A Fleck of Paint Blinded Hubble

NASA's billion-dollar telescope opened its eye in 1990, and every star was a blurry smudge. In 1981, a laser lining up the tool built to test Hubble's main mirror bounced off a worn spot of black coating. One lens inside the tool sat 1.3 mm out of place. The mirror was polished until it passed that flawed test—perfectly smooth, but too flat at the edge by about 2 microns. Two other tests showed the error, but both were dismissed. 3D scenes are illustrations; the M100 galaxy images are real Hubble photographs. Sources: NASA, The Hubble Space Telescope Optical Systems Failure Report (1990), https://ntrs.nasa.gov/citations/19910003124; NASA, Hubble's Mirror Flaw, https://science.nasa.gov/mission/hubble/observatory/design/optics/hubbles-mirror-flaw/ M100 images: NASA/STScI (1993); ESA/Hubble & NASA (2012), CC BY 4.0. #shorts #hubble #space #engineering