Brace yourselves, people. I have a revelation.

The plot of Armageddon was flawed.

Take a moment to digest and come to terms with that.

It all comes down to that little sequence when at Mission Control Centre, they're planning the emergency response. The English douche, dubbed the Smartest Man on the Planet, berates the President's scientific adviser's suggestion of changing the course of the asteroid with nuclear explosion. He does this by calling attention to his poor grade in astrophysics at university. Of course, in this instance the guy's ability to differentiate neutron stars from white dwarves is not a critical factor.

Instead, of course, they have to go with the idea of drilling into the core of the asteroid (800ft in a 1500 mile wide asteroid counts as the core apparently). But this is absurd. Without going into any numbers, think about it.

Plan A involves using nuclear explosions to deliver sideways momentum to the asteroid so it misses the planet. Plan B involves using nuclear explosions to break the asteroid into two peices and then deliver to each major part sufficient sideways momentum so they miss the planet.

Both plans involve delivering momentum, and of course the requisite kinetic energy, so that the asteroid misses the planet. Plan A delivers kinetic energy so the whole thing is moved to one side. Plan B delivers kinetic energy so half if moved one way and half is moved the other. But the speed required is the same either way, so the energy required is the same.

However, with Plan B, you also have to supply chemical energy to break the asteroid into two pieces. I haven't run the calculations on what would be required to do that, but a cursory glance will see that the energy requirements of Plan A are substantially less than Plan B.

Hence, the English douchebag is wrong. Listen to the President's scientific advisor, even if he doesn't know much about quasars.

Actually, as I mentioned in an earlier post, drilling would have worked just as well for the diversion plan, since exploding the nuke below the surface results in the bit above the explosion to work as reaction mass, making the nuke many times more effective for the course change.

Had they instead used a need to drill down far enough to make the reaction mass large enough for the needed course change, the movie could have been essentially the same, except for slightly different CGI, two lines of dialog, and having at least some part that was real physics.

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‘To those who regard “crime fiction” as some sacred icon which must follow a rigid formula, I will always be the man who writes 18-syllable haiku.’Trying to make sense of computers, The Error Log.

Henrik, wouldn't they have needed a larger explosive in the case of your altered plan A? If less mass is uses as propellant, wouldn't it need more energy to generate the same amount of thrust?

RE, the OP, placing an explosive in a container allows it to do more work as the energy is absorbed by more of the material. If you explode a nuke near the surface of an asteroid, only a small fraction of the energy released would fall upon the surface since most would radiate in other directions from the omnidirectional/spherical explosion. Moreover, Reflectance and emission of that energy can further reduce the amount of propulsive power.

Putting the nuke inside the asteroid not only allows all of the energy to be captured, it acts as a tamper, holding together long enough to allow more of that energy to be converted into mechanical energy. This is what happens when you pop a nuke in the atmosphere. You don't just get one release of energy, you get two, hence the characteristic double-flash. Actually, saying it's two releases is probably over-simplifying, but I think it exemplifies the concept. The first release is seen, but then the surrounding air heats up so much that it becomes opaque. Then it absorbs more energy, then radiates more energy itself at lower temperatures/freqencies. The fireball expands, and as it does so it cools by multiple methods, adiabatic, conduction and radiation. A lot is released as thermal radiation due to the clarity of the atmosphere at certain wavelengths. Inside an asteroid, however, much of this thermal energy would continue to be absorbed, producing vapors from various materials, the phase-change expansion and thermal expansions of which would continue to provide mechanical energy to propel the asteroid explosion.

All this really means is, it's not how big it is, but how you use it.

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"What you think you thought you saw you did not see." Agent J, MiB - Manhatten Bureau

The smart guy was correct in his assessment that more work would be done from within. But the only reason it worked to the Earth's advantage was that the asteroid cleanly broke into two pieces just in time to miss.

Realistically, his plan possibly would have been a worse scenario, splintering the body into many pieces that would impact in several areas. But given the setup, there wouldn't really be a good way out. It's time that's the big factor, if we don't have a lot of that, even a small rock would be a problem.

Nobody ever listens to the science advisor... not even the director.

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I want to go back to the moon.
I don't care which rocket you use, whichever one you pick, I'll like it, I swear.
"If you think the LHC will create black holes, you might as well believe Hobbits are at the bottom of your garden."- Dr. Mike Inglis
Rovers forever! - ToSeek

Clearly, you've not seen the White House press briefing on Onion-Span 2 entitled "President to Face Down Monster Attack, Own Demons in Action Packed Schedule". (I'd link to it, but it contains some naughty words, so I don't know if the mods would be approving of that. A quick google flail on the terms president+monster+onion will yield the correct video, however. It absolutely nails the whole summer monster movie genre from the perspective of a White House press briefing, BTW.)

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We want our children to go to the planets. Burt Rutan 6/21/04 K.I.L.L. S.M.U.R.F.S.
Tuckers! Automotive Oddities! Building my hot rod with the help of the intarwebs Those who would delay scientific progress for a little temporary prosperity shall have neither. MachineCast Save the planet, by leaving it! "To be second in space is to be second in everything," LBJ.

Actually, I did see that before, and it was very funny.

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I want to go back to the moon.
I don't care which rocket you use, whichever one you pick, I'll like it, I swear.
"If you think the LHC will create black holes, you might as well believe Hobbits are at the bottom of your garden."- Dr. Mike Inglis
Rovers forever! - ToSeek

I worked through two conventional definitions of "own" before I fully understood that headline.

Perhaps "pwn" would have made more sense.

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"What you think you thought you saw you did not see." Agent J, MiB - Manhatten Bureau

It would have. Another issue is the fact that I almost never use "own" in that context.

Hey , that's not any English douchbad.. That's Lucius Mallfoy ... better take back the Douchbag comment before he does all Dark Arts on you.....

(Jason Issacs - great character actor , and real hollywood favourite these days ...)

Just checking that calculation at the beginning of the movie. The dinosaur killer was 6 miles across. Let's call it a sphere of radius of 5000m. Let's also assume a density of 2000 kg/m³, the density of Ceres. That means the mass of the impactor would be around 10^15 kg.

Assuming that it came from a very long way away starting with a gravitional potential energy of 0. It falls to 6000km radius (the surface of Earth), which means a GPE drop of 7e22 J.

Converting this to that all important scientific unit of "nuclear weapon", we're stumped as to which one. Little Boy or La Bomba? Assume La Bomba, with a yield of 50 megatonnes of TNT equivalent and since a megative of TNT equivalent is 4e15 J, then that means the impactor transferred energy on the order of 350,000 "nuclear weapons".

Somebody did a comparison to the one which is thought to have killed the dinos, and came up with the one in the film being significantly larger. IIRC, their comment was, "That's not a dinosaur killer, that's a planet killer." as the level of destruction would wipe out the biosphere almost completely.

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We want our children to go to the planets. Burt Rutan 6/21/04 K.I.L.L. S.M.U.R.F.S.
Tuckers! Automotive Oddities! Building my hot rod with the help of the intarwebs Those who would delay scientific progress for a little temporary prosperity shall have neither. MachineCast Save the planet, by leaving it! "To be second in space is to be second in everything," LBJ.