Reaching the parts ...

Herschel will be the largest space telescope of its kind when launched. Herschel's 3.5-metre diameter mirror will collect long-wavelength infrared radiation from some of the coolest and most distant objects in the Universe.

Infrared radiation is invisible for the human eye. It is actually 'heat', or thermal radiation. Even objects that we think of as being very cold, such as an ice cube, emit infrared radiation. For this reason, infrared telescopes can observe astronomical objects that remain hidden for optical telescopes, such as cool objects that are unable to emit in visible light.

Earth's atmosphere acts as an 'umbrella' for most infrared wavelengths, preventing them from reaching the ground. A space telescope is needed to detect this kind of radiation invisible to the human eye and to optical telescopes.

The Herschel satellite is a tall 'tube' 7.5 metres high and 4 metres wide, with a launch mass of around 3.3 tonnes. It will carry the infrared telescope and three scientific instruments. The bulk of the spacecraft consists of a liquid helium thermos bottle inside which the instrument detectors sit and are cooled down to only a few degrees above absolute zero.

Herschel will be launched in 2008 with another mission, Planck - a mission to study the cosmic microwave background radiation - on an Ariane rocket. The two spacecraft will separate about 2.5 hours after launch and will operate independently. In less than six months, Herschel will reach its operational orbit around a point in space known as the second Lagrangian point (L2), situated at 1.5 million kilometres away from the Earth.

Exploring formation of stars and galaxies, ESA's Herschel space observatory (formerly called Far Infrared and Submillimetre Telescope, or FIRST) will give astronomers their best view yet of the universe at far-infrared and sub-millimetre wavelengths, bridging the gap in the spectrum between what can be observed from ground and earlier space missions of this kind.

Herschel overview
Reaching the parts .…. with Herschel and SPIRE from SciTech
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The Science and Technology Facilities Council SciTech
Formed by Royal Charter in 2007 (by combining CCLRC and PPARC), the Science and Technology Facilities Council is one of Europe's largest multidisciplinary research organisations supporting scientists and engineers world-wide.
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