Hubble Space Telescope Launches, Then Gets Fixed in Orbit
A flawed mirror threatens the mission until astronauts perform the first in-space telescope repair
Quick facts
- Launch date
- 24 April 1990, aboard Discovery
- Flaw discovered
- Spherical aberration in primary mirror
- Repair mission
- Servicing Mission 1, completed 18 December 1993
- Observations to date
- 1.7 million+, feeding 23,000+ peer-reviewed papers
What happened
The Hubble Space Telescope launched on 24 April 1990 aboard the space shuttle Discovery, the culmination of decades of planning that began when the project was first conceived in the 1940s under the name Large Space Telescope and was built through the 1970s by NASA with contributions from the European Space Agency, after delays including the 1986 Challenger disaster pushed the launch back from an originally planned 1983 date. Soon after reaching orbit, astronomers found that Hubble's images were not the crisp, point-like star images they had expected but were instead surrounded by large, fuzzy halos of light, caused by the edges of the telescope's primary mirror having been ground too flat by a fraction of the width of a human hair. NASA sent astronauts to fix the flaw on the Servicing Mission 1 shuttle flight, and on 18 December 1993 scientists at the Space Telescope Science Institute watched and cheered as the first corrected image, free of the earlier blurriness, appeared on their monitor. Over its operating lifetime Hubble has taken more than 1.7 million observations, which astronomers have used to publish more than 23,000 peer-reviewed scientific papers.
Why it matters
Hubble's repair in orbit proved that a space telescope could be serviced and upgraded rather than treated as disposable once launched, a template NASA would repeat across four more servicing missions. Once corrected, Hubble went on to reshape nearly every field of astronomy it touched, from mapping the age and expansion rate of the universe to imaging planet-forming disks around young stars.
How we know
Hubble's launch, its mirror flaw, and its 1993 repair are documented in NASA's own mission records and contemporaneous accounts from engineers and astronomers at the Space Telescope Science Institute, and Hubble's subsequent scientific output is tracked through its own extensive publicly archived observation and publication record.
Sources
- NASA Science. The History of Hubble · Reputable sourcescience.nasa.gov · The domain "science.nasa.gov" is on our Reputable source registry. · Link is live and its text matches the event's key terms (Jul 2026)
- NASA Science. Edwin Hubble · Reputable sourcescience.nasa.gov · The domain "science.nasa.gov" is on our Reputable source registry. · Link is live and its text matches the event's key terms (Jul 2026)
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Related timelines
- Space Exploration → · Hubble's launch aboard the space shuttle Discovery and its 1993 repair mission were both shuttle-era spaceflight operations; see the Space Exploration timeline for the shuttle program's wider history.