Saturday, September 14, 2002

Space junk

And speaking of stuff in orbit around the earth, didja know that there's an awful lot of junk up there? Spent booster stages from rockets. Thousands of satellites, many of them no longer working and long since replaced, but still up there. Fragments from launch vehicles that exploded in orbit. One estimate has some 4 million pounds of junk in orbit up there, and that's just in low-Earth orbit (LEO).

So what happens to them? The items in LEO come into contact with wisps of atmosphere from time to time, and so their orbit decays, (albeit fairly slowly), and they fall back to earth. Most are small enough to burn up in the atmosphere, although big hunks of junk (like SkyLab in 1979) actually hit Earth. Not to fear, though, as Earth is 3/4ths water and the rest is largely uninhabited.

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