30% of Nuclear Arsenals, for what?

[Airbrush]

Asteroid pushing practice!

 

We would look to the world like the good guys if we convinced the world nukes are an efficient means for saving the world from doomsday. We embark on robotic missions to NEOs and see what kind of effect nuclear explosions in close proximity will do to alter the path of asteroids and comets of various sizes and compositions.

[Moontanman]

I'm betting the crazies would go berserk at the thought of nukes in space.

[rogerxd45]

I'm betting the crazies would go berserk at the thought of nukes in space.

 

like our nukes could even hold a candle to the nukes that are already in space.

but then again thats probably why they are called crazies

[SH3RL0CK]

Considering the varied nature of asteroids, from a single solid rock to a rubble pile, also containing a widely varying amount of water and other ices and/or metal and/or carbon, there is going to be a vastly different response to a nuclear explosion on the surface which would be difficult to accurately model, even if we could catagorize the composition of an asteroid likely to impact the earth. If the asteroid is either very fragile or a pile of rubble, exploding nukes on it will likely not alter its path because there is nothing really to push against. So instead of a pile of rubble falling to earth we could wind up with a radioactive pile of rubble falling to earth.

 

Also, as happens on occasion, launch rockets fail. I doubt a launch failure would cause the bomb to go nuclear. However, I'm concerned by the possibility of radioactive material (such as used in a nuclear bomb) falling across a very large portion of the earth in an uncontrolled fashion. Couldn't this be an environmental catastrophe?

 

I'd prefer to spend the money on other asteroid pushing possibilities (such as the gravity tractor). Some of these possibilities don't depend at all on the composition of the asteroid and need only the trajectory (very easy to determine) to be known to be effective.

[Moontanman]

Considering the varied nature of asteroids, from a single solid rock to a rubble pile, also containing a widely varying amount of water and other ices and/or metal and/or carbon, there is going to be a vastly different response to a nuclear explosion on the surface which would be difficult to accurately model, even if we could catagorize the composition of an asteroid likely to impact the earth. If the asteroid is either very fragile or a pile of rubble, exploding nukes on it will likely not alter its path because there is nothing really to push against. So instead of a pile of rubble falling to earth we could wind up with a radioactive pile of rubble falling to earth.

 

I doubt a nuclear explosion would make an asteroid dangerously radioactive, they are already bombarded by considerable radiation in space and a single nuclear explosion wouldn't make much of the asteroid radioactive or add to that radiation in space.

 

Also, as happens on occasion, launch rockets fail. I doubt a launch failure would cause the bomb to go nuclear. However, I'm concerned by the possibility of radioactive material (such as used in a nuclear bomb) falling across a very large portion of the earth in an uncontrolled fashion. Couldn't this be an environmental catastrophe?

 

Probably not, most modern war heads are quite tough and do not split wide open on impact and spew highly radioactive materials all over the place, even the old fragile nukes of the cold war did not do that.

 

Two multimegaton warheads are accidentally dropped on or near Charlotte NC and one of them is still embedded in the ground. the other was recovered, in pieces, but no serious radioactive contamination occurred.

 

I'd prefer to spend the money on other asteroid pushing possibilities (such as the gravity tractor). Some of these possibilities don't depend at all on the composition of the asteroid and need only the trajectory (very easy to determine) to be known to be effective.

 

Almost certainly the best way to go, I have my doubts about a nuclear war head really doing the job anyway.

[Airbrush]

Because we already have plenty of nukes, we should at least explore the possibility of using them for short-notice NEOs. Send robotic probes to several Earth-crossing NEOs. They should have the ability to test the object for how solid it is. They also have a nuke on board to test an explosion at a safe distance if the object is solid enough.

 

Even if the NEO is a loose rubble pile, a series of nuclear explosions at an appropriate distance will only HEAT up one side of the NEO. Then outgassing will push it slightly. We should at least test the idea before embarking on far more expensive and time-consuming projects like gravity tractors. But why not test both? The money is there for robotic missions, since cutting manned missions from the NASA budget is a huge savings.

[Moontanman]

I don't have a problem with giving it a try and seeing what happens. I wonder how far away in the night sky a nuclear explosion of half a megaton would be visible from the earth.

[Mr Skeptic]

I'm betting the crazies would go berserk at the thought of nukes in space.

 

We've signed international treaties against nukes in space. And for good reason: we don't want the US and Russia to freak out every time they see something falling over their country from space. Also, nukes are probably one of the worst ways to deal with asteroids, although they may be the only alternative in certain conditions.

 

I'll have a serving of telescopes in space, please, with a side of actually being able to see what might crash into us.

[Airbrush]

Because of treaties against nukes in space, there would have to be some kind of joint mission, including USA, Russia, China, or some others. These other nations will provide international verification that the missions are peaceful. The missions can by financed by the USA, and any other interested nations, and verified by Russia, China, or other nuclear power.

 

We might try something with Apophis when is comes by in the near future. Other than experimenting on a few nearby objects, most of the missions will be probably very far away, beyond the orbit of Mars. How far away is the nearest NEO of significant size?

[Mr Skeptic]

We might try something with Apophis when is comes by in the near future. Other than experimenting on a few nearby objects, most of the missions will be probably very far away, beyond the orbit of Mars. How far away is the nearest NEO of significant size?

 

No, we most definitely do not want to test that near earth. One is the issue of the EMP from the nuke. Another is that if you deflect it near earth, it is much more likely to hit the earth. It would change the orbit but the orbit would still have to pass through that point (ie, where it is now), and if that point is near earth the new orbit could bring it on a collision course.

[toastywombel]

I would like to see what a 100 megaton blast could do. I have always thought a better idea would be to send a bunch of drones to latch onto a side of the asteroid. When they latch on they then can deploy rockets that will alter the course of the asteroid.

 

This situation is overall much safer than using nukes, more controlled, and more predictable.

 

Plus the idea of multiple drones that are the same build, is simply better odds. Some may get taken out, but if you send a hundred, there is a good chance of getting quite a few on the asteroid.

[Airbrush]

Mr Skeptic: "No, we most definitely do not want to test that near earth. One is the issue of the EMP from the nuke. Another is that if you deflect it near earth, it is much more likely to hit the earth. It would change the orbit but the orbit would still have to pass through that point (ie, where it is now), and if that point is near earth the new orbit could bring it on a collision course."

 

OK then, we might start with NEOs that are so far away that even if we blunder the results will not be disaster.

 

I like Toastywombel's ideas, but those will take much longer, and cost a lot more than simply using what we already have. Nukes are a cheap and efficient way to deliver a powerful punch to a far away destination. And we already have them. Now all you have to do is build the robotic probes that will carry out the missions. The nuke push has the great advantage of simplicity. Of course, the robotic probe will stand off at a safe distance watching what happens and measuring the effect of the blast.

Edited April 14, 2010 by Airbrush

[toastywombel]

Mr Skeptic: "No, we most definitely do not want to test that near earth. One is the issue of the EMP from the nuke. Another is that if you deflect it near earth, it is much more likely to hit the earth. It would change the orbit but the orbit would still have to pass through that point (ie, where it is now), and if that point is near earth the new orbit could bring it on a collision course."

 

OK then, we might start with NEOs that are so far away that even if we blunder the results will not be disaster.

 

I like Toastywombel's ideas, but those will take much longer, and cost a lot more than simply using what we already have. Nukes are a cheap and efficient way to deliver a powerful punch to a far away destination. And we already have them. Now all you have to do is build the robotic probes that will carry out the missions. The nuke push has the great advantage of simplicity. Of course, the robotic probe will stand off at a safe distance watching what happens and measuring the effect of the blast.

 

Despite what you seem to think, Nukes are not cheap, in any way or form,

 

http://www.brookings.edu/projects/archive/nucweapons/50.aspx

 

If you look at this link you will see that nuke are not cheap.

 

On the other hand, the probe, deep impact.

 

The total cost of developing the spacecraft and completing its mission reached $330 million

 

http://en.wikipedia.org/wiki/Deep_Impact_(space_mission)

 

The type of probes I proposed may be more expensive than that, but even if they were a $500 million a piece, the prices would be comparable to nuclear weapons.

 

The only downfall is the technology for nuclear weapons is here right now. But launching a nuke is not cheap, especially considering nukes weigh quite a bit.

[Airbrush]

Nukes ARE cheap. We already paid for them.

 

Sending a gravity tractor, or rockets to attach to an asteroid, will be heavy payloads, maybe heavier than a few nuclear devices. How much does a one megaton nuke weigh? *

 

My guess is the weight of the actual nuclear device(s) will be small in comparison to the fuel needed to get to the asteroid belt, then change course dramatically, slow down, and match the speed of the asteroid, so it will fly along side.

 

*"The W54 warhead used on the Davy Crockett weighed just 51 pounds and was the smallest and lightest fission bomb (implosion type) ever deployed by the United States, with a variable explosive yield of 0.01 kilotons (equivalent to 10 tons of TNT"

 

http://www.brookings.edu/projects/archive/nucweapons/davyc.aspx

 

At that ratio, a one megaton would weigh about 5,100 lbs. But that was 50 year old technology (1961). I think a modern one megaton does not weigh that much. Maybe 500 lbs. It does not need a heavy, hardened steel casing, like an IBM, to penetrate the atmosphere at high re-entry speed. Anyone know?

 

What does Wiki say?

 

"The Peacekeeper was a MIRV missile; the MX could carry up to 10 re-entry vehicles, each armed with a 300-kiloton W87 warhead/MK-21 RVs (twenty times the power of the bomb dropped on Hiroshima during World War II."

 

http://en.wikipedia.org/wiki/MX_missile

 

There you have it. The missile carried 10 nukes of 300 kilotons each (3 megatons). That did not need the Saturn V rocket to launch it. Not too heavy.

Edited April 14, 2010 by Airbrush

[Moontanman]

Theoretical limit

 

http://en.wikipedia.org/wiki/Nuclear_weapon_yield

 

The yield-to-weight ratio is the amount of weapon yield compared to the mass of the weapon. The theoretical maximum yield-to-weight ratio for fusion weapons is 6 megatons of TNT per metric ton (25 TJ/kg).[1] The practical achievable limit is somewhat lower, and tends to be lower for smaller, lighter weapons, of the sort that are emphasized in today's' arsenals, designed for efficient MIRV use, or delivery by cruise missile systems

 

If I'm reading this correctly a 100 megaton warhead would weigh a little more than 16 tons.

 

300 lbs for a one megaton war head would be about right.

[PaulS1950]

The problem, as I understand it, for using nukes to "push" an asteroid is that they push too hard. If it breaks an asteroid up then you have multiple pieces each or all of which can continue on the same trajectory. Using a shock wave to try to move a rubble mass is just crazy - it separates and then reassembles.

The other drawback with using nukes is that you have to be a LONG way from earth because in micro gravity the effects are more severe for us here on the earth.

 

The alternatives are many and varied. The gravity tractor is a good idea if you have a few years to manipulate an asteroid abd the laser or solar "jet" is an effective and inexpensive way to handle asteroids of large volumes or closer to the earth. Attaching an impulse engine to an asteroid seems doomed to me but I suppose with the correct science it might be workable for some asteroids. Perhaps an orbital directed energy device - like a neutron gun - might work as a reaction engine to move large rocks at moderate ranges.

It boils down to being able to identify the kind of asteroid that we are dealing with in time to actually do something about it. Then choosing the right device to handle that mass. I don't think there is any simple answers here.

[Airbrush]

Theoretical limit

 

http://en.wikipedia.org/wiki/Nuclear_weapon_yield

 

If I'm reading this correctly a 100 megaton warhead would weigh a little more than 16 tons. 300 lbs for a one megaton war head would be about right.

 

Thanks for your help Moontanman. Since I want to conduct a larger number of experiments, send 20 nuclear devices of half a megaton each. That is a total of 10 megatons, so the payload, using 6mt/2200lbs, 10mt would weigh less than two US tons (sorry as an American I'm not familiar with metric tons).

 

The idea is to probe, survey, and test the asteroid to find out how solid it is. Then set off a half megaton device from a great distance and measure the effect. Then you set them off closer and closer. Nuclear devices, which are already paid for and setting in an inventory, is the most efficient, thrifty, and time-saving method of any other you can name.

 

The answer to asteroid threat mitigation is ALL THE ABOVE (gravity tractors and attaching rockets, which will take decades longer, kinetic impactors, etc.) by many different means. However nukes should be forward, center, something already available. All you need to build is the robotic rocket to take them out there.

 

Paul, there is no shock wave in the near-vacuum of space. All you can do with a nuclear explosion is heat one side of the asteroid to cause outgassing which will push like thousands of tiny rocket engines.

Edited April 15, 2010 by Airbrush

[Mr Skeptic]

Paul, there is no shock wave in the near-vacuum of space. All you can do with a nuclear explosion is heat one side of the asteroid to cause outgassing which will push like thousands of tiny rocket engines.

 

It's not space anymore when you fill it with hot plasma.

[SH3RL0CK]

a nuclear explosion ... heat(s) one side of the asteroid to cause outgassing which will push like thousands of tiny rocket engines.

 

But if the asteroid rotates, as is almost certainly the case, then the outgassing will essentially be balanced due to the rotation. I suppose it would be possible to ignite the nuke along the rotational axis...which I presume would accomplish the objective of altering the solar orbital trajectory.

 

The composition of the asteroid would be critical. If it did not contain water or other volatile compounds, I doubt much would be accomplished by doing this as there would be no outgassing. Unless the explosion was close enough to vaporize the stone or metal, in which case I think there is a definite risk of breaking the asteroid up into multiple peices, each of which would pose a significant threat (turning one problem asteroid into many).

 

Not that I am really opposed to this type of research (I would say we should do this provided we can afford it), I'm just reinforcing my opinion that other techniques such as gravity tractors appear more promising to me.

[Airbrush]

Interesting point Mr. Skeptic. Then the question is what effect will this plasma have on asteroids of various compositions, from various distances? I would like to find out.

 

Sherlock, you make an excellent point about from what angle to set off an explosion, relative to the asteroid's rotation. Aligned with it's rotational axis will give the most push, but is that the ideal direction? These are all questions that can only be answered by trying it.

 

My wiki research led me to this story about a proposed problem for experts at MIT in 1967 to prevent Icarus from impacting Earth in 15 months. Their decision was a series of nuclear devices. But hope for success was minimal.

 

http://www.thespacereview.com/article/175/1

 

"...A slow rendezvous, or even a soft landing, was totally out of the question: Icarus would be moving too fast for a spacecraft to reach it and then reverse direction for a rendezvous....The only option was a fast intercept—fly out to Icarus and detonate a bomb near the surface to change its course.

 

"What the group decided to do was to take six Saturn V rockets then in production, and with only minimal modifications to their payloads use them to carry smaller bombs to Icarus. The first launch would have to take place by April 1968, only a year away, and five more launches would have to follow at two-week increments.

 

"Despite studying several asteroids up close with robotic probes and even landing on one with the NEAR spacecraft, planetary scientists are still unsure how they’re composed. One theory, known as the “rubble pile,” is that many asteroids are not really rocks, but bundles of rocks and dust. Hitting one with a nuclear explosion might accomplish little, as it would absorb the blast and not move very much. Compare trying to push a rock across the floor with one finger with pushing a pile of peanuts, or sand, across the ground with a finger."

 

If it turns out to be a rubble pile, then all you need to do is penetrate to the center of the pile and explode the nuke. Fragments will fly in all directions and you will reduce the amount of material that makes it all the way to Earth.

 

That was over 40 years ago, I would like to see an updated scenario using modern technology.

Edited April 15, 2010 by Airbrush

[Leader Bee]

Theoretical limit

 

http://en.wikipedia.org/wiki/Nuclear_weapon_yield

 

 

 

If I'm reading this correctly a 100 megaton warhead would weigh a little more than 16 tons.

 

300 lbs for a one megaton war head would be about right.

 

 

Tsar Bomba, a nuclear device originally planned to be 100 Megatons but downscaled to 50, incidentally also the biggest nuke to ever be atmosphericlaly tested, weighed close to 29 tons.

 

With todays boosting technology I reckon you might be able to get it closer to 16.

 

If you look up the nuclear test series of Starfish Prime you'll see this deals with testing nukes in space and EMP managed to knock out all of Hawaii and several other places.

[Airbrush]

On the topic of "Asteroid Impact Avoidance" under "Collision Avoidance Strategies" the first two listed options are nuclear devices and kinetic impactors, which could be effective against the more solid objects of some sizes. What will deliver more energy to move the object a nuclear bomb or a kinetic impactor of the same mass? A series of nuclear explosions would take advantage of the large stockpiles of thousands of nuclear weapons, and put them to work for a worthy cause, "saving the world". Since Obama and the Russians have agreed to reducing nuclear arsenals by 30%, those bombs could be used for missions to NEOs.

 

From Wikipedia:

 

http://en.wikipedia.org/wiki/Asteroid_impact_avoidance#Collision_avoidance_strategies

 

"Detonating an explosive nuclear device above the surface (or on the surface or beneath it) of an NEO would be one option, with the blast vaporizing part of the surface of the object and nudging it off course with the reaction. This is a form of nuclear pulse propulsion. Even if not completely vaporized, the resulting reduction of mass from the blast combined with the radiation blast and rocket exhaust effect from ejecta could produce positive results.

 

Another proposed solution is to detonate a series of smaller nuclear devices alongside the asteroid, far enough away as not to fracture the object. Providing this was done far enough in advance, the relatively small forces from any number of nuclear blasts could be enough to alter the object's trajectory enough to avoid an impact. This is a form of nuclear pulse propulsion. The 1964 book Islands in Space, calculates the nuclear megatonnage necessary for several deflection scenarios.

 

The hurling of a massive object at the NEO, such as a spacecraft or another near-earth object, is another violent possibility. A small asteroid or large mass in a stable high-Earth orbit would have tremendous kinetic energy stored up. With the addition of some thrust from mounted rockets (plasma or otherwise), it could be used like a stone from a slingshot to deflect the incoming threat.

 

An alternative means of deflecting an asteroid is to attempt to directly alter its momentum by sending a spacecraft to collide with the asteroid.

 

The European Space Agency is already studying the preliminary design of a space mission able to demonstrate this futuristic technology. The mission, named Don Quijote, is the first real asteroid deflection mission ever designed.

 

In the case of 99942 Apophis it has been demonstrated by ESA's Advanced Concepts Team that deflection could be achieved by sending a simple spacecraft weighing less than one ton to impact against the asteroid. During a trade-off study one of the leading researchers argued that a strategy called 'kinetic impactor deflection' was more efficient than others."