How to test a 200 MT nuclear bomb?

Skwinty said:
In space there is no atmosphere to transmit a pressure wave.

So the only pressure exerted on the asteroid or comet would be gamma rays, other electromagnetic energy and particles from the bomb itself.

Whether that would be sufficient to dislodge the asteroid from its current trajectory is debatable.
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You will vaporize facing side of the asteroid. That is supposed to give the impulse. IMHO it's the best method we have at the moment. It's doable with what we have.

Engine on the asteroid is nonsense, as any engine we have at the time is just too weak. It simply must be nuclear. Also the asteroids usually rotate, which complicates things.
 
The problem with rotation can be handled by using a "gravitational tractor".
That is, the motor assembly hovers in a pattern over the asteroid on the away from earth side. Gravity is a two way thing so the pull is excerted without bothering with landing or tethering the asteroid.

Sure, there would be problems with getting a strong enough engine in place in time. :(
 
Dr.Sid said:
You will vaporize facing side of the asteroid. That is supposed to give the impulse. IMHO it's the best method we have at the moment. It's doable with what we have.

Engine on the asteroid is nonsense, as any engine we have at the time is just too weak. It simply must be nuclear. Also the asteroids usually rotate, which complicates things.
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I agree with vaporization on the condition that the nuclear bomb is on the surface of the asteroid.

The next problem would be when the asteroid breaks up into pieces.

If the bomb is not on the surface but some distance away, then perhaps the method will not work.

I am led to believe that a gravity tug would be the most effective providing the tug is in situ well in advance.

The problem with an engine on the asteroid is not the strength of the engine, but rather that the asteroid is more than likely rotating to some degree.

I am not an expert in these matters, so may well be wrong.:)
 
Toke said:
The problem with rotation can be handled by using a "gravitational tractor".
That is, the motor assembly hovers in a pattern over the asteroid on the away from earth side. Gravity is a two way thing so the pull is excerted without bothering with landing or tethering the asteroid.

Sure, there would be problems with getting a strong enough engine in place in time. :(
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Yeah .. it's a neat method, still not very workable at the moment. The engine would have to do all the work anyway. And it can only use very small thrust (so it does not fly away). Good for long term trajectory alteration .. not good for emergency ..
Btw.Do I know you from LPF ? Laser could be interesting too .. again, in a way to create thrust by warming/vaporizing asteroid material. Laser could be nuclear powered. Still the nukes would be million times simpler. We even have them.
 
Skwinty said:
The problem with an engine on the asteroid is not the strength of the engine, but rather that the asteroid is more than likely rotating to some degree.
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Also the possibility that the asteroid is a rubble pile that an engine can't easily be attached to.
 
Skwinty said:
In space there is no atmosphere to transmit a pressure wave.

So the only pressure exerted on the asteroid or comet would be gamma rays, other electromagnetic energy and particles from the bomb itself.

Whether that would be sufficient to dislodge the asteroid from its current trajectory is debatable.
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That is not fully true , but true enough. The nuke would heat the side of the comet it explode on, and heated comet material emit gas, which will in turn give some impulse. That is what i was referring to in my post.
 
Aepervius said:
That is not fully true , but true enough. The nuke would heat the side of the comet it explode on, and heated comet material emit gas, which will in turn give some impulse. That is what i was referring to in my post.
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I would imagine this would be true for a frozen gas comet.

Would this happen with a huge rock asteroid?
 
The largest device ever tested was in 1961: the Soviet's "Tsar Bomba", with a yield estimated (yields are always estimated) at about 50 megatons. The various effects of that event were felt at some pretty impressive distances, but because the inverse square law applies, quadrupling it would only have increased those distances by about half, so a device that size would not be a planet-killer. Still, a bit tricky to find just the right spot to test it. Benjamin Netanyahu might have one or two ideas on that.

As for the comet, I say we just smack it on one side with the great-grandfather of all paintballs -- flat black -- and let the sun do the rest.
 
Dr.Sid said:
Why so strong ? Would not series of smaller bombs be more practical ?
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Well I was taking my cues from project Icarus. After I calculated the mass of the comet (roughly 12 kilometers diameter with a higher than normal rock content) I figured out that we might get enough diversion with 7-9 offset blasts in a controlled sequence with each blast at least 200 megatons yield.

So I figured that you need some insurance so we launch 12 of the devices, 5 from the USA, 4 from Russia and 3 from China using an ad-hoc arrangement of the engines designed for the Energia. It was the only way I could figure out to get them on their way considering that we have only 14 months from detection of the comet until impact.

So there really won't be a lot of launchers to spare. Maybe one more for a space detonation test. But I would think we would want a full test here on Earth just to make sure the physics actually work.

TubbaBlubba said:
Yikes. Middle of the pacific, maybe?
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This was a thought too. Perhaps a barge in the middle of the cyclonic wind zone?
 
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Beerina said:
IIRC, the 100-megatonners would leave a crater 19 miles in diameter.
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Actually, from "The Effects of Nuclear Weapons" by Glassstone and Dolan, crater size for a ground burst is 60 x Y^.3 feet, where Y is the weapon yield expressed as a multiple of 1 kT. Since 200 MT is 200,000 times 1 kT, crater size is about a half mile. I'm not sure if the scaling applies exactly, but it's pretty clear that the 19 mile figure refers to something else - probably the area of total destruction (usually 15 psi overpressure).
 
WhatRoughBeast said:
Actually, from "The Effects of Nuclear Weapons" by Glassstone and Dolan, crater size for a ground burst is 60 x Y^.3 feet, where Y is the weapon yield expressed as a multiple of 1 kT. Since 200 MT is 200,000 times 1 kT, crater size is about a half mile. I'm not sure if the scaling applies exactly, but it's pretty clear that the 19 mile figure refers to something else - probably the area of total destruction (usually 15 psi overpressure).
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I was thinking the same thing. I'm not sure what assumptions Cecil was using when he calculated the crater size at 19 miles, but that sounds high to me even for a ground burst. If that's close, 200 MT should be adequate to essentially vaporize an average sized comet, but if the size of the crater is the thing we have to determine by actual testing, then that's problematic. Of course, I guess the ejecta might help at least a little bit to mitigate some of these global warming problems we've been having, but that issue pales into insignificance as soon as you realize that you're in the path of a comet. Surface burst in Siberia is starting to sound okay. Texas, maybe.
 
A surface burst will kick up more fallout though. How much would this thing weigh? Is it possible to drop it via parachute for an airburst?
 
Travis said:
A surface burst will kick up more fallout though. How much would this thing weigh? Is it possible to drop it via parachute for an airburst?
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Tsar Bomba (50 MT) weighed 30 tons. Tricked out for 100 MT it would have weighed about the same.

And the fireball was 8 km in diameter, so I'd guess that for a first approximation of the crater.
 
How about Antarctica?

It's a huge continent. There's only a tiny human population, concentrated in a few places; very easy to evacuate anybody who needs to be. Away from the coastline there isn't even any wildlife. Plus the high albedo surroundings will help to reflect the flash upwards, the thick ice will absorb a lot of the heat and then simply refreeze.

Seems ideal.
 
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