Experiments with rocketry progressed through the early 20th century. The first rockets to reach space were the German V-2 rockets of World War II. The first artificial satellite (Sputnik) was launched by the Soviet Union on October 4, 1957, followed by the US Explorer I in 1958.

The first manned flight was the Earth orbit by cosmonaut Yuri Gagarin on Apil 12, 1961. Manned flights by the US were by Alan Shepard and Gus Grissom, followed by the three-orbit flight of John Glenn on February 20, 1962.

The US space program under NASA culminated in six manned Moon landings between July 20, 1969 and December 14, 1972. Space exploration since that time has been almost entirely by unmanned probes, such as the Voyager 1 and Voyager 2 missions to the outer planets from 1977 to 1989, and the Viking mission (and subsequent rovers) sent to Mars in 1975.

Manned space flight continued with Mir, Skylab, and the International Space Station. The Russian Soyuz flights are continuing, both manned and unmanned, while the US fleet of Space Shuttle orbiters (1977-2011) has now been retired.

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