In the frame of the ESA e.Deorbit study (Architecture Definition phase), a highly integrated and collaborative MBSE process related to Systems Modelling and Simulation has been developed and applied for supporting the iterative generation and maturation of the system requirements, architectures and system budgets at phase B1 level. e.Deorbit is a compelling mission concept that addresses the most pressing debris challenge for Europe: the post-life disposal of ESA’s environmental satellite Envisat. The e.Deorbit robotic-based chaser is characterized by strong safety (avoid collisions between chaser and target) and autonomy (capabilities to operate automatically with ground supervision) features. Additionally, the system complexity w.r.t.