What is the exact launch date of the Hubble Space Telescope?

The exact launch date of the Hubble Space Telescope was April 24, 1990. It launched aboard Space Shuttle Discovery during mission STS-31 from Kennedy Space Center in Florida.

The launch was originally planned for April 10, but engineers scrubbed that attempt only minutes before liftoff because of a faulty auxiliary power unit valve. After repairs and a rescheduled countdown, Discovery lifted off at 8:33:51 a.m. Eastern Daylight Time on April 24.

A common mix-up is April 25, 1990. That was the date astronauts deployed Hubble from Discovery's payload bay into low Earth orbit. Launch and deployment were separate events: Discovery carried the telescope into space on April 24, then released it the following day.

STS-31 was Discovery's tenth flight and placed Hubble in an unusually high shuttle orbit. The telescope began its mission carrying five original scientific instruments, including the Wide Field and Planetary Camera and the Goddard High Resolution Spectrograph.