Testing for verification and validation of an onboard orbit determination system exploiting GNSS : A nanosatellite application for HERMES-SP

Abstract: When developing products for space, including nanosatellites, the verification and validation process is a mandatory part of any project conducted within the European space industry. Within such a process, testing is a method for verification and validation. In this degree project, the appropriate tests for verification and validation of a nanosatellite were investigated. The project was conducted at the Royal Institute of Technology and the Polytechnic of Milan, as part of a larger research project under the name HERMES-SP. The research project was, at the time at which the degree project was taking place, in its first phase of the verification process. Therefore, tests for verification and validation of the Orbit Determination System (ODS) had not yet been defined. HERMES-SP is developing a nanosatellite platform with a very precise and reliable ODS, combining both Inertial Navigation System (INS) and Global Navigation Satellite System (GNSS). This degree project was thus conducted with HERMES-SP as an applicative case to investigate tests for a ’nanosatellites onboard ODS focusing on the GNSS. The ODS developed for the nanosatellite platform was studied, along with the underlying theory for ODS and GNSS. The plan for verification defined within HERMES-SP was also examined, and the presented methodology for test development was followed. To fully answer the project’s research question, the appropriate tests had to be identified and defined. This was done by first determining the requirements related to the ODS, and then identifying the tests that were needed to verify the requirements. Lastly, the tests were defined in test specifications and procedures. It was found that the relevant tests in the verification process were a handful of tests on the Equipment Test (ET), Software Test (SWT), and Subsystem Integration Test (SSIT) test levels. The tests were needed for verification of individual components in the system, as well as integrated components and their interfaces. The defined tests were considered appropriate for verification and validation for the first phase of the verification process. The project contributed to the identification and definition of tests for a restricted part of the verification process, related to the specified system of the HERMES-SP nanosatellite. The findings could be used in other nanosatellite projects with similar ODS by following the process and the methodology for test development documented in this report.