The Hubble Space Telescope's main feature is it high tech mirror which was originally designed in 1986. This mirror measures 8 feet in diameter and weighs almost 1800 lbs. It is constructed of ultra-low expansion silica glass and coated with a thin layer of pure aluminum to reflect visible light. A thin layer of magnesium fluoride is layered over the aluminum in order to reduce the risk of oxidation and the reflection of ultraviolet light. The telescope measures 44 feet in length, 14 feet in diameter, and weighs almost 13 tons. The orange cylinder attached to the telescope is one of the two solar arrays that will unroll in orbit providing a 40 foot long solar panel that will provide 1200 watts of power to the Hubble Telescope's batteries. Its deployment was delayed for 4 years due to the unfortunate Challenger accident, but in 1990 space shuttle Discovery sent it on its way.
Operations
The telescopes tracking system is pin-point accurate. This system is comprised of reaction wheels that are responsible for the mechanical movement of the telescope. Gyros report its position, while star trackers are responsible for providing reference points. All the systems are tied in together by Hubble's on board computer that controls and monitors the entire pointing process. The data it collects is relayed to Earth very differently than previous explorer satellites. First the telescope receives images which are converted into a digital code and sent by radio waves toward Earth. This is accomplished by using its high-gain antennas which transmit at a rate of one million bits per second. Once received, the digital codes in transferred into photographs and spectrograph readings that are used by scientists.