Herschel Space Telescope
Herschel is the largest space telescope ever launched. Its 3.5 m-diameter mirror will give astronomers their best view yet of the Universe at far-infrared and sub-millimetre wavelengths.
The European Space Telescope will launch on 29 April 2009 from Kourou with an Ariane V rocket, together with the Planck Satellite. The mission is named after the German-British astronomer William Herschel that is best known for the detection of the infrared radiation and the planet Uranus.
The Herschel Space Telescope was formerly known as Far Infrared and Sub-millimetre Telescope (FIRST) and is the first infrared telescope that covers the full far infrared and submillimetre waveband (covering approximately the 55-672 micron range). 
The instruments will be cooled with liquid helium, boiling away in a near vacuum at a temperature of approximately 1.4 K. The 2,000 litres of helium on board will limit its operational lifetime.
The key science objectives of the Herschel observatory are:
Infrared radiation can penetrate the gas and dust clouds that hide objects from optical telescopes, allowing astronomers to see deep into star-forming regions, galactic centres and planetary systems. Unlike a ground based telescope where Earth’s atmosphere blocks most infrared wavelengths is in space a free view.
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