The use of model-based systems engineering (henceforth MBSE) can help offset some of the technical challenges associated with the realisation of adaptive optics systems for future extremely large aperture telescopes (ELTs). The establishment and maintenance of the single version of the truth (i.e. the model) for a large and complex project, increases the likelihood of project success. To this extent, the AAO-Macquarie and collaborators (ONERA/LAM/ALPAO) have adopted an MBSE approach for the proposed Gemini North Adaptive Optics Bench Phase A (AURA project). We use architecture representations and system decompositions using the SysML elements, both functional and structural, with diagrams, allowing each project stakeholder to focus on aspects of the problem. The SysML elements can be traced to requirements and other elements, making it easier to assess risk and prevent costly mistakes discovered during development and operational phases. Therefore, the knowledge gained being beneficial to the system modelling of future adaptive optics systems.