Since the first launches of Ariane family and Vega rockets, many upper stages as well as multiple-launch structures have remained into orbit due to the absence of deorbitation maneuvers for these elements. Mainly, the orbits impacted by these residual launcher elements are the geostationary transfer orbit and low Earth orbits. For Ariane rockets, the non-deorbited elements are the upper stage and the dual launch system SYLDA. For Vega, the majority of the flights enable to deorbit the upper stage, therefore the element remaining in orbit is the multiple-launch structure SSMS or adaptor. This study tries to evaluate the orbital status of the remaining elements through their orbital region presence and their estimated lifetime in order to determine the impacts on the most critical regions (protected orbits, populated orbits). This analysis of the orbital status also helps the comparison with the initial targeted orbit at injection to estimate the evolution of the orbit with respect to time. Moreover, it may be a first hint to understand a possible relationship between targeted orbital parameters at injection and effective lifetime. If such a correlation could be observed, it would enable to suggest some recommendation on the injection point for non-deorbited missions.
Mélissa Zemoura (2025) studied this question.