From: henry@spsystems.net   
      
   In article <1117109593.595381.203360@g49g2000cwa.googlegroups.com>,   
   Cray74@gmail.com  wrote:   
   >Changing topics a bit, a ship at the Earth-moon L1 point would stand to   
   >benefit from a perigee burn with Earth or the moon, because it hardly   
   >has to spend any fuel to leave the L1 point, correct?   
      
   The cost for leaving the L1 point is negligible, but it's then in a   
   relatively high orbit around Earth (orbital velocity circa 1km/s), and to   
   drop down close to Earth it would have to kill most of that.  (The cheapest   
   way to do that propulsively is a two-burn strategy, boosting *outward* to a   
   very high apogee and doing a small burn there to drop perigee down.)   
      
   Arranging a close lunar flyby would probably be possible at minimal cost.   
   You might be able to exploit that to kill the orbital velocity.  Three-body   
   dynamics get complicated and it's hard to give reliable answers without   
   burning a lot of CPU cycles on simulations.   
   --   
   "Think outside the box -- the box isn't our friend."    |   Henry Spencer   
                                   -- George Herbert       | henry@spsystems.net   
      
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