Abstract: A spacecraft propulsion system which integrates the function of the apogee kick motor (AKM) and reaction control system (RCS) is disclosed. In accordance with this invention, a pump-fed AKM is employed which results in lightweight main tanks and pressurization systems. The RCS thrusters are operated by small bellows tanks which are intermittently pressurized by a gas pressurization system to provide high pressure for operation of the RCS thrusters. The system according to this invention enables use of lighter weight main propellant tanks since they do not have to withstand high internal pressures and also enables realization of the numerous advantages of a pump-fed AKM. Several embodiments describe various methods for cycling the bellows tanks.