walking orbit

A walking orbit. also known as a precessing orbit, is an orbit in which the orbital plane moves slowly with respect to fixed inertial space. It can be achieved intentionally by choosing the parameters of a spacecraft's orbit so that advantage is taken of some or all of the gravitational influences that give rise to precession. These factors include the deviation from perfect sphericity of a planet and the gravitational influence of other bodies such as the Sun or nearby moons.