Through-life modelling of nano-satellite power system dynamics

This paper presents a multi-fidelity approach to finding optimal, mission-specific power system configurations for CubeSats. The methodology begins with propagation of the orbit elements over the mission lifetime, via a continuous-time model, accounting for orbital perturbations (drag, solar radiation and non-spherical geo-potential). Analytical sizing of the power system is then achieved at discrete long-term intervals, to account for the effects of variations in environmental conditions over the mission life. This sizing is based on worst case power demand and provides inputs to a numerical assessment of the in-flight energy collection for each potential solar array deployment configuration. Finally, two objective functions (minimum deviation about the orbit average power and maximum average power over the entire mission) are satisfied to identify the configurations most suitable for the specific mission requirement. Most Nano-satellites are designed with relatively simple, static-models only and tend to be over-engineered as a result, often leading to a power-limited system. The approach described here aims to reduce the uncertainty in energy collection during flight and provide a robust approach to finding the optimal solution for a given set of mission requirements.