Hubble Space Telescope Launched
The Hubble Space Telescope was deployed from Discovery, transforming astronomy
April 24, 1990
Eyes Above the Clouds
The Hubble Space Telescope launched on April 24, 1990, aboard the Space Shuttle Discovery. The idea was simple: put a telescope above Earth's atmosphere, which blurs ground-based observations, and get a crystal-clear view of the universe. What followed transformed our understanding of everything from the age of the universe to the existence of dark energy.
The Flaw and the Fix
Within weeks of launch, scientists discovered Hubble's primary mirror had been ground to the wrong shape — off by just 2.2 micrometers, about one-fiftieth the width of a human hair. The resulting images were blurry. NASA was humiliated. In 1993, astronauts on the Space Shuttle Endeavour spent five spacewalks installing corrective optics — essentially contact lenses for the telescope. The repair mission worked perfectly and Hubble became the most productive scientific instrument in history.
What It Revealed
Hubble helped pin down the age of the universe at 13.8 billion years. It discovered that nearly every large galaxy has a supermassive black hole at its center. It captured the famous "Pillars of Creation" image showing stars being born inside clouds of gas. It has made over 1.5 million observations and contributed to more than 19,000 scientific papers. Its successor, the James Webb Space Telescope, launched in 2021 and sees even deeper into the universe.