Gleaned from NASA and Hubblesite.org, here are some facts you may not know about the Hubble Space Telescope (HST).
1. The HST’s history is longer than you might have thought, going back to just after World War II. In 1946, the astronomer Lyman Spitzer (1914-97) identified the main advantages that a space-based observatory would have over ground-based telescopes. Spitzer spent much of his career to pushing for the building of a space telescope.
2. Originally the HST was to have been bigger. NASA began seriously planning it in the mid-1970s. It was originally proposed to have a mirror diameter of 3m, but this was reduced to 2.4 m to save money.
3. The HST is still bigger than you might think. It weighs 11 tonnes and is 15.9 m long. That’s nearly as long as a couple of Routemaster doubledecker buses (each 8.4m long).
4. The HST doesn’t use as much power as you think. It uses about 2800 watts, while a typical kitchen kettle is rated at 2200 watts. Hubble gets its power from a couple of solar panels (each 2.6 x 7.1 m).
5. Hubble is pretty fast for a telescope, speeding around the world at 28 000 km/h. This is twelve times as fast as the cruising speed of the Concorde supersonic airliner (2270 km/h).
6. The HST can observe the furthest away galaxies ever seen but there are a couple of nearby objects it cannot look at. These are the Sun (so bright it would damage its sensors) and the planet Mercury, which is too close to the Sun.
7. Hubble is essentially a giant camera but it doesn’t use film. Its instruments capture the light from the Universe with electronic detectors (CCD’s) so it is basically a giant digital camera.
8. Hubble’s images of the wonders of the cosmos are recorded in shades of black and white, not colour. The final colour images we all love are actually combinations of two or more black-and-white exposures made through coloured filters. During image processing the colours matching the filters are added to the picture.
9. The HST has achieved all the objectives it was designed for. Probably its greatest achievement was measuring the age of the Universe to be about 13.8 billion years. This figure was more accurate than any previous measurement.
10. The Hubble telescope is in the final phase of its life. Sometime after 2014 failure of its vital systems will render it useless. Unless some kind of rescue is made, which is pretty unlikely, it will re-enter the Earth’s atmosphere and burn up sometime between 2019 and 2030. Goodbye Hubble, we’ll miss you. But don’t be sad, it will be replaced by the even larger James Webb Space Telescope.
Admin note: This article was first published in 2011. The HST is still in operation today and is helping astronomers the world over make fascinating discoveries. There are plans to have it running right through to 2020, with the hopes that it will be replaced by the James Webb Space Telescope.