STS-31

The primary mirror was 2.4 metres across, ground to a prescription with a spherical aberration of 2.2 micrometres — the result of a measuring error during manufacture.

No one knew that yet.

On 24 April 1990, Space Shuttle Discovery lifted from Kennedy Space Center carrying the 11,110 kg Hubble Space Telescope into an orbit approximately 569 kilometres above Earth — the highest a Shuttle had flown to that point. The crew deployed the observatory the following day, placing a large optical telescope above the atmosphere for the first time.

Two months later, NASA announced the flaw. The telescope's initial science output was sharply limited. In December 1993, a servicing mission installed corrective optics, and Hubble returned its first corrected images that month.