Strategies for Thermal Control of a Multifunctional Power Structure Solar Array

Abstract

Multifunctional power structures (MFPS) are fully integrated subassemblies that perform both structural and power functions for spacecraft. By combining functions across subsystems into single units, mass and volume savings can be achieved. Focusing on battery-based MFPS in Earth-orbiting spacecraft, the embedded lithium ion batteries that are used have strict temperature limits, outside of which efficiency and safety is compromised. Considering the limits of the model’s prediction accuracy, numerical simulation has shown that a range of Earth orbits exist where an MFPS mounted in a deployed solar array would not require the addition of further thermal control with respect to the nonmultifunctional case. The numerical simulation consisted of a lumped parameter reduction of the model to a discrete set of layers. Thermal control is required to prevent overcooling of the battery in eclipse and to extend the range of orbits where MFPS can be used. An assessment of current thermal control was performed to establish the viability of each technology, with viability defined by feasibility and the mass of the system. The use of coatings, insulation, heaters, and phase-change materials were considered. It was found that the range of viable orbits is dependent on the quantity of MFPS savings that can be sacrificed.