A Brief History of the Hubble Space Telescope

Mirror, Mirror
The Hubble's primary mirror, nearly eight feet across. A flaw in the mirror was discovered after the Hubble was in space; thanks to miscalibrated equipment, its glass had been ground slightly too finely at the edges. Though the imperfection measured just one-fiftieth of the thickness of a piece of paper, it distorted the Hubble's images. Astronauts fixed the problem in 1993.

• Animals in Space