Formation flying and constellation station keeping in near-circular orbits

if the spacecraft in near-circular orbits (including circular orbit) satisfy the given constraints, the relative secular drifts due to the non-spherical Earth's perturbation would vanish between the orbits. Therefore the designed orbits can be used for formation flying and constellation station keeping. The solution is one of the solution sets drawn from a general solution in the sense of a first order approximation. The method is compared with the zero solution for the same problem and the significance of the method is explained. Results from high precision simulations show the accuracy and effectiveness of the method. The influence of drag on this approach is also demonstrated through the simulation.