The use of spacecraft to invetigate outer space. On 4 October 1957, the first artifical satellite, SPUTNIK 1, was launched into Earth orbit by the Soviet Union. The first US satellite was Explorer 1 which was lanched on 31 January 1958 . The “ space race ” began in earnest. Within
the next decade the two superpowers launched more than 50
unmaned SPACE PROBES to the moon Soviet cosmonauts,and their Americans equivalents, astonauts, orbited the earth soon after.

By 1968 Soviet space scientists had developed techniques for returning a moon orbiter safely to earth . In 1969 the US Apollo 11 mission became the first to place a man on the moon. Meanwhile, the Soviet Union had sent probes to explore Mars and Venus.