Decay of debris in geostationary transfer orbit

This paper reports on some current difficulties encountered in the prediction of the re-entry of objects on highly eccentric orbits. Concerned here are uncontrolled objects usually called debris. After recalling the importance of following the orbital evolution of space debris, the particular case of debris on Geostationary Transfer Orbits is treated. Although third body perturbation is the main perturbation in this type of orbit, it will be shown how the atmospheric drag, acting at perigee, may considerably change the evolution of the orbit. The prediction of re-entry date of a debris on a high eccentricity orbit is usually rather accurate. For GTO however, the effect of the drag at perigee may render the prediction totally uncertain. This is illustrated in an example taken from the recent re-entry of the first Ariane launch payload.