Propulsion and Thruster

"The propulsion system that a satellite carries is dictated by the orbital position that it needs to reach and by the type of mission. Additionally to the launch vehicle-provided propulsion, there may be an upper stage (e.g. Fregat) that delivers the spacecraft to a higher or to an escape orbit. The spacecraft itself may carry its own (attached or jettisonable) propulsion module for orbital manoeuvres or orbit adjustment. Finally, smaller thrusters may be  included for fine orbit adjustments and orbit maintenance, the so-called stationkeeping. [...] Most satellites also have simple hydrazine thrusters and/or reaction or momentum wheels to control attitude and orbit." (ESA, 2013)