The odds of being hit by a falling satellite — in this case NASA’s wobbly Upper Atmosphere Research Satellite — would seem to be astronomical. But they’re not.
Mark Matney, a scientist in the Orbital Debris Program Office (the people who track space junk) says the odds that someone will be hit are 1 in 3,200.
But the odds that you will be that one are somewhere better for all concerned — one in several trillion, according to Life’s Little Mysteries.
To make this calculation, Matney explained, analysts work out how much debris will actually make landfall. (Most falling junk just burns up in the atmosphere.) They then make a grid of how the human population is distributed around the globe. Oceans, deserts and the North and South poles are largely devoid of people, for example, whereas coastlines are brimming with them. In short, they must figure out which patches of Earth have people standing on them.
Throwing in a few more minor details, such as the latitudes over which satellites spend most of their time orbiting, the scientists calculate how likely it is that a piece of space debris will strike the ground where a person happens to be. This time around, the odds are 1-in-3,200, and there’s a one-in-several-trillion chance that not only will a person get hit, but that person will be you.
“The annual risk of a single person to be severely injured by a re-entering piece of space debris is about 1 in 100,000,000,000,” according to Heiner Klinkrad, head of the ESA’s Orbital Debris Office. As near as I can tell 100 billion is a lot smaller than several trillion.
All of these calculations go out the window, of course, if the experts eventually pin the satellite’s re-entry path in the vicinity of your cul de sac.
Some experts on the SeeSat Internet mailing list have calculated the satellite will return to earth “Friday at 2004 GMT (3:04 p.m. CDT) plus or minus five hours, and descending on 19.1 degrees north, 128.5 degrees east over the West Pacific near the northwest coast of Japan.”
In other words: it’ll probably fly over flyover country well before it returns to earth, but put on the show elsewhere.
But officials won’t be predicting where that might be until two days, one day, 12 hours, six hours and two hours before the calculated point of return.
Should you be concerned? An average of 13 people die each year from falling vending machines. You don’t change your plans because of them, right?
(h/t: Matt Black)