Outer space seems vast and empty, but the space directly above Earth
is quite crowded with satellites and … space junk!
Between the launch of Sputnik on 4 October 1957 and 1 January 2008, approximately 4600 launches have placed some 6000 satellites into orbit; about 400 are now traveling beyond Earth on interplanetary trajectories, but of the remaining 5600 only about 800 satellites are operational – roughly 45 percent of these are both in LEO and GEO. Space debris comprise the ever-increasing amount of inactive space hardware in orbit around the Earth as well as fragments of spacecraft that have broken up, exploded or otherwise become abandoned. About 50 percent of all trackable objects are due to in-orbit explosion events (about 200) or collision events (less than 10).