This is the backup mirror for the Hubble Space Telescope, 2.5 m in diameter, on display at the National Air and Space Museum of the Smithsonian Institution in Washington, DC. This mirror was polished by hand to a precise paraboloidal shape by Kodak. The mirror sent into space was machine-polished to a precise spherical shape by Perkin-Elmer, a mistake that crippled the telescope. An additional mirror system was later installed by Space Shuttle astronauts to compensate, allowing the Hubble to send back the many amazing photographs we’ve seen.