Nice. I guess it shouldn’t be a surprise, but it sure makes diverting anything out there a much bigger problem. Maybe the trick is to just put a whole head of nukes throughout the structure and try to scatter it as much as possible. No easy answer I suspect.
A bit of (another) aside, but I was wondering if 2008 TC[SUB]3[/SUB] might be a rubble pile–this was the first asteroid/meteoroid detected as it approached the Earth, detected as it entered, and recovered as meteorite fragments. When collected from the strewn field, the meteorites turned out to be from three different types of asteroids. But it turns out that the rotation period pre-entry was less than 2 minutes, so no chance that it was a mini rubble pile, and must have been a chunk of regolith that fused long ago on the parent body.
No. The Tungsten comes from this : Project Orion (nuclear propulsion) - Wikipedia
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The “propellant” is tungsten. This device does not try to contain the explosion. It is directional, however -you have to aim the tungsten side towards the asteroid.
That diagram gets used in a number of places, not just the one linked. In some uses the claim is made that the x-rays are contained or reflected by the thick unlabelled layer surrounding most of the radiation case. (That his layer is unlabelled in this version of the diagram is curious as well, some diagrams call this layer the radiation case.) I tend to think that most uses of the diagram are made up at best. On reflection, I will include mine.
You can however tune a bomb between neutron and gamma production, and I would imagine that this would be done to maximise gamma production.
Again, apply conservation of momentum to just the nuke. You can’t have a nuke create directional momentum.
Some descriptions of the Casaba Howitzer use the same diagram, some say it is modified from here. It claims to create a directed jet from the tungsten - a very fine jet (some claim small units of degrees, some claim a fraction of a degree) designed to be used as a space weapon capable of destroying missiles. What you can’t do is somehow create a weapon that preferentially directs the weapon’s total momentum one way or another - the jet of tungsten plasma must be countered by the momentum of the rest of the weapon in the other directions. Thus the jet actually contains quite a low proportion of the weapon’s absolute momentum (which is as we have already noted is quite low) but it can contain a highly destructive amount of energy at a range where the base nuke would not be so destructive.
There is so little actual real science about this design available, and so much fanciful rubbish, and a significant number of questions about whether it would or could actually work as claimed, I remain, at best, highly sceptical.
I agree the problem analysis is simpler than it has been made to appear, but I also think you are wrong if you are implying the internal composition doesn’t have a *practical * importance, SamuelA.
A thermonuclear explosion delivers almost entirely energy, very little momentum. The effect on a nearby rock would be almost entirely the rapid heating and consequent ablation of the solid surface, and this would generate a short-lived but potentially quite powerful reaction on the mass via Newton’s Third Law. In essence, you are setting off a rocket on the rock’s surface, powered by the nuke and with reaction mass supplied by the rock itself.
What that impulse does is straightforward in the sense that it can only cause linear acceleration of the center of mass, angular acceleration (faster rotation), or internal vibrations, which would eventually decay to heat.
Presumably one’s goal is to achieve the greatest amount of acceleration of the center of mass. Faster rotation and internal vibrations do no good at all. One can hope to minimize the angular acceleration by judicious targeting, and hope that the internal vibrations don’t suck up too much energy because the strongest frequencies in the rocket effect don’t couple well to internal modes – although, who knows, there could be perverse circumstances where they would.
But *even if * you successfully deliver your entire impulse to acceleration of the center of mass, the composition matters, because it’s your hope that the motion of all of the rock is very similar to that of the center of mass, the classic rigid body motion. But that’s not guaranteed. If the rock breaks up in a perverse way, you could have one 100kg chunk shooting off in the direction you want at a hellacious clip – while the entire rest of the beast continues on the evil trajectory, more or less, with the sum of the momentum vectors of the speeding chunk and the rest of the material adding up perfectly to one solid asteroid sedately moving away the way you want. (Others have made this point, I think, above, and it sounds like that was StrangerOAT’s point as well.)
An analogy: someone has thrown 50g of water at you, and you can deflect it at arms length by sticking out your index finger and allowing the water to bounce off the tip. Your goal is for none of the water to hit your face. Your fingertip has no problem delivering enough impulse to the water to change its trajectory. If the water is solid ice, it will bounce off your fingertip nicely. If it’s liquid water, however, you get wet, because the motion of all the water does not track well the motion of its center of mass, like it does with the ice.
I don’t know a way to create a directional jet. I am assuming the cone angle is very large - doesn’t matter, you can obviously choose a detonation distance where any cone angle smaller than 180 degrees will be absorbed fully.
The mass of a fraction of the bomb core traveling away at nearly the speed of light is the other half of that momentum equation. Obviously. The huge advantage of this method is that you’re getting more push - more momentum - out of that 300-500 kilogram device (even the guidance thrusters and maybe solar panels you need are going to become propellant vapor as well) than anything else we can make today. Only an antimatter or fusion engine would be better, and we obviously are much farther from being able to build something like that. Above, I took a guess at an effective ISP of 7500. So same as a high end ion engine, except that the impulse gets delivered all at once. An ion engine spacecraft would need years to burn all it’s fuel, it’s obviously much better to make a larger velocity change at the beginning of a 10 year period than to make the same dV change spread out over 10 years.
The whole idea is you can only throw so many rockets full of something at the asteroid, this gives you the most bang for your buck. Literally. And like someone here pointed out, you’re going to need some serious velocity to even reach the asteroid at a decent distance from the earth, which means you’ll need to burn almost all your launch mass as fuel. Another big advantage is you don’t have to brake, you can do a flyby of the asteroid going several kilometers per second. This additional velocity vector would be negligible since the primary one imparted is coming from the nuke at more like 75 kps. Though it obviously requires perfect timing to do this.