An Atlas 3 rocket lifted off into space early Thursday carrying a secret military payload for the National Reconnaissance Office, the agency that oversees the nation's constellation of spy satellites.
The launch was the sixth and final mission for the 170-foot Atlas 3 rocket, which has been replaced by the Atlas 5, a larger, more powerful rocket designed to reduce costs and provide reliable access to space for heavier military cargoes.
The liftoff also marked the end of an era for Launch Complex 36, which has been a springboard to space since 1962.
Over the past four decades, 145 Atlas launches have taken place from the complex's two pads, including missions to Venus, Mars, Mercury and the lunar surface. The pads have also served as the starting point for an assortment of military and communications satellites. The last mission to lift off from pad 36A, an Atlas 2AS carrying an NRO payload, took place last summer.
Shortly after Thursday's liftoff, Atlas officials marked the end of the complex's use with a ceremony that was capped off by a symbolic shutdown of the lights at the pad.
Atlas 5 rockets lift off from Launch Complex 41, just a short distance away. The rockets are assembled in a nearby building and rolled to the pad on a mobile launch platform, dramatically decreasing the amount of time the rockets sit exposed on the pad.
Atlas officials refused to release the cost of the mission.