The THOR Space Station at EML2: analysis and preliminary design of an innovative adaptable docking system

This paper reflects the effort of ISAE University of Toulouse to conform with the Global Exploration Roadmap (GER): it is focused on the analysis and the preliminary design of an innovative universal docking system of the THOR (Trans-lunar Human explORation) station located at the second Earth-Moon Lagrangian Point. The Roadmap brings under light a way of exploring a larde array of destinations situated beyond Low-Earth orbit by following a Moon, near-Earth asteroids or Mars pathway. \nThe THOR station consists of seven cylindrical modules (whose dimensional reference is ATV) and two spherical modules: each part, with a specific role, will be launched separately. Nowadays, the dynamic of the docking is still in development : one option is to assembly the two modules at LEO and another one is to have the spacecraft put together at EML2. By coping with design criteria imposed by the deep-space environment, the docking system has been designed. The aim is to have an 'universal type of junction' between the stations and the re-supply manned or unmanned shuttles. At first, a detailed analysis of the kinematics of the rendezvous has been conducted in order to identify the optimal time windows for the orbital transfer at EML2. The docking system must be able to perform a structural connection between the hubs and the cylindrical modules or external vehicles to allow fuel, power and transfer data and moreover to function as a passageway for crew and materials. It will be fitted on the spherical hubs. Because of severe constraints, the functioning of the docking system has been improved in order to consent the control of the trajectory in the critical phases of the mission. Taking as reference the kinematics of the ATV and all the previous docking/berthing systems, the structural design of the subsystem has been performed, and adding up the kinematic analysis, a realistic video of the rendezvous has been produced. This innovative system presents at the same time all the benefits of the docking systems and of the robotics arm: its adaptability to several visiting vehicles and the passive functioning are strong points that can pave a new road for the future of the docking systems.