The Space Race was a mid-to-late 20th century competition between the Soviet Union (USSR) and the United States (US) for supremacy in space exploration. Between 1957 and 1975, the Cold War rivalry between the two nations focused on attaining firsts in space exploration, which were seen as necessary for national security and symbolic of technological and ideological superiority. The Space Race involved pioneering efforts to launch artificial satellites, sub-orbital and orbital human spaceflight around the Earth, and piloted voyages to the Moon. It effectively began with the Soviet launch of the Sputnik 1 artificial satellite on 4 October 1957, and concluded with the co-operative Apollo-Soyuz Test Project human spaceflight mission in July 1975. The Apollo-Soyuz Test Project came to symbolize détente, a partial easing of strained relations between the USSR and the US.

The Space Race had its origins in the missile-based arms race that occurred just after the end of the World War II, when both the Soviet Union and the United States captured advanced German rocket technology and personnel.

The Space Race sparked unprecedented increases in spending on education and pure research, which accelerated scientific advancements and led to beneficial spin-off technologies. An unforeseen effect was that the Space Race contributed to the birth of the environmental movement; the first color pictures of Earth taken from deep space were used as icons by the movement to show the planet as a fragile "blue marble" surrounded by the blackness of space.