4. Conclusion

The actual orbital motion of a satellite results from central attraction and much weaker forces that can be treated as perturbations. This article reviews the equations of perturbed motion, integration methods, the different types of perturbations and their effects. The most important perturbation comes from the Earth's flattening. It is responsible for nodal precession, which is used to great advantage on sun-synchronous missions. The general effect of disturbances can be broken down into secular, long-period and short-period variations. Couplings between different disturbances can lead to resonance phenomena.

Prediction of actual motion is necessary for operational satellites in order to plan station-keeping maneuvers and the associated propellant consumption. It is also useful for predicting the trajectories of space debris and anticipating the risks of collision...