A -183°C Cryogenic Freezer for the International Space Station 2000-01-2325
In the frame of the CRYOSYSTEM A-phase study financed by the European Space Agency, AIR LIQUIDE (France) and ORBITAL HYDRAULIC-BREMEN (Germany) have been studying a -183°C freezer to be used on-board the International Space Station for freezing and storing biological samples. The CRYOSYSTEM facility is composed of the following elements:
the Cryogenic Storage Freezer (CSF), which is a 100 litre dewar vessel capable of storing up to 2000 vials below -183°C; the dewar is cooled by a Stirling machine producing 3.8 W at 90 K;
the Quick-Snap Freezer (QSF), which is a 30 litre dewar vessel to be operated at the Life Science Glovebox (or anywhere else in the station) and to be used for rapid freezing (22 K/min) of liquid samples and ultra-rapid freezing (at 106 K/sec) of solid samples such as rat skeleton muscles or lettuce roots; the freezer is also cooled by a Stirling machine;
the On-Orbit Preservation Rack (OPAR), which is a standard payload rack (ISPR) accommodating both CSF and QSF;
the Transportation Rack (TRACK), which is also an ISPR used for transporting the CSF in the Mini Pressurized Logistic Module (MPLM).
The OPAR and the QSF will remain permanently on-orbit for the lifetime of the station (12 years) while three CSF units and two TRACKs will support the cyclic upload/download of samples. When one CSF is on-board the ISS, another one is inside the MPLM ready for the next mission, while the third one is on ground.
This paper presents the cryogenic design and the analyses of the QSF and the CSF. A breadboard of the ultra-rapid freezing equipment has been built and patented. The good test results of this equipment are presented, as well.