5th Global Trajectory Optimisation Competition: Results of Team 5 Dario Izzo, Francesco Biscani, Chit Hong Yam, Luis Felismino Simoes Advanced Concepts Team, European Space Agency, The Netherlands
David di Lorenzo, Bernadetta Addis, Andrea Cassioli, Fabio Schoen, Marco Locatelli Global Optimization Laboratories, University of Florence
November 1, 2010
1 Introduction and Method The solution proposed to this year problem for the fth edition of the Global Trajectory Optimization Competition was obtained by us using a two-step process. 1. We build an ad hoc analytical model for the optimal minimum time transfer from an orbiting object to itself constraining the relative re-encounter velocity to a minimum of 400 m/s. The model returns an analytical estimate for both time of ight and mass spent. The linear model is then used in conjunction to a multiple revolution lambert solver to search for good 'chemical representations' of trajectories. A branch and prune approach is adopted to search the immense tree of resulting possibilities. 2. The chemical trajectories candidates are then turned into low-thrust by keeping epochs and asteroid sequence as initial guess to our global optimization methods for constrained optimization problems. We work directly on a high delity trajectory model constructed using a variant to the sims- anagan transcription and applying monotonic basin hopping as main solving paradigm.
2 Solution Overview Our nal solution accumulates a total primary score of J = 16.0 with a secondary objective τ = 14.19 years - The launch V∞ = 2.35 km/s the nal mass mf = 500 kg ( nal penetrator mass accounted). A summary of the complete trajectory is given in the table below. The visualization of the ecliptic projection of all inter asteroid phases is also reported in the gures below.
