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ISO in ESTEC test facility
Since the first liquefaction of Helium-4 and the discovery of superconductivity by H. Kamerlingh-Onnes (1908 and 1911), cryogenics and its applications have come a long way.
Cryogenics is now recognised as a highly important mission enabling technology, allowing Earth observation and deep space observation satellites to be more effective. It is mainly used on space instruments to cool down the detectors covering the complete frequency range and the optics of Infrared Instruments. On-board the ISS, cryogenic cooling is used for long-term storage of samples.
Since the 1970s ESA has been involved in the development of space cryogenic systems. In the beginning the research was mainly focussed on superfluid Helium cryostats, which enabled the successful launch of the ISO cryostat in 1995 and is currently used for the Herschel cryostat, to be launched in 2008.
In the mid-80’s, Oxford University (UK) developed the first long-life Stirling cooler for Space application, which has been launched on the ISAMS satellite. With support from ESA, the technology has been transferred to industry, providing the first commercial space cryocoolers (80K Stirling cooler). Further improvements on the design lead to the 50-80K Stirling coolers, which have been used on several spacecrafts such as Envisat (MIPAS, AASTR), Integral and other non-ESA missions. To reach temperatures below 20K with active coolers, two-stage Stirling coolers have been developed in the past. The compressor technology used for the Stirling coolers have also been used for 4K He-JT coolers which are currently used on Planck. Pulse Tube coolers, also using linear compressors, but having no moving parts in the cold end, have been developed for future missions to provide cooling down to 50K. To overcome the problems of exported vibrations associated with the linear compressors, a vibration-free He-sorption JT cooler has been developed for sensitive missions as e.g. Darwin.
Long-life Stirling cooler
To reach temperatures below 1K, a He3-sorption pump cooler reaching temperatures down to 300mK has been qualified and is currently used on two instruments on the Herschel Space Telescope. Current developments are targeting temperatures down to 50mK, involving the use of Adiabatic Demagnetisation Refrigerators.
A reverse Turbo-Brayton cooler, providing cooling down to 190K has been developed in the past and is currently used on-board the ISS (MELFI) to enable long term sample storage.
Reverse turbo-Brayton cooler
Last update: 28 March 2007
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