When the development of an advanced satellite, called Object D, lagged behind, Soviet engineers decided to launch a simpler, smaller satellite named PS-1, or "Sputnik".
Laika the dog (Laika means "barker" in Russian) flew aboard the USSR's Sputnik 2 spacecraft. She died from overheating just a few hours into the flight.
Vanguard 1 was America's first attempt to launch an artificial satellite. The rocket suffered a failure and exploded on the launch pad. The press dubbed the bid "dudnik" and "kaputnik".
The men behind Explorer 1, America's first successful satellite launch. Left to right are Nasa director William Pickering, scientist James Van Allen and engineer Wernher von Braun.
A pensive Yuri Gagarin takes the bus to the launch pad on 12 April 1961. That day, he soared into the history books, becoming the first man into space in his Vostok 1 capsule.
On 5 May 1961, Alan Shepard became the first American into space, piloting his Mercury capsule on a sub-orbital flight. Here, he is rescued after splashing down in the Atlantic.