Monday, September 19, 2011

The Sky is Falling!

It might be a good idea to start wearing a hard hat after Wednesday. According to this story by Joel Achenbach in The Washington Post, a satellite the size of a school bus is “tumbling in orbit and succumbing to Earth’s gravity.”

It is expected to fall from the sky sometime between Thursday and Saturday. The question is where.

“Out-of-control crashing satellites don’t lend themselves to exact estimates even for the precision-minded folks at NASA. The uncertainty about the “when” makes the “where” all the trickier, because a small change in the timing of the reentry translates into thousands of miles of difference in the crash site.”

The doomed satellite is expected to break up on reentry into a hundred pieces spread over 500 miles. The largest of these pieces could be three hundred pounds.

On second thought that hard hat won’t be much help. Then again, the chance of getting hit by a piece of space debris are about the same as your chance of winning the lottery.

“NASA did a calculation of the odds that someone would be struck by UARS debris. It’s very unlikely: about a 1-in-3,200 chance that one person somewhere in the world would be hit. That’s not the odds for any specific person (say, a reader of this story), but for the entire human population, which is about 7 billion.”
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