Definition: Hubble Space Telescope
Launched in April 1990, this orbiting telescope views star material some 10 to 12 billion light years from earth, and its digital images have contributed greatly to our knowledge of astronomy and science. Hubble was designed to receive periodic visits from space shuttle astronauts who would perform routine maintenance and instrument upgrades. The last such service visit took place in 2002, and with NASA authorization on hold for a fourth and final service, the projected lifespan of Hubble's work is 2010. For a fascinating look at Hubble's optics and operation plus extraordinary photos of its solar system targets, visit www.hubblesite.org.