An orbital stage system has an orbital stage and one or more launch stages. The orbital stage incorporates an orbital maneuvering system (OMS) and an abort propulsion system which both utilize the same propellants, propellant tankage, and propellant pressurization system, but which employ radically different engines. The OMS engines are comprised of at least two engines which have a combined thrust in the neighborhood of 1/10 the weight of the orbital stage, an area ratio of 50 or more and an operating life of many hundred seconds, preferably many thousands of seconds or more. The abort engine may be a single engine and typically has a thrust of three, four, or more times the weight of the vehicle and an area ratio in the neighborhood of two and an operating life of at most a few tens of seconds.