TITLE: A dynamical systems approach for the station keeping of a Solar Sail AUTHORS: Ariadna Farres and Angel Jorba Departament de Matematica Aplicada i Analisi Universitat de Barcelona Gran Via 585 08007 Barcelona, Spain E-Mails: ari@maia.ub.es, angel@maia.ub.es ABSTRACT: In this paper we have considered the movement of a solar sail in the Sun - Earth system. As a model we have used the RTBP adding the solar radiation pressure. It can be seen that we have a 2D family of equilibria parametrised by the two angles defining the sail orientation. Most of these equilibrium points are unstable and require a control strategy to keep the sail close to them. We have designed a control strategy that uses the knowledge of the position of the invariant manifolds and how they vary when the sail orientation is changed. We have tested our strategy with two known missions: the Polar Observer and the Geostorm Warning Mission. Simulations up to 30 years have been done taking into account errors on the position and velocity determination of the sail and on the sail orientation.