Optimisation of novel low-cost Earth-Moon transfers

Abstract

It is possible to exploit multi-body gravitational dynamics to reduce the cost of space missions and allow new mission profiles other than the ones obtained by using the traditional patched conics methods. However, the design and optimisation of these multi-body trajectories is much more complex than that in the two-body approach, requiring a combination of dynamical systems theory and global and local optimisation techniques. Recently, novel short-transfer-time solutions have been shown to exist in the ideal patched three-body approximation connecting quasi-periodic orbits on two-dimensional tori of the Sun-Earth-Spacecraftsystem with L1 or L2 transit solutions of the Earth-Moon-Spacecraft. The main goal of this research project is to find fully-refined, low-cost, short-time transfers to the Moon, that ensure ballistic capture, using these novel solutions. This will be done by applying ad-hoc numerical optimisation techniques, using the patched trajectories as an initial guess and considering a full ephemerides model. In addition, the optimisation process will also allow to minimise the Delta v and the transfer time. The outcome of this part of the study is a flexible software tool that can be used to optimise trajectories accurately in multi-body dynamics, and a set of fully optimised solutions for the specific Earth-Moon case, presenting a trade-off between time of flight and cost. The study will continue with the investigation of future efficient propulsion options, to reduce the cost of future missions. These include hybrid low- and high-thrust thrusters, as well as rocket-based propulsion hybridized with solar sailing or electric sailing. Considering any of these propulsion options will require a further development of the trajectory optimisation process, to take into account the constraints of each strategy, such as maximum thrust, specific impulse, and for the sails, non-linear effects. This will allow to assess future, low-cost options to transfer to the Moon, including their requirements in terms of the propulsion system. (AU)