According to the U.S. Space Surveillance Network, there are more than 13,000 man-made objects in orbit that are large enough to track. This number is much larger if you consider the smaller orbiting space junk that aren’t picked up by radar. This debris is called space junk, and can be very problematic; causing damage to satellites and posing a threat to space walkers.
Space junk includes a variety of objects such dysfunctional satellites, paint chips, satellite fragments and other debris. Anything that humans leave in space (especially if it doesn’t work any longer), contributes to this collection called space junk.
Space junk has become a concern because of the potential destruction it can cause to viable equipment and space walkers in orbit. For example, in 2007, a Chinese test of an anti-satellite weapon, generated millions of new pieces of space junk. This event will pose a danger to working satellites in orbit and astronauts for years to come.
After experiencing a malfunction, a Russian rocket booster exploded over Australia in 2007. The US Air Force radars detected over 1,000 fragments; which poses additional hazards to equipment and people in orbit.