Physical properties and long-term evolution of the debris clouds produced by two catastrophic collisions in Earth orbit

Abstract The population of cataloged orbital debris increased by approximately 40% in just a couple of years, from January 2007 to February 2009. This was due to two collisions in space, which involved the catastrophic destruction of three intact satellites (Fengyun 1C, Cosmos 2251 and Iridium 33) in high inclination orbits. Both events occurred in the altitude range already most affected by previous launch activity and breakup events, thus boosting the cataloged population in low Earth orbit by more than 60%. In order to investigate the long-term orbit evolution of the three resulting debris clouds and to assess their lifetimes, an updated and more refined estimate of the ballistic parameter and area-to-mass ratio distributions of the fragments was accomplished. On 20 April 2010, the fraction of cataloged objects in orbit with a high area-to-mass ratio (>1 m 2 /kg) was approximately 3% for the Fengyun 1C cloud, 2% for the Cosmos 2251 cloud, and 18% for the Iridium 33 cloud. This was less than had been obtained previously, due to the greater decay rate of these objects. Their relative depletion will continue in the coming years and most will have reentered the atmosphere by 2015. The Iridium 33 cloud will be the fastest to decay from orbit, with 50% of the cataloged fragments left in space around 2015, and 10% around 2024. The Cosmos 2251 cloud will stay a little while longer, with 50% of the cataloged fragments left in space around 2021, and 10% around 2037. The Fengyun 1C cloud, on the other hand, will burden the environment significantly longer, with 50% of the cataloged fragments still in orbit around 2025 and 10% left in space around 2090.