A Nanosatellite System Modelling Architecture for EIRSAT-1 and Future Missions

The use of CubeSats by industry and research has grown significantly in recent years, lowering the barrier to entry, especially for universities. The Educational Irish Research Satellite (EIRSAT-1) is a 2U CubeSat that has been designed and developed by students and staff of University College Dublin and implemented through the "Fly Your Satellite!" programme of the European Space Agency’s Education Office. The ground station, which provides the radio link between the Space and Ground Segments, was designed and assembled in UCD and supports two-way communications with the EIRSAT-1 satellite. This thesis describes the Ground Segment and the testing of communication with EIRSAT-1. Validation of the communications system performance, including the end-to-end communication link, was a crucial element of the mission’s Flight Acceptance Review. The preparation of the requirements verification control document, another key deliverable for Flight Acceptance, is also described in the thesis. EIRSAT-1 was developed using the traditional, document-driven, V-Model Systems Engineering approach. The lessons learned from EIRSAT-1 motivated this study of Model-Based Systems Engineering (MBSE) for accelerated CubeSat mission development within a University setting. MBSE is an alternative Systems Engineering approach based on the use of models created through modeling languages, such as SysML, rather than documents. Trade-off studies were conducted to select the most appropriate tool and method for adopting MBSE into the CubeSat life cycle. Conceptual and parametric data from the EIRSAT-1 development process were used to build a CubeSat standard model using the CATIA Magic MBSE tool. The functional architecture of EIRSAT-1 was modeled as a base model, since most of the subsystems are common across CubeSats. SysML diagrams were used to create functional and behavioural models of the EIRSAT-1 subsystems that can be reused for future missions. In addition to MBSE implementation, a key focus of this work was integrating the subsystem test models with external test scripts as part of closed-loop testing to automatically update the verification matrix.