Optimal deep-space heliocentric transfers with an electric sail and an electric thruster

An electric solar wind sail is a propellantless propulsive system that generates thrust by exploiting the electrostatic interaction between solar wind ions and one or more charged tethers. Assuming a realistic near-term design in which the sail is composed of a limited number of tethers, the propulsive acceleration provided to the spacecraft is small. Moreover, according to a recent thrust model, the propulsive acceleration vector is constrained to lie in a cone centered on the outward radial direction with half-angle equal to about 20 degrees, resulting in a small circumferential component of the propulsive acceleration. In order to overcome these issues, a possible strategy con-sists in combining the electric sail with an electric thruster that provides a low thrust steerable around the circumferential direction. The effectiveness of such a combination is thoroughly analyzed in this work for deep-space heliocentric transfers. Transfer trajectories are obtained as outputs of a multi-objective optimization procedure, in which a suitable linear function of the flight time and the propellant consumption is minimized, considering different relative weights of the two competing requirements. Two exemplary case studies, con-sisting of Earth-Mars and Earth-Venus ephemeris-free circle-to-circle transfers, are presented to show the effectiveness of the proposed arrangement. (c) 2023 COSPAR. Published by Elsevier B.V. All rights reserved.