Amount of space debris on Earth orbit has reached a critical threshold. According to estimates of specialists National Research Council, which is the executive body of the National Academy of Sciences of the United States, now in near-Earth space there is more than 22 thousand manmade debris, movement of which can be monitored from Earth. Space debris is fragments of satellites, worked out stage of rockets and other items. The main contribution to the pollution of outer space have made only two events that have occurred in recent years. It is the test of new weapon by Chinese on their own satellite in 2007 and the clash of the old Soviet satellite with the current U.S. in 2009.
According to Donald Kessler these two incidents have doubled the number of near-Earth objects. Also he think that each year the risk of collision the working satellites with debris is growing, and the rapprochement with dangerous objects more often make adjustments to astronauts’ work on the ISS.