Once the Nazi rocket technology was mastered, further space related development was inevitable.
From 1947 to 1950 the Americans carried out numerous tests on the V2 rocket with the help of Von Braun, but it was the Russians that made the first major advance. On the 4th of October 1957 they launched a satellite called Sputnik 1 and on the 3rd of November 1957 they launched a second satellite containing a dog. In December 1957 the Americans first attempt of putting a satellite into orbit failed when the Vanguard rocket exploded. The Vanguard project was subsequently scrapped and full backing was switched to Von Braun. In January 1958 the Americans finally put a satellite into orbit, but it was far lighter than the Russian satellite. In 1960 John F Kennedy was elected. He realised the potential of the Space Race and used it to gain public support and to score propaganda points against the Russians. On the 12th of April 1961 Yuri Gagarin became the first man to orbit the Earth. A few weeks later the Americans put Alan Sheppard into space, but for less time. On the 25th of May 1961 Kennedy astonished the World by announcing that before the end of the decade America would put a man on the moon.
Between 1945 and 1961 many international events were taking place, some of which helped to increase the tension between the Russians and Americans. These events included the Korean War in 1950, Cuba becoming communist, and the Russian invasion of Hungary.
I think the most important factor resulting in the development of space technology was the Cold War. If it were not for the Cold War both nations would have had little motivation to develop their technology. As it was, the great rivalry between the two nations meant that development occurred rapidly. This was beneficial during the Cold War as the technology could be used for spying, weaponry and propaganda. Development was also necessary for the sake of national prestige.
