Development of an ECSS-SMP Compliant Satellite Digital Twin

The growing complexity of modern space missions, combined with the push for more sustainable orbital operations, calls for advanced tools that can support design, testing, and operations. Among these, digital twins are emerging as crucial assets. Acting as dynamic, high-fidelity virtual counterparts of space systems, they evolve in step with real-time data, enabling predictive analysis, autonomous testing, and risk mitigation throughout a mission’s lifecycle. This thesis presents the first functional implementation of a Digital Twin for the Italian Space Agency’s In-Orbit Servicing (IOS) mission. The mission is designed to showcase critical technologies for satellite servicing, including repair, refueling, debris removal, and in-orbit assembly. The project was carried out in collaboration with Thales Alenia Space – Turin, with a focus on modeling and simulating the satellite’s Electric Power System (EPS). To ensure modularity, reusability, and smooth integration across simulation and operational platforms, the Digital Twin was developed in compliance with the European Cooperation for Space Standardization (ECSS) Simulation Model Portability (SMP) standard. The EPS Digital Twin incorporates detailed models of the Solar Array Wing (SAW), Solar Array Drive Assembly (SADA), Battery (BTA), and Power Control and Distribution Unit (PCDU). In addition, a simplified thermal model of the Robotic Control Unit (RCU) was created, including basic thermal control logic. All components were interconnected through standardized interfaces and implemented in C++ to guarantee performance and deterministic behavior, both essential for real-time simulation. Model development and validation were conducted using ESA’s SIMULUS framework. A major aspect of the work was ensuring SMP compliance, achieved by organizing models according to standardized interfaces and metadata definitions. This approach allows for seamless portability of the models into CNES’s ISIS operational ground segment environment without redevelopment. As a result, the Digital Twin can move directly from being a development tool to becoming an operational asset, supporting mission control in tasks such as anomaly detection, predictive simulations, and operational planning. Validation was performed through test cases designed to verify the physical accuracy of subsystem behaviors and the robustness of their interactions. The results confirmed that the EPS Digital Twin reproduces expected system dynamics with sufficient fidelity to meet the mission’s preliminary validation requirements. The main limitations identified relate to simplifications in the thermal modeling and to the lack of sufficient technical specifications, which are planned to be refined in future development phases. This work represents the first step toward building a complete Digital Twin of the IOS satellite. It contributes to Europe’s wider effort to develop interoperable, reusable simulation assets and demonstrates a scalable methodology that can be applied to future space programs. Beyond the IOS mission, the models and approach developed here provide a foundation for supporting sustainable and autonomous space operations in Low Earth Orbit and beyond.