XPost: sci.space.moderated, sci.space.shuttle   
   From: jsb@at.hal-pc-dot.org   
      
   In this article on MSNBC.com:   
      
   http://www.msnbc.msn.com/id/3217961/   
      
   "At the start of the trip, the [near-] Earth station would focus its   
   particle beam on the magnetic sail of a Mars-bound space taxi, pushing it to   
   speeds of tens of thousands of miles an hour. During the approach to Mars,   
   the Red Planet station would fire its own beam to decelerate the   
   spacecraft."   
      
   Nowhere is mention made that this particle beam causes any "equal and   
   opposite" action at the particle-beam source. If this near-Earth station is   
   blasting a particle beam into space that causes a spaceship to accelerate   
   (momentum transfer) to "tens of thousands" of mph ... what is the source   
   doing to maintain position or orbital velocity? Am I missing something?   
      
   Jon   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)