Since the launch of Sputnik 1 on October 4, 1957, thousands of rockets have carried payloads into space. Eventually, the tug of Earth's gravity causes satellites' orbits to decay, and they fall into the atmosphere. Even so, at last count there are nearly 2,500 satellites orbiting Earth. Of those, 712 are American, and 1,361 are Russian.
Image: Center for Satellite Engineering Research

TELSTAR 1 launched in 1962, sparked a revolution in communications and opened space to commerical users.
The U.S. kicked off the communications revolution in space on July 10, 1962, when Telstar 1 transmitted the first live transatlantic telecast. Today Telstar's descendants are arrayed in stationary orbits 23,500 miles above the equator, where they beam down hundreds of channels of television.

Other satellites relay millions of telephone conversations, keep a watch on the weather, monitor crops and the environment, and tell pilots and ship captains their precise positions. And, of course, there are a fair number of others owned by various governments, which decline to discuss their purposes.

But satellites are only part of the picture--there is also a lot of junk up there. The flotsam and jetsam of the space age include the bodies of spent rockets that carried satellites to orbit, satellite fragments, as well as discarded nose cone shrouds, lenses or hatch covers. These account for an additional 6,000 or so man-made objects soaring around the planet.

To avoid collisions with the space shuttles or expensive new satellites, all this space clutter is closely watched by the U.S. Air Force Space Command. It collects more than 70,000 observations each day on anything orbiting Earth, from the size of a baseball to the Mir space station. These data are compiled by the National Aeronautics and Space Administration into a document called the Satellite Situation Report, which lists both objects in orbit and objects recently departed.