# How would skeptics know that a single-engine plane could not destroy a falling meteor?

So I'm writing a story and decided to use Hida Furukawa as the location. It has a high school with a field of 650 ft that theoretically could be used for a small aircraft to be use to take off. In the story, a meteor falling that can wipe the town out. A man decides to fly a plane into the meteor with some explosives on it to destroy the meteor and is successful at the cost of his "life."

I intentionally put that in quotes. As he is some dimensional traveler that controlled the meteor to fall. He staged a fake heroic death to jump into another dimension. In my story, I want to know what science/astronomer critics would say to give clues to how unnatural this is, so it helps the female protagonist believe that he is still alive and probably in another dimension.

Note (08/02/18) Based on everyone's feedback, I've changed location to Kakamigahara, Gifu Japan. It has a private airport that is sometimes used by the Japanese Airforce :) While I'm not going the fun with W-59 @CortAmmon suggested, I was tempted since I'd have access to planes that could fly higher lol.

• Just be aware that scientists are not experts in "other dimensions". Their expertise is pretty much limited to what we can observe – Raditz_35 Jul 26 '18 at 16:52
• @Raditz_35: The question is not about the other dimensions; the question asks what would skeptic critics have to say about a small aircraft with a bomb on board stopping a large-ish meteorite bound for an innocent Japanese town. – AlexP Jul 26 '18 at 16:55
• Scientists and astronomers are going to have a lot less trouble with this plot than explosive experts and pilots. – A. I. Breveleri Jul 26 '18 at 16:56
• a meteor that could destroy a town will not be stopped by a small plane maybe if your dimensional traveler has a nuke in his pocket but even then the damage will turn the town into rubble and lots of people will die but maybe this Impact calculator will help you get a better size simulator.down2earth.eu/planet.html?lang=en-US – Creed Arcon Jul 26 '18 at 16:59
• Critics would say: "As smart as Independence Day but without the lovable antics of Will Smith" – Jamie Clinton Jul 26 '18 at 17:33

I’m going to address this as a general question about using airplanes to stop meteors, rather than the very plot specific way the question is worded.

Nope. For one very simple reason:

Speed.

Meteors are not the slow moving flaming behemoths of Hollywood. In reality they’ll be moving at or above Earth's escape velocity (11km/s) when they hit the atmosphere, and anything big enough to hit the ground with any destructive force wont have shed much of that speed by the time it does. This means that they’ll clear the distance from your plane’s operational ceiling to the ground faster than you can twitch your joystick.

There are also serious concerns with the energy involved (no plane can carry enough energy to stop an impactor from impacting) and the fact that by the time it hits the plane it will already likely be in fragments.

On the other hand: your extradimensional guy can be using any number of weird technobabbly things to achieve his goal, employing advanced tech to make sure he’s in the path of the meteor and absorbing the energy to make the jump, but then it would appear more like he was just very, very unlucky (or weirdly prescient) rather than demonstrably heroic.

EDIT FOR A FUN NOTE:

If the meteor were large enough to not be completely in pieces before it hit the ground it would also compress the air underneath it to such an extent that people would be incinerated before the meteor crushed them. Physics!

• @AlexP: That meteor in Russia some years back only slowed down to about 15km/s(from 30km/s) before breaking apart. The world's fastest plane maxed out at about 1km/s. – Giter Jul 26 '18 at 17:06
• @Alexander: He can, but it would look at best like a freak accident and at worst like he planned to get hit by the meteor. The first is freakishly unlikely, the second is patently ridiculous. There is no scenario where he looks like he heroically saved the town. – Joe Bloggs Jul 26 '18 at 17:57
• @jamesqf 30 km is well above the altitude reachable by practically any airplane, let alone what could be reached quickly. Jetliners normally cruise at around 10-12 km (some 30-35 thousand feet). – a CVn Jul 27 '18 at 7:15
• @AlexP Joe Bloggs is right. Suppose the rock is moving at even just a measly 5 km/s relative to the Earth. The Karman line is at 100 km, and that's the altitude at which "space" officially begins. If unimpeded by the thickening air, the asteroid would need 20 seconds to get from there to ground. While in reality the asteroid will be impeded by the atmosphere, (1) it will be moving much faster than that, and (2) the atmosphere doesn't become thick enough to truly matter before you get quite close to the ground. It just won't have time to slow down by any appreciable amount in the atmosphere. – a CVn Jul 27 '18 at 7:19
• We should not forget, the destructive energy of the meteor comes from the sudden deceleration. For that, it doesn’t matter whether the deceleration happens when hitting the ground or when being stopped by a plane (if that was possible). It still would release the energy and cause devastation. In fact, nuclear weapons are ignited high up in the air, because that will cause more destruction than exploding on the ground… – Holger Jul 27 '18 at 9:31

Not possible because meteorites move with 11 to 72 km/s. The best chemical explosive octanitrocubane create shockwaves with 10 km/s.

This means if the shockwave of the entering meteorite is not powerful enough to disintegrate it (as it often happens), chemical explosives can't do it. When the hit would trigger the explosives immediately (which it cannot), the meteorite simply outruns(!) the explosive gases.

How can a meteorite be destroyed?

Let's say it is the same size like the Chelyabinsk meteor, 20 m diameter and 10 000 ton weight.

Heat.
One possibility is to try to vaporize it, we need 3000°C to vaporize most stones. Stone has a specific heat capacity of ~1 kJ/kg*K, so we need 3 MJ/kg yielding 30 TJ ($30 \cdot 10^{12}$Joule) to vaporize the meteorite. If we could use the full energy of the most massive bomb ever built, the Tsar Bomba, we have 20 Petajoule ($20 \cdot 10^{15}$ Joule) of energy available which would be sufficient. Problem: The duration of the explosion was 39 nanoseconds which is equivalent to 0.39 millimeters of meteorite path, so we would need pinpoint precision.

Pressure
Another option is a powerful enough shockwave. You only need to split the meteorite in small enough parts that the atmosphere can vaporize them. So apart from being powerful enough it must be dispersed in sufficient height because otherwise your city is hit like a shotgun.

Even if we have a nuclear weapon, we still have many problems:

• Trigger: We would need a trigger with nanosecond precision to detonate the bomb exactly when it is needed.

• Distance: We would need a distance measuring method which would be able to accurately estimate something which is flying faster than a bullet.

• Path convergence: 20 m diameter is very, very small, you pass that in less of a second in the slowest airplane. How exactly do you find the exact path?

• Height: It does not matter if you destroy the meteorite in 5 km height because half a second later the debris will blow away your town. You need at least intercept it at stratosphere height (20 km).

No, it is not possible. It is even a formidable task for today's technology.

• All these problems are because our atmosphere is a VERY good defense system. Anything that beats it are extremely catastrophic and are well beyond our ability to defend against. – Nelson Jul 27 '18 at 2:50
• "20 m diameter is very, very small, you pass that in less of a second in the slowest airplane" Actually, 20 m/s sounds like about the lower limit for maneuverability in the motor airplane I fly. You're teetering on the brink of an aerodynamic stall around 50-60 km/h indicated airspeed in that particular one (better hope you don't get a gust of tailwind!), but around that speed, it's still controllable. I'm not sure I'd call what you're doing at that point flying, though... it's more that you're avoiding literally (not proverbially, but really literally) falling out of the sky. – a CVn Jul 27 '18 at 7:26
• Of course, after exploding a Tsar Bomba at a hight a small aircraft can reach, it will be mostly irrelevant if the asteroid was destroyed, as the town will no longer exist anyway. Even if the explosion made the asteroid vanish completely (no debris). – celtschk Jul 27 '18 at 9:09
• You can use explosives on something moving faster than the shock front. You just need to be in front of it when the explosives detonate so the object runs into the shock front rather than the shock front futilely chasing it down. – Loren Pechtel Jul 27 '18 at 14:43
• I strongly disagree with your computation. The Tsar bomba is nearly 1000 stronger than needed and would cause much more harm than the meteorite, so please use something more realistic. +++ These 39 nanoseconds seem completely irrelevant to me and these 0.39 millimeter even more. How could 0.39 mm be relevant to an object of 20 m diameter??? +++ That all said, your conclusion is surely right. – maaartinus Jul 28 '18 at 0:26

The answer is no. And if you really feel like it, you can ignore the explosives entirely.

In physics, we can always choose our frame of reference to simplify the problem. Let's take our frame of reference to be that of the meteor. If it is traveling at 6km/s with respect to the earth (a conservative estimate made by Joe Bloggs that I like), that means that, from the meteor's point of view, the plane is traveling at 6km/s towards it! A Cesna 172 has a mass of roughly 1100kg. At 6km/s that's about 40,000MJ of energy. TNT releases around 4MJ/kg, so the kinetic energy alone accounts for about 1000kg of TNT.

In other words, the energy from your relative velocity with respect to the meteor is equivalent to the explosive energy you'd have if you made your entire plane out of TNT!

Now the energy required to level a town is on the order of nuclear weapons. You're talking hundreds if not thousands of tons of TNT equivalent. Your plane's energy is pretty darn minuscule by comparison. Destroying a town is on the rough order of 1-2 MT of TNT equiv. so your plane is something like 0.1% of the mass that this meteor has.

"Do you know how much damage this bulldozer would suffer if I allowed it to roll straight over you Mr. Dent?"

"How much?"

"None at all." - Hitchiker's Guide to the Galaxy

Also, note that the ceiling for a Cesna 172 is about 4.5km. That means that you will hit the meteor at most 0.75 seconds before it impacts. Most of the meteor is going to... well.. continue on to its destination. It's not going to have the time it needs to pick up tangental velocity to spread the impact away from the town.

• Sounds like he would need a nuked tied to the aircraft and it would need to some how go higher than 4.5km. The nuke would probably be too heavy for the Cesna 172 at that point haha. At which point, the nuke is just as big of a threat as the meteor. – jemiloii Jul 26 '18 at 18:58
• Yeah, for some reason, I feel like if the protagonist showed up with a W-59 in hand, I'd have to start questioning his status as a protagonist. – Cort Ammon Jul 26 '18 at 19:19
• A Cesna could lift off with that XD, well he isn't the protagonist of this story. This is actually the start of it. He is just doing his usually, fake an epic death and dip strategy. – jemiloii Jul 26 '18 at 19:23
• Of course, it probably doesn't help that a Cesna 172's ceiling is almost the ideal height for setting off a W-59 for maximum damage (thanks to Nukemap) – Cort Ammon Jul 26 '18 at 19:46
• a Cessna 172 won't take off in 650 ft without a really strong headwind, though. Source: about 200 hours in 172s. – Erin Anne Jul 27 '18 at 2:57

He fakes it with his dimensional powers

To answer your question NO he will not make it in time; and even if he did blow up the meteor the fallout would kill everybody anyway

BUT

IF the dimensional traveler could just use his powers to take a huge part out of the meteor into another dimension. then blow what’s left up with his plane and make it look like he did it. then fake his death for the whole world to see and just be left confused

The science/astronomer critics will be baffled as to why they are not dead based on the size of the meteor and that could be the protagonist clue for her to believe he’s alive. It’s both sound of mind and helps you avoided the “jumped the shark moment”

• Haha, thanks for the input, while it doesn't answer the question of what critics would say, this does help make the situation more believable! – jemiloii Jul 26 '18 at 18:53
• I was just going to write this same thing. Yes, the "science/astronomer critics" would be baffled as to how the plane with explosives could have stopped the meteor and its effects. Since there was video of the event they know it was successful, they just won't be able to figure out how (unless they know about extra dimensions.) – Tracy Cramer Jul 26 '18 at 20:26
• Now this is an answer. – Cem Kalyoncu Jul 29 '18 at 18:54
• How is this the answer? This is basically just describing the setup of the question. – mattdm Jul 29 '18 at 20:18

When any object comes from space into our atmosphere it undergoes ablation - the intense friction and pressure (from air compression) generates heat and corrodes the object away. That's why the smallest bodies never reach the ground, disintegrating in the upper atmosphere. Larger objects may hit the ground after losing some mass to ablation.

Blowing up a falling meteor may actually be a good idea. By tearing it into chunks more surface would be exposed to ablation, and the smaller pieces might disintegrate in the upper atmosphere.

However, a town destroying asteroid might be too massive and tenacious for a simple explosive. Also it is moving too fast - these things enter the atmosphere at multiples of the speed of sound. Last but not least you need to intercept it pretty high in the atmosphere, or in space preferably. This is a job for missiles of the heaviest kind - we are talking ICBM's here.

Your character's feat will not take a scientist to debunk. Anyone with high school knowledge of physics will see that this is farfetched enough even for Holywood.

• While friction does contribute to heating a meteor, most of it comes from compression of the air that literally doesn't have time to go out of the way and gets rammed against the meteor. Not that it invalidates the answer, of course, as both do pretty much the same for an observer anyway. – Eth Jul 26 '18 at 18:00

After everyone being a downer I'm go to help you out here. Realistically? No he couldn't do it. Technically? Of course, he could use the caloric energy contained within 11,048,505,945,548,076,923.077 chocolate chip cookies.

This is all assuming that this is a very large meteor traveling at 41.5 Km/s (average meteor speed is between 11 and 72Km/s so lets cut that in half) and is made out of iron and has a radius of 30.89km and is also striking at a 90 degree angle for maximum energy deliverance so it's powerful enough to destroy the whole of Hida-Furukawa. (These numbers are from http://down2earth.eu/impact_calculator/, fun little tool.) This is all assuming that region of japan is mostly made of igneous rock which was an assumption of my part.

The energy of this meteor at such a velocity upon impact is about 3.60811375*10^21 J which can be converted into 8.6178316375275x10^20 cal and the all powerful god google told me that there are about 78 calories in a chocolate chip cookie. Divide the necessary amount of energy to stop the meteor to stop the meteor by the amount of energy in a cookie and you find how many cookies you need.

TL;DR If you ate and absorbed 100% of the energy in 11,048,505,945,548,076,923.077(ish) chocolate chip cookies you would be able to stop the meteor with your fist and still have room for a snack.

Refs: Speed of a meteor: https://www.amsmeteors.org/meteor-showers/meteor-faq/

Meteor size and density needed: http://down2earth.eu/impact_calculator/