In addition to satellites and the international space station, there is a lot of other stuff orbiting the Earth of man made origin: space debris.  Space debris moves at around 18,000 miles an hour so even pea-sized piece of debris can cause great damage to a satellite or other space vehicle.

The amount of space debris continues to increase as old satellites leave service and drift, rocket boosters are added to orbit, and collisions and explosions occur.  For example, in January 2007, the Chinese government destroyed an aged weather satellite in a missile test, creating what was estimated to be 2,500 pieces of new debris. That was followed by the February 2009 collision of a defunct 1,900-pound Russian  satellite with a 1,200-pound Iridium Communications Inc. satellite 490 miles above Siberia, generating even more orbital waste. The more junk in space, the greater the number of collisions, which in turn creates more junk.  And so on. This collision cascading effect is called the Kessler Syndrome.

There are a number of companies that have been formed for the purpose of cleaning up space debris. There are a number of international agreements with respect to space operator hygiene that hopes to limit the growth of space junk in the future relating to satellite and rocket booster disposal and the like. Hopefully, these actions are effective as we’re in danger of low Earth orbit ceasing to be useful for satellites.