|Back to Press Kit|
|1 December 2003|
ISO was the world's first space observatory able to see the sky in infrared light. This pioneering position allowed ISO to unveil a new 'face' of the Universe, its infrared face. This has changed radically our view of the Universe. ISO operated between November 1995 and May 1998, and made 30 000 scientific observations.
Infrared light is invisible to the human eye and to optical telescopes, which are sensitive to the same light the human eye can see. Moreover, the Earth's atmosphere prevents most infrared radiation from reaching the ground, so a space telescope is needed to detect it. For these reasons, the infrared universe was very poorly known until ISO. All objects emit infrared radiation. The sky therefore looks very different when seen in the infrared. ISO could see objects and processes that are too cold or too dusty, or both, to appear when you look through optical telescopes, such as clouds in which stars are being born.
ISO's results impact most fields of astronomical research, from comets to cosmology. One of ISO's greatest achievements was the discovery that the water molecule is very common in many regions on the Universe, even in distant galaxies. Astronomers from all over the world continue to make frequent discoveries by studing the observations stored in the ISO data archive.
Scientific highlights to date
ISO has more than fulfilled scientists' expectations. More than 1000 papers based on ISO observations have been published so far in refereed scientific journals, and the publishing rate is not decreasing. Some of the most outstanding ISO results are:
About 615 million Euros. This includes all aspects of the mission (spacecraft, launch, operations, and the current archiving phase until December 2006), except the scientific payload provided by the research institutes that was funded by their national governments.
ISO was launched by an Ariane-44P launcher from Europe's spaceport in Kourou, French Guiana, on 17 November 1995.
ISO orbited the Earth. Its highly elliptical orbit had a perigee at around 1000 kilometres; an apogee at 70 500 kilometres; and a period of almost 24 hours.
ISO's lifetime had been estimated initially as 20 months, but it was extended to more than 28 months (until May 1998). ISO's lifetime was limited by its liquid helium supply. The helium was used to keep ISO detectors extremely cold, at temperatures close to absolute zero (- 273°C). If the detectors had been warmer, their own infrared emission would have made it impossible to detect the infrared light from cold astronomical objects. When the liquid helium ran out, ISO had to stop observing.
ISO essentially consisted of: a large liquid-helium tank (a cryostat); a telescope with a 60-centimetre diameter primary mirror; four scientific instruments, and the service module.
2400 kilograms total launch mass.
Height: 5.3 metres Width: 3.6 metres Depth: 2.8 metres
The ISO satellite was developed, manufactured, integrated, and tested by an industrial consortium made up of 32 companies, mostly from Europe, headed by Aérospatiale, France.
What's on board?
ISO's four scientific instruments were developed by multinational teams with leaders in France, Germany, the Netherlands, and the United Kingdom.
Infrared Camera - ISOCAM Pictured the 'infrared face' of astronomical objects at a high resolution. It covered the 2.5-17 micron band with two different detectors.
Principal Investigators: C. Cesarsky, CEN-SACLAY, France.
Photo-polarimeter - ISOPHOT Detected the amount of infrared radiation emitted by an astronomical object. Covered a broad range of wavelengths: between 2.5 and 240 micron.
Principal Investigators: D. Lemke, MPI für Astronomie, Heidelberg, Germany.
Short-Wave Spectrometer - SWS Detected many molecules in space and revealed something about their physical conditions, such as temperature or density. Covered the 2.4 to 45 micron band.
Principal Investigators: Th. de Graauw, Lab. for Space Research, Groningen, The Netherlands.
Long-Wave Spectrometer - LWS Observed cooler objects than SWS. It was especially useful studying the physical condition in very cold dust clouds in the space between stars. Covered the 43 to 197 micron band.
Principal Investigator: P. E. Clegg, Queen Mary and Westfield College, London, United Kingdom.
ESA Mission Manager: Martin Kessler
Copyright 2000 - 2011 © European Space Agency. All rights reserved.