A Concurrent Model-Based Systems Engineering Methodology for SmallSat Lunar Mission Design

This paper presents a Concurrent Model-Based Systems Engineering (CE-MBSE) methodology aimed at improving the design of complex space missions by combining the collaborative nature of Concurrent Engineering (CE) with the rigor and traceability of Model-Based Systems Engineering (MBSE). The proposed approach is centred on an integrated system model acting as a single source of truth across all lifecycle phases, enabling consistent management of requirements, system architectures, and multidisciplinary data. The methodology adapts concurrent workflows to different maturity stages, from early mission definition to verification and operational phases, while progressively increasing model fidelity. A modular and interoperable toolchain is introduced, integrating the Capella MBSE environment with the Altium Requirements & System Portal (RSP) through Python-based synchronization mechanisms, ensuring digital continuity and real-time data consistency across domains. The approach is applied and preliminarily assessed through its application to the BioMoon mission, a lunar CubeSat constellation designed to investigate the radiation environment and its effects on biological systems. Results demonstrate improved traceability across abstraction levels, enhanced multidisciplinary coordination, and the integration of quantitative engineering analysis within the verification workflow, while highlighting some challenges related to toolchain complexity, synchronisation overhead, and scalability to larger and more complex systems. Overall, the CE-MBSE methodology represents a promising framework to support coherent, knowledge-driven, and lifecycle-oriented design processes for next-generation space missions.