Design of the fault tolerant command and data handling subsystem for ESTCube-1

This paper presents the design, implementation, and pre-launch test results of the Command and Data Handling Subsystem (CDHS) for ESTCube-1. ESTCube-1 is a one-unit CubeSat, which will perform an electric solar wind sail experiment. The development process of the CDHS for ESTCube-1 was focused on robustness and fault tolerance. A combination of hot and cold hardware redundancy was implemented. Software, including a custom-written internal communications protocol, was designed to increase the system's fault tolerance further by providing fault detection and fall-back procedures. Tests were carried out to validate the implementation's performance and physical endurance. The final CDHS design is operational within the set requirements. Tests that verify fault tolerance of the system in orbit are suggested.