Scientific and Engineering Aspects of the Active Phase Separator

The development of the Active Phase Separator (APS), which was initiated by the rather extreme demands for the GIRL (German Infrared Laboratory) mission, is reviewed. As a final result the APS model V is presented, which is suitable for space qualification and can be considered not only as an universal phase separator but also as a multifunctional component for space cooling systems, allowing a simplification of the valve plan. Besides discussing the scientific results obtained with annular flow channels and presentation of performance tests with the APS, the status of the actual IR telescopes IRAS, (Infra Red Astronomy Sattelite), GIRL, and ISO (Infrared Space Observatory) is summarized.