J-2 (rocket engine)
Rocketdyne was a Rocket engine design and production company headquartered in Canoga Park, California, United States. The company was related to North American Aviation for most of its history. NAA merged with Rockwell International, which was then bought by Boeing in December, 1996...

's J-2 rocket engine was a major component of the Saturn V
Saturn V
The Saturn V was an American human-rated expendable rocket used by NASA's Apollo and Skylab programs from 1967 until 1973. A multistage liquid-fueled launch vehicle, NASA launched 13 Saturn Vs from the Kennedy Space Center, Florida with no loss of crew or payload...

 rocket used in the Apollo program to send men to the Moon. Five J-2 engines were used on the S-II
The S-II was the second stage of the Saturn V rocket. It was built by North American Aviation. Using liquid hydrogen and liquid oxygen it had five J-2 engines in a cross pattern...

 second stage, and one J-2 was used on the S-IVB
The S-IVB was built by the Douglas Aircraft Company and served as the third stage on the Saturn V and second stage on the Saturn IB. It had one J-2 engine...

 third stage. The S-IVB was also used as the second stage of the smaller Saturn IB
Saturn IB
The Saturn IB was an American launch vehicle commissioned by the National Aeronautics and Space Administration for use in the Apollo program...

 rocket used to launch Apollo spacecraft
Apollo spacecraft
The Apollo spacecraft was composed of five combined parts designed to accomplish the American Apollo program's goal of landing astronauts on the Moon by the end of the 1960s and returning them safely to Earth...

 into Earth orbit. There were proposals to use various numbers of J-2 engines in the upper stages of an even larger rocket, the planned Nova
Nova rocket
Nova was a series of proposed rocket designs, originally as NASA's first large launchers for missions similar to the production-level Saturn V, and later as larger follow-ons to the Saturn V intended for missions to Mars. The two series of designs were essentially separate, but shared their name...


Unlike most liquid-fueled rocket engines of the time, the J-2 engine used on the Saturn V third stage was designed to be re-started once after shutdown.