07-07-2007 Space Observatories (Article 93)

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Simon Kenny
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07-07-2007 Space Observatories (Article 93)

Post by Simon Kenny » Wed Feb 04, 2009 11:10 am

Space Observatories (Article 93)

The last two decades have been a golden era in the development of telescopes of all kinds. The revolution in amateur telescope design, such as the Dobsonian or Cassegrain, combine features never before seen on a telescope: high quality optics, straightforward to use, easy to transport and set up. Nowadays, a good 200 millimetre scope is well within reach of most amateur astronomers.

At the other end of the spectrum, the revolution in high-end telescope design has been even more dramatic. The latest cosmic discoveries are being led by telescopes orbiting the Earth. The chief of these are NASA’s Four Great Space Observatories: the Hubble Space Telescope, launched in 1990, the Compton Gamma Ray Observatory, launched a year later, the Chandra X-Ray Observatory, launched in 1999 and the Spitzer Space Telescope, launched in 2003.

The Hubble was the first and most famous of these. Its successful deployment 600 kilometres above earth, well above the atmosphere, was rewarded with visual images of breathtaking clarity. However, astronomers and the public had to wait until 1993 for Hubble to show its full capabilities, when a space shuttle mission was launched to insert a module to upgrade its 2.4 metre primary mirror. Ever since, it has continued to provide us images from the Visual, Infra-Red and Ultra-Violet regions of the spectrum, contributing immensely to our knowledge of the evolution of stars and galaxies. Hubble is still going strong after nearly seventeen years. Its great success proved the viability of space telescopes.

Hubble, however, was designed only to examine relatively confined areas of the electromagnetic spectrum. Above the earth’s atmosphere, a telescope can examine a much wider spectral range, all the way to X-Rays and high-energy gamma-rays. Other space observatories now systematically explore these other spectra, providing a wealth of new knowledge of the cosmos.

The Compton Observatory, called after Arthur Compton, the X-ray researcher, was designed to observe the sources of cosmic X-Rays. These are known to come from extremely violent events in stars and galaxies. The data it collected is helping scientists understand violent events such as Quasars, Gamma-Ray Bursts and Black Holes. In June, 2000, its work complete, the 17-tonne observatory was allowed burn up in the Earth’s atmosphere.

The Chandra Observatory was named after Subrahmanyan Chandrasekhar, the 1983 Nobel laureate for his work on stellar evolution. This observatory studies evidence that may clarify the origin, evolution and destiny of our universe. Its powerful sensors and very high quality mirrors enable Chandra to take X-Ray maps of supernovae, quasars, black holes, and dark matter in unprecedented detail.

The fourth Great Observatory was the Spitzer Space Telescope. Named after Lyman Spitzer, who first proposed the idea of a space telescope in 1946, this telescope currently searches the infra-red part of the spectrum with its super-cooled instruments to detect the presence of cool, faint objects such as extra solar planets, molecular clouds and organic molecules in the inter-stellar medium. Clear skies!

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