TITLE: On the stabilizing effect of Solar Radiation Pressure in the Earth-Moon system AUTHORS: Marc Jorba-Cusco^(1), Ariadna Farres^(2) and Angel Jorba^(1) (1) Departament de Matematiques i Informatica Universitat de Barcelona, Gran Via 585, 08007 Barcelona, Spain (2) University of Maryland Baltimore County E-mails: marc@maia.ub.es, ariadna.farres@maia.ub.es, angel@maia.ub.es ABSTRACT: Solar sails change the natural dynamics of systems: The typical trajectories are displaced and changed because of the effect of Solar Radiation Pressure (SRP). Moreover, if the effectivity of the sail is large enough, the instability of certain orbits can be diminished and even removed. In this paper we modify two models for the motion of a probe in the Earth-Moon system that include the effect of Sun’s gravity to take also into account the effect of SRP. These models, the Bicircular Problem (BCP) and the Quasi-Bicircular Problem (QBCP), are periodic perturbations of the Earth-Moon Restricted Three Body Problem (RTBP). The models are modified to consider the effect of the SRP upon a Solar Sail. We provide examples of periodic orbits that are stabilized (or made less unstable) due to the effect of SRP.