After the S-II (second) stage dropped away, the S-IVB (third) stage ignited and burned for about two minutes to place itself and the Apollo spacecraft into the desired Earth orbit. At the proper time during this Earth parking orbit, the S-IVB stage was re-ignited to speed the Apollo spacecraft to escape velocity, injecting it and the astronauts into a moon trajectory. Developed and manufactured by the Douglas Aircraft Company in Huntington, California, the S-IVB stage measures about 21.5 feet in diameter, about 58 feet in length and is powered by a single 200,000-pound-thrust J-2 engine with a re-start capability. The S-IVB stage was also used on the second stage of the Saturn IB launch vehicle. The fully-assembled S-IVB (third) stage for the AS-503 (Apollo 8 mission) launch vehicle is pictured in the Douglas' vertical checkout building.