CubeSat Thermal Testing Methods and Thermal Environment Simulation Trade-off

Spacecrafts face a harsh thermal environment with thermal variabilities induced by a varying sun flux, eclipse, or change in altitude, which emphasizes the importance of spacecraft thermal control verification, and in particular thermal vacuum test. A wide variety of solutions are currently used in agencies and industries around the world, however, when it comes to the selection of a simulation method, questions arise as to which method is best to implement. This is primarily regarding the spacecraft's specific needs of spectral coverage, lead time, cost, simulation accuracy (spatial uniformity), thermal controllability (cooling rate), and the overall representation accuracy of the thermal space environment. On another side, in academia, such as in CubeSat teams around the world, solar flux simulations are rarely implemented into their subsystem-level thermal vacuum tests. This is due to the anticipated complexity of the engineered sunlight as well as the justification for it. This paper will outline a thorough trade-off of the current approaches to sun simulation for regular sized spacecrafts, as well as a secondary trade-off highlighting the possible methods that can be used with more limited resources for CubeSat teams. Both these trade-offs will take into account a generic single-node study of typical CubeSat orbits (e.g. Low Earth Orbit, Medium Earth Orbit and Geostationary Orbits) to provide a more justifiable selection. In addition, European and North American CubeSat team’s current approaches to thermal tests will be illustrated. This paper aims to encourage CubeSat teams to use solar simulator flux during their thermal vacuum tests by providing a trade-off of possible approaches, and also ease the method selection for larger spacecrafts.