A 90 K freezer, currently named CRYOSYSTEM, will support biological and medical experiments on board the International Space Station. The samples produced are intermediately stored under cryogenic conditions and downloaded to ground for further examination. Typical samples are animal tissue, organs, and plants, as well as organic fluids and protein crystals. A Development Model (DM) of the freezer has been manufactured and tested by AIR LIQUIDE. The system is composed of a vacuum insulated shell equipped with a revolving magazine capable of freezing and storing up to 880 2-ml vials. The cryogenic cooling is produced by an engineering model Stirling cryocooler specially adapted for the needs of CRYOSYSTEM from a THALES Cryogenics BV tactical cryocooler. This paper presents test results regarding the quick freezing of liquid samples, the snap freezing of solid samples, and the capability of the freezer to withstand power-off periods and to recover within the allocated time. Some preliminary correlations with ESATAN predictions are discussed.
