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Celest Mech Dyn Astr (2009) 105:179195
DOI 10.1007/s10569-009-9200-y
ORIGINAL ARTICLE
Giovanni Mengali Alessandro A. Quarta
Received: 15 September 2008 / Revised: 9 December 2008 / Accepted: 20 February 2009 / Published online: 24 March 2009 Springer Science+Business Media B.V. 2009
Abstract An electric sail is capable of guaranteeing the fulfilment of a class of trajectories that would be otherwise unfeasible through conventional propulsion systems. In particular, the aim of this paper is to analyze the electric sail capabilities of generating a class of displaced non-Keplerian orbits, useful for the observation of the Suns polar regions. These orbits are characterized through their physical parameters (orbital period and solar distance) and the spacecraft propulsion capabilities. A comparison with a solar sail is made to highlight which of the two systems is more convenient for a given mission scenario. The optimal (minimum time) transfer trajectories towards the displaced orbits are found with an indirect approach.
Keywords Electric sail Displaced non-Keplerian orbit Trajectory optimization
Solar sail
1 Introduction
An electric sail is an innovative propulsion concept that, similar to a more conventional solar sail, allows a spacecraft to deliver a payload to some high-energy orbit (McInnes 1999) without the need for reaction mass (Janhunen and Sandroos 2007). 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. The electric eld generated by the tethers shields the spacecraft from the solar wind ions that, impacting on it, generate a continuous thrust that decays as (1/r)7/6, where r is the Sun-sailcraft distance. To control the spacecraft thrust angle (dened as the angle between the thrust direction and the Sun-spacecraft line), the sail-plane attitude may be varied with the aid of potentiometers
G. Mengali (B) A. A. Quarta
Dipartimento di Ingegneria Aerospaziale, University of Pisa, Via G. Caruso 8, 56122 Pisa, Italy e-mail: [email protected]
A. A. Quartae-mail: [email protected]
Non-Keplerian orbits for electric sails
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Fig. 1 Electric sail schematic view
placed between the spacecraft and each tether. For an in depth analysis of the electric sail performance, the reader...