5 April 2011
Last updated at 12:02
Before they were prepared to launch a human on a rocket, both the Soviet and American space agencies sent animals on short flights into space. Ham the chimpanzee blasted off from Cape Canaveral, Florida, in January 1961. He came back to Earth unharmed, but showed little appetite for a return mission.
In the early 1960s, the Soviet Union knew America was planning to launch an astronaut, but they did not know when. The USSR's chief space scientist Sergei Korolev pushed for a manned launch with the utmost urgency. Yuri Gagarin orbited Earth in April 1961, beating the US by less than a month.
Nasa's chief rocket designer Wernher von Braun (L) and Mercury 7 astronaut Gordon Cooper (R) are photographed during the operation to recover America's first man in space Alan Shepard, whose Freedom 7 capsule splashed down as planned in the Atlantic Ocean after a 15-minute sub-orbital flight in May 1961.
Soviet premier Nikita Khrushchev (C) holds up the hands of Valentina Tereshkova, the first woman in space, and Valery Bykovsky, who held the record for the most time spent in space. Khrushchev was acutely aware of the propaganda value of successes in space.
Astronaut John Glenn exudes cool as he relaxes aboard the USS Noa after his historic flight aboard the Friendhip 7 capsule. In February 1962, Glenn circled the globe four times during a flight lasting nearly five hours. The Noa picked him up after he landed in the Atlantic near Grand Turk Island.
In March 1965, cosmonaut Alexey Leonov notched up another first for the Soviet Union by making the first ever spacewalk. Leonov's suit inflated during the 12-minute walk, preventing him from getting back inside the spacecraft. A valve allowed the cosmonaut to bleed air out of his suit, saving his life.
By the mid-1960s, the US was still playing catch-up to the Soviet Union. Nasa astronaut Ed White (pictured) became the first American to walk in space in June 1965, nearly three months after Leonov. A spare thermal glove became an early piece of space junk when it floated away from White.
Astronauts Gus Grissom (L) and John Young (R) practise getting out of the Gemini spacecraft after it splashes into the ocean at the end of a mission. This picture was taken during training in a water tank at Ellington Air Base, Texas, in 1965.
The Gemini 6 and 7 spacecraft were launched simultaneously to perform the first manned rendezvous in space. The ships, crewed by Thomas Stafford and Walter Schirra, came within 30cm of one another during their maneouvres in space.
During the Gemini 9 mission, astronauts Eugene Cernan and Thomas Stafford were supposed to use their space capsule to test docking manoeuvres with the Augmented Target Docking Adapter (pictured), also known as the "angry alligator". The crew was unable to dock with it due to a technical problem.
The lessons learned on the Mercury and Gemini missions were vital for the success of Nasa's Moon programme. This photo from 1964 shows a lunar landing research vehicle being tested at Edwards Air Force Base in California.