The Agena rocket was a two-stage launch vehicle developed by the Lockheed Corporation in the 1950s and used for a variety of space missions. It was used as the upper stage of the Gemini rocket, which was the first American spacecraft to carry two astronauts into space. The Agena provided the thrust necessary to propel the Gemini spacecraft into orbit and to perform rendezvous and docking maneuvers with other spacecraft.