Long Term Evolution of Earth Orbiting Debris

The space environment is presently dominated by man-made debris, for particles larger than 1 mg. A comprehensive survey of the debris population from 1 mg to the larger sizes in view of the recent data from radar and optical observations, and from the analysis of materials retrived from space is given. A brief description of the major source and sink mechanisms acting on the debris population is given, along with a very short introduction to the two models for the long term evolution developed by the group in Pisa in the last years. The results of the long term evolution analysis are presented in some detail. A likely scenario of the future space activities leads to a large growth of mm-size particles due to several catastrophic collisions. The simulation highlights the necessity of more realistic explosion models, since the current ones overestimate the 10 cm-sized fragments.