On Saturday, April 7, 2018 at 6:43:55 AM UTC-5, eripe wrote:   
   > On Monday, February 19, 2018 at 4:57:46 PM UTC+7, me_...@yahoo.com wrote:   
   > > On Saturday, February 17, 2018 at 1:30:08 AM UTC-5, johnny1...@gmail.com   
   wrote:   
   > > > Hypothetically, imagine a starship comes across a human-inhabited,   
   Earth-like world, on which the former cities and centers of civilization have   
   been heavily nuked.  Assume it's been at least decades since the bombs fell.   
   > > >    
   > > > My question is, what if any signs would differentiate the results of a   
   big, world-wide nuclear exchange by locals on the planet, Cold War style, from   
   a space-based bombardment carried out by outside forces?  Would there be   
   anything that would    
   strongly indicate one scenario over the other?   
   > >    
   > > The fallout areas would contain ions of nuclear material that did not   
   fission and also daughter compounds of materials that did.  So you could, for   
   example, prove that the nukes that hit cities A and B had 41.2% U235 and a   
   plutonium 239 trigger, City    
   C had 48.4% U235 and City D got nuked by a plutonium only tactical device. You   
   can further finger-print the plutonium source by the amount of pu240 and other   
   isotopes mixed in with the 239.  The nuclear exchange will probably destroy   
   some weapons so City    
   C probably has some non-exploded ordnance with 41.2% U235 a facility that   
   contained(s) 41.2% U235, and a processing plant that was capable of separating   
   the isotopes.  You can also look at the blast size and irradiated components   
   from the vehicle(bomb)   
   that held the physics package. If all of that matches then you can make a   
   strong case for city C firing the nukes at A and B in an exchange.     
   > >    
   > > If there are no nuclear reactors, no nuclear waste storage containers, no   
   remnants of nuclear leaks, and no uranium mines then it is unlikely that the   
   natives had nukes.  Since these are humans on an earth-like planet did they   
   travel there?  They    
   could have transported nukes with them when they arrived.     
   > >    
   > > The space launched weapons would need re-entry heat shields and probably   
   rockets or some way to aim.  ICBMs also need reentry devices but they can be   
   much smaller.  Remnants could still be found.  A device designed to plunge   
   into an atmosphere    
   vertically would look a lot different from heat shields designed to slow down   
   a vehicle.  If the vehicle did not slow down the heat shield would still be in   
   front of the physics package when the nuclear explosion occurs. That would   
   change the fallout    
   pattern for fission materials and you would find a separate fallout pattern   
   for neutron irradiated elements that were components of the heat shield.     
   > >    
   > > If an interplanetary bombardment had any misses they could still be   
   floating around the system.  If any detonated in space there would be some   
   fallout on asteroids and moons.   
   >    
   > So a ship capable of interstellar flight either pops out of hyperspace,   
   launches 500 missiles at earth and then pops out again? I can see how that   
   would be a prudent move to keep the neighbors in the dark ages, and they would   
   be in a hurry because    
   there is a lot of stars to visit. But if you can do hyperspace, wouldn't you   
   have something more fancy than Pu-bombs, such as antimatter?   
      
   Antimatter is a bitch to make, store, and handle, and doesn't do anything for   
   you in a bomb that fission and fusion don't (generally speaking, there are   
   special cases).  Fission and fusion bombs are fairly safe to store, if   
   properly made they last a long    
   time and remain viable, they're compact and effective, and you can pack a lot   
   of them into a small space.   
      
   It takes stupendous amounts of energy to accelerate an object to relativistic   
   velocities.  You can steer an asteroid into an intercept orbit, but it's slow,   
   and obvious, and there's a long lead time during which your opponent can try   
   to do something    
   about it.   
      
   Nukes are fast, effective, and relatively cheap.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)