Satellite Propulsion

How Satellite Propulsion Systems Work

A satellite or spacecraft orbiting the earth or traveling through the solar system encounters very small forces. For this reason, many satellite propulsion systems must deliver very precise ``impulse bits'' in order to accurately control the position or attitude of these objects. Reliability is of utmost importance in these systems since there is normally no real opportunity to service them over their entire lifetime. High performance is also a must; higher Isp systems provide additional on-orbit lifetime or the capability to increase the "payload" portion of the spacecraft. Traditionally, chemical propulsion systems using monopropellant (single fluid) or bipropellant (two fluid) liquid thrusters have been employed for these applications. However, the growth in spacecraft power has led to the use of higher energy electric propulsion (EP) systems for many modern missions. Arcjet thrusters heat a working fluid such as ammonia gas to very high temperatures by flowing the gas through a spark between two closely-spaced electrodes. More recently, ion thrusters have seen service on commercial spacecraft. These thrusters operate by accelerating heavy ions created in a plasma inside the device. Hall effect thrusters work on similar principles; these devices are the focus of many current studies.

Details of Various Satellite Propulsion Systems

Comparison Tables of Various Engines

Chemical Propulsion Systems
Make Model Thrust Isp (s) Propellant(s) Weight Applications
TRW VTE 130-1300 lbf 275-310 sec NTO/MMH 15 lb LMDE, Delta
MRE 0.1 0.8 N 216 sec Hydrazine 0.5/0.9 kg Attitude Control
MRE 1 5 N 210-220 sec Hydrazine 1.8 lbm Pioneer
MRE 4 18 N 217 sec Hydrazine 0.5 kg Attitude control
MRE 5 36 N 232 sec Hydrazine 1.5 kg Attitude control
MRE 15 86 N 228 sec Hydrazine 1.1 kg Station Keeping/Attitude control
Atlantic Research Corp. Leros 1R 110 lbf 320 sec MON3/Hydrazine 8.3 lbm Orbit Insertion
Leros 2 125 lbf 312 sec MON3/MMH 7.5 lbf Orbit Insertion
Leros 2R 125 lbf 316 sec MON3/MMH 8.3 lbf Orbit Insertion
Leros 20 5 lbf 293 sec MON3/MMH 1.25 lbm Attitude Control
Leros 20H 5 lbf 300 sec MON3/Hydrazine 0.9 lbm Attitude Control
Leros 20R 5 lbf 307 sec MON3/MMH 1.25 lbf Attitude Control
Daimler-Benz CHT 0.5 0.5 N 2230 m/s Hydrazine 195 g Attitude Control
CHT 1 1 N 2230 m/s Hydrazine 377 g Attitude Control
CHT 5 5 N 2234 m/s Hydrazine 220 g Attitude Control
CHT 10 10 N 2260 m/s Hydrazine 240 g Attitude Control
CHT 20 20 N 2300 m/s Hydrazine 360 g Attitude Control
CHT 400 400 N 2240 m/s Hydrazine 325 g Attitude Control
S 10/1 10 N 2815 m/s MON/MMH 350 g Attitude Control
S 10/2 10 N 2860 m/s MON/MMH 310/530 g Attitude Control
S 4 4 N 2795 m/s MON/MMH 290 g Attitude Control
S 400/1 400 N 2972 m/s MON/MMH 2.8 kg Orbit Insertion
S 400/2 400 N 3120 m/s MON/MMH 3.4 kg Orbit Insertion

Liquid Engines : Advanced Systems