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Blast in space?

by b.conway
Tags: blast, space
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Morbius
#55
Jun17-11, 10:46 PM
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Quote Quote by Joseph Chikva View Post
Simply. Bob states that kinetic hit would be ineffective and nuke blast yes - effective.
But he did not answer embodiment method:
• how to carry nuke charge to asteroid?
• at what altitude or after hit detonation should be? As I am afraid that if after hit, simply nuke device will be destroyed without detonation.
• Or there is planed to do as in Armageddon movie - to send two teams of oil well drillers on two Shuttles
You carry it on a missile. The majority of the work is to get to Earth orbit. For the Moon mission, getting to Earth orbit required the large first and second stages of the Saturn V.
The energy to get from Earth orbit to the Moon was delivered by the relatively modest third stage.

We have missiles that can carry a multiple warhead payload to high, but suborbital trajectory. If we reduced the payload to a single warhead, we can send the warhead a great distance.

The distance is many miles. The optimal distance is a certain fraction of the object's "diameter". I don't think the warhead is going to be in danger of being damaged before detonation, and those warheads were made to be reliable.

Dr. Dearborn shows scenes from Armageddon in his seminars as an example of what NOT to do.

Dr. Gregory Greenman
Morbius
#56
Jun17-11, 10:56 PM
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Quote Quote by Joseph Chikva View Post
And sure that the momentum which asteroid should acquire as result of nuke blast can be easily acquired also by kinetic hit as well. And it seems me as more easy, rational and reliable way.
Joe,

Kinetic kill vs nuclear weapon was very heavily studied by LLNL back in the 1990s.

The nuclear weapon can deliver orders of magnitude more energy than can a kinetic kill.

The idea is we want to change the orbit of the asteroid, and that takes energy. If the asteroid is large, we have no way with our chemical rockets to put enough energy into a kinetic kill vehicle to be able to deflect a very large asteroid.

Again, for very large asteroids, or very short time for deflection; the nuclear weapon is the ONLY viable option. It beats kinetic impactors, "gravity tractors"... hands down.

One of the other problems with kinetic kill is that many of the asteroids are what are called "rubble piles". They are not one rock, but a bunch of rocks held loosely together by mutual gravity. A kinetic kill will deflect the rock it hits in a rubble plie, but won't deflect the bulk of the others. The only force between the impacted rock and some of the others is gravity, and gravity is too weak for the short time scale to impart enough momentum.

Dr. Gregory Greenman
Morbius
#57
Jun17-11, 11:08 PM
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Quote Quote by HowlerMonkey View Post
Your post stated what my earlier post stated and now you are adding an angle not mentioned in your earlier post where you attempted to correct me by restating almost exactly what I had posted.

This is called a spin.
NO - your feeble attempt above is "spin". If you "think" that what you posted is exactly what I did - then you still don't understand it. Shall we recall what you posted in post #9:

If a nuke is detonated in the near perfect vacuum of space, there isn't anything more than the matter contained within the bomb itself that will expand."

This is WRONG since you state "there isn't anything more than the matter contained within the bomb itself that will expand".

I CORRECTED that by saying there is a lot more to a nuclear explosion in space than just the expansion of bomb debris. There is one hell of a lot of energy contained in the accompanying radiation wave.

More to the point, it's the energy of that radiation, and not the energy of the expanding debris that is used to deflect asteroids. So you left out the most important part about deflecting asteroids, and now you arrogantly say that your representation is exactly the same as what I am saying.

Dr. Gregory Greenman
Morbius
#58
Jun17-11, 11:11 PM
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Quote Quote by Drakkith View Post
Even if the warhead was detonated on the surface of the asteroid only about half of the blast would be absorbed by it anyways. Detonating 100 ft above the surface would provide almost the same effect I think.
Dr Dearborn calculates the optimal height for maximal effect, and if memory serves the optimal distance is measured in miles and not feet.

Dr. Gregory Greenman
Joseph Chikva
#59
Jun17-11, 11:15 PM
P: 202
Quote Quote by Morbius View Post
You carry it on a missile. The majority of the work is to get to Earth orbit. For the Moon mission, getting to Earth orbit required the large first and second stages of the Saturn V.
The energy to get from Earth orbit to the Moon was delivered by the relatively modest third stage.

We have missiles that can carry a multiple warhead payload to high, but suborbital trajectory. If we reduced the payload to a single warhead, we can send the warhead a great distance.

The distance is many miles. The optimal distance is a certain fraction of the object's "diameter". I don't think the warhead is going to be in danger of being damaged before detonation, and those warheads were made to be reliable.

Dr. Dearborn shows scenes from Armageddon in his seminars as an example of what NOT to do.

Dr. Gregory Greenman
So, your statement is to explode nuke warhead carried on interceptor missile after hit?

If so:
• What deceleration that warhead will experience after hit before explosion?
• And admissible deceleration for reliable operation of mechanisms?

And I doubt that existing MCBMs can be used. I am sure that new interceptor should be developed. That would not be a problem on base of just today's technology. But that will be a new missile much more agile than MCBM.
Joseph Chikva
#60
Jun17-11, 11:19 PM
P: 202
Quote Quote by Morbius View Post
Joe,

Kinetic kill vs nuclear weapon was very heavily studied by LLNL back in the 1990s.

The nuclear weapon can deliver orders of magnitude more energy than can a kinetic kill.

The idea is we want to change the orbit of the asteroid, and that takes energy. If the asteroid is large, we have no way with our chemical rockets to put enough energy into a kinetic kill vehicle to be able to deflect a very large asteroid.

Again, for very large asteroids, or very short time for deflection; the nuclear weapon is the ONLY viable option. It beats kinetic impactors, "gravity tractors"... hands down.

One of the other problems with kinetic kill is that many of the asteroids are what are called "rubble piles". They are not one rock, but a bunch of rocks held loosely together by mutual gravity. A kinetic kill will deflect the rock it hits in a rubble plie, but won't deflect the bulk of the others. The only force between the impacted rock and some of the others is gravity, and gravity is too weak for the short time scale to impart enough momentum.

Dr. Gregory Greenman
Ok, thanks.
Morbius
#61
Jun17-11, 11:35 PM
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Quote Quote by Joseph Chikva View Post
So, your statement is to explode nuke warhead carried on interceptor missile after hit?.
Joe,

Not at all. You don't have to hit the asteroid. You want to explode it a few miles above the surface, so you arrange for the missile's trajectory to pass just in front of, or just behind ( depending on what new orbit is desired ) and you detonate the warhead at the proper time.

There's no "hitting" the asteroid involved.

Dr. Gregory Greenman
Drakkith
#62
Jun17-11, 11:51 PM
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Quote Quote by Joseph Chikva View Post
So, your statement is to explode nuke warhead carried on interceptor missile after hit?

If so:
• What deceleration that warhead will experience after hit before explosion?
• And admissible deceleration for reliable operation of mechanisms?

And I doubt that existing MCBMs can be used. I am sure that new interceptor should be developed. That would not be a problem on base of just today's technology. But that will be a new missile much more agile than MCBM.
As Morbius said there is no need to hit the asteroid. Current warheads are already equipped with the ability to detonate at different altitudes either based on time or proximity/impact. Actually, the cruise missiles I work on have impact fuzes in the nose for a ground burst detonation option. It is trivial to time the detonation right down to milliseconds or less.
Joseph Chikva
#63
Jun17-11, 11:57 PM
P: 202
Quote Quote by Morbius View Post
Joe,

Not at all. You don't have to hit the asteroid. You want to explode it a few miles above the surface, so you arrange for the missile's trajectory to pass just in front of, or just behind ( depending on what new orbit is desired ) and you detonate the warhead at the proper time.

There's no "hitting" the asteroid involved.

Dr. Gregory Greenman
Ok, Greg,
I understood that from your second another post. Thanks.
Very little amount of energy can be delivered in that case. Was that calculated?
Joseph Chikva
#64
Jun18-11, 12:03 AM
P: 202
Quote Quote by Drakkith View Post
As Morbius said there is no need to hit the asteroid. Current warheads are already equipped with the ability to detonate at different altitudes either based on time or proximity/impact. Actually, the cruise missiles I work on have impact fuzes in the nose for a ground burst detonation option. It is trivial to time the detonation right down to milliseconds or less.
I know something about warheads, fuses, as well as proximity, point detonating, delay modes. Thanks.
As some times ago proposed to my country’s Government to produce modern fuses here in Georgia http://www.fuchs.co.za/technology/
Drakkith
#65
Jun18-11, 12:06 AM
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Quote Quote by Joseph Chikva View Post
Ok, Greg,
I understood that from your second another post. Thanks.
Very little amount of energy can be delivered in that case. Was that calculated?
Why would very little energy be delivered? I'd venture a guess and say that if you got really close you could get 40%+ of the energy of the nuke transferred to the asteroid.
Joseph Chikva
#66
Jun18-11, 04:01 AM
P: 202
Quote Quote by Drakkith View Post
Why would very little energy be delivered? I'd venture a guess and say that if you got really close you could get 40%+ of the energy of the nuke transferred to the asteroid.
From what do you get numbers?
Not only in this case.
Radiation propagated to all directions (4pi steradian).
Distance to asteroid a few miles.
Bob mentioned asteroid’s mass M = 8.6 x 10^7 tonnes (metric tons).
It corresponds ~1.1 x 10^7 m3 of volume if asteroid is from iron and about 10^8 if from ice.
If asteroid spherical the diameter should has an order of a few hundred meters.
And if even if 100% radiation energy absorption much less than 40%. But some energy will be reflected.
Drakkith
#67
Jun18-11, 07:53 AM
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Hrmm, I guess I should have been more specific. I meant that if a nuke is detonated above the surface of an asteroid, at least 50% of the blast will simply go into space above. The other 50% should interact with the asteroid somehow. I took 10% away simply because I don't think exactly 50% will hit the asteroid due to the altitude of the blast. Some should get radiated close to the asteroid but barely miss it.
Joseph Chikva
#68
Jun18-11, 08:16 AM
P: 202
Quote Quote by Drakkith View Post
Hrmm, I guess I should have been more specific. I meant that if a nuke is detonated above the surface of an asteroid, at least 50% of the blast will simply go into space above. The other 50% should interact with the asteroid somehow. I took 10% away simply because I don't think exactly 50% will hit the asteroid due to the altitude of the blast. Some should get radiated close to the asteroid but barely miss it.
If you have an interest you can estimate that on base of provided by me data.
That is an elementary geometry exercise.
I am too lazy for that.
But think that on a few orders lower than you guess.
Drakkith
#69
Jun18-11, 08:20 AM
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I'm not talking about the actual amount of energy absorbed or whatever by the asteroid. I'm just referring to the amount of the blast that should impact it. Please tell me someone understands what I'm saying.
DaveC426913
#70
Jun18-11, 08:24 AM
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Quote Quote by Drakkith View Post
I'm not talking about the actual amount of energy absorbed or whatever by the asteroid. I'm just referring to the amount of the blast that should impact it. Please tell me someone understands what I'm saying.
Certainly. Of the expanding sphere that is the blast, a cone-shaped portion will intersect the asteroid, imparting energy.

The percentage of the sphere that is the cone is determined by the distance from cone apex to cone base (i.e. nuke's point of detonation to asteroid surface).

At distance zero, the cone is effectively a plane, making it 50% of the sphere.
Drakkith
#71
Jun18-11, 08:26 AM
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That is exactly what I mean. Thank you Dave.
Joseph Chikva
#72
Jun18-11, 09:59 AM
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Quote Quote by Drakkith View Post
That is exactly what I mean. Thank you Dave.
That is not a matter what you meant.
As by Morbius Dr. Dearborn who really was engaged with this problem told about explosion not near surface but at a few miles away.
So, much less than you guess.


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