The traditional approach to satellite design is a customized and highly optimized satellite bus. The primary design
driver is to minimize mass but often at the expense of schedule and non-recurring engineering costs. The result after
years of development is a high performance system with minimal flexibility. Consequently, there is a need for
responsive, small satellites that are able to accommodate different missions, changing threats, and emerging
technologies for which the traditional development approach is unable to satisfy. Instead, systems must be modular
and/or robust. One of the subsystems that will be challenging for the development of modular and/or robust
architectures is the thermal control subsystem (TCS). To design a traditional TCS, virtually every aspect of the
mission, the satellite, and the components must be known before an intense design program can be completed.
However, the mission, payload, components, and requirements are largely unknown before mission initiation. To
provide a baseline for the TCS design and to help bound the problem for the development of robust thermal systems,
the range of external and internal heat loads for small satellites were evaluated. From this analysis, the realistic worst
design cases were identified along with other requirements for robust thermal control systems. Finally, the paper will
discuss the merits of various thermal architectures and the challenges associated with achieving the requirements for
robust thermal control for responsive satellite buses.