The J-2 liquid propellant rocket engine, using liquid hydrogen and liquid oxygen, was the powerplant for the second and third stages of the Saturn V launch vehicle that took astronauts to the Moon in the Apollo program. The engine shown here was an early developmental model and produced 200,000 pounds of vacuum thrust. It made three tests for a total duration firing time of 291 seconds.
The Saturn V's second stage used a cluster of five J-2s, while the third stage had one J-2 that was gimballed, or steerable, so that this stage could be steered on its way to the Moon. The J-2 was developed and built by the Rocketddyne Division of the Rockwell International Corporation. NASA transferred this J-2 engine to the Smithsonian in 1970.