When U.S. astronauts planted the flag on the surface of the Moon in 1969 it signaled the final triumph of the United States over the Soviet Union in the space race, nothing more nor less. Indeed, this singular achievement of Project Apollo during NASA's early years—one that was particularly focused on demonstrating American preeminence as a spacefaring nation to the people of the world—made possible the cooperative ventures that followed.
The effort to land Americans on the Moon came about because of a unique confluence of political necessity, personal commitment and activism, scientific and technological ability, economic prosperity, and public mood. When President John F. Kennedy announced on 25 May 1961 his intention to carry out a lunar landing program before the end of the decade, he did so as a means of demonstrating U.S. technological virtuosity. In so doing Kennedy responded to perceived challenges to U.S. world leadership not only in science and technology but also in political, economic, and especially military capability.
For the next eleven years Project Apollo consumed NASA's every effort. It required significant expenditures, costing $25.4 billion in 1960s dollars over the life of the program to make it a reality. Only the building of the Panama Canal rivaled the Apollo program's size as the largest nonmilitary technological endeavor ever under-taken by the United States; only the Manhattan Project was comparable in a wartime setting.
The first mission to capture public attention was the flight of Apollo 8 . On 21 December 1968 it took off atop a Saturn V booster from the Kennedy Space Center in Florida. Three astronauts were aboard—Frank Borman, James A. Lovell, Jr., and William A. Anders—for a historic mission to orbit the Moon. After Apollo 8 made one and a half Earth orbits, its third stage began a burn to put the spacecraft on a lunar trajectory. It orbited the Moon on Christmas Eve and then fired the boosters for a return flight. It splashed down safely in the Pacific Ocean on 27 December. Two more Apollo missions occurred before the climax of the program, but they did little more than confirm that the time had come for a lunar landing.
That landing came during the flight of Apollo 11, which lifted off on 16 July 1969 and, after confirmation that the hardware was working well, began the three-day trip to the Moon. Then, on 20 July 1969 the lunar module—with astronauts Neil A. Armstrong and Edwin E. "Buzz" Aldrin aboard—landed on the lunar surface while Michael Collins orbited overhead in the command module. After checkout, Armstrong set foot on the surface, telling millions who saw and heard him on Earth that it was "one small step for [a] man—one giant leap for mankind." Aldrin soon followed him out and the two explored their surroundings and planted an American flag but omitted claiming the land for the United States, as had been routinely done during European exploration of the Americas. They collected soil and rock samples and set up scientific experiments. The next day they rendezvoused with the Apollo capsule orbiting overhead and began the return trip to Earth, splashing down in the Pacific Ocean on 24 July.
Five more landing missions followed at approximately six-month intervals through December 1972, each of them increasing the time spent on the Moon. The scientific experiments placed on the Moon and the lunar soil samples returned have provided grist for scientists' investigations ever since. The scientific return was significant, but the program did not answer conclusively the age-old questions of lunar origins and evolution. Three of the latter Apollo missions also used a lunar rover vehicle to travel in the vicinity of the landing site, but despite their significant scientific return none equaled the public excitement of Apollo 11.
Even as Project Apollo proceeded, the United States and the Soviet Union—as well as other nations—crafted in 1967 the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, commonly known as the Outer Space Treaty. Its concepts and some of its provisions were modeled on its predecessor, the Antarctic Treaty. Like that document it sought to prevent "a new form of colonial competition" and the possible damage that self-seeking exploitation might cause.
After years of discussion this treaty became a possibility on 16 June 1966 when both the United States and the Soviet Union submitted proposals to the United Nations. While there were some differences in the two texts, these were satisfactorily resolved by December 1966 in private consultations during the General Assembly. This allowed the signature of the treaty at Washington, London, and Moscow on 27 January 1967. On 25 April the U.S. Senate gave unanimous consent to its ratification, and the treaty entered into force on 10 October 1967. This treaty has remained in force and both provides for the nonmilitarization of space and directs use of the Moon and other celestial bodies exclusively for peaceful purposes. It expressly prohibits their use for establishing military bases, installations, or fortifications; for testing weapons of any kind; or for conducting military maneuvers. After the treaty entered into force, the United States and the Soviet Union began to collaborate in several joint space enterprises.