A thermal management system for a spacecraft module includes a baseplate and wall system that is precharacterized to provide a given level of thermal performance regardless of an orientation of the spacecraft relative to a source of solar energy. The system is characterized at a worst-case hot orientation, and at a worst-case cold orientation. The characterization provides a maximum temperature and a minimum temperature of components mounted on the baseplate as a function of the height of the walls. The height of the walls is selected to provide a suitable temperature range for the components, based on the power dissipation of the components. The system is designed to be symmetric, so that this temperature range is assured regardless of the orientation of the spacecraft.