During the Cold War, the two dominant world powers, the United States and the Soviet Union, competed to design superior spaceflight technology. Building superior technology was seen as a necessity of national security. The Soviet Union started off strong by launching the first man-made satellite in 1957 and by putting the first human into orbit in 1961. The United States answered by completing the first human expedition to the moon. The following documents explore the most important events and individuals from this period.