Never tell me the odds - wait, no, please tell me the odds.
February 16, 2009 6:56 AM   Subscribe

With things falling out of the sky with a little more regularity then usual lately, and what with me being a bit of a flybaby, I was hoping some of the Metifilter geniuses could help reassure me with some science...

I hate flying. I have to do it quite often, and sometimes I'm sort of OK with it, but I'm having a lot of anxiety about my upcoming flight (I'm pretty sure it's because I'm moving away from one city which I don't really love, and to another that I'm pretty excited about and am just doing my usual "Gee, I sure hope nothing goes wrong" thing).

I know this is stupid. I really do feel stupid for even asking this. But here goes:

What are the chances that some bit of the satellites that collided above the earth would still be a hazard at 30k feet? If the stupid FAA hadn't put out a stupid "hey pilots, watch out for bits of space debris as you fly" and didn't put any sort of end time for the warming, I'd likely be less insane about this. Also, honestly, what would the chances be of avoiding some bit of flaming something flying at you from the upper atmosphere if you were a flying a commercial jet? I'm guessing not so much.
posted by monkey!knife!fight! to Travel & Transportation (14 answers total) 2 users marked this as a favorite
An NTSB report estimates that the chances of a meteorite penetrating the hull of a domestic aircraft over the U.S. are once every 59,000-77,000 years. The full report can be found ">here
posted by DreamerFi at 6:58 AM on February 16, 2009

Crap, that link didn't go well.


And then there's this:

"It is certainly possible for a meteorite to strike a commercial airliner, although the probability is low. We can make a very rough estimate by comparing the area of airliners with the area of cars in the U.S. A typical car has an area on the order of 10 square meters, and there are roughly 100 million cars in the U.S., for a total cross-sectional area of about 1,000 square kilometers. The typical airliner has a cross-sectional area of several hundred square meters, but the number of planes is much smaller than the number of cars, perhaps a few thousand. The total cross-sectional area of airliners is therefore no more than 10 square kilometers, or a factor of at least 100 less than that of cars. Three cars are known to have been struck by meteorites in the U.S. during the past century, so it would appear that the odds are against any airplanes having been hit, but it is not impossible that one might have been.
posted by DreamerFi at 7:07 AM on February 16, 2009

I don't thing there is any science behind it aside from the law of gravity. The more stuff that's being put up there, the more likely the event that something will malfunction, collide or go off course and in that environment stuff is going to be falling at a much higher rate than a decade ago when the skies were *friendlier*. Now, one needs simply to trust the universe that all will be ok regardless of the odds.
posted by watercarrier at 7:16 AM on February 16, 2009

The poster isn't talking about naturally occurring meteorites. The 2 satellites that collided put tens of thousands of more pieces of debris in the atmosphere than are usually there. How does that increase the odds?
posted by pearlybob at 7:17 AM on February 16, 2009

Best answer: Really, really vanishingly small.

The odds of a fatality are so small that statisticians (I'm not one, but I work in a related field) have a difficult time explaining how small the odds in fact are. Even to other mathematicians. Humans just aren't good at wrapping their heads around numbers that small.

Here's a lecture from a person from MIT who gives the subject a much better treatment than I can. It's probably worth watching (and understanding it doesn't rely on any deep understanding of math).

I looked at the NOTAMs, by the way, and didn't see any mention of space debris. If you're referring to the two satellites that just collided (the Iridium v. defunct Russian satellite), even the small and light bits that will be the first to de-orbit will still take quite some time to do that. And, by nature of being small and light, their chance of making it through the atmosphere is essentially nil. The satellite collision is a danger to other satellites, but certainly not to aircraft.

So, to recap: your chances of dying in an commercial air crash is essentially 0%. The chances of a bit of satellite making it through the atmosphere (especially when you're talking about flying) is also essentially 0%. The chances of a piece of a crashed satellite colliding with your aircraft and killing you? We're talking stupidly-small.
posted by oostevo at 7:28 AM on February 16, 2009

Supposedly, the debris has already deorbited. I doubt whats left will make it through the atomosphere. Id be more worried about cancer and bird strikes than space garbage hitting a plane. Historically that has never happened, even during the launch happy days of the cold war.
posted by damn dirty ape at 7:50 AM on February 16, 2009

Best answer: This website claims one in a trillion. I imagine those odds include people in buses, cars, planes, etc.

So far its happened to one person.
posted by damn dirty ape at 7:57 AM on February 16, 2009

The most relevant question is "does the difference in elevation between 30k feet and 0 feet make a difference in the chance of getting hit?"

Because otherwise, the odds are the same as sitting at your computer asking this question.
posted by smackfu at 8:27 AM on February 16, 2009

Response by poster: Smackfu - that's pretty much true, as I would assume that less pieces would have burned away at 30k feet then by the time it would hit me as I'm sitting here typing this. Plus, it would have to go through a few apartments above me, and if it hit a different part of my building, the whole building wouldn't plummet to the ground in flames going hundreds of miles per hour.

In general, I expected the answer to be "really really tiny" and I thank you all for giving me the odds. Since most of it seems to have fallen over North America, and I'm in Europe, that should (maybe?) help reduce the tiny tiny odds to even smaller bits.

Basically, I guess I'll shift my fear of flying freakout to "hmm...hope those bolts are all tightened correctly" or "hope the pilot that flew into Kiev last night at 1:30 am and now is flying me out at 5:30 am spent those few hours sleeping instead of sampling the fine local vodkas."

Thank you again, internet friends!
posted by monkey!knife!fight! at 8:46 AM on February 16, 2009

Think about how many flights take off or land at your local airport every hour. It's quite a few. Now think about how many flights take off or land at your local airport ALL DAY LONG. It's a lot, and that's just at your local airport.

Now think about how many flights take off in your entire country today.
Now think about how many flights take off in the entire world today. many fatalities were there?

Thus - you're perfectly safe. Have a nice flight. ...oh, and please be careful when driving to the airport. THAT'S not safe :)
posted by 2oh1 at 9:42 AM on February 16, 2009

I think Flanders and Swann said it best.
posted by fearnothing at 10:34 AM on February 16, 2009

Eep, apparently bad links plague us today! I'm tired, that's my excuse.

correct link here.
posted by fearnothing at 10:35 AM on February 16, 2009

Best answer: Try this on for size. OK, the earth is a sphere. Gravity pulls stuff toward the center of that sphere. If you were somehow sitting right at the center of that sphere, you'd be hit by everything. The further you get from the center of the sphere, the larger the surface area of the sphere is. That means, to me, that there is relatively more area for stuff to go where you aren't, lessening the odds of being hit.

So, the diameter of earth = 41 851 050 feet
radius of earth = 20 925 525 feet
surface area = 5 502 527 513 875 753 sq feet

adding 30 000 feet to the radius gives a surface area of
5 518 316 284 420 093 sq feet

So I guess that means that when you are 30000 feet above the surface of the earth, there is 15 788 770 544 340 more square feet worth of area for stuff to go besides hitting you. Which looks to be about a third of a percent larger.

Thus, I think, the odds are very slightly less when you are in a plane than when you are on the ground. Additionally, I would suspect that given the size of the space junk, that it would burn up long before it got to the ground or your plane. So, nothing. You're still far more likely to win the lottery, get elected president and be struck by lightning during your inauguration than be injured by space junk.
posted by gjc at 10:53 AM on February 16, 2009 [2 favorites]

Response by poster: gtc...i love you. exactly what i wanted to hear.
posted by monkey!knife!fight! at 2:20 PM on February 16, 2009

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