Fact Impact: The Hubble Space Telescope
o The Hubble Space Telescope orbits 350 miles above our heads.o It travels at 7½ km/s ...o ... and circles the Earth every 97 minutes.o Its mirror measures 2½ m across...o ... and its tube is 13 m from end to end.o The whole structure weighs over 11 tonnes.o It draws three kilowatts of power, as much as an electric kettle...o ... and needs the equivalent of 20 car batteries worth of storage, as well as its solar panels.
o It was launched aboard the Space Shuttle Discovery in 1990 ...o ... and celebrated 20 years in space last April.o It's been serviced five times by the space shuttle...o ... and it can carry five different cameras and spectroscopes at any one time.
o Two on-board computers control Hubble: one steers the telescope and the other records the images.o Originally, custom-designed machines were used...o ... but for the past 10 years, an on-board Intel 486 has controlled Hubble's instruments.
o From space, Hubble can observe in infrared and ultraviolet light...o ... even though these wavelengths are completely invisible from the ground as they're blocked by the Earth's atmosphere.o Hubble has 20 times better resolution than traditional ground-based telescopes...o ... but it hasn't always been that way; for its first four years a fault in its optics made it little better at all.
o Hubble has measured the expansion of the Universe with unprecedented accuracy...o ... it has seen distant supernovae and found evidence for dark energy ...o ... it has seen debris discs in the Orion nebula which might one day form into planets ...o ... it has produced images of distant members of the solar system, Pluto and Eris ...o ... but it has never been pointed at Mercury, which is too close to the Sun to be observed safely.