Hubble Space Telescope Repaired
Shuttle astronauts repaired Hubble's flawed mirror, restoring the telescope to full capability
December 11, 1993
A Telescope With a Blurry Eye
NASA launched the Hubble Space Telescope in April 1990. Scientists expected crisp, clear images from above Earth's blurring atmosphere. Instead, the first photos were fuzzy. Engineers discovered that Hubble's primary mirror had been ground to the wrong shape — off by just 2.2 micrometers, about 1/50 the width of a human hair. This tiny flaw made the $1.5 billion telescope nearly useless, and it became a very public embarrassment for NASA.
The Repair Mission
In December 1993, NASA launched Space Shuttle Endeavour on a mission to fix Hubble. Seven astronauts conducted five spacewalks over 11 days to install corrective optics — essentially contact lenses for the telescope. The mission was broadcast live and gripped the public with suspense. When the repaired Hubble sent back its first new images in January 1994, they were stunning: razor-sharp pictures of galaxies billions of light-years away. The mission is still considered one of the most successful in NASA history.
Hubble's Legacy
After the repair, Hubble transformed our understanding of the universe. It helped scientists determine the age of the universe at about 13.8 billion years. It captured the famous "Pillars of Creation" image showing newborn stars forming inside gas clouds. It confirmed the existence of supermassive black holes at the centers of galaxies. Hubble also provided evidence for dark energy, the mysterious force accelerating the universe's expansion. The telescope remains one of the most productive scientific instruments ever built. Use our age calculator to see how old Hubble is today.