This is the J-2 rocket engine that powered the second (S-II) and third stages (S-IV-B) of the Saturn V launch vehicle that took astronauts to the Moon in the Apollo program. The J-2 used liquid hydrogen and liquid oxygen and produced a thrust of 200,000-230,000 pounds. The Saturn V's second stage used five J-2's and the third stage had a single J-2. The Saturn V flights were carried out from 1968-1973. The engine shown here was used in the S-II Stage Battleship program and was fired in 63 tests for a total firing duration of 1,089 seconds. In the Battleship progam, the stage was never intended for flight but was desdigned to withstand the stress of repeated firings to more fully develop the cluster of five J-2s for flight. Transferred to the Smithsonian from the NASA/Marshall Space Flight Center in 1977.