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Over the past two years, Starsys and The Johns Hopkins University Applied Physics Laboratory (APL) have been working toward the development of a thermal panel that uses a spacecraft’s internal power to control its temperature. The panel incorporates two different thermal technologies: a thermal switch and a high conductivity composite radiator. While thermal switches have been used before, the design and testing costs associated with each new design make them an undesirable alternative. The MISER panel incorporates a fully tested thermal switch with a radiator into a modular system that can be easily added onto any spacecraft structure. The lightweight radiator makes it self-supporting, so interfaces with the mounting structure are simplified. The same panel can provide thermal control over a wide range of environmental conditions, making constellation spacecraft viable with significantly different orbits.

A new type of thermal radiator has been developed to provide cooling for a spacecraft or spacecraft sub-system. It consists of a very thin, and in some cases, very flexible composite laminate fabricated from composite materials incorporating high thermal conductivity pitch fibers and a space-qualified polymer resin system. The radiator is light and flexible enough to be easily attached to the outside of the spacecraft's thermal blankets by non-structural means. It is fabricated as a flat panel, yet, in some configurations, can be flexible enough to be bent to conform to the shape of the thermal blanket. Since the approach described here is extremely flexible and lightweight, it experiences negligible stresses and imparts negligible loads to the spacecraft. Therefore it can be easily designed and installed with very little schedule and cost impact. Prototypes of this concept have been successfully designed, fabricated, and tested at JHU/APL, the results of which are described here.

The use of composite materials with high thermal conductivities is increasingly widespread in space flight applications. However, as opportunities for these new materials expand, practical limitations restrict their use. Some limitations are inherent in the composite materials themselves, like thermal conductivity and radiation shielding, and some are imposed by external design rules, like electro-magnetic interference (EMI) shielding and grounding. This paper reviews the work done at the Johns Hopkins University / Applied Physics Laboratory (JHU/APL) to quantify the thermal characteristics of high conductivity fiber/polymer matrix composites, to identify the other design constraints that limit their use, and the ongoing effort to reduce those limitations.