Model-Based Design of the Envoy Satellite Bus for Earth Observation Payloads

As the demand for cost-effective and scalable Earth Observation (EO) missions continues to grow, OHB seeks to develop a standardised satellite platform capable of supporting various payloads while maintaining flexibility across different mission requirements. This thesis contributes to that effort by identifying key engineering drivers and applying Model-Based Systems Engineering (MBSE) methods to analyse and optimise the platform design, with a particular focus on the Payload Data Handling Unit (PDHU) for an optical payload. The study follows a structured approach, beginning with the identification of engineering drivers that guide the design and sizing of the Envoy platform. By selecting requirements that encompass all potential mission needs - prioritising the highest values to ensure broad applicability - the platform is designed to remain consistent across multiple missions, minimising redesign efforts and reducing long-term costs. As a result, the key drivers of Envoy are identified, representing the sizing values that ensure the platform can meet the requirements of every mission under consideration. Functional and logical analysis is then conducted within the MBSE framework using the Cameo Systems Modeler tool, leveraging an existing, though incomplete, model to generate meaningful outputs. These analyses result in block diagrams, functional and logical trees, interface diagrams, and functional-to-logical connection diagrams - providing solutions that not only serve as visual representations but also encapsulate valuable data within each defined element. Additionally, logical components and functions are identified across all levels, from equipment to platform scale. This analysis evaluates whether MBSE can replace traditional Systems Engineering (SE), recognising that a full transition requires time and resources. While this shift demands application across all mission phases and addressing potential gaps, it also improves traceability, reduces documentation, and enhances communication. Finally, the PDHU is selected to complete the payload integration process within the multi-mission platform. This involves refining interfaces, performance parameters, and operational modes to ensure seamless adaptability within the standardised architecture. As a result, a mini-specification is developed, providing the foundation for the documentation needed to interface with suppliers and ensure all mission objectives are met. By addressing these key aspects, this thesis aims to enhance the efficiency, reliability, and sustainability of EO satellite platforms, supporting OHB’s vision of a more modular and cost-efficient approach to satellite development.