Traditionally, the forces in analytical theories for Earth satellite orbits are expressed in a coordinate frame which involves the equatorial plane. However, for distant satellites, the Moon and Sun attractions are equally important, and those forces are expressed more conveniently in a frame associated to the ecliptic. In this work, we develop an analytical satellite theory in which all the forces are expressed with respect to the ecliptic plane. The main advantage of the method is that, after the averaging process, all timedependent terms disappear from the formulation yielding a model suitable for preliminary orbit design
