Updated Results on the Long-term Evolution of the Space Debris Environment

The long-term evolution of artificial debris in earth orbit has been analyzed, taking into account a detailed traffic model, explosions, collisions and the effects of air drag. Several scenarios, most of them implementing mitigation measures discussed at international level, have been simulated over a 200-year time span. Moreover, the sensitivity of the results to different collision model assumptions has been assessed. The simulations confirm the importance of spacecraft and rocket bodies passivation to avoid in-orbit explosions, but the de-orbiting of upper stages is needed as well to curb the debris and collision rate increase and to avert the onset of an exponential growth of artificial objects in the near earth space. The additional removal of end-of-life spacecraft does not improve the outcome dramatically, but may be able to reduce the collision rates in low earth orbit, reversing the historical trend of the last four decades. Of course, the fragmentation models and the simulation assumptions are still affected by a certain degree of uncertainty, but the results of the sensitivity analysis show that our conclusions are consistent and reliable, at least for the first century.