Structural response of Helianthus solar sail during attitude maneuvers

The Helianthus mission proposal is based on maintaining an artificial L1-type equilibrium point in the Sun-Earth gravitational field by means of a square solar sail, which should provide the required propulsive acceleration without any consumption of propellant. That vantage point would enable a scientific observation of the Sun and guarantee an effective monitoring of its activity, thus ensuring early warning in the event of catastrophic solar flares. Due to the intrinsic instability of artificial L1-type equilibrium points, the spacecraft dynamics is regulated by an advanced attitude control system based on electrochromic devices, which can adjust their optical properties through the application of a suitable electric voltage. In particular, a sliding mode controller has been recently proposed to commute the activation state of those devices by assuming that the solar sail (that is, the assembly of a large reflective membrane and its supporting booms) behaves like a perfectly rigid body. The aim of this work is to validate the predicted spacecraft dynamics by performing an accurate structural analysis of the solar sail under operating conditions through a numerical approach. In particular, a finite element method is used to evaluate the sail dynamic response to control torques in the context of some reorientation maneuvers.