In this chapter, I summarize the use of solid motors in orbital launch vehicle upper stages and satellite propulsion systems, concentrating on United States rocket motors. Early attempts to use the apogee motor technique were unsuccessful, but after a several-year gap apogee motors became a common feature of payloads. Over several generations of solid rocket technology, as launch vehicle final stage motors have been replaced by more powerful successors, the older motors began new roles as spacecraft apogee motors. Some motors have been used in a large number of different roles, and I describe several of the most widely used examples. Finally, I give a brief overview of the motors used in worldwide space programs.
