4 ms·

ELI5: why don't they use "tiny nukes", basically engineer a small (less than 10cm/1in) nuclear bombs that explode in a chamber at the back of the space ship?

• uup 4y ago
  https://en.wikipedia.org/wiki/Outer_Space_Treaty https://en.wikipedia.org/wiki/Outer_Space_Treaty
• deleted 4y ago
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• MetalLord 4y ago
  It was thought of https://en.m.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion) https://en.m.wikipedia.org/wiki/Project_Orion_(nuclear_propu... Now I don't know how feasible is making a nuke as small as you suggest.
  • _8j50 4y ago
    Thanks, now i remember hearing about this. > Project Daedalus later proposed fusion explosives (deuterium or tritium pellets) detonated by electron beam inertial confinement. This is the same principle behind inertial confinement fusion. Theoretically, it could be scaled down to far smaller explosions, and require small shock absorbers. That's an interesting tidbit about the size. Also reminds me of the Deadalus spaceship from the stargate universe. But it sounds like politics is the only limit here, surely they can ammend the treaty to allow space-travel work under IAEA supervision.
  • foobarian 4y ago
    Welp, why make a small one then? Just make a big one :-)
• detaro 4y ago
  - Can't make nukes that small (you literally can't fit critical mass in that size I think, afaik smallest developed ever are 155mm artillery shells) - massive mess if it goes wrong in any way - putting nukes in space is banned by treaty and would be an ugly precedent -Japan has committed to not making nukes and has for obvious historical reasons a difficult relationship with the topic. (If Japan wanted to become a nuclear power, they relatively easily could for a country that doesn't have any, but that would be a major thing and not a side thing of some science project)
  • _8j50 4y ago
    I hope they amend the treaty with IAEA being able to enforce things and all. I think we can leave japan out of this too, I don't see why one country is so important. Isn't 155mm 15cm? Close enough I would say if it was an actual fission explosion. As for safety, nukes in space are safe and you can launch them using conventional propulsion and use nukes only in space and also launch from point nemo or cook islands so you are at least 3000mi away from large populations. I get these challenges are real but if the advantage over ion propulsion is great then it sounds like they are worth overcoming.
    • MichaelCollins 4y ago
      The 155mm W48 nukes were real nukes, but very inefficient. One 155mm nuclear shell weighed 54kg and had a yield of 0.072 kilotons of TNT. A 16" nuclear shell weighed about 20x as much but had a 200x greater yield (15-20 kilotons of tnt)
      • deleted 4y ago
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    • kbenson 4y ago
      Maybe I have a biased view of world events, but it feels like there's less respect for joint agreement in the world and less respect for regulation, or allowing regulation the ability to function as designed, at least in the U.S. (and it seems like the world is heading a similar direction). Lessening an absolutist stance on this in favor of a more nuanced regulatory policy that requires more in depth checking seems to me like something we'll regret later when we find the agency is toothless, either because it always was in regards to this or because it was slowly defanged without people noticing.
    • lantry 4y ago
      > you can launch them using conventional propulsion and use nukes only in space and also launch from point nemo or cook islands so you are at least 3000mi away from large populations. If something goes wrong during the launch and the rocket explodes, isn't that basically exploding a dirty bomb in the upper atmosphere? Is 3000 miles really enough of a buffer zone? https://en.m.wikipedia.org/wiki/Dirty_bomb https://en.m.wikipedia.org/wiki/Dirty_bomb
• deleted 4y ago
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• tjpnz 4y ago
  Sibling comment is a good summary of most of the issues. I would add that you would lose quite a bit in payload mass to the additional shielding you would need so as to not fry your electronics/kill your crew. This would be in addition to what you would already be carrying to protect against existing ionising radiation from solar flares and alike.
  • _8j50 4y ago
    Your last point about having to do radiation shielding anyways is interesring. I wonder if there are now materials or designs that can address this since it was firsr researched in the 70s and 80s.
• retrac 4y ago
  The critical mass of a bare sphere of plutonium-239 (the isotope usually used to make bombs) is about 10 kg. Some percent can be shaved off this with a neutron reflector around the core and other design tricks. The American W54 warhead of the 1950s was 23 kg and the core was probably around one-third of the entire mass of the bomb. That is likely the practical limit for traditional designs. As for what might be feasible within the laws of physics, rather than current engineering, I'm not sure there's a clear answer. Increasing the density of the fissile matter reduces its critical mass, which is why they implode the core with conventional explosives in most designs. There are other ways of compressing matter to very high densities. For example, subjecting it to hot enough plasma, like in a magnetic confinement fusion reactor, might work. But stuff like that is science fiction and will be for a long time.
  • oceanplexian 4y ago
    W48 is the best we could do in 1963, that was 59 years ago. I’m sure if they did build a better one we wouldn’t hear about it. For example Suitcase nukes are probably a real thing, or at least something like the soda machine from Sun of All Fears.