Physics Help Forum How Do We Nuke A Comet?
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 Apr 6th 2019, 10:05 AM #1 Junior Member   Join Date: Apr 2019 Posts: 14 How Do We Nuke A Comet? Sooner-or-later, at random, the world will be faced with the threat of a large Long Period Comet impact. Our only recourse will be to Nuke it. In order to know how large the thermonuclear device needs to be to either deflect or destroy it there are two questions: - What is the expansion velocity of vaporized water ice in Space? - Per Mt of yield (net) what volume/mass of water ice would be vaporized? KISS please. I need to explain this to politicians...
Apr 6th 2019, 05:13 PM   #2
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 Originally Posted by GaiaShield Sooner-or-later, at random, the world will be faced with the threat of a large Long Period Comet impact. Our only recourse will be to Nuke it. In order to know how large the thermonuclear device needs to be to either deflect or destroy it there are two questions: - What is the expansion velocity of vaporized water ice in Space? - Per Mt of yield (net) what volume/mass of water ice would be vaporized? KISS please. I need to explain this to politicians...
I don't know that anyone can give numbers for this. At least nothing specific. There may be a way to guesstimate average values for your questions.

The problem is that the answers will depend on the composition and density of the comet. Most comets are composed of rock and ice, mixed into a loose matrix of varying densities. A bomb will do more damage to a comet that is loosely held together than it would for one more compact.

We also have the question of vaporization. Just as with asteroids you are not likely to change the overall momentum of the asteroid much by hitting it with a bomb, though you might be able to shatter the comet. That means we would have a large debris field on a collision course with Earth and that might make things even worse.

Much study would have to be done on the individual comet before any true method to disrupt it can be decided. (A bomb is not the only way. If we have time we can deflect its orbit with rockets, gravity sources, light deflection, etc. There are many ideas out there.)

But again, there may be a way to generate some "average" numbers for you. Hopefully someone here can help you more but you'd be better off trying to talk to NASA or some such.

-Dan
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 Apr 6th 2019, 05:49 PM #3 Junior Member     Join Date: Jan 2019 Posts: 20
 Apr 6th 2019, 06:24 PM #4 Senior Member   Join Date: Mar 2019 Location: cosmos Posts: 553 size What is the size of a COMET?
Apr 6th 2019, 06:45 PM   #5
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 Originally Posted by topsquark I don't know that anyone can give numbers for this. At least nothing specific. There may be a way to guesstimate average values for your questions. The problem is that the answers will depend on the composition and density of the comet. Most comets are composed of rock and ice, mixed into a loose matrix of varying densities. A bomb will do more damage to a comet that is loosely held together than it would for one more compact. We also have the question of vaporization. Just as with asteroids you are not likely to change the overall momentum of the asteroid much by hitting it with a bomb, though you might be able to shatter the comet. That means we would have a large debris field on a collision course with Earth and that might make things even worse. Much study would have to be done on the individual comet before any true method to disrupt it can be decided. (A bomb is not the only way. If we have time we can deflect its orbit with rockets, gravity sources, light deflection, etc. There are many ideas out there.) But again, there may be a way to generate some "average" numbers for you. Hopefully someone here can help you more but you'd be better off trying to talk to NASA or some such. -Dan
Topsquark,

The question is about water ice... And to keep this thread on track feel free to contact me back channel by email through the moderator and I can address the rest of your perceptions

GaiaShield

Apr 6th 2019, 07:03 PM   #6
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 Originally Posted by GaiaShield Topsquark, The question is about water ice... And to keep this thread on track feel free to contact me back channel by email through the moderator and I can address the rest of your perceptions GaiaShield
If you are assuming that the whole comet is simply water-ice then yes, you could probably calculate it. Unfortunately I have tapped out my knowledge of the subject.

-Dan
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 Apr 6th 2019, 09:14 PM #7 Senior Member   Join Date: Mar 2019 Location: cosmos Posts: 553 1. The velocity of expansion of vapor in space is approximate the max velocity of expansion of the fire ball... Adequate data in the past few decades, I think, no illegal test is needed again. 2. Dan is right. Solution rest on structure of the asteroid. 3. If the major component is water ice...wellcome, beer. Last edited by neila9876; Apr 6th 2019 at 09:43 PM. Reason: correct word
 Apr 6th 2019, 10:20 PM #8 Senior Member   Join Date: Apr 2017 Posts: 506 Many underwater detonations have been carried out on Earth . In a fraction of a second the energy is released , near the center super heated steam produces incredible pressure . Even so nothing too spectacular explosion wise ... And comet water is ICE ... a lot of the energy would be lost just in melting the ice .... Still, consensus is that it is Loosely packed dust sand ice methane ... so it shouldn't take much to blow it all apart .... average density of a comet nucleus is only 0.5 ... on the plus side lots of solid carbon dioxide, carbon monoxide, methane, and ammonia , this is where the main "push" will come from , the nuclear heat needs to be turned into pressure , and these compounds have low latent heat of fission and evaporation and so will do a much better job at turning heat into pressure than water ice. I would bet a 100MT device , placed in the center , could obliterate ,(send flying in all directions) the largest known comet (aprox 10Km dia). I don't think comets are a problem , these would fall apart in Earth's atmosphere . The real danger must be asteroid type objects ... very solid and strong , impossible to blow up. Last edited by oz93666; Apr 6th 2019 at 10:40 PM.
 Apr 7th 2019, 04:26 AM #9 Senior Member   Join Date: Mar 2019 Location: cosmos Posts: 553 I see that there is one good motor engineer above. If unfit drillers are needed, here is one volunteer.
 Apr 7th 2019, 04:39 AM #10 Senior Member     Join Date: Jun 2016 Location: England Posts: 1,000 Might Work? My own idea would be a series of nukes all aimed at the same carefully chosen spot, timed to detonate when that spot (for a rotating comet) is pointing in the same direction (relative to its orbit). The repeated detonations would create a crater, which would help direct the products of the detonations in the chosen direction, which would push the comet into a safer orbit. The key for any possible solution will be early detection to allow time for solutions to be planned and executed. Getting Bruce Willis to drill into the comet, to get the nuke deep enough into the comet to break it apart, is just fiction. __________________ ~\o/~

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