The @Hubble Space Telescope, also called the @HST, is a telescopic observatory that orbits 600 kilometers above the @Earth. It is the first scientific mission of any kind designed for routine service by astronauts. It is one of the largest and most complex satellites ever built and was deployed April 25, 1990 from the space shuttle @Discovery.
When Hubble was designed in the 1970s, @NASA stated that its main scientific objectives were to determine:
* The constitution, physical characteristics, and dynamics of celestial bodies.
* The nature of processes that occur in the extreme physical conditions existing in and between astronomical objects.
* The history and evolution of the universe.
* Whether the laws of nature are universal in the space-time continuum.
That's a pretty tall order for a relatively small object!
The Hubble Space Telescope is as large as a tractor-trailer (43.5 feet long and 14 feet in diameter) and weighs 12 tons. It looks like nothing more than a five-story tower of stacked silver canisters. But each canister houses important telescope equipment. The telescope has focusing mirrors, computers, imaging instruments, and pointing and control mechanisms. Extending from the telescope are solar panels for generating electricity and antennae for communicating with operators on the ground.
Scientists can see better with Hubble than with any telescope on the ground because Hubble travels above the atmosphere. On Earth, the atmosphere makes pictures taken by visible-light telescopes look smeary û clouds, precipitation, and atmospheric temperature changes get in the way. But in the near vacuum of space, Hubble can take very clear, crisp pictures -- no clouds or atmosphere exist between it and the star or galaxy it's observing.
Every day Hubble archives between three and five gigabytes of data and sends 10 to 15 gigabytes to astronomers around the world. Once the telescope gathers the data, its computers turn the information into long strings of numbers that are beamed to @Earth as radio signals. This information streams through a series of satellite relays to the @Goddard Space Flight Center in @Greenbelt, @Maryland. Then it travels by telephone line to the Space Telescope Science Institute in @Baltimore.
