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The ISAS's space VLBI satellite HALCA was successfully launched in February 1997. The spacecraft HALCA consists of a box shaped main structure and a large deployable mesh antenna with 8 m effective diameter. The integrated spacecraft with the mesh structure antenna is so large and complex that the thermal design and tests had been performed separately for the main structure and the large antenna. No thermal vacuum test had been conducted in the fully integrated spacecraft configuration. The complex heat exchange between the antenna and the main structure had been taken into account in the numerical thermal analysis. Good correlation between in-orbit temperature and flight prediction has proved validity of the design and the verification method where no integrated spacecraft thermal vacuum test was performed.

The MUSES-B spacecraft will be launched in 1996 by the Institute of Space and Astronautical Science (ISAS). Its primary mission is experiments on space Very Long Baseline Interferometry (VLBI) for radio astronomy using a large deployable antenna. A challenging thermal design must be compatible with a wide range of sun angle and an 86 minute eclipse. The thermal design and verification has been performed separately for the major modules of the spacecraft; a main structure, a deployable antenna and Reaction Control System (RCS). Special attention is paid to the exposed RCS whose solar input varies significantly depending on the sun angle. This paper describes the thermal design concept for MUSES-B and verification results of its thermal model test focusing on the main structure and the RCS.