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Cooling detectors down to 0.1K will be of great importance for future far infra red and submillimeter space telescopes during the next few years. This objective can be reached using a Stirling Cryocooler and a Joule Thomson (JT) expansion stage to precool to 4K. The low temperatures are then obtained by an open cycle dilution refrigerator circulating 3He and 4He. This system does not need any cryogenic reservoir and can be launched at room temperature. In this paper, we present the characteristics and performances of the two parts of the refrigerator measured separately, showing the feasibility of such a system. Expected performances of the complete system are a base temperature of 100mK with 100nW heat load and a life time of 5 years with a reasonable gas storage weight (20-50 kg).

A novel orbital disconnect support (ODS) for cryogen tanks is described which makes use of the change of length of a “shape memory alloy (SMA)” element located at the warm end of a strap-type support. At room temperature the SMA-element is at its extended length with the support strap in disconnected condition. Upon heating the SMA-element to approximately 9O°C, it contracts such that it gets in contact with the support strap and provides the strap tensioning force. During testing of a breadboard ODS a ratio of up to 6,4 between the connected and disconnted heat flux via the ODS was demonstrated.