When the Space Shuttle 'Discovery' launches as planned on October 5th, NASA will be celebrating it's 100th Shuttle launch. The work to design a reusable rocket and orbiter system first began in 1970 and six years later NASA built the test vehicle 'Enterprise'. After numerous tests the first shuttle to finally launch into space was the Space Shuttle 'Columbia' in April 12, 1981. Despite the 'Challenger' disaster in 1986, the Space Shuttle is the most reliable rocket system in use today. NASA currently use a total of four shuttles, each one designed to last one hundred missions.