The Service Propulsion System (SPS) was an AJ10-137 rocket engine produced by Rocketdyne. The SPS was responsible for moving the Command and Service Module to transearth and translunar injections as well as for mid-course corrections, if necessary. The engine used hypergolic propellant (Aerozine 50 and nitrogen tetorxide) and produced over 20,000 pounds of thrust.
