17 November 1995
ISO, ESA's Infrared Space Observatory, was successfully launched by an Ariane 44P launcher from Europe's spaceport in Kourou at 22h20, on 16 November 1995, (02h20 CET on 17 November 1995).
ISO is a high-technology telescope facility designed and built in Europe for use by the scientific community in Europe, Japan and the USA. It will provide astronomers with an unprecedented opportunity - the only one in the next decade - to make scientific observations of a wide variety of weak infrared radiation sources such as cold gases, galaxies and stars dying and being born. ISO represents a leap forward in space technology harnessed for astronomical observation of the universe.
ISO is the world's first astronomical observatory in space operating at infrared wavelengths. To observe the weakest heat sources in the universe, its four scientific instruments have to be cooled to extremely low temperatures, using superfluid helium which evaporates slowly at minus 271 or about 2 degrees above absolute zero. The scientific instruments, telescope and liquid helium are all contained in a cryostat, which has been likened to an extraordinarily well insulated thermos flask. It is the first such cryogenically cooled satellite developed in Europe and employs very advanced technologies, notably for the scientific instruments, telescope and attitude control system.
ISO will be controlled from the ESA's Space Operations Centre (ESOC) in Darmstadt, Germany, for the first few days, until the final orbit is achieved, and then operational control will be passed to a dedicated ESA operations centre in Villafranca, Spain. The first 21/2 months of operations will be given over to commissioning the satellite and verifying the performance of the scientific instruments. The observation programme is planned to start in early February 1996. ISO's lifetime is expected to be 20 months, by the end of which the helium, steadily evaporating as it cools the cryostat, should be exhausted.