The Hubble Space Telescope
The NASA and ESA observatory launched into low Earth orbit in 1990, whose repairs and discoveries — from the age of the universe to the first images of exoplanets — transformed astronomy and public engagement with science.
Timeline
A Space Telescope Proposed
Astrophysicist Lyman Spitzer published a paper arguing that a telescope above Earth's atmosphere could observe the universe without atmospheric distortion. The idea, dismissed as impractical at the time, became the seed of the eventual Large Space Telescope project four decades later.
Location: USA
Congress Approves the Project
After years of lobbying by astronomers, the US Congress approved funding for what became the Hubble Space Telescope, with the European Space Agency joining as a partner. Construction was assigned to Perkin-Elmer for optics and Lockheed for the spacecraft.
Location: Washington, D.C., USA
Launch Aboard Discovery
The Space Shuttle Discovery deployed the Hubble Space Telescope into orbit about 540 kilometers (335 miles) above Earth after years of delays, including the 1986 Challenger disaster. It was named for astronomer Edwin Hubble, whose work established the expansion of the universe.
Location: Kennedy Space Center, Florida, USA
The Flawed Mirror
Weeks after launch, engineers found that Hubble's 2.4-meter primary mirror had been ground to the wrong shape — spherical aberration that blurred its images. The flaw became a public controversy over NASA's quality control, and late-night comedy made the telescope a national punchline.
Location: USA
The Repair Mission
Shuttle Endeavour's STS-61 mission installed corrective optics — the COSTAR system and a new Wide Field camera — in a series of spacewalks. The fix restored the telescope's intended vision, and the first sharp images redeemed the project and NASA's reputation.
Location: Low Earth orbit
Deep Fields and the Age of the Universe
Hubble's Deep Field images — long exposures of tiny "empty" patches of sky — revealed thousands of galaxies from the early universe. Combined with distance measurements of variable stars, Hubble data pinned the universe's age at roughly 13.8 billion years and pinned down the expansion rate debate.
Location: Space Telescope Science Institute, Baltimore, USA
The Accelerating Universe
Observations from Hubble and ground telescopes of distant supernovae showed that the universe's expansion is accelerating, implying the existence of dark energy. The discovery, which overturned assumptions about cosmic slowing, earned the 2011 Nobel Prize in Physics for the teams' leaders.
Location: USA
First Direct Image of an Exoplanet
Hubble captured the first visible-light image of a planet orbiting another star, Fomalhaut b. Exoplanets had been detected indirectly since 1995, but direct imaging opened a new window on worlds beyond the solar system.
Location: Space Telescope Science Institute, Baltimore, USA
Final Servicing Mission
Shuttle Atlantis's STS-125 mission — reinstated after cancellation following the 2003 Columbia disaster — installed the Wide Field Camera 3 and repaired the Advanced Camera for Surveys during five spacewalks. It was the fifth and last servicing mission, leaving Hubble at peak capability for the coming decades.
Location: Low Earth orbit
Three Decades and a Legacy in Orbit
Hubble marked 30 years in orbit, having made more than a million observations and fueled over 20,000 published papers. Expected to operate into the late 2020s alongside the James Webb Space Telescope, it remained the most productive observatory in the history of astronomy.
Location: Low Earth orbit