Model-Based Systems Engineering Approach in Capella for Concept of Operations and Operating Modes: Methodology Comparison Across Space Systems Domains

In recent years, it has become more and more evident how Model-Based Systems Engineering (MBSE) has emerged as a key approach to managing system complexity and ensuring rigorous traceability throughout the lifecycle of a system. When working particularly in highly constrained and mission-critical domains such as space exploration - where a high number of stakeholders and actors are to be involved and/or updated on various aspects - MBSE plays a vital role in enhancing system consistency, collaboration, and validation. This paper focuses on modeling the Concept of Operations (ConOps) and Operating Modes (OMs) using Capella - an MBSE tool widely used by space domain actors. This work emphasizes their role in defining system behavior and mission scenarios from the early design stages. ConOps and OMs form the backbone of mission planning, enabling engineers to foresee system responses under nominal and non-nominal conditions, optimize resource allocation, and improve system resilience. We present a methodology comparison for defining and modeling ConOps and OMs within the MBSE framework, where flexibility is the key to adapting to different mission architectures and dynamic operational constraints. Our approach application is illustrated through two different case studies - a lunar habitat and a small-satellite - showing how MBSE can be leveraged to develop robust, adaptable, mission-ready systems. Through these examples, the benefits of integrating ConOps and OM early in the design phase are highlighted, improving decision-making, requirements validation, and mission assurance. The paper concludes with a discussion of the scalability of the approach and potential advances of MBSE methodologies for future space exploration missions.