This is an attitude control motor, or APS (Auxiliary Propulsion System), for the S-IVB (third stage) of the Saturn V launch vehicle developed for Project Apollo to carry humans to the Moon. APS motors provided three axis control of roll, pitch and yaw control for the S-IV during Earth orbit and injection into lunar orbit. Each motor produced 150 pounds of thrust.
APS engines were used in all the Apollo Saturn V flights from 1967 to 1972. The Saturn V last flew when it lifted Skylab, the U.S.'s first Earth-orbiting space station, in 1973. The APS shown here was transferred to the NASM in 1974 by the McDonnell Douglas Co.
Gift of McDonnell Douglas Astronautics Company