The European Space Agency's (ESA) Herschel Space Observatory is the largest ever infrared space observatory. It collects radiation from some of the coldest and most distant objects in the Universe. The UK has led the development of one of the three instruments on board.
A new infrared space observatory
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Artist's impression of the Herschel satellite.
Launched on 14 May 2009
See also Planck
Herschel observes previously unexplored wavelengths of light in the far infrared region of the electromagnetic spectrum to examine the formation of galaxies and stars.
Stars form inside big clouds of gas and dust, which act as a thick fog when viewed using visible light. Herschel is sensitive in the far infrared so astronomers are able to see through these clouds to witness what is going on inside.
Herschel's major objectives are discovering how the first galaxies formed and evolved to give rise to present day galaxies like our own. It is also to investigate the continuing formation of stars in our galaxy today. Herschel observes clouds of gas and dust where new stars are being born, disks out of which planets may form and cometary atmospheres packed with complex organic molecules.
Herschel has a 3.5 m telescope, much bigger than on any previous far infrared satellite. It can therefore collect more light and produce better images.
For more information on Herschel, visit either of the following ESA pages: Launch Special: Herschel or Science & Technology: Herschel and the UK Herschel website.
Herschel was originally named FIRST (Far Infrared and Sub-millimetre Telescope) but was renamed in honour of the pioneering astronomers William and Caroline Herschel.
Herschel was launched on an Ariane 5 rocket together with ESA's
spacecraft. The two spacecraft separated after launch.
Prior to launch, all the instruments were installed in the spacecraft and thoroughly tested as part of the complete system. The complete Herschel satellite then underwent further tests at the ESA technology centre ESTEC, in the Netherlands, where it was put in a test chamber to simulate the space environment. Finally Hershel was transported to Kourou in French Guiana for the launch.
The Herschel spacecraft is approximately 7.5 m high and 4 x 4 m in overall cross section. Its launch mass was a hefty 3.3 tonnes.
With a diameter of 3.5 m, Herschel has the largest mirror ever built for use in space.
The spacecraft comprises two modules. The power supply, computers and communication systems and the pointing system are housed in a service module. The payload module consists of the telescope, a sunshade with solar panels and three scientific instruments contained inside a large liquid helium tank or 'cryostat'.
In order to make measurements at infrared and sub-millimetre wavelengths, parts of the instruments have to be cooled to as near absolute zero (-273.15 °C) as possible. The instruments and their common mounting structure are contained within the cryostat. More than 2,000 litres of liquid helium will be used during the mission to keep everything cold.
A key component of the satellite was led by the UK. The SPIRE (Spectral and Photometric Imaging Receiver) instrument has been developed by an international consortium. It is led by a Principal Investigator from Cardiff University.
The assembly and testing of SPIRE took place at the STFC Rutherford Appleton Laboratory (RAL) in Oxfordshire. The instrument was delivered for installation in the Herschel satellite in April 2007. Other UK institutes involved in SPIRE are Imperial College London, University College London's Mullard Space Science Laboratory and the UK Astronomy Technology Centre, Edinburgh. The UK SPIRE team has lead responsibility for instrument operations.
UK companies involved in the mission include AEA Technology, Analyticon, BOC Edwards, Datasat, MT Satellite Products and System International.