English: Prior to installation, technicians inspect the primary mirror of the Hubble Space Telescope (HST). The first in a series of great observatories launched by NASA, the HST was designed to last approximately 15 years. The Marshall Space Flight Center had management responsibility for the development of the HST and played a major role in ground tests and orbital checkout of the telescope. The HST was launched April 24, 1990 aboard Space Shuttle Discovery's STS-31 mission.