%0 Journal Article %T Cumulative Perturbations Affecting a Spacecraft on a Mars Equatorial Orbit from the Waxing and Waning of the Polar Caps of the Planet %A Jean-Pierre Barriot %J Open Access Library Journal %V 2 %N 12 %P 1-9 %@ 2333-9721 %D 2015 %I Open Access Library %R 10.4236/oalib.1102272 %X We demonstrate in this paper that periodic variations of the J2 gravity coefficient of a planet induce small cumulative perturbations on a given family of circular equatorial orbits, and that these perturbations could be measurable with current radiosciences technology. For this purpose, we first consider a Poincar¨¦ expansion of the Newtonian equations of motion. Then, by using Floquet¡¯s theory, we demonstrate that, unlike the excitation mechanism, the perturbations are non- periodic, and that the orbit is not ¡°stable¡± in the long-term, with perturbations growing exponentially. We give the full theory and an application to the case of planet Mars. %K Mars¡¯ Length-of-Day %K Orbit Perturbations %K Floquet¡¯s Theorem %U http://www.oalib.com/paper/3154220