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There's nothing wrong with refining models, but it's a bit besides the point. At a 1995 Planetary Defense workshop Edward Teller proposed the development of a 1
by dkbrk 3y ago
There's nothing wrong with refining models, but it's a bit besides the point. At a 1995 Planetary Defense workshop Edward Teller proposed the development of a 1Gt device for that purpose. Fusion bombs are actually quite straightforward to scale by adding more stages, so it wouldn't be terribly more difficult to produce a 10Gt device instead. What the model tells you is how large a device you need, but all that's needed is a conservative model that tells you the minimum size you need, and then you can add a generous margin of safety on top of that. The goal is to stop the asteroid hitting Earth, there's nothing wrong with deflecting it "too much".
But right now we have exactly zero such devices prepared. Existing nuclear devices are about 3 orders of magnitude too small, and none of them are set up for a launch into an intercept. That's where the focus should be -- getting something, anything, of roughly the right order of magnitude that would provide a credible response to a detected inbound asteroid.
- andyjohnson0 3y ago> But right now we have exactly zero such devices prepared. Who would build/host/control such a weapon?
- coldtea 3y agoNot sure, but it would be deployed by a ragtag team of oil rig miners...
- jltsiren 3y agoWhoever is capable of solving the real challenge of delivering the warhead. Extrapolating from the existing high-yield bombs, the mass of a 1-gigaton warhead could be something like 200 tons. The Starship would probably be large enough to launch it into orbit, if you integrate the warhead in the upper stage and discard the lower stage. Then you would need 10+ refueling flights before you can launch it towards the asteroid. A 10-gigaton bomb would need a rocket 10x bigger than the Starship. Or you would have to build it in the orbit.
- avar 3y agoIvy Mike was around 70 tons and yielded 10 Mt, the B41 was around 5 tons yielding 25 Mt. Extrapolating from that a 10 Gt device should weigh around negative 25 thousand tons. You wouldn't need the starship to launch it, just attach it to the HMS Invincible and it would spontaneously float upwards into space.
- ragebol 3y ago> The goal is to stop the asteroid hitting Earth, there's nothing wrong with deflecting it "too much". I'm not sure sure about that. With orbital dynamics being complicated, I'm pretty sure you want to push it to a known orbit. Otherwise, it might hit a body (planet/moon/asteroid) we have some base/colony on by that time. Or it will hit Earth in it's next orbit.
- OscarCunningham 3y agoSpace is mostly empty, a random orbit is very unlikely to hit anything.
- lupusreal 3y agoHitting Earth later is better than now. If nothing else it buys time for a new plan. And if it did wipe out a Moon base with dozens of people, at least it wasn't a city with millions...
- zemvpferreira 3y agoPardon the glibness but I feel humanity will survive longer without an asteroid-deflecting technology than if we own 1Gt nuclear devices. If that's the scale required, I propose ignoring the possibility.
- Gare 3y agoTsar bomba was 100 Mt design, about 50 Mt test. Not much of a difference, you're going to be toast anyway (multiple "smaller" warheads are more economical and harder to intercept anyways).
- lupusreal 3y agoThat's 5x larger than the Krakatoa explosion; huge but not alone big enough to exterminate humanity. The most dangerous nukes are actually the smallest, since politicians may convince themselves that just a few small nukes is permissible, resulting in a rapid escalation that sees every major city showered with megaton h-bombs, destroying civilization and sending humanity into a poisoned dark age. If it seems implausible that politicians might use tactical nukes, ask what those nukes were created for. The US made many thousands of them to be used against a conventional Soviet ground invasion of West Germany; lobbing small nukes at tank columns. Escalation from a conventional war to a nuclear war was a common assumption in the military planning of the late cold war. But sides anticipated it and were prepared to perform that escalation themselves.
- perihelions 3y agoWe should consider ignoring asteroid-deflection itself as a possibility. The scale of an asteroid impact, deliberately instigated by deflection as an act of war, is far larger than what humanity's capable of with nuclear weapons alone.
- leoedin 3y agoSurely anyone on earth who has the technical ability to deflect an asteroid precisely to hit one part of the planet, would also have the technical ability to just bomb that part of the planet directly - with much lower risk of accidentally hitting the wrong part?
- krisoft 3y ago> The goal is to stop the asteroid hitting Earth, there's nothing wrong with deflecting it "too much". Unless of course you don't deflect it but break it up into chunks where some of the chunks are still heading towards us.
- ganzuul 3y ago100 gigaton, then Oh, lets just glass a side of the moon like a fresnel and zap the asteroids like an ant under a magnifying glass. I call it project Disco Moon
- cookingmyserver 3y agoWhich is why you would use waves of consecutive detonations consisting of more and more (smaller) nukes. Think of a cone pointed towards the asteroid. The tip would be the first initial large nuke. Because of the mass and velocity of the asteroid, it is unlikely that the fragments would spread out all that much. You are right that there would likely be fragments that still have an orbit that would lead to collision. After the first explosion you would detonate 5 more nukes spread out evenly to further perturb and break down the asteroid remnants. You would repeat this many times. Each time the nukes could be smaller as the mass of the asteroid remnants would be getting smaller and smaller making the force of the nukes more effective against them. This would probably only be suitable for ruble pile asteroids, but I would imagine those are the hardest to use ablation with, so it may still be appropriate to use more destructive methods. There are two goals with this: (1) break down or deflect any large chunks to prevent damage related to ground impacts. (2) cause enough change to the orbits of the asteroid remnants such that any subsequent collision with earth would be spread out over time to prevent overheating of the atmosphere via clouds of debris. The best solution is always to have the asteroid remain as intact as possible, but for certain asteroid types and scenarios, it may just have to be good enough especially as a backup.
- elzbardico 3y agoHate to derail a bit from the discussion you're starting, but let's always keep in mind that Teller would propose a 1GT for frying bacon if you let him.
- jdewerd 3y agoYes, but he also figured out how to use ablation drive in his fusion bombs because otherwise a fission bomb doesn't squeeze nearly hard enough. If you had to design a really big ablation drive to push a really big asteroid, who would you call? Prof. Ablation Drive? Or some other guy? (Yeah, he's not with us anymore, but you know what I mean.)
- hermitcrab 3y agoI'd rather take my chances with rogue asteroids than allow anyone to assemble a 10Gt fusion bomb here on earth.
- throwaway4aday 3y agoIt's not like it's going to be set off by a discarded cigarette.
- hermitcrab 3y agoThere have been plenty of nuclear accidents since 1945. It seems to be more luck than anything else that we haven't seen an accidental detonation yet.