How a tiny washer nearly destroyed the world's most famous space telescope
In short: The Hubble Space Telescope was a triumph of engineering, yet its launch in 1990 revealed a catastrophic flaw. A simple, one-millimetre washer left in a test rig caused the primary mirror to be polished into the wrong shape, rendering the telescope's vision no better than ground-based instruments.
The dream of placing a telescope above Earth's atmosphere dates back to before the space age, championed by visionaries like Lyman Spitzer. By the 1970s, NASA sought a new purpose following the Apollo program, eventually settling on a 2.4-metre aperture design derived from US spy satellites. The project was over forty years in the making, involving international support from European and Canadian agencies, but the reality of space travel proved more difficult than anticipated. Following the 1986 Challenger disaster, the high cost of shuttle missions meant that the planned frequent servicing of the telescope became impossible.
When Hubble launched in April 1990, the optical system failed to deliver the expected crisp imagery. An investigation traced the error to Perkin-Elmer, the main contractor, where a misplaced washer in the mirror-shaping test equipment led to a precise but incorrect polish. This was a public relations disaster for NASA, as the telescope's inability to provide sharp views made it an object of ridicule. Because the telescope was in low Earth orbit, however, it was uniquely positioned for a rescue mission that would have been impossible elsewhere.
In December 1993, astronauts aboard Endeavour installed corrective optics known as COSTAR, a solution partly inspired by a hotel showerhead. The fix was an immediate success, allowing Hubble to capture iconic images of the universe. These included the 1994 impact of Comet Shoemaker-Levy 9 on Jupiter and the Hubble Deep Field, which revealed the early universe. Beyond these milestones, Hubble transformed our understanding of stellar evolution, particularly the late stages of intermediate-mass stars, which shed their outer layers to form planetary nebulae—enigmatic, short-lived structures that reveal the complex interplay of magnetic fields and multiple star systems.
Opens the Intellect+ feed with this card first. Swipe up for the next one.
Sources
- Summary by Intellect · source: A Mirror in the Sky - Chris Lintott
- Also: A Mirror in the Sky
- Also: podcast.gresham.ac.uk — A Mirror in the Sky - Chris Lintott - Gresham College Lectures
To cite this card, link to https://intellectplus.co.uk/app/ideas-a-mirror-in-the-sky-chris-lintott-2.
How we source, check and correct cards: Editorial standards.
General information, not professional advice. Spotted an error? Flag the card or see corrections and complaints.
Intellect Plus is a visual educational discovery platform for exploring fascinating facts and ideas. Brain Food, Not Brain Rot. What is Intellect Plus?
