Ever since the first rocket was launched into space, we have been polluting the environment above the Earth. Pieces of junk and debris from spacecraft have been accumulating in orbit around the Earth and are beginning to present a distance hazard to both manned spacecraft and artificial satellites. The space junk ranges in size from dead satellites and spent rocket stages to individual flecks of paint from spacecraft. Surveys carried out in recent years by NASA estimate that there are perhaps 1,00,000 pieces of debris 1 cm (1/2 inch) or more across and 10,00,000 pieces 1 mm across in orbit around the Earth. See the graphic below.
In February 1997, while the space shuttle Discovery was docked with the Hubble Space Telescope, mission control in Houston ordered the crew to fire the shuttle’s maneuvering jets in order to avoid a lethal chunk of debris. This piece of space junk was from a Pegasus rocket, which had exploded a few years earlier. Hubble was launched into space in April, 1990 and since that time it has been pitted with hundreds of holes ranging in size from less than 1 mm to a few centimeters. In 1996, a small British built satellite called CERISE was disabled when it was struck by a fragment from an Ariane rocket, which had blown up shortly after launch several years earlier.
Space debris (Wikipedia)