I am having a debate on one of the FB forums about the significance of the location of the launch centre, as far as the latitude. In particular, there is a Wiki page about Kourou, French Guiana Launch Centre. Specifically:
Kourou is located approximately 500 kilometres (310 mi) north of the equator, at a latitude of 5°. It is a common misconception that the main advantage of launching a rocket from the equator is the extra boost provided by the speed of the Earth's rotation. For example, the eastward boost provided by the Earth's rotation is about 463 m/s (1,035 miles per hour) at the Guiana Space Centre, as compared to about 406 m/s (908 miles per hour) at the United States east coast Cape Canaveral and Kennedy Space Center spaceports which are at 28°27′N latitude in Florida. This means that rockets need around 60 m/s more delta-v to reach Low Earth Orbit (LEO) from Cape Canaveral, which is an insignificant disadvantage.
In reality, the main benefit of Kourou is that the near-equatorial launch location provides an advantage for launches to low-inclination (or geostationary) Earth orbits compared to launches from spaceports at higher latitude. This is because rockets can be launched into orbits of with an inclination of as low as ~6°.
A prevailing opinion is that this is simply wrong. What is your take on this?
I'm not a rocket scientist, but I'll tell you as I know it, hope I understood you correctly. Rockets do get a little boost when launching to East - closer to the equator, the more boost you get (the speed of the Earth's rotation is greater, due to the larger distance from spinning axis). And when launching a satellite to orbit every kilo is important, so if you can put more payload on for that 60 m/s boost, then I don't see, why isn't it worth it. And yeah the capability to launch satellites to low-inclination orbit is also an advantage because inclination change maneuvers require a lot of delta-v in orbit.
The reason Kennedy Space Center and the Cape Canaveral Air Force Station are ideal, is their location, yes, but also the government owns a signficant portion of the land, and in the event of a catastrophic failure of a launch vehicle, it can be self-destructed without debris, fuel, and fire, raining down on schools, churches, shopping centers, and homes. This was done intentionally for the safety of the community. I'm not sure the other space ports you're referencing have residential or commercial areas close to them, but safety is always paramount and that's why KSC is the best, and most ideal site. Also, for real, Launch Pad 39B has been re-configured and remodeled to fit the new SLS system with the Orion Crew capsule. I hope this helps.
I learned this information as a member of the NASA Social group when we were allowed access to the Launch Control, and one of the launch control firing rooms (there are actually 4 at KSC, and you have to take an elevator to get to them) and the director of the launch control center went over this with a map, which showed us where houses stopped, and KSC/CCAFS property began, and why.
There is a benefit of the launch boost from being closest to the equator for a launch site. Even though relatively small between Kourou and KSC, the benefit is there especially for high performance needs (maxing out a rockets payload carried in mass). There was a whole commercial rocket launch developed called SeaLaunch that used a converted floating oil drilling platform for exactly the purpose of being able to be towed to the equator itself. This is a small satellite launcher but the benefits were enough to go to that trouble at the time.
Both Kourou and KSC are located on the East coasts of the continents for the safety reasons of launching over the ocean and not exposing populations to risk by overflight of land masses. Similarly, SeaLaunch went out in the middle of the Pacific Ocean for the same reason. As for the choice of Kourou for a launch site, the prevailing benefit to the choice was likely the safety overflight reason (as otherwise France is located on the west coast of Europe and is not appropriate for launches) and the equatorial location was a benefit for performance.
So I think I'm basically saying both reasons are correct. Choices to make huge infrastructure investments of a launch site would rarely boil down to 1 singular reason rather than a variety of factors.