Space Race

The Space Race was a 20th-century competition between two Cold War enemies, the Soviet Union (USSR) and the United States (US), to achieve better spaceflight capability than the other. It had its origins in the intercontinental ballistic missile-based nuclear arms race between the two nations following World War II. Both governments saw having better spaceflight technology as necessary for national security. The Space Race enabled the first launches of artificial satellites, uncrewed space probes to the Moon, Venus, and Mars, and human spaceflight in low Earth orbit and ultimately to the Moon.
The competition began on August 2, 1955, when the Soviet Union responded to the US announcement four days earlier of intent to launch artificial satellites during the "International Geophysical Year" (July 1, 1957 to December 31, 1958), by declaring they would also launch a satellite "in the near future". The Soviet Union achieved the first successful artificial satellite launch on October 4, 1957 of Sputnik 1, and sent the first human to space with the orbital flight of Yuri Gagarin on April 12, 1961. The USSR demonstrated an early lead in the race with these and other early firsts over the next few years, including flight durations measured in days instead of hours, the first multi-person crewed spaceflight, and the first spacewalk.
But the USSR lost its early lead after US president John F. Kennedy raised the stakes by setting a goal of "landing a man on the Moon and returning him safely to the Earth". American spaceflight capability overtook that of the Soviets with flights up to two weeks long; two craft meeting in space (rendezvous) and joining (docking); astronauts working outside spacecraft; and using high-energy liquid hydrogen as rocket fuel in the Saturn family of rockets. Kennedy's Moon landing goal was acheived in July 1969, with the flight of Apollo 11, which sent and returned three men and landed two of them, a singular achievement far outweighing any combination of Soviet achievements. The USSR pursued two crewed lunar programs, but failed to develop a launch vehicle powerful enough to land one human on the Moon before the US, and eventually canceled them to concentrate on Earth orbital space stations, while the US landed five more Apollo crews on the Moon.
A period of détente followed with the April 1972 agreement on a co-operative Apollo-Soyuz Test Project (ASTP), resulting in the July 1975 rendezvous in Earth orbit of a US astronaut crew with a Soviet cosmonaut crew and joint development of an international docking standard APAS-75. Apollo–Soyuz began a period of transition from the Space Race to an age of US / Russian space cooperation by December 1991, when the dissolution of the Soviet Union brought the end of the Cold War and enabled the Shuttle-Mir and International Space Station programs between the US and the newly founded Russian Federation.