Inverse Solar Sail Trajectory Problem

Abstract

SOLAR sailing has long been considered for a diverse range of future mission applications. Although low-performance solar sails can be utilized for interplanetary transfer using heliocentric spiral trajectories, high-performance solar sails can enable exotic applications using non-Keplerian orbits. A simple example of such an exotic applicationis levitation,with the solar radiationpressure accelerationexperiencedby the sail exactly balancing solar gravity. Such a static equilibrium allows the solar sail to remain stationary with respect to the sun, or indeed if the sail is turned edgewise to the sun it will fall sunwards on a rectilinear trajectory. Although this static equilibrium is simple to identify, the question of transfer to it from an Earth escape trajectory remains open. This Note will derive an analytic sail steering law that allows the solar sail is be maneuvered from a circular heliocentric orbit, to a static equilibrium location at the same heliocentric distance. The required trajectory will be deŽ ned a priori with the resulting sail steering law derived from the equations of motion. An inverse trajectory problem is, therefore, being solved.