Multidisciplinary mission and system design tool for a reusable electric propulsion space tug

According to the Global Exploration Roadmap, a Getaway in the lunar vicinity will enable the human exploration of the Moon, paving the way toward Mars and further in the deep space. A reusable transportation system, the Lunar Space Tug (LST), can be a key support transportation system to achieve a continuous and sustainable connection between the Earth and the orbital lunar outpost. Exploiting an electrical propulsion technology consisting in Hall Thrusters (HTs), this reusable space cargo system can maximize the delivered payload, with a lower propellant consumption with respect to a chemical-based platform. This significant improvement comes with two main throwbacks: a long transfer time between Earth and Moon and a complex multidisciplinary design of the overall LST. The first issue can be overcome with good mission planning in order to reduce the layover times and maximize the use of the LST. However, the peculiarities of the adopted propulsion technology shape the overall mass and power distribution of the space tug, as well as its transfer trajectory. The design complexity introduced by this subsystem can be effectively investigated if the mission analysis, trajectory generation and subsystem sizing are merged together in one software. In fact, the low-thrust transfer trajectories are highly affected by orbital perturbation and eclipse periods. At the same time, the high demand in power of the propulsion system puts constraints on the mass breakdown and power allocations of the LST, therefore on the reachable thrust level. The trajectory and subsystems sizing limitations call for a particular accurate mission analysis in order to succeed. Only combining all those elements, it is possible to define feasible design boundaries without performing countless simulations trying to optimize each element as a stand-alone part. Politecnico di Torino, in collaboration with the European Space Research and Technology Centre (ESTEC), developed a MatLab-based preliminary design tool for electric propulsion space tug missions, called MultidisciplinAry desiGN Electric Tug tOol (MAGNETO). Starting from the mission analysis of the lunar space tug, the tool building blocks and capabilities are presented. Moreover, the build-in trajectory module will be analysed in-depth. The potentiality of the trajectory generation tool in MAGNETO enables a refined design of the initial design envelope of the LST. For this reason, the improved results will be confronted with the previous LST design tool developed by Politecnico di Torino.