In 1990 NASA launched the finest telescope ever built, and it came back blurred. Its mirror had been polished more precisely than any large mirror in history — to the wrong shape, too flat at the edge by about two microns, one-fiftieth the width of a human hair.
They had checked it against an instrument built for the purpose. A lens inside that instrument was in the wrong place by one and a third millimetres. So the mirror was measured against a ruler that lied, and it passed beautifully.
But they had two other instruments. Both said something was wrong. Both were disregarded — for being the cheap ones.
The Magnanimous Doctor Warthan opens the file on the most precisely manufactured mistake in history: the test that was skipped to save money, the review team disbanded the week the polishing finished, the spectacles built for a telescope, and the five spacewalks that fixed it. Plus the detail almost nobody knows — they never fixed the mirror. It is still the wrong shape tonight.
Technical details drawn from the NASA Hubble Space Telescope Optical Systems Failure Report (the Allen Commission, November 1990).
The Doctor’s voice and the Society’s imagery are synthesized.