Electric Sail Performance Analysis

Abstract

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\ud\ud 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\ud\ud to obtain a spacecraft acceleration of about 1 mm/s^2. These values render the electric sail a potentially competitive\ud\ud propulsion means for future mission applications. The aim of this paper is to provide a preliminary analysis of the\ud\ud electric sail performance and to investigate the capabilities of this propulsion system in performing interplanetary\ud\ud 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

Electric solar wind sail mass budget model

“…The purpose of this paper is to develop such a parametric model. The new mathematical model deepens and updates the previous simplified approach of Mengali et al (2008).…”

“…We assume 100 % gun efficiency and neglect the low voltage cathode heating power. The electric power P eg varies with the distance r from the Sun and can be related to the total length N L of the main tethers through a linear power density β, whose value essentially depends (Mengali et al, 2008) on the main tethers voltage and on the Heytether (Seppänen et al, 2011) total surface area. In particular, using the current Heytether configuration, the expression for the linear power density is…”

Artificial equilibrium points for a generalized sail in the circular restricted three-body problem

“…This is possible by simply specializing the value of η. For example η = 2 describes the thrust provided by a solar sail (McInnes, 1999b) or a magnetic sail (Zubrin and Andrew, 1991), while η ∈ [1, 7/6] corresponds to an electric sail model (Janhunen and Sandroos, 2007;Mengali et al, 2008;Janhunen, 2010). Finally η = 0 represents a constant propulsive acceleration, or a thrust that is independent of the distance from the massive attractor.…”

Non-Keplerian orbits for electric sails

“…The spacecraft is spun around the symmetry axis (Mengali et al 2008b) and the rotational motion is used to deploy approximately one hundred long conducting tethers ( Fig. 1) held at a high positive potential through an electron gun, whose electron beam is shot roughly along the spin axis.…”

“…To control the spacecraft thrust angle (defined as the angle between the thrust direction and the Sun-spacecraft line), the sail-plane attitude may be varied with the aid of potentiometers placed between the spacecraft and each tether. For an in depth analysis of the electric sail performance, the reader is referred to Mengali et al (2008b).…”