5 ms·

You may guess that if you like, but it is physically impossible in this universe.

• adastra22 4y ago
  Project Orion used fission bombs "the size of a soda can" to power its propulsion. Designing such bombs was a big part of the military aspect of the project and how it got government funding. Now the results are still classified, of course, but it appears they were successful from a design angle. At least the scientists involved seem to think it was possible. This source gives an estimate that a 1 kg fissile mass plutonium can yield about 100 tonnes of explosive power, which is a sphere of plutonium about 2 inches in diameter: http://nuclearweaponarchive.org/Nwfaq/Nfaq4-2.html http://nuclearweaponarchive.org/Nwfaq/Nfaq4-2.html In principle there isn't really a limit to how small you can make it, just with decreasing efficiency and (with traditional implosive designs) a higher detinator-to-fissile material ratio. Things like laser implosion remove this design constraint, however, and would let you consider things like millimeter-sized pellets.
  • ncmncm 4y ago
    1 kg is the amount of fissile material, but it needs quite a lot of high explosive around it. The file you linked says 16kg, and 28 cm by 30 cm. I suspect the soda-can sized charges you recall were conventional explosives for the small, non-nuke prototype they tried out.
  • pfdietz 4y ago
    Project Orion did not use fission bombs the size of a soda can. It may have used bombs whose CORE was the size of a soda can, but to get that to explode requires much more high explosive (than in a typical nuclear weapon) to implode it more aggressively. That's fine, as the mass of all that high explosive acts as reaction mass.