The Spacecraft Early Analysis Model: An MBSE Framework for Early Analysis of Spacecraft Behavior

Model-based systems engineering (MBSE) represents a move away from the traditional approach to systems engineering. MBSE has the potential to promote consistency, communication, clarity and maintainability within systems engineering projects. MBSE also has the potential to address one of the well-known issues of the systems engineering process—the late discovery of errors or design faults. In this article, the development of the “Spacecraft early analysis model” (SEAM) is detailed and the current version is presented. The SEAM is a model-based framework developed by the authors to define, execute and analyze spacecraft structure and behavior during preliminary design. The SEAM comprises multiple modules (Project, Requirements, Mission, System, Operations) that enable the definition of the spacecraft and its supporting systems, and enables each to be updated independently. The SEAM incorporates a novel behavioral pattern that structures the modes and functions of the spacecraft using state machines and activities. Using this pattern, the behavior itself is not prescribed, as is common in similar model-based representations of spacecraft. The user defines individual functions and modes, and the user then simulates the behavior of the spacecraft in response to a concept of operations (ConOps). In this article, the need for the SEAM, the development approach, the SEAM composition and the limitations of the SEAM are presented and discussed.