In the course of CRYOSYSTEM phase B (development phase) financed by the European Space Agency, AIR LIQUIDE (France) and Astrium Space Infrastructure (Germany) have developed an optimized design of a −183°C freezer to be used on board the International Space Station for the freezing and storage of biological samples.
The CRYOSYSTEM facility consists of the following main elements:
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the CRYORACK, an outfitted standard payload rack (ISPR) accommodating up to three identical Vial Freezers
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the Vial Freezer, a dewar vessel capable of fast and ultra-rapid freezing, and storing up to approximately 900 vials below −183°C; the dewar is cooled by a Stirling machine producing > 6 W at 90 K. The Vial Freezer is operational while accommodated in the CRYORACK or attached to the Life Science Glovebox (LSG).
One CRYORACK will remain permanently on-orbit for several years while four Vial Freezers and two additional CRYORACKs support the cyclic upload/download of samples. When one or two Vial Freezers are on-board the ISS, the third is inside the MPLM ready for the next mission, while the fourth is on ground.
This paper presents an overview of the CRYOSYSTEM architecture and mission profile; the cryogenic design, which merges the cooling and cold storage functions in one freezer unit; and results of breadboards of critical components, such as the cooler.