Since its launch into low-earth orbit by Space Shuttle Discovery in 1990, the Hubble Space Telescope has been humankind’s eye in the sky. This year celebrates 25 years of Hubble’s work in opening up the mysteries of space and time through observations unclouded by the earth’s atmosphere. Hubble’s images of deep space objects are artworks in their own right, and the data it has collected have reshaped our notions of the cosmos and the laws of physics.
Named after American astronomer Edwin Hubble (1889-1953), who discovered other galaxies outside our own, and showed that the universe was expanding in ways consistent with the Big Bang theory, the telescope has lived up to its famous namesake. Its initial project to measure distances to Cepheid variable stars helped to determine the rate of expansion and thereby the age of the universe. Hubble high-resolution images helped to prove the existence of black holes at the center of most galaxies. In 1994, Hubble captured images of the collision of Comet Shoemaker-Levy with Jupiter. Ongoing projects like Hubble Deep Field, Hubble Ultra-Deep Field, and Hubble Extreme Deep Field, which images the remotest galaxies, also offer a wealth of information about the early universe.
Built jointly by NASA and the European Space Agency, the telescope is theoretically open to use for observation by anyone regardless of nationality or affiliation. In practice, high demand means that only about one fifth of all proposed projects are approved. The Hubble Space Telescope was designed for versatility and access by space shuttle crews for servicing and repairs. Repairs, for example, were needed at the outset to correct problems with the lens, which had been ground incorrectly. There have been five service and repair mission; the last in 2009. Hubble is due to be replaced in 2018 by the James Webb Space Telescope, but may continue until orbit decay ends its mission.
As intended, Hubble has captured the popular imagination with its images of deep space objects and celestial events. Scheduled anniversary celebrations include concerts, lectures and online events. Projects like Citizen Science and the weekly Hubble Hangouts invite participation to continue the excitement and adventure of discovery.