Variations in Right Ascension of Ascending Node of Sun-Synchronous Orbit Under the Lunar and Solar Perturbations

Earth-observation satellites carrying synthetic aperture radar (SAR) instruments are typically deployed on the exact repeat-ground-track (RGT) sun-synchronous orbit (SSO) in order to achieve effective repeat-pass SAR interferometry. The exact RGT maintenance of these satellites have stringent requirements on the variation modeling accuracy of right ascension of ascending node (RAAN). Due to the significant effects of third-body attraction on the orbital plane evolutions, variations of RAAN under the lunar and solar perturbations are modeled for the SSO with local time of descending node at 00:00, 06:00, 12:00, and 18:00. An analytic method for RAAN variation modeling is proposed based on the quasi-mean element method. Coupling effects between the J2 perturbation and third-body attractions are considered to achieve a high precision of the variation model. Comparisons with precise numerical orbit propagator show that the analytical method provides good results for lunar and solar perturbation modeling on the variations of RAAN. The maximum relative error is only 2.6% and 5% for lunar and solar perturbations, respectively.