The Marshall Center's first major program was the development of Saturn rockets to carry heavy payloads into and beyond Earth orbit. From this, the Apollo program for crewed Moon flights was developed. Von Braun initially pushed for a flight engineering concept that called for an Earth orbit rendezvous technique (the approach he had argued for building his space station), but in 1962, he converted to the lunar orbit rendezvous concept that was subsequently realized. During Apollo, he worked closely with former Peenemünde teammate, Kurt H. Debus, the first director of the Kennedy Space Center. His dream to help mankind set foot on the Moon became a reality on 16 July 1969, when a Marshall-developed Saturn V rocket launched the crew of Apollo 11 on its historic eight-day mission. Over the course of the program, Saturn V rockets enabled six teams of astronauts to reach the surface of the Moon.