Space research has been making significant progress over the past twenty-five years. The International Space Station (ISS) has served as a central platform for technological innovation in human spaceflight, while in-orbit servicing, assembly, and manufacturing (ISAM) have emerged strongly in autonomous or tele-operated spaceflight. In this framework, the IVA robotic free-flyer space system, designated as ‘MELISSAI’, which stands for Modular free-flying Elements for experiments on In-Space Servicing & Assembly on-board the International Space Station, aims at establishing a platform on the ISS for Italian and European researchers to perform research on in-space servicing and assembly, focusing on advanced robotic applications. The objective of this Master Thesis is to develop the preliminary design of the MELISSAI space system, which includes initial contextualisation, feasibility studies and preliminary design of the system.