Small Satellite Validation of a Simulation Approach for Assessing Dynamic Temperatures in Orbit

Small satellite launches have proliferated as an economically-efficient approach for space access. Accurately predicting satellite temperatures during orbit is of interest to the satellite community due to a high rate of thermal failure combined with limited means of thermal control due to size, weight, and power constraints. Primary contributors to this radiation-dominant simulation problem include optical surface properties and orbit altitude, which impacts view factors. Additionally, the photovoltaic (PV) panel power output and internal components such as circuit board assemblies and battery cells must be considered, since the PV panels charge the battery pack, which powers the electronics.

To address this simulation need, we developed an automated approach for dynamic orbit thermal prediction. TAITherm, a comprehensive heat transfer simulation software, uses an explicit 3D geometric representation of a satellite to automatically create the radiation and conduction nodal networks necessary for transient thermal simulation. Thermal and optical properties are used as inputs for conduction and radiation, respectively; similarly, space environment, solar position, and solar irradiance boundary conditions are also collected via simple user inputs. CoTherm, a simulation process automation tool, handles the dynamic positioning of the satellite as it orbits the Earth.

In this paper, we detail this dynamic orbit thermal simulation methodology and describe a successful validation of this approach via comparison to published results for a representative 3U CubeSat. We then demonstrate the integration of PV power yield predictions, which depend on temperature, incident angle and radiation degradation. We also incorporate a battery pack using equivalent circuits, include charging of the battery cells from the PV panels, and show how electronic circuit board assemblies can be used in assessing power budgets. This study lays the groundwork for thermal predictions of battery packs, interior electronics, exterior surfaces, and solar panels of an orbiting satellite.