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I think it is mostly about the path the rocket is allowed to travel during launch. In the US, for equatorial orbits, one launches from Cape Kennedy to the east,

I think it is mostly about the path the rocket is allowed to travel during launch. In the US, for equatorial orbits, one launches from Cape Kennedy to the east, and for polar from Vandenburg to the south. Maybe off angle launches aren't allowed so a lot of correction is needed after the satellite reaches orbit to get to an inclined orbit? I am not an orbital mechanics specialist or space launch planner. Corrective comments are encouraged.

walrus01 8y ago
Vandenberg is mostly used for polar orbit launches because it's a path over the ocean. Not possible to launch eastbound from there because first stages would fall on populated areas. This is also the reason why the Israeli space program launches into rare retrograde orbits (opposite direction of earth's rotation), westbound over the ocean, because they don't want to drop 1st stages on their eastern neighbours.
- njarboe 8y ago
  Correct. But the question is, if one wants an inclined orbit, why can't you launch out of Kennedy to the northeast or out of Vandenberg to the southwest. Wouldn't this save all the delta v correction you need to do after getting into an equatorial or polar orbit and then transitioning to an inclined orbit?
  - khuey 8y ago
    You can do both of those. NRO missions have launched out of Kennedy to the northeast (e.g. NROL-76) and Vandenberg to the southwest (e.g. NROL-25).
    - njarboe 8y ago
      According to bisby at the head of this thread, one of the reasons that SpaceX did not recover the booster is that the rocket had to enter an inclined orbit. Maybe it did launch in the direction for an inclined orbit and used a little extra fuel, like a polar orbit does, due to the fact that you don't have all the speed of the spinning earth adding to your orbital velocity. I didn't know that the spinning Earth speed was a significant factor on payload to orbit of rockets.

walrus01 8y ago

Vandenberg is mostly used for polar orbit launches because it's a path over the ocean. Not possible to launch eastbound from there because first stages would fall on populated areas. This is also the reason why the Israeli space program launches into rare retrograde orbits (opposite direction of earth's rotation), westbound over the ocean, because they don't want to drop 1st stages on their eastern neighbours.

njarboe 8y ago
Correct. But the question is, if one wants an inclined orbit, why can't you launch out of Kennedy to the northeast or out of Vandenberg to the southwest. Wouldn't this save all the delta v correction you need to do after getting into an equatorial or polar orbit and then transitioning to an inclined orbit?
- khuey 8y ago
  You can do both of those. NRO missions have launched out of Kennedy to the northeast (e.g. NROL-76) and Vandenberg to the southwest (e.g. NROL-25).
  - njarboe 8y ago
    According to bisby at the head of this thread, one of the reasons that SpaceX did not recover the booster is that the rocket had to enter an inclined orbit. Maybe it did launch in the direction for an inclined orbit and used a little extra fuel, like a polar orbit does, due to the fact that you don't have all the speed of the spinning earth adding to your orbital velocity. I didn't know that the spinning Earth speed was a significant factor on payload to orbit of rockets.