If you see NASA’s falling satellite today, remember to duck

If you see NASA’s falling satellite today, remember to duck:

Good news: If you are reading this story on Friday evening or Saturday morning, it means that you have yet again survived the momentous (but incredibly common) impact of a meteorite here on Earth. If you’re reading this on Friday morning, though, on your way to work perhaps, be sure to keep an eye out for NASA’s 20-year-old, 6.5-ton, bus-sized Upper Atmosphere Research Satellite which is scheduled to begin its fiery descent through our planet’s atmosphere some time today.

UARS, which was deployed by Space Shuttle Discovery on STS-48 back in 1991, was originally tasked with studying the Earth’s ozone layer. Its mission was only meant to last three years, but by the time it was finally decommissioned in 2005, six out of its 10 instruments were still operational. Now, six years after it was (intentionally) placed into an orbit that would impact the Earth, UARS is heading home.

The satellite will splinter into hundreds of pieces as it tumbles towards Earth, and much of it will burn up during re-entry, but 26 larger metal chunks — fuel tanks, support struts, and so on– will survive the friction and strike the Earth at around six miles per second, or 21,000mph. Needless to say, if you end up on the wrong end of a hundred-pound fuel tank moving at 20 times the speed of sound, you are unlikely to emerge the victor; on the other hand, the meteorite will be moving so quickly that you won’t even see it coming, so at least your messy, fragmented death will be relatively peaceful.

The good news is that no one — at least in recorded history — has ever been killed by a meteorite, a happy statistic that is made positively amicable by the fact that over 3,000 meteorites slam into Earth every day. 75% of the Earth’s surface is water, you see — and out of the remaining 25%, we humans only occupy a few percent. “Earth’s City Lights,” a photo of the Earth’s surface at night (and ironically enough, captured by a satellite), shows just how sparsely spaced our settlements are.

NASA UARS concept art

Still, the most worrying thing is that NASA doesn’t know where the satellite debris will strike; it only knows that it will hit between Friday evening and Saturday morning, that the meteorites will stretch across a 500-mile path, and that it won’t hit North America; good news if you want to see tomorrow’s dawn, but bad news if you were hoping for a glimpse of the firework display that will occur when the satellite begins to burn up — or if you happen to be outside North America…

Overall, NASA says there’s a 1-in-3200 chance of someone being struck by the satellite — and if you extrapolate that out to the actual chance of you being hit by it, it’s something like 1-in-a-few-trillion. In other words, you have more chance of winning the lottery tomorrow than being struck by the satellite.

Read more at Space and The New York Times (which includes a hilarious quote from a rabbi…), or the BBC (which has a video of the satellite falling)