Investigating the Flexibility of the MBSE Approach to the Biomass Mission

Model-based systems engineering (MBSE) represents a move away from the traditional approach of document-based systems engineering (DBSE), and is used to promote consistency, communication, clarity, and maintainability within systems engineering projects. MBSE offers approaches that can address issues associated with cost, complexity, and safety. One way that this can be achieved is by performing early functional validation of the high-level spacecraft functional avionics system. The use case discussed in this article focusses on the Biomass model, a systems modeling language-based representation of the Biomass Earth-observation mission. The MBSE approach is used to calculate the required size of the data handling unit onboard the Biomass spacecraft. The functional response of the system in terms of the onboard memory usage throughout the mission is simulated. Traditionally, this level of analysis would not be available at this early stage. The approach aims to replace ad hoc, spreadsheet-based calculations with a formal representation of the system that can be executed, interrogated and quantified. The flexibility of this MBSE approach is demonstrated by applying changes to the Biomass project and assessing the time required to implement these changes in the Biomass model and propagate them through to the results of the simulation. The changes have been made independently of each other and include: changes to the logical architecture, changes to the functional definition, changes to the mission profile, and changes to the requirements. Potential areas for improvement regarding the structure of the Biomass model are highlighted and discussed.