) With H2, Isp s 700sec(but storage problems) Allows efficient waste gas disposal(Space Station) (2b) Arciets(with hydrazine, ammonia, H2) n=0.4, Isp= 600s(hydrazine 700s(ammonia) 1000s(H2) P from 0.5 KW to 30 KW(or as available Moderately high F/P=2n (good if mission time limited High operating T(thermal isolation difficult Efficiency not very Some flight experience base (Telstar) Relatively simple Power Processing Unit(PPU) 16.522, Space P rtinez- sanchez Lecture 1a Prof. Manuel martinez Page 2 of 3

16.522, Space Propulsion Lecture 1a Prof. Manuel Martinez-Sanchez Page 2 of 3 F from 2.25 lb ( ) ≈ 10 N to 26,000 lb (Shuttle RCS) Large experience base (but less than monop.) Relatively complex system Short Pulsing difficult, but can do re-starts Toxic propellants Better Isp than monoprops. High cost (1c) Solid Propellant (Aluminized HTPB/AP typically) Isp ≈ 280 - 300sec F from ≈ 10lb to very large boosters Simple integration (no plumbing) Very light casing and inerts ( ≈ − 15 20% of propellant) Isp comparable to biprops. Non-restartable 1-5% dispersion in impulse, direction (requires trim engines for precise maneuvers) Moderate-to-high cost (2) Electrical Broad range of power and Isp. Cost moderate to high (excluding power systems) 2 F Fc = = 2m 2 IV IV η i (2a) Electrothermal (Heated hydrazine, heated H2 or heated waste gas). High η , low Isp Very simple, limited by material T Can raise monoprop. N2H4 to Isp ≈ 310sec (Intelsats) With H2, Isp ≈ 700sec (but storage problems) Allows efficient waste gas disposal (Space Station) (2b) Arcjets (with hydrazine, ammonia, H2) η ≅ ≅ 0.4, 600 Isp s (hydrazine) 700s (ammonia) 1000s (H2) P from 0.5 KW to 30 KW (or as available) Moderately high 2 F P c η = (good if mission time limited) High operating T (thermal isolation difficult) Efficiency not very high Some flight experience base (Telstar) Relatively simple Power Processing Unit (PPU)

(2c) Hall Thrusters(with Xenon propellant 1=04-0.6Isp=1500s-1800s→3000(NAsA) P from 0. 5KW to 10KW(can be increased) Isp in very favorable range for many missions(reasonable F/P, good fuel efficiency) Reasonable efficiency Some flight experience(mostly in Russia), more coming on many missions Some concerns on contamination emi, interference Complex PPU (2d) Ion Engines (with Xe propellant) 1≈0.6-0.75Isp=25005-40005→7000(NASA) P from 0. 3KW to 5KW(can be increased) Very good efficien High ISP good for high AV missions Some flight experience(from 1970s), more coming soon(Hughes'XIPs on Galaxy busse Adequate life arge relatively heavy engine (2e) Pulsed Plasma Thrusters(Ppt's with Teflon propellant) 70.05-0.1sp≡1000-1200sec P from o 1 to 1 Kw Very short (us )pulses, widely controllable pulse rate Excellent for precise maneuvering Solid fuel, very simple systems Very low eff Difficulty handling large propellant mass Some flight experience(VELA satellites), more coming (2f) Colloid Engine, Field Emission Electrostatic Propulsion(FEEP Very small unit power(from F N 0.1 HN, P N 0.5 mW) Ideal for high precision missions 500 s to 1500s(colloid Isp from 2000-6000s(colloid in ion-emitting mode 6000s FEEP (liquid metal) Can be multiplexed for mN Thrust. Relatively heavy ancillary components Pro f a spa m artie ssn Lecture 1a 3 of 3

16.522, Space Propulsion Lecture 1a Prof. Manuel Martinez-Sanchez Page 3 of 3 (2c) Hall Thrusters (with Xenon propellant) η ≅ ≅⇒ 0.4 - 0.6 1500 1800 3000 (NASA) Isp s - s P from 0.5KW to 10KW (can be increased) Isp in very favorable range for many missions (reasonable F/P, good fuel efficiency) Reasonable efficiency Some flight experience (mostly in Russia), more coming on many missions Life adequate Some concerns on contamination, EMI, interference Complex PPU (2d) Ion Engines (with Xe propellant) η ≈ ≅⇒ 0.6 - 0.75 2500 4000 7000 (NASA) Isp s - s P from 0.3KW to 5KW (can be increased) Very good efficiency High ISP good for high ∆V missions Some flight experience (from 1970’s), more coming soon (Hughes’ XIPs on Galaxy busses) Adequate life Very complex PPU Large, relatively heavy engine (2e) Pulsed Plasma Thrusters (PPT’s with Teflon propellant) η ≅ ≅ 0.05 - 0.1 1000 1200sec Isp - P from 0.1 to 1 KW Very short ( µs ) pulses, widely controllable pulse rate Excellent for precise maneuvering Solid fuel, very simple systems Very low efficiency Difficulty handling large propellant mass Some flight experience (VELA satellites), more coming (2f) Colloid Engine, Field Emission Electrostatic Propulsion (FEEP) Very small unit power (fromF ~ 0.1 N, P ~ 0.5 mW µ ) Ideal for high precision missions Isp from 500 s to 1500 s (colloid) 2000 - 6000 s (colloid in ion - emitting mode) 6000 s FEEP (liquid metal) Can be multiplexed for mN Thrust. Relatively heavy ancillary components