Internally stowed, radially deployed radiator panels for passive CubeSat thermal control

Abstract

CubeSats experience significant thermal loads due to solar irradiation and the dissipation from electrical components. The high heat dissipation per unit volume can lead to mission failure if not properly managed. Deployable radiators that are externally stowed and passively actuated in response to changes in CubeSat temperature have been explored as a viable solution. This work describes a radially deployed fin array that is stowed within the CubeSat body when the required heat dissipation is low and passively deploys when the required heat dissipation is high. Internal stowage improves thermal transport to the deployable fins and minimizes heat loss when thermal inputs are small. A test article was manufactured and tested in a cryogenically cooled vacuum chamber environment. Thermal simulation of the radiator system was developed using Thermal Desktop and calibrated using test data. A primary goal of this work was to determine the turndown ratio (largest cooling power / smallest cooling power) of the system which specifies the range of dynamic thermal control. For the experimental test conditions, a turndown ratio of 1.98 was achieved when considering heat loss from the entire CubeSat test article when the CubeSat body temperature is 325 K. However, the turndown ratio is much larger when considering only heat loss from the radiator panel thermal control system (8.35), as the heat loss from the panels is minimal when stowed. Results demonstrate the efficiency of a passive thermal control design in regulating CubeSat temperatures and the benefits of an internal stow design. This approach is shown to achieve a reduction in CubeSat body temperature of 60 °C with a phase lag of 10 min.