nation to land an astronaut on the Moon by the end of the decade, with a safe return to Earth. NASA worked towards this goal incrementally, sending astronauts into space during Project Mercury and Project Gemini, leading up to the Apollo program. The goal was achieved with Apollo 11, which landed on the Moon on July 20, 1969. Neil Armstrong and Buzz Aldrin walked on the lunar surface while Michael Collins orbited the Moon in Command Module Columbia. The mission returned to Earth on July 24, 1969, fulfilling Kennedy's challenge. NASA had contracted for fifteen Saturn V rockets to achieve the goal; at the time no one knew how many missions this would require. Since success was obtained in 1969 with the sixth SaturnV on Apollo 11, nine rockets remained available for a hoped-for total of ten landings. After the excitement of Apollo 11, the general public grew apathetic towards the space program and Congress continued to cut NASA's budget; Apollo 20 was canceled. Despite the successful lunar landing, the missions were considered so risky that astronauts could not afford life insurance to provide for their families if they died in space. Even before the first U.S. astronaut entered space in 1961, planning for a centralized facility to communicate with the spacecraft and monitor its performance had begun, for the most part the brainchild of Christopher C. Kraft Jr., who became NASA's first flight director. During John Glenn's Mercury Friendship 7 flight in February 1962 (the first crewed orbital flight by the U.S.), one of Kraft's decisions was overruled by NASA managers. He was vindicated by post-mission analysis and implemented a rule that, during the mission, the flight director's word was absolute – to overrule him, NASA would have to fire him on the spot. Flight directors during Apollo had a one-sentence job description, "The flight director may take any actions necessary for crew safety and mission success." In 1965, Houston's Mission Control Center opened, in part designed by Kraft and now named for him. In Mission Control, each flight controller, in addition to monitoring telemetry from the spacecraft, was in communication via voice loop to specialists in a Staff Support Room (or "back room"), who focused on specific spacecraft systems. Apollo 13 was to be the second H mission, meant to demonstrate precision lunar landings and explore specific sites on the Moon. With Kennedy's goal accomplished by Apollo 11,