The Hubble Telescope Launched with a Blurry Mirror — and NASA Fixed It in Orbit with Glasses
When NASA's $1.5 billion telescope sent back its first images in 1990, they were blurry. The mirror was ground wrong by 1/50th the width of a human hair. The fix? Give the telescope corrective lenses — in space.
Key Takeaways
- •Hubble's mirror was ground 2.2 microns too flat — a catastrophic manufacturing error
- •COSTAR corrective optics installed in 1993 by astronauts during 5 spacewalks
- •Has made 1.5 million+ observations and contributed to 19,000+ scientific papers
- •Still operating in 2026 — 36 years into a mission designed to last 15
Root Connection
The Hubble Space Telescope traces its roots to Lyman Spitzer's 1946 paper proposing a telescope above Earth's atmosphere — 44 years before it launched.
Timeline
Lyman Spitzer proposes a space telescope in a classified paper
Congress funds the Large Space Telescope project (later renamed Hubble)
Hubble launches aboard Space Shuttle Discovery — and sends back blurry images
Astronauts install COSTAR corrective optics during a 5-day spacewalk mission
Hubble captures the iconic 'Pillars of Creation' in the Eagle Nebula
Hubble still operating after 36 years — far beyond its 15-year design life
On April 24, 1990, the Space Shuttle Discovery carried humanity's greatest eye into orbit. The Hubble Space Telescope was the culmination of 44 years of dreams, $1.5 billion in funding, and the work of thousands of engineers. It was supposed to revolutionize astronomy.
Then it sent back its first images. They were blurry.
The reaction was immediate and brutal. Late-night comedians mocked NASA. Congressional hearings were called. The telescope that was supposed to see the edge of the universe couldn't focus properly.
The mirror was off by 2.2 microns — 1/50th the width of a human hair. It was the most precisely wrong mirror ever made.
The problem was the primary mirror. At 7.9 feet across, it was the most precisely shaped mirror ever made — but it was precisely wrong. During manufacturing, a device called a null corrector was assembled incorrectly. A tiny spacing error — 1.3 millimeters — caused the mirror to be ground 2.2 microns too flat at its edges. That's 1/50th the width of a human hair.
The irony was devastating. The mirror was the most accurately figured optical surface in history — it was just accurately figured to the wrong shape. Perkin-Elmer, the company that made it, had ignored test results that showed the error.
NASA had two options: bring Hubble back to Earth (impossibly expensive and risky) or fix it in orbit. They chose orbit.
COSTAR was essentially a pair of glasses for a telescope. Astronauts performed eye surgery on a satellite moving at 17,000 mph.
The solution was COSTAR — Corrective Optics Space Telescope Axial Replacement. Think of it as a pair of glasses for a telescope. Engineers designed coin-sized mirrors that would intercept Hubble's light path and correct the distortion before it reached the instruments.
On December 2, 1993, Space Shuttle Endeavour launched with a crew of seven astronauts. Over five days, they performed five spacewalks totaling 35 hours. Working in bulky pressure suits with thick gloves, they opened Hubble's instrument bay, removed a device the size of a phone booth, and installed COSTAR.
Story Musgrave, the lead spacewalker, had trained for this mission for 11 months. He later said it was like performing brain surgery while wearing oven mitts.
The fix worked perfectly. When the corrected images came back, the difference was staggering. Stars that had been fuzzy blobs became pinpoints. Galaxies revealed spiral arms. Nebulae showed intricate detail.
What followed was arguably the greatest scientific comeback in history. Hubble went on to determine the age of the universe (13.8 billion years), prove that the expansion of the universe is accelerating, discover that nearly every galaxy has a supermassive black hole at its center, and capture images that changed how humanity sees its place in the cosmos.
The 'Pillars of Creation' — Hubble's 1995 image of star-forming columns of gas in the Eagle Nebula — became one of the most iconic photographs ever taken by any camera, anywhere.
As of 2026, Hubble has been operating for 36 years — more than double its 15-year design life. It has made over 1.5 million observations and contributed to more than 19,000 scientific papers. Even with the James Webb Space Telescope now operating, Hubble continues to deliver groundbreaking science.
The root lesson? Sometimes the greatest achievements come not from getting it right the first time, but from refusing to give up when you get it wrong.
How did this make you feel?
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