From: henry@spsystems.net   
      
   In article <1116765254.914901.266740@g43g2000cwa.googlegroups.com>,   
   Cray74@gmail.com  wrote:   
   >I'm interested in finding out if there's any use escaping Mars' gravity   
   >from Deimos by using a perigee burn low over Mars, or if it'd just be   
   >better to make a direct launch from Deimos to escape velocity without   
   >the perigee burn.   
      
   If you start out from a circular orbit, you do not see a benefit from such   
   a two-burn sequence (first burn drops your perigee down, second is done at   
   perigee) until your desired velocity *after* escaping is sizable.  To be   
   specific, it has to exceed about 1.4 times the initial orbital velocity.   
   For anything less, you lose more on the first burn than you gain by making   
   the second more effective.   
      
   More complicated three-burn sequences improve the situation some, but you   
   still don't see any serious gains unless you're going significantly beyond   
   escape velocity.   
   --   
   "Think outside the box -- the box isn't our friend."    |   Henry Spencer   
                                   -- George Herbert       | henry@spsystems.net   
      
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