Space junk is a big problem. As of 2000, there were an estimated 250,000 pieces of space junk in orbit around the Earth. Most space junk is in the form of nuts, bolts, wrenches, etc. But some of it is in the form of larger pieces of metal. All of it is dangerous to space craft and satellites. Keep in mind everything in orbit travels at 18,000 miles per hour. The bigger problem is how to get rid of it. One design, still on the drawing board, is for an orbiting 'vacuum cleaner', that will 'collect' it. But that's still tears away from being tested.