Sunshade Demonstrator Spacecraft Earth Sphere of Influence Escape Using a Propellant-free AOCS

Abstract: This thesis provides insights to what is peculiar about a solar sail attitude and orbit control system and provides the assessment, in the form of a feasibility study, of the effectiveness of sail tip vanes as a control hardware to escape the Earth sphere of influence. The demonstrator aims to prove the technology for the Sunshade project, a constellation of solar sails located at the Lagrangian point L1 to obscure part of the solar radiation directed towards earth. Solar sailing poses a few fundamental challenges to spaceflight and it is a yet-to-be-proven branch of space engineering. Other tentative design exist but there is no standard to follow or off-the-shelf component that can be straightforward used. Moreover the scalability to the final project has to be accounted for in every step of the project. The project is divided in a preliminary dimensioning, followed by a Simulink\textsuperscript{\tiny\textregistered} based simulation which tests preliminary decisions. The simulation, performed on an orbit on the ecliptic plane, integrates models of Earth's eclipse and environmental disturbance torques. The escape time for a \SI{100}{\metre \square} solar sail is found to be \SI{1215}{} days, with a nonlinear PD control algorithm and sail tip vanes as the only control hardware. Attention is also posed on the consequence of a simplified sail film deformation in terms of centre of pressure to centre of mass off-set.