Commercial Off-The-Shelf (COTS) electronic components offer cost-effective solutions for the development of On-Board Computers (OBCs) in the small satellite industry. However, the COTS parts are not originally designed to withstand the space radiation environment. Traditional fault-tolerance practices rely on expensive radiation tests or are based on circuit-level knowledge which are not easily available. This work proposes a novel simulation-based statistical approach to assist the satellite designers in performing OBC fault-tolerance analysis. The presented novel approach is based on high-level system modeling and an object-oriented fault injection mechanism. Such a technique allows the comparison between fault-tolerance techniques and reveals the consequences of radiation effects in the COTS parts at early development stages. The work covers the implementation of the proposed simulation framework which includes the OBC and fault modeling. The fault models are based on the conducted radiation environment analysis. The range of software and hardware fault detection and mitigation techniques are investigated as case studies. They include time and hardware Triple-Modular Redundancy, FPGA-based memory scrubbing with Hamming encoding, and watchdog/co-processor monitoring. The case studies reveal that the proposed approach can be used to choose suitable fault-tolerance techniques, increase their efficiency, and reduce the required hardware resources. Three papers are included: - SystemC-based On-board Computer Modeling for Design Fault-Tolerance Assessment - A Simulator of On-Board Computers for Evaluating Fault-Mitigation Techniques - System Fault-tolerance Analysis of Small Satellite On-board Computers