Circular Formation Design for LL-SST

The tremendous advances made by GRACE have led to an interest in launching a follow-up mission with better performance. To improve the ranging performance, a new formation is developed for gravity measurement from low-low satellite to satellite tracking. Firstly, orbit element is used to describe the relative motion between two satellites and give a formation parameter. Then, in order to keep formation stable under Earth oblateness, a formation design method is given which has taken into account of J2 and J3 perturbation. The initial orbit element is computed for the two satellites. At last, a numerical simulation is proposed. The result indicates that the formation meets the demand of improvement for gravity measurement, which can be more stable than the formation designed by reckoning on only J2 perturbation, and there are 99.980 %, 99.976 %, 99.710 % less excursion in three directions.