Innovative Solar Sail Earth-Trailing Trajectories Enabling Sustainable Heliophysics Missions

Abstract

The presented trajectory design study demonstrates that near-future solar sails can reach and maintain innovative science orbits about non-traditional Earth-trailing equilibrium points. The proposed configurations can enable long duration stereoscopic solar imaging while potentially alleviating telemetry requirements constraining current solar sail studies. Initial guesses for controlled periodic orbits about equilibrium points that trail the Sun-Earth line by 1.5∘-15∘ are constructed from a linearized solar sail circular restricted three body problem equations of motion. Orbits are then converged in the full nonlinear model using a high order direct collocation method. Transfers to Earth-trailing orbits are then constructed under the assumption that the solar sail is a secondary payload on a larger spacecraft en-route to the Sun-Earth L1 Lagrange point. Naturally occurring gravitational manifolds flowing towards the Lagrange point, as well as navigation data from previous Lagrange point missions, are used to generate a set of baseline trajectories for the primary spacecraft. End-to-end trajectory design and optimization is then carried out to construct time optimal solar sail transfers to each target science orbit from initial conditions constrained to lie on the carrier spacecraft’s Lagrange point trajectory. Additionally, trade studies are performed to assess how sail performance and Earth-trailing orbit selection affect transfer time of flight and instrument pointing accuracy. Results indicate that, based on current technological developments, near future solar sails are capable of station keeping about periodic Earth-trailing orbits while maintaining near-constant solar observation. Moreover, time of flights on the order of 1 year are observed for most combinations of sail performance and feasible initial conditions.