XPost: sci.military.moderated   
   From: schillin@spock.usc.edu   
      
   rellim113@hotmail.com (Bob Martin) writes:   
      
   >>     Read it again - the book specifically noted that they built (and   
   >> later used) a backup catapult, with its own fusion plant, concealed to   
   >> avoid bombing by the UN forces. And that the secret weapon remained a   
   >> secret long after the war ended.   
      
   >Which book was this?  I've read Starship Troopers and I'm trying to   
   >figure out which of his other ones would be good/similar to that one.   
      
      
   The book many people here are referring to and nobody is actually   
   naming because everybody assumes everybody else knows what it is,   
   is Robert A. Heinlein's "The Moon is a Harsh Mistress", published   
   in 1966.   
      
   One of the classics, tMiaHM shows up on an awful lot of "top ten   
   science fiction novels ever" lists, so you'd need a pretty good   
   reason *not* to find and read it.  One possible such reason is that   
   it is rather dated; if you can't rewind your brain forty years you   
   may bounce off parts of it.   
      
      
   The general plot is that, in 2076-as-forecast-from-1966, the denizens   
   of a Lunar penal colony decide they've had enough of taking orders   
   from Earth and organize a revolution.  The particular bit that is   
   relevant here is their choice of weaponry - they can make small arms   
   locally, but their way of bringing the war to Earth is to use an   
   electromagnetic catapult that used to launch hundred-ton cargo barges   
   on an Earthward trajectory, to launch hundred-ton rocks instead.   
      
   A hundred tons of rock free-falling from the Moon to the Earth will   
   arrive with, and liberate on impact, kinetic energy comparable to   
   the Hiroshima Slum Clearance Event.  So it makes for a nice show of   
   force.   
      
   Unfortunately, this is one of those parts that's a bit dated.  In   
   1966, it was a reasonably well thought extrapolation, but in the   
   years since people who can afford to put more time into doing the   
   math than can even a diligent SF writer have found the relevant   
   scaling laws: electromagnetic catapults get a *lot* more expensive   
   as you make the payload bigger, and only a little more expensive   
   as you make the repetition rate higher.   
      
   So anything built for mercantile rather than military purposes, as   
   was the original lunar catapult in tMiaHM, will be designed to launch   
   hundred-pound buckets every second rather than hundred-ton barges every   
   hour.  And a hundred-pound projectile will shed almost all of its energy   
   harmlessly in the upper atmosphere.   
      
      
   Still a good story, you just have to remember that much of the technical   
   extrapolation is obsolete.   
      
      
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