Shape Estimation of Gossamer Structures Using Distributed Sun-Angle Measurements

Abstract

This paper proposes a novel approach to monitor the shape of gossamer structures, such as solar sails, using sun-angle measurements obtained directly on the sail membrane. These measurements can be easily provided by already installed thin-film solar arrays or dedicated low-impact sensors. A general nonlinear least-squares formulation is first presented, and then it is reduced to a linear least-squares problem for large sails. A rank deficiency is observed in the estimation method, but it is avoided by considering measurements at multiple epochs, reconstructing a time-averaged shape. Multiparticle models of the Japan Aerospace Exploration Agency’s IKAROS and solar power sail are used to evaluate the performance of the method. The method provides accurate shape estimation with errors of 0.1–0.5 m. Including additional sensors in critical locations can help reduce the error when a low number of sensors is used. In addition, the forces and torques generated by solar radiation pressure are computed and compared with the multiparticle model data. The presented results suggest that the proposed method can easily provide continuous shape estimation of gossamer structures such as solar sails.