On a satellite the propulsion system is designed to provide a means to control the satellite and maintain it’s orbit.  The two most common applications are mono-propellant and bi-propellant. The mono-prop system utilizes one type of fuel, where the bi-prop system uses a fuel and an oxidizer combination to produce thrust. In it’s simplest form this system is comprised of thrusters,  a fuel tank, tubing for fuel lines, heaters, valves and filters. More complex designs also include a dedicated processor, oxidizer tank, pressurization tanks and lines, additional power supplies, and safety relays and fuses. The propulsion system can be pressurized prior to launch and operate in a blow down mode. When pressurization tanks are added to the system it can operate in a combination of pressure regulated and blow down modes. Electric Ion thrusters have been used, they have a low specific impulse and require high current and long maneuver durations so are therefore normally reserved for use in planetary missions. The mission life is determined primarily by the efficient use of the fuel loaded into this system.

In some applications due to short mission life, on the order of 6 months to a year the propulsion system is or can be eliminated. These are normally proof of concept, flight qualification and special scientific missions that do not require long durations.

Satellites in LEO orbits use thrusters to adjust the satellites velocity, orbiting altitude and inclination.

On GEO satellites the designs normally include the use of thrusters for Attitude control as a back-up system. Under 2-Axis control the fuel tanks can be oriented to utilize the centrifugal effect of the spinning satellite to force the fuel out to the thrusters.  While in 3-Axis control the thrusters can be used to reduce the momentum stored in the reaction wheels. During the launch phase the use of solid fuel motors to achieve a circularized orbit at GEO has been replaced in some cases with bi-propellant thrusters to conserve weight and potentially extend mission life.