Modeling of the flight system design in the early formulation of the Europa Project

During the early formulation stage of a mission concept, the multiple and frequent changes made to the system design present various systems engineering challenges, including: ensuring the internal consistency of multiple engineering reports describing distinct aspects of the same flight system; capturing the interdependencies between subsystems to guide the design iteration process; minimizing the amount of rework needed when the design is modified; managing multiple architectural alternatives while leveraging commonality; and finally providing traceability of the design changes made over time. This paper describes how such challenges have been partly addressed by the Model-Based Systems Engineering Team (MSET) on the Europa Project at the Jet Propulsion Laboratory (JPL), through the application of Model-Based Systems Engineering (MBSE) techniques. The paper first discusses the principle of Single-Source-of-Truth (SSoT) and how it can be supported by the use of a well-structured system model relying on a rich vocabulary (e.g., based on the SysML language). The application of modeling patterns to organize the Flight System design information and make it queryable is then examined, with specific examples used on the Europa project (such as launch dry mass, electrical power, thermal power, fields-of-view). The benefits of checking formal rules to verify the correctness of the model and ensure that changes were properly incorporated are also discussed. The paper then presents model organization strategies that maximize the reuse of information across multiple design architectures that are explored in early formulation, as well as various practices used to control the numerous changes made to the model as the design matures. Finally, the paper concludes with a summary of the lessons learned from using a system model on the Europa project in order to capture design information about the Flight System. This has proved to play a key role in delivering high-quality representations of the spacecraft design to a variety of stakeholders as well as demonstrating its viability.