Here is was I found out :
In the history of Space Exploration, Space Exploration has improved a lot over time and will continue to improve day by day. The first space shuttle that was launched into space was in 1961 May 5th, when Alan Shepard, Jr. became the First American in Space aboard the Mercury Redstone 3. A month beforehand, Yuri Gagarin became the first person in space by orbiting the Earth in a Vostok Spacecraft on April 12 1961.
Unfortunately, as many as twenty four successful space shuttles succeeded in Scientific and Military requirements until January, 1986. That was when the Challenger Tragedy occurred on 28 January 1986, the Shuttle exploded due to an external tank explosion. The Space Shuttle broke apart because gasses in the external fuel tank mixed and caused it to explode and be torn apart.