Mission Design for an Interstellar Probe with E-Sail Propulsion System

Missions towards the Solar System boundaries are of great scientific interest and represent a hard technological challenge. The use of an advanced propulsion system is a necessary means to maintain the flight time within reasonable limits. This paper analyzes missions to the heliosheath nose and to the heliopause nose, under the assumption that the primary propulsion system of the spacecraft is constituted by an electric solar wind sail. The study is performed using an optimal approach, by minimizing the total flight time required to reach a prescribed point of the Solar System. A number of results are presented using two mission parameters, i.e. the spacecraft maximum propulsive acceleration and the distance at which the electric solar wind sail is jettisoned from the scientific probe. Numerical simulations show that an electric solar wind sail with performance consistent with the currently available technological level is able to reach a solar distance of 100 au in about 23 years. The flight time can be further substantially reduced using an advanced electric solar wind sail with near or mid-term technology.