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Good performance of the Columbus water loop active control system has been demonstrated by several analyses, ground test and is further confirmed by the current flight data. Even so, a comprehensive description of the control within the classical theory is needed, in order to complete the system description, posing also the basis for similar applications to come. Thermal and hydraulic control loops are considered as two separate systems and linear control methods are applied. Loop stability and performance is discussed by computing stability regions of the PI control coefficients at different loop configurations and results compared with available test, flight and simulation data.

Over the past 5 years ESTEC has funded work at the Rutherford Appleton Laboratory and BAe concerning the development of very low temperature (4K and 2.5K) cryocoolers with operational lifetimes in excess of 3 years. Therefore it was natural when taking into account the advantages of a closed cycle 3He refrigerator and the ESA 2.5K cryocooler that the idea of incorporating them into a 0.3K cryocooler should arise. In-house work at ESTEC started in 1992 with the goal of eventually obtaining a space qualified 3He refrigerator/2.5K cryocooler for long term operation, free of cryogen replenishment, which should weigh less than 40Kg and require less than 110W of power input. Two 3He refrigerators have been manufactured, which are still being tested. In this paper we will present the design of those 3He refrigerator. The experimental results on the thermal/mechanical behaviour of the refrigerator, using a liquid 4He bath cryostat as the pre-cooling stage, will be presented at the conference.

This paper describes the main changes affecting the APM Environmental Control System (ECS) as a consequence of the Space Station Freedom (SSF) restructuring and Columbus APM overall reconfiguration. The main purposes of this reconfiguration are: minimize the number and complexity of the interfaces with Space Station Freedom (SSF) centralize avionics command and monitoring tasks revisit the failure tolerance concept of some ECS functions unify/standardize similar functions in the two subsystem adjust lifetime requirements and simplify maintenance concept of equipment. The APM ECS consists of the following functions: active thermal control (ATCS) passive thermal control (PTCS) atmosphere pressure and composition control air revitalization and cabin ventilation temperature and humidity control vacuum and venting nitrogen supply fire detection and suppression. The new ATCS configuration provides a cooling capability for a reduced number of P/L racks by means of its moderate loop.

ESABASE/SUNLIGHT is a software tool to calculate illumination, effective illumination, exposure time, incident electromagnetic power, absorbed electromagnetic energy for spacecraft surfaces during planet orbiting missions considering sun and planet irradiation, effects of eclipse and self-shading, multireflections, transmission, pointing and (variable) geometry. Calculation applies a fast Monte Carlo raytracing algorithm and is based on wavelength dependent spectra and material properties. ESABASE/SUNLIGHT is fully integrated in the CAE-frame ESABASE which offers a powerful geometry specification language, orbit generator, pointing facility and advanced libraries as well as gateway, pre-, postprocessing and display tools with the benefits of standardisation and exchange to other analysis tools.

The European Space Agency ESA is preparing a mission to planet Mercury called BepiColombo in cooperation with ISAS, the Japanese space agency. Advanced thermal control materials and components are under development to allow the performance of the mission. The present paper gives an overview of the BepiColombo thermal control design and give emphasis to the continued effort in the development of a Solar Reflector Coating (SRC), an Optical Solar Reflector (OSR) and an Infra-Red Rejection Device (IRRD). Key issue in the development and validation of the components and related technologies is the long-term stability under the high temperature and high intensity radiation environment in the vicinity of Mercury. Therefore thermal and radiation endurance testing plays a major role. Candidate materials have been selected and the component design been defined. Development tests will establish mechanical, thermal and optical properties for the initial and end of life conditions.

As it is not possible to directly use commercial liquid flow meters in spacecraft fluid loops, a study was carried out for the European Space Agency to adapt commercial flow meter assemblies for space applications. The various activities (described in detail) eventually led to the selection of two commercial units, which were redesigned/adapted to be used in spacecraft single-phase (water) and two-phase (ammonia) thermal control loops. These flow meter assemblies were tested according to an agreed test programme, that included performance and calibration tests in a test bench (developed during the study), vibration testing and EMC/EMI testing. The results are discussed in order to assess to what extent the study objectives were met. Recommendations for future work are given also.