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.