Start buying your metal umbrellas with maximum headroom. President Bush has ordered the Pentagon to shoot down a failing U.S. spy satellite before it can reenter the atmosphere sometime in early March. He wants to make sure the bus-sized satellite doesn't hit anyone and contaminate the impact area with its toxic fuel. Instead, he wants to spread the debris and the fuel across a wider area. (Yeah... We can do more damage that way.) I guess the plan is that the smaller debris and fuel would be more likely to burn up before reaching Earth, but he's taking a big risk that it will. In 1985 the U.S. tested shooting down a satellite and the debris problem prompted both the U.S. and U.S.S.R. to stop testing. China did a successful test last year, but that satellite was in a much higher orbit, and not already falling.