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Astrodynamics

Article Title

Optimal solar sail transfers to circular Earth-synchronous displaced orbits

Keywords

solar sail, synchronous displaced orbit, trajectory optimization

Abstract

The aim of this paper is to evaluate the minimum flight time of a solar sail-based spacecrafttowards Earth-synchronous (heliocentric) circular displaced orbits. These are specialdisplaced non-Keplerian orbits characterized by a period of one year, which makes themsuitable for the observation of Earth’s polar regions. The solar sail is modeled as a flatand purely reflective film with medium–low performance, that is, with a characteristicacceleration less than one millimeter per second squared. Starting from a circular parkingorbit of radius equal to one astronomical unit, the optimal steering law is sought byconsidering the characteristic acceleration that is required for the maintenance of the targetEarth-synchronous displaced orbit. The indirect approach used for the calculation of theoptimal transfer trajectory allows the minimum flight time to be correlated with severalEarth-synchronous displaced orbits, each one being characterized by given values of Earth–spacecraft distance and displacement over the ecliptic. The proposed mathematical model isvalidated by comparison with results available in the literature, in which a piecewise-constantsteering law is used to find the optimal flight time for a transfer towards a one-year Type Inon-Keplerian orbit.

Publisher

Tsinghua University Press

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