P.s. Here are some links to the spaceweather.com and NASA Jet Propulsion Laboratory websites archives for the June 1 meteoric events. Also, links to articles on space debris.
http://spaceweather.com/archive.php?view=1&day=01&month=06&year=2009
http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2009%20KR21;orb=1;cov=0;log=0;cad=1#cad
http://orbitaldebris.jsc.nasa.gov/
http://www.space.com/spacewatch/space_junk.html

If you hit a leading edge on a wing it is (unlike the space shuttle) unlikely to do critical damage.

Striking the top of the wing would likely result in a fuel leak, but the critical hydraulic lines and structural wing spar offer much smaller and better protected targets.

The front of the cockpit might be an especially vulnerable area (assuming the strike takes out both pilots, or happens when only one is in his/her seat), but again, that’s probably just the windows and the area right around them.

The tail surfaces are probably the most vulnerable, though if the assumption is correct that a strike would be head-on, even those should be pretty robust, and again, small targets.

What strikes me as interesting is the idea that aircraft may have already struck smaller meteors and nobody noticed. As an earlier poster mentioned, anything that didn’t penetrate the skin would likely be mistaken for a bird strike, hail, or a foreign object kicked up on a runway. The people reporting and investigating these things likely would have no idea what to look for to spot such an impact.

But I’m pretty sure that such incidents and repairs are maticuliously documented and recorded. and it might be possible for an industrious researcher with better knowledge of meteors to dig through them an spot previously missed impacts (if any).

The Boeing 737 that landed in Hawaii with most of its roof missing is an extreme example of the former. But note that, while the damage there looked (and was) severe, most of the planes critical systems (and a lot of its structure) is in the lower half of the fuselage.

On the other hand, a few metal shavings in rudder actuators have apparently been enough to bring down multiple 737s over the years (obviously this isn’t an example of externally caused damage, but it does demonstrate how a small failure at a critical point can doom an aircraft).

In general, modern aircraft are very robust, and have enough redundancy of critical systems to survive all sort of damage. I suppose you could come up with some sort of “critical damage target area” for any given aircraft, and using this would bring down the likelihood of a meteor-impact loss even farther.

But even that doesn’t take into account the KIND of impact. Speed, area, mass, and the mechanical characteristics of the rock would have to be taken into consideration. A pebble sized rock traveling at a few hundred miles per hour isn’t likely to do much damage unless it hits a particularlly vulnerable area. It might damage a window in a cockpit. It might even cause an engine failure, though such failures are rarely fatal these days.

I suppose it might also damage a fuel tank, but that’s unlikely to be as catastrophic a problem as an earlier poster imagines. Burning jet fuel requires an ignition source and a proper fuel-air mixture, and the flame would have to burn close to the structure of the aircraft before being swept away in the slipstream. Most likely, it would simply result in a fuel leak with out ignition, with all the problems that result from that. Assuming the fuel loss didn’t result in an emergency landing, I’d imagine the pilot would notice the fuel loss and probably run (or vent) the tank dry before landing as a precaution.

A large, slow moving boulder, on the other hand, could do considerable damage no matter where it hit. (So would a dropped piano, for that matter, if Mars were to toss one down as it passes by.)

But when you think about it, it comes back to the same issues as the Hawaii 737. Unless the meteor is very large, or very fast, it is rather less likely to do critical damage, as the most vulnerable systems are mostly on the bottom (structure, landing gear, hydraulics, electrical system) or on the rear (control surfaces). If you punch a hole in the roof, you might depressurize the cabin

I wonder if it could have been a meteor strike, followed by hitting severe turbulence and electrical storms – each individually survivable, but not in combination? From the BBC article (http://news.bbc.co.uk/2/hi/americas/8087303.stm), the aircraft had at least one problem that it survived that caused loss of radio contact, and it did not crash until many minutes later.

As someone else pointed out, several aircraft could have already have been hit by meteors without people ralizing it was meteors causing the damage.

GAry 7

And I noted that you all go ballistic on terms.

Commercial jets have a lot of damage tolerance. There are many cases of airliners making safe or at least partly controlled landings with all sorts of damage, a few of the causes being:

* skin or door failure leading to cabin pressure explosion
* gross upset leading to airspeeds and/or G loadings far in excess of design limits
* attack by military weapons
* bird strike
* flight through volcanic ash
* engine explosion
* collision with ground structures during takeoff

Based on this history, I would expect that an airliner would have a good chance of surviving collision with a small meteor. My understanding being that the frequency of meteors increases dramatically with diminishing size, I would expect many survivable meteor strikes for each catastrophic outcome.

It is further my opinion that if a jet had a hole or other damage from meteor impact, analysis would very likely reveal the material, so meteor damage would have a good chance of being identified as such.

If these inferences are correct, the absence of reports of meteor damage during, say, the past 50 years suggest that the probability of a catastrophic incident is a lot less than once in 50 years.

The probability of the plane running into the meteoroid increases as the meteoroid becomes slower, as it will be in the area where collision is possible for a longer time (and a faster plane will cover more horizontal space, increasing the probability of hitting a meteoroid). Likewise, the plane will be exposed longer if it is slower.

However, the space the plane takes up seen from above remains the same, no matter how fast the plane is and how fast the meteoroid is. In other words, the probability of hitting a plane that is going at a higher speed is now lower; it will simply be a different plane that will be hit by a different meteoroid if, say, all planes go twice as fast (but remain in the sky for the same amount of time). Time is what really matters; if a plane is in the air 10 hours, it’ll be hit from above twice as likely as one that is in the air 5 hours. How fast the planes go doesn’t matter.

All things considered, a slower comet will be more likely to touch a plane than a faster comet. Hitting from above has the same probability, but hitting horizontally increases in probability.

Mystery solved.

Next question?

should be…

“So if one meteor is in the way of an aircraft, the chances are high that others will also be.”

Clicking on my original comment, came up with the error “load failed” or some such! Hence, I added a new comment.

So consider the possibility of a meteor of about 0.1 metre diameter breaking up. This would vastly increase the chance of multiple strikes on the same aircraft from one meteor.

Also remember that meteors normally come in swarms, rarely just as individual rocks – assuming this is from a comet.

Do if one meteor is in the way of an aircraft, the chances are high that others will also be.

So statistically speaking, the chance of an aircraft being hit by one or more meteors are much lower than indicated by a naive assumption that the probability of being hit is a ratio of areas times the number of meteors per unit time… However, when an incident DOES OCCUR then the odds of being hit multiple times are very high.

The interesting thing about (1-p)^N, where p = 1/N, is that you can define the mathematical constant e by e = limit(N-> infinity) (1+1/N)^N.

(More generally, e^x is defined by limit(N->inf) (1+x/n)^N.)

So for this case, N=1,000,000 we’ve pretty much limited on the final value, e^-1, and the value we came up with should have been expected.

– John, who still thinks of himself as a Liberals Arts Type, too.

Imagine playing Russian roulette once. There is a (5/6) chance (83.33%) of getting spared. If you spin the cylinder and play it a second time, there is also a (5/6) chance of surviving and therefore a (5/6) of (5/6) chance of surviving an attempt at two games. Attempt to play the game three times and your chance of survival is (5/6) x (5/6) x (5/6). Try to play the game six times (you must spin the cylinder each time to keep the probability of an individual hit at (1/6)) and your chance of survival is (5/6)^6, or about 33.5%. So your chance of getting shot is 66.5% (not 100%). As long as you spin the cylinder of bullet chambers each time, your luck doesn’t necessarily have to be “used up” after six attempts.

Now imagine having a 1000 by 1000 pixel screen (one million pixels) where every pixel is white. Now every second you randomly target a pixel to “hit” to turn it to black (regardless of whether it is already black). At first, the number of pixels that are white will decrease more or less linearly because every second it is almost 100% likely that a new pixel will be “hit” and turned to black. It seems that when we make our one millionth “hit” all one million pixels will be turned black. However, after a little while enough black pixels accumulate so that you begin to “hit” more and more pixels that are already black. The rate of decay of remaining white pixels slows down. So instead of hitting all one million pixels, some are spared and some are hit more than once. After one million seconds, the fraction that are spared is 0.999999 to the power of one million, or 36.79% (very close to e to the power of negative one). So the fraction that is hit is 63.21%.

Given the usual explanation of the Tunguska event as a meteoric air burst, I can see why you’d say that.

And no, I’m not going to succumb to the temptation myself.

Taking this to extremes, imagine a plane moving so fast that it traverses the entire surface area of the globe in one second, and a meteoroid falling so slowly that it takes one full second to pass through the plane’s altitude. In this scenario, the chance of collision is 100%.

In other news, I just flipped open my copy of Hartmann and went digging for meteor flux information. A 1-m (in space) body hits the Earth of average once an hour. According to Hartmann, when get below 10 m, you’re starting to see things break up in the atmosphere. So 1-m radii bodies are reasonably in the ballpark of the minimum sized bodies you’d need to wipe out a plane. If you accept that, this throws the calculations off and reduces the odds of any plane being taken down in the past twenty years to 0.03% (check my math?).

While the speculation is interesting, lets be respectful … a lot of people died in this tragic event!