End of this week - UARS will hit the earth (Wash. Post good news - bad news coverage)

http://www.washingtonpost.com/ REPORTER Joel Achenbach

It’s the biggest piece of NASA space junk to fall to Earth in more than 30 years. It should create a light show. The satellite will partially burn up during reentry and, by NASA’s calculation, break into about 100 pieces, creating fireballs that should be visible even in daytime.
An estimated 26 of those pieces will survive the re-entry burn and will spray themselves in a linear debris field 500 miles long. The largest chunk should weigh about 300 pounds.
As the Friday-ish crash gets closer, NASA will refine its estimate of timing and location, but the fudge factor will remain high.
“There are too many variations on solar activity which affect the atmosphere, the drag on the vehicle,” said Nicholas Johnson, chief scientist for orbital debris at NASA. He said that when NASA estimates that the satellite is two hours away from hitting Earth, there will still be a margin of error of 25 minutes.
“That equates to plus or minus 5,000 miles. That’s a lot of real estate,” he said.
The good news is that UARS will probably splatter into the open ocean, because Earth is a water planet. And humans, for all their sprawl, occupy a very limited portion of its surface.
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.
Used fuel tanks and rocket bodies fall to Earth frequently, Johnson said, “and in over 50 years of these things coming back around the world, no one has ever been hurt. There has never been any significant property damage.”
The satellite was launched on the space shuttle Discovery in 1991 and spent 14 years studying the atmosphere as part of an effort to understand, among other things, the human influence on climate change. It measured chemicals that damage the ozone layer, aerosols from Mount Pinatubo and changes in solar radiation that affect the upper atmosphere.
http://www.washingtonpost.com/national/health-science/nasa-satellite-expected-to-hit-earth-this-week/2011/09/18/gIQARnpVdK_story.html?hpid=z3