Evolution of the satellite’s orbital elements due to the effect of its own tidal dissipation, for varying relaxation times. Panel a: the Moon’s semi-major axis; panel b: the Moon’s eccentricity; panel c: Phobos’ semi-major axis; panel d: Phobos’ eccentricity. The linear approximations from the tidal theory are given by Eqs. (58a) and (59) for the semi-major axis and eccentricity, respectively, and the contribution of librations is described by Eq. (65).