Space station long-duration orbit design using a two-level optimization approach

Abstract

Space station orbit design missions are characterized by a long-duration and multi-step decision process, which makes its optimization design very complicated. An integrated nonlinear programming (NLP) model is developed by considering the interaction effects of different flight segments of a space station. A two-level optimization approach is proposed to optimize the total propellant consumption while satisfying different constraints. The up-level problem employs the orbital altitudes of each flight segment as design variables, and adopts the simplex method to search for the optimal solutions; the low-level problem employs the maneuver impulses and times within each flight segment as design variables, and the objective function is calculated by combining approximate an analytical method and a shooting iteration method. The proposed approach is evaluated in two test cases of a six-month orbit mission and a nine-month orbit mission. The results show that the proposed approach can effectively optimize the space station long-duration orbit design problem, and can save considerable propellant by 60-70% compared with previously proposed space station orbital strategies. © 2014 The Japan Society for Aeronautical and Space Sciences.