Electric Sail Performance Analysis

An electric sail uses the solar wind dynamic pressure to produce a small but continuous thrust by interacting with an electric field generated around a number of charged tethers. Because of the weakness of the solar wind dynamic pressure, quantifiable in about 2 nPa at Earth’s distance from the sun, the required tether length is of the order of some kilometers. Equipping a 100-kg spacecraft with 100 of such tethers, each one being of 10-km length, is sufficient to obtain a spacecraft acceleration of about 1 mm/s^2. These values render the electric sail a potentially competitive propulsion means for future mission applications. The aim of this paper is to provide a preliminary analysis of the electric sail performance and to investigate the capabilities of this propulsion system in performing interplanetary missions. To this end, the minimum-time rendezvous/transfer problem between circular and coplanar orbits is considered, and an optimal steering law is found using an indirect approach. The main differences between electric sail and solar sail performances are also emphasized