Design of sun-synchronous orbits for the Mercury based on non-ideal solar sail model

As the oblateness of Mercury is nearly zero, the orbits about the planet will not precess without an acceleration provided by the solar sail propulsion system. The solutions for the problems in the past are based on a perfect model, which leads to the big deviation from the fact. Therefore, this paper designs Mercury sun-synchronous orbits based on non-perfect solar sail model. In the design, the variation of the solar flux over a Mercury year is also considered. Finally, this paper gives the simulation results by a numerical method. It is shown that the elliptic sun-synchronous polar orbit with periapsis near the north pole of Mercury is more suitable for the Mercury observation mission due to its low orbital altitude, stable inclination and no need of quickly solar sail attitude maneuver.