Development of a Practical Approach for Thermal Vacuum Cycling Tests for CubeSat Applications

Abstract

For a CubeSat-based mission to succeed, several development stages are required: concept definition, technology development, verification and validation, and, finally, integration and launch. Among these stages, one of the most critical is testing the CubeSat’s systems and subsystems, as it ensures they can withstand the harsh conditions encountered during and after launch. Thermal-related tests are particularly significant, as they ensure the CubeSat remains operational throughout multiple orbits under constant vacuum exposure and thermal variations. To simulate these conditions, the thermal vacuum cycling test (TVCT) must be performed. Although this test is considered one of the most critical in the qualification process, it is often procedurally complex, costly, and not easily accessible to university-based groups, especially for preliminary evaluation. Furthermore, defining and conducting the TVCT are not straightforward tasks. Standards such as those established by the European Cooperation for Space Standardization (ECSS) specify parameters and requirements for TVCT, often tailored to high-performance facilities. As a result, applying these procedures to small-scale or low-cost setups becomes challenging, particularly when the objective is preliminary or subsystem-level evaluation. To address these constraints, the Laboratory of Applications and Research in Space (LARS), in partnership with SpaceLab from Federal University of Santa Catarina (UFSC), developed an adapted set of procedures for performing TVCTs using a low-cost thermal vacuum chamber (TVAC), focusing on accessibility while maintaining methodological rigor. To verify the methodology, an open-source electrical power system (EPS) model and conformal coating materials were tested in accordance with the proposed procedures, enabling a preliminary evaluation of component behavior under thermal-vacuum conditions. The tests were conducted at pressures ranging from 1 × 10−2 mbar to 1 × 10−5 mbar. Cooling was provided by liquid nitrogen, while thermal control was achieved through electrical resistances controlled by a proportional–integral–derivative (PID) control system, resulting in ambient temperature variations of approximately -20°C to 55°C. The authors thank the financial support provided by the Brazilian Space Agency (AEB) under Grant No. 202112791 (SIGPEX). The EPS components were evaluated before and after the tests and showed consistent performance, indicating no degradation from vacuum exposure or temperature cycling. The test campaign also allowed assessment of the operation of the EPS’s integrated heaters, which performed as expected, and of a commercial conformal coating, which showed poor performance under thermal-vacuum conditions. These results demonstrate that the proposed set of procedures helped conduct preliminary evaluations and can be replicated by other groups using similar facilities. Moreover, the LARS’s TVCT provides a viable and accessible alternative for initial testing before more rigorous qualification campaigns.