How is inclination change performed for satellites inserted into GEO?

With most launches performed from spaceports at various high latitudes, it's impossible to launch directly into equatorial inclination. And I know inclination change maneuvers are awfully expensive in terms of delta-V, plus there are quite a few strange tricks to save up on that expense (including both a Moon flyby and atmospheric entry with wings...)

How is the maneuver performed typically, in case of GEO insertions though? Where? Which engines/stages are used? What's the typical delta-V?


There's two ways that are typically done. The first is to use a "Super Synchronous" orbit to reduce the delta-v overall. Essentially, the initial orbit is around twice geostationary orbit, which makes the inclination change cheaper. The second is to just do it directly. They are always done as far out in the orbit as they can. There's a number of orbital arrangements that allow for this to happen.

The engines can vary dramatically. Progress is being made to slowly move to an electric system for maintaining and achieving the proper orbit. Usually it is a mono-propellant system on the satellite. Occasionally it is the last stage in a rocket system, but that is considered far more expensive, and is usually reserved for military purposes.

  • $\begingroup$ Isn't part of the inclination change done during leo->GTO burn over the equator? Combining the two should save some fuel (together with Oberth effect). $\endgroup$
    – jkavalik
    Nov 25 '16 at 14:44
  • $\begingroup$ I suppose it could be, I hadn't thought about that. Hmmm... $\endgroup$
    – PearsonArtPhoto
    Nov 25 '16 at 20:38
  • 1
    $\begingroup$ Close but not quite, @jkavalik, you suggested LEO->GTO, which if you think about it means starting with a small circular orbit and changing it to an ellipse with an apogee at 42164km. Recall that delivery is usually into GTO in the first place and so a kick at apogee is used to expand the perigee up to a circular GEO. It is this latter manoeuvre which is commonly combined with a reduction in the inclination. $\endgroup$
    – Puffin
    Nov 26 '16 at 0:51
  • $\begingroup$ @Puffin It is a common operation to have a very short term LEO orbit, holding in that orbit for about 20 minutes to get to the correct location to do a longer burn. It could make sense to correct some inclination there. $\endgroup$
    – PearsonArtPhoto
    Nov 26 '16 at 2:00
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    $\begingroup$ @Puffin you can see for example in SpaceX Thaicom 8 webcast at 48:50 how the inclination slowly changes during the apogee raising burn. When you go to GEO (or even only GTO), you will find yourself in almost circular LEO at some point. Afaik most launchers make it a parking orbit, waiting with the GTO burn until the vehicle crosses the equator, because that ensures apogee is over the equator too for the final GEO. And as I understand it, the geometry is such that doing small inclination change with it is more efficient than separate burn. $\endgroup$
    – jkavalik
    Nov 26 '16 at 10:48

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