Star Dreck; January 1996; Scientific American Magazine; by Powell; 1 Page(s)
Conjuring images of "meteor storms" in bad science-fiction movies, the map below includes 7,800 of the larger man-made objects--including dead satellites--that are circling the earth. But contrary to appearances, "the sky is not falling just yet," says Nicholas L. Johnson of Kaman Sciences Corporation, which created the image. For clarity, the dots representing bits of debris are enormously exaggerated in size--which can give a false impression of the magnitude of the problem. Not a single functional satellite has been lost owing to space junk.
Nevertheless, the danger is real. Collisions in earth orbit occur at velocities of up to 15 kilometers per second, so a discarded bolt or lens cap could destroy a satellite or endanger astronauts. Objects as small as one centimeter across--hundreds of thousands of which lie in near-earth orbit-- could knock out critical components on a spacecraft. And such tiny items cannot be tracked by current technology, so they strike without warning.