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The satellite ‘HALCA’ was launched in February 1997 by the Institute of Space and Astronautical Science (ISAS), Japan. HALCA is a scientific satellite with a large deployable antenna to make experiments on space VLBI. The deployable antenna, developed under the requirements of large aperture area and accurate reflector surface, is formed of complicated structures and lots of mechanisms. Though heat exchange in the antenna was complicated and difficult to evaluate, antenna thermal performance in orbit was within expectations and all mechanisms were adequately controlled until the antenna deployment. This paper describes thermal control design of the large deployable antenna, thermal design verification in the thermal balance test, and evaluation of performance in orbit.

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.