<p>Satellite failure detection isolation and recovery (FDIR) is the discipline that involves monitoring a system, identifying faults and recovering from them. Established implementation are either based on a flexible but limited PUS-based approach or a dedicated implementation in software for more complex failure handling. Being able to implement complex rules in a more flexible manner improves FDIR implementation efficiency and operation. The aim of this paper is to demonstrate the usage of a knowledge base to collect and use expert knowledge more directly and provides a flexible implementation for FDIR engineers. Therefore, a rule-based system based on the CLIPS production rule system is integrated into an Onboard Software (OBSW) reference implementation and validated on a rover platform. It was shown that rule-bases can be implemented to interface with existing OBSW services to provide a simple usage of this concept. This makes it possible to implement and verify FDIR rules in the rule base before integrating it in the OBSW. Moreover, it allows to explain reactions to failures.</p>