From: ranma@saotome.demon.co.uk   
      
   "Henry Spencer" wrote ...   
   > In article ,   
   > Paul Blay  wrote:   
   > >Both Thuraya 1 and 2 were launched on Zenit SL from equatorial located   
   Odyssey   
   > >mobile platform.  Although the platform was located (as far as I can   
   > >tell) at 154W 0N the launch /target/ at satellite separation was   
   > >6.3deg.  Wouldn't that introduce a fuel life penalty?   
   >   
   > Only a small one.  Doing a small plane change as part of a large burn   
   > (e.g., GSO insertion) is almost free.   
   >   
   > Which doesn't explain *why* they did this.  Sea Launch can pretty much   
   > dial in your choice of orbit inclination.  For the first few launches,   
   > they did launch at a slight inclination to avoid any possibility that a   
   > launch failure could drop debris on the Galapagos, but that's long since   
   > been discontinued -- they *have* done launches to essentially zero   
   > inclination.   
   >   
   > It might perhaps be a constraint on where the second stage falls.  It's   
   > not uncommon for Zenit 3SL second-stage burnout to be in a suborbital   
   > trajectory, with the third stage supplying the final push to an initial   
   > parking orbit.  Not *all* the suborbital-staging launches have been at a   
   > significant inclination, mind you, but it could be a function of things   
   > like payload mass.   
      
   Actually the answer turned out to be that Thuraya doesn't do N/S   
   stationkeeping.  The initial inclination was chosen so that natural   
   changes would gradually bring it down 'n' through zero inclination   
   so that it would be at a reasonable inclination for as much of its   
   design life as possible.   
      
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