Tuesday, March 4, 2008

Sense, nonsense, and pretense about the destruction of USA 193


James Oberg

I’m sorry, but I just hate the phrase “satellite shoot down”. It’s not just because, in fact, hitting a satellite with a missile—like last February 20—doesn’t really knock it out of the sky. It’s because trying to bend “earthside” words around the unearthly, unfamiliar reality of outer space is a bad fit—and if it fools us into thinking the words are proper, then our clear thinking about the events will be crippled.

“Shoot-down” implies that a physical attack has destroyed a characteristic of the target that previously had enabled it to remain aloft. For an aircraft, it could be its wings, or engine, or pilot; for a flying animal, it might be its very life. Once attacked, the object can no longer fly, and it falls to the ground.

But for a satellite in orbit around the Earth, the physical principle that keeps it “up” is not its own power or guidance, but merely its forward speed—the so-called “orbital velocity”. An attacker that does not substantially change that velocity cannot drive the satellite out of orbit. No matter how much physical damage it does, it cannot “shoot down” the target or even the fragments of it that remain after the attack.

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