Nuclear explosions in space?

If you can, as you suggested, manage to get one tenth of one percent of the meteor going at 5,000 mph, then you can get the remainder of the meteor going at 50 mph. However, all of the ejected material has to go in exactly the same direction or else some of the momentum is wasted in the vector sum, and the amount of velocity imparted to the meteor is less. Typically, material ejected from an explosion does not all go in one and only one direction. It goes in many different directions. If you want to take a meteor several miles in diameter and get one tenth of one per cent of it going in a unidirectional beam at 5,000 mph, at a bare minimum, you will have to skillfully bury the explosives to produce a shaped explosion. Or, if you must acquiesce to having something less than a unidirectional beam of ejecta going at 5,000 mph, maybe you need to get 2 tenths or 3 tenths of the meteor ejected. It's conservation of momentum. Arguing with me isn't going to help.

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Not even if you're off by a decimal point?

Oh well. It's not arguing if we agree anyways, and are just fixing up the terminology.

I'm thinking we could call it Icarus or Daedulus or
some kind of puppy name. Ideas?

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CodeBorg wrote:

Not even if you're off by a decimal point?

Oh well. It's not arguing if we agree anyways, and are just fixing up the terminology.

I'm thinking we could call it Icarus or Daedulus or
some kind of puppy name. Ideas?

Hopefully not Icarus, since he died when he flew too near to the sun. Maybe someone in mythology who brought some sort of gift.

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Ah yes, let's name it Prometheus . . . now there's a real winner . . .

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Seems to me you're just arguing the degree of efficiency, Brandon. One nuclear device not enough? We have plenty of them sitting around getting dusty....

A name? Boom-boom, Boomerang, Skippy, (or, if your calculations are off just a hair... Snuffy).

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DrewDad wrote:

Seems to me you're just arguing the degree of efficiency, Brandon. One nuclear device not enough? We have plenty of them sitting around getting dusty....

I'm arguing that without landing, burying the bombs, hopefully in such a way as to produce a shaped explosion, ejecting at least a few tenths of a percent of the meteor so that most of it goes in a single direction, it will fail to deflect the meteor appreciably.

Merely bringing the bombs next to the meteor and detonating them will not work, even if we use quite a few bombs, because the mass of the explosive material is such an insignificant fraction of the mass of the meteor. It might also be noted in passing that more than half of the already grossly insufficient bomb mass would blow harmlessly off into space without making contact with the meteor.

You might also try to break the meteor up early enough that the pieces would dissipate by the time their center of mass reached the Earth.

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Brandon9000 wrote:

DrewDad wrote:
Seems to me you're just arguing the degree of efficiency, Brandon. One nuclear device not enough? We have plenty of them sitting around getting dusty....

I'm arguing that without landing, burying the bombs, hopefully in such a way as to produce a shaped explosion, ejecting at least a few tenths of a percent of the meteor so that most of it goes in a single direction, it will fail to deflect the meteor appreciably.

So if it the first bomb results in too little deflection, just hit it again. Or use a bigger hammer.

Or are you saying that a surface detonation would result in no vector change whatsoever?

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Brandon9000 wrote:

You might also try to break the meteor up early enough that the pieces would dissipate by the time their center of mass reached the Earth.

I'd think that breaking up the object would be even more difficult than deflecting it. You'd need either much higher yields, or you'd have to bury the device much deeper, or both.

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DrewDad wrote:

Brandon9000 wrote:
DrewDad wrote:
Seems to me you're just arguing the degree of efficiency, Brandon. One nuclear device not enough? We have plenty of them sitting around getting dusty....

I'm arguing that without landing, burying the bombs, hopefully in such a way as to produce a shaped explosion, ejecting at least a few tenths of a percent of the meteor so that most of it goes in a single direction, it will fail to deflect the meteor appreciably.

So if it the first bomb results in too little deflection, just hit it again. Or use a bigger hammer.

Or are you saying that a surface detonation would result in no vector change whatsoever?

I am saying that, to make up a few numbers that may not be accurate but will illustrate the point, for each nuclear missile:

Missile Mass: 10^3 kg
Participating missile mass: 200 kg

Meteor mass: 10^7 kg

Even if the gasses, dust, missile vapor that hits the meteor has a speed of 10^4 mph, since the ratios of the masses are also 10^4, in this example, the meteor will change it's velocity by 1 mph. And this is even ignoring the fact that the explosive material that hits the meteor will actually have some cancelling horizontal components to its force vectors.

These numbers are baloney, but they illustrate a point that is not - that without using some of the meteor material itself as reaction mass, you don't stand much of a chance. Of course, you could also strap a bunch of rocket motors to the thing and keep re-filling their fuel. That would work.

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DrewDad wrote:

Brandon9000 wrote:
You might also try to break the meteor up early enough that the pieces would dissipate by the time their center of mass reached the Earth.

I'd think that breaking up the object would be even more difficult than deflecting it. You'd need either much higher yields, or you'd have to bury the device much deeper, or both.

Breaking it up would be hard, but deflecting it using only the material of the explosion (bits of the missile) would be close to impossible.

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Not so much arguin' with ya here, Brandon, but rather pursuin' the Idea. I think you're overlookin' a key component in your calculations. E=MC², right? The component of that formula to which I'm referrin' is "E"; do you have any concept of the "E" resultant from a 50 or 60 megaton (a large, but existant and, by contemporary standard and practice, not uncommon, missile-deliverable warhead) thermonuclear blast? The forces involved approach the relatavistic, while the all-but-instantantaneous temperature gradient spikes to a multiple of the surface temperature of a fairly bright star - several thousand degrees greater than Sol, for instance. That's a helluva lotta effect to inflict upon the interior of a mass of a few cubic miles. A whole buncha the mass of the target would be converted to plasma, plasma which would radiate more or less equally outward from the center of the blast at such velocity as to preclude re-accretion, and which, as it cooled, would convert to little more than microscopically fine dust, one must expect. At least, so it would seem to me.

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From that Airforce article I posted a few pages back:

To effect a 1 cm/sec velocity change:

Code:



Asteroid          Proximal          Surface

Size               burst             burst

.1 km            .1-1 kt            500 kg

 1 km            100 kt-1 mt         90 kt

10 km            100 mt-1 gt        200 mt

1 cm/sec is pretty small, but so are the yields listed (well, small yield relative to what our current capabilities are, pretty big if you're setting it off in your back yard Shocked

).

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timberlandko wrote:

Not so much arguin' with ya here, Brandon, but rather pursuin' the Idea. I think you're overlookin' a key component in your calculations. E=MC², right? The component of that formula to which I'm referrin' is "E"; do you have any concept of the "E" resultant from a 50 or 60 megaton (a large, but existant and, by contemporary standard and practice, not uncommon, missile-deliverable warhead) thermonuclear blast? The forces involved approach the relatavistic, while the all-but-instantantaneous temperature gradient spikes to a multiple of the surface temperature of a fairly bright star - several thousand degrees greater than Sol, for instance. That's a helluva lotta effect to inflict upon the interior of a mass of a few cubic miles. A whole buncha the mass of the target would be converted to plasma, plasma which would radiate more or less equally outward from the center of the blast at such velocity as to preclude re-accretion, and which, as it cooled, would convert to little more than microscopically fine dust, one must expect. At least, so it would seem to me.

To get anything like a beam of reaction matter, you'd probably have to bury the bombs and try to shape the explosion. Remember that the total momentum afterwards is exactly what it was before the explosion. You would also want to make sure that the meteor didn't disintegrate before you could finish imparting the momentum to it. The more I think about it, the more I think that attaching some rockets to the meteor and refilling their fuel over and over is the safest way to go, although I am not sure we have the technology for that mission right now.

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I don't disagree the fittin' of rocket motors to the asteroid would likely be a very good way to change the asteroid's trajectory - prolly the best way. On the other hand, the subsidence crater resultin' from a 1 or 2 megaton subterranean nuclear test exceeds a mile in diameter and a few hundred feet in depth - a real big bowl - an awful lot what was under that crater was converted to plasma by the blast. I'm not talkin' velocity change here, or trajectory shift; I'm talkin more-or-less effectively "GONE".

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DrewDad wrote:

From that Airforce article I posted a few pages back:

To effect a 1 cm/sec velocity change:

Code:Asteroid Proximal Surface Size burst burst .1 km .1-1 kt 500 kg 1 km 100 kt-1 mt 90 kt 10 km 100 mt-1 gt 200 mt

1 cm/sec is pretty small, but so are the yields listed (well, small yield relative to what our current capabilities are, pretty big if you're setting it off in your back yard ).

Well, it sure would be a hard thing to do. The WW2 bombs had yields around 15 or 20 Kt. Today's hydrogen bombs are in the two digit megaton range. I don't think we can make a 200 mt bomb yet. But the main thing to remember is that as long as you are transferring momentum to the meteor from bomb matter massing less than a tenth of a percent of the mass of the meteor, you are going to find it terribly difficult.

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timberlandko wrote:

I don't disagree the fittin' of rocket motors to the asteroid would likely be a very good way to change the asteroid's trajectory - prolly the best way. On the other hand, the subsidence crater resultin' from a 1 or 2 megaton subterranean nuclear test exceeds a mile in diameter and a few hundred feet in depth - a real big bowl - an awful lot what was under that crater was converted to plasma by the blast. I'm not talkin' velocity change here, or trajectory shift; I'm talkin more-or-less effectively "GONE".

But the ejected material will also travel every which way, and any horizontal (non-perpendicular) momentum component of one bit, will likely be cancelled by an opposite horizontal component of another bit, so, in effect, only the momentum directed perpendicularly away from the surface does any good.

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Brandon9000 wrote:

timberlandko wrote:
I don't disagree the fittin' of rocket motors to the asteroid would likely be a very good way to change the asteroid's trajectory - prolly the best way. On the other hand, the subsidence crater resultin' from a 1 or 2 megaton subterranean nuclear test exceeds a mile in diameter and a few hundred feet in depth - a real big bowl - an awful lot what was under that crater was converted to plasma by the blast. I'm not talkin' velocity change here, or trajectory shift; I'm talkin more-or-less effectively "GONE".

But the ejected material will also travel every which way, and any horizontal (non-perpendicular) momentum component of one bit, will likely be cancelled by an opposite horizontal component of another bit, so, in effect, only the momentum directed perpendicularly away from the surface does any good.

OK. So we ignore the horizontal component. There's still quite a bit of vertical component.

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Brandon9000 wrote:

DrewDad wrote:
From that Airforce article I posted a few pages back:

To effect a 1 cm/sec velocity change:

Code:Asteroid Proximal Surface Size burst burst .1 km .1-1 kt 500 kg 1 km 100 kt-1 mt 90 kt 10 km 100 mt-1 gt 200 mt

1 cm/sec is pretty small, but so are the yields listed (well, small yield relative to what our current capabilities are, pretty big if you're setting it off in your back yard ).

Well, it sure would be a hard thing to do. The WW2 boms had yields around 15 or 20 Kt. Today's hydrogen bombs are in the two digit megaton range. I don't think we can make a 200 mt bomb yet. But the main thing to remember is that as long as you are transferring momentum to the meteor from bomb matter massing less than a tenth of a percent of the mass of the meteor, you are going to find it terribly difficult.

Again, we're not talking about just the bomb matter. The mass of the bomb is irrelevant. It's the yield of the bomb that matters. We're using the asteroid's own material as reaction mass.

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BTW, the article I cited also has yields necessary for destroying the same sized asteroids.

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Brandon9000 wrote:

These numbers are baloney, but they illustrate a point that is not - that without using some of the meteor material itself as reaction mass, you don't stand much of a chance. Of course, you could also strap a bunch of rocket motors to the thing and keep re-filling their fuel. That would work.

Using the body's own mass for reaction mass is exactly what we've been discussing.

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