Orbital debris, not functional satellites, make up 95 percent of the objects in this computer-generated illustration of objects in low-Earth orbit. That veritable explosion of space junk is causing problems, and it's getting worse. NASA estimates that there are more than 500,000 pieces of hazardous space debris orbiting Earth.
And as time goes on, the bigger pieces of abandoned debris, such as satellites, begins to collide with other objects, or each other, resulting in the larger pieces of junk turning into more and more smaller pieces of junk, increasing the population of hazardous debris.
DARPA is so concerned with the problem that it's started what it calls the SpaceView program, which seeks to enlist amateur astronomers as sky watchers, helping to track all the debris floating above.