Electric Sail Mission Analysis for Outer Solar System Exploration

摘要

Missions toward the boundaries of the solar systemrequire long transfer times and advanced propulsion systems.rnAn interesting option is offered by electric sails, a new propulsion concept that uses the solar wind dynamic pressurernfor generating a continuous thrust without the need for reaction mass. The aim of this paper is to investigate thernperformance of such a propulsion system for obtaining escape conditions from the solar system and planning arnmission to reach the heliosphere boundaries.The problemis studied in an optimal framework byminimizing the timernto reach a given solar distance or a given hyperbolic excess speed. Depending on the value of the sail characteristicrnacceleration, it is possible that, in an initialmission phase, the sailcraftmay approach the sun to exploit the increasedrnavailable thrust due to the growing solar wind electron density. The corresponding optimal trajectory is constrainedrnto not pass inside a heliocentric sphere forwhich the admissible radius is established by thermal constraints.Once thernescape condition is met, the sail is jettisoned and the payload alone continues its journey without any primaryrnpropulsion system.Amedium-performance electric sail is shown to have the potentialities to reach the heliosheath, atrna distance of 100 astronomical unit fromthe sun, in about 15 years. Finally, the InterstellarHeliopause Probemissionrnis used as a reference mission to further quantify the electric sail capabilities for an optimal transfer toward thernheliopause nose (200 astronomical unit).