Polishing Hubble's Mirror

This photograph shows the Hubble Space Telescope's primary mirror being polished at the Perkin-Elmer Corporation's large optics fabrication facility. After the 8-foot-diameter mirror was ground to shape and polished, the glass surface was coated with a reflective layer of aluminum and a protective layer of magnesium fluoride, 0.1- and 0.025-micrometers thick, respectively. The Marshall Space Flight Center was responsible for the design, development, and construction of the spacecraft, and the Perkin-Elmer Corporation, in Danbury, Connecticut, developed the optical system and guidance sensors.

Credit: NASA