• AOCS
• E2E
• end-to-end tests
• functional verification campaign
• polarity test
• subsystem integration
• V&V
• verification and validation

This thesis explores the Verification and Validation (V&V) process applied to the Attitude and Orbit Control System (AOCS) for the CASSINI IOD/IOV mission, a European CubeSat project aimed at demonstrating the effectiveness of new space technologies. The purpose of the CASSINI project is to strengthen the competitiveness of the European space sector by reducing dependency on non-European suppliers and promoting an innovative development model.
Through a thorough analysis of V&V activities, the thesis details the complex process of a functional test campaign conducted in accordance with European Space Agency (ESA) standards (ECSS) to ensure the quality and reliability of the AOCS for this mission.
The V&V phase is crucial in the development of space missions, playing an even more significant role for CubeSats, which are experiencing rapid growth thanks to the "New Space economy." This approach aims to reduce time and costs through the adoption of standardized commercial off-the-shelf (COTS) components, making CubeSat engineering more accessible and faster. However, the use of COTS components introduces complex challenges in terms of reliability and system integration. In this context, a robust and well-structured V&V process is essential to identify and correct potential design flaws, integration errors, and unexpected interactions between subsystems, thereby increasing the chances of mission success.
The thesis provides a general overview of the CASSINI mission, describing its objectives and architecture with particular attention to the AOCS subsystem. It then delves into the functional verification process, focusing on AOCS polarity tests designed to verify the proper functioning and integration of sensors and actuators in flight-like operational conditions, and to detect any anomalies in component responses.
A crucial aspect involves the use of various test platforms throughout the V&V campaign. Each platform plays a specific role in subsystem validation, covering both simulated and hardware tests, with the goal of progressively approximating flight conditions. Continuity and consistency across the results obtained from different test benches were fundamental in ensuring the system's reliability in operational conditions. The management of telemetry communications between subsystems and the onboard software was another key aspect to ensure data integrity and synchronization, essential elements for correct operation in orbit.
The thesis details the functional verification plan, outlining specific test requirements, particularly end-to-end SIM and HW tests for the magnetometer and reaction wheels. By adopting a rigorous approach based on the "V-model," systematic test procedures were defined to mitigate risks and detect anomalies early in the development cycle. The test setups, procedures, and pass/fail criteria for the two subsystems are presented, highlighting how well-structured tests are critical in clearly assessing test success or failure, thus ensuring the proper functioning of the system and compliance with requirements.
A significant part of the thesis is dedicated to the practical implementation of tests for the magnetometer and reaction wheels. During this phase, significant issues arose, such as telemetry data loss during reaction wheel tests and an unexpected orientation of the magnetometer reference system, causing inverted measurements. Thanks to the iterative and thorough analysis made possible by the "V-model" approach, these issues were addressed effectively. Configuration code modifications and repeated testing allowed for the resolution of these anomalies, ensuring compliance with system requirements. This methodology highlighted the complexity of managing anomalies in integrated systems, showing how even seemingly minor issues can significantly impact system functionality.
The thesis then analyzes the main results and challenges encountered during the V&V campaign, demonstrating how a robust V&V campaign can make the difference between mission success and failure. For the CASSINI mission, the adoption of a methodical approach was a key factor in achieving the objectives. End-to-end tests provided a clear view of the AOCS system's response to commands and stimuli, confirming the system's stability and compliance with mission requirements. This made it possible to successfully validate the integration of the analyzed components and ensure reliable operation under realistic operational conditions.
This work makes a significant contribution to the AOCS verification campaign for the CASSINI mission by developing detailed procedures, executing tests in both simulated and hardware environments, analyzing results, and documenting the entire process. The growing demand for CubeSats requires increased attention to system quality and reliability, and this work demonstrates how accurate and structured verification can make a difference, ensuring reliable and sustainable performance.
The analysis of the results and challenges faced shows how a strong V&V campaign is essential for the success of CubeSat missions. In a high-risk sector with limited resources, the V&V process is not just a safety measure but an indispensable strategy to maximize return on investment and ensure the sustainability and long-term success of space missions. The results of the CASSINI AOCS test campaign highlight the importance of a verification process that enables early identification of critical issues and the necessary corrections, minimizing the risk of in-orbit failures.
Finally, the thesis underscores the value of meticulously documenting each phase of the V&V process. Each test step, each iteration, and each implemented solution have been recorded in detail, allowing not only a thorough understanding of the choices made during the test campaign but also facilitating the work of future teams who may face similar challenges. The ability to refer to precise and comprehensive documentation is indeed an added value, as it saves time and resources and consolidates the knowledge gained.
In summary, this thesis demonstrates how a solid Verification and Validation process is essential to ensuring the success of CubeSat missions, especially in a New Space context where innovation and rapid development are priorities.