Design Solutions for Green Propellants-based Orbital Transfer Vehicles

Upper stages are critical for the space sector, as they are necessary to deliver precious payloads into orbit. In recent years, these systems have been required to possess an increasingly complex set of capabilities, often beyond what classical launch providers can offer. This has led to the development of a new class of vehicles, which can be seen as an additional stage, promising to meet these new requirements. Many of these systems are currently in development and are the reference scenario of the present work. These devices are gaining importance rapidly within the framework of space logistics, and the future of space transportation is expected to evolve significantly through their development. The main focus of the thesis is the intersect between the development of these new vehicles and the utilization of green propulsion technologies. Green propulsion is a topic studied from decades, aiming to improve the sustainability of new technologies for future systems by utilizing compounds that are less harmful than traditional propellants. Developing greener alternatives is a critical step toward achieving a broader environmental and economical goal. The principal green solutions available in the sector are reviewed and analysed within the application reference scenario, and the two main green bipropellant technologies—hydrogen peroxide-based and nitrous oxide-based—are studied and advanced separately. The research includes the development of components and hot firing tests of a new green technology based on hydrogen peroxide, HIP_11, as well as new models and concepts for the nitrous oxide option, which has been less studied and developed until now.