What some factors to consider when they choose launch sites like Cape Canaveral or Baikonur Cosmodrome? Is it possible to have a launch site anywhere in the world (if so why does the ESA launch its Ariane rockets from French Guiana?)
If this is a big question could the factors only be briefly laid out so further research can be performed!
Some factors might be:
Proximity to the equator. The closer the launch site to the equator, the easier it is to launch to equatorial orbit, and the more help you get from Earth's rotation for a prograde orbit. Unless launching to a polar orbit, there's at least some benefit to launching from as close to the equator as you can get.
Downrange safety. You want to be sure that spent stages dropped along the launch path or failed launches don't fall on people or property. Eastern coasts are good for that, as long as you can exclude marine and air traffic along the launch path.
Every launcher in the world, except for polar orbits, launches to the east to take advantage of the rotation of the Earth. That is except Israel's Shavit, which launches to the west (Overflying its eastern neighbours looks like an attack).
Thus an eastern coast is a good choice, with lots of ocean downrange for dropping stages.
For polar/sun synchronous orbits a mostly northern direction, which in the US is usually from Vandenberg AFB in California.
The Russian sites use large expanses of desert to simulate downrange ocean.
Launch site safety/security. There needs to be an exclusion zone of some size (depending on the size of your vehicle) in all directions around your launch site to keep unauthorized people away from your launch facility, and keep things/people out of harm's way if the vehicle has a catastrophic failure at or close to the launch pad. Even if all goes well, exhaust from a big rocket can do serious damage to things on the ground from just the acoustic energy (shock waves, vibration).
Proximity to transportation infrastructure. Your launch site needs to be well clear of anything a failed launch can damage, but still close enough to roads/rails/docks to be able to bring people and material to or from it in support of launch activities.
Beyond the political aspect of not being tied to any one nation, launching from the ocean offered a number of compelling advantages. For one, it was much safer should the rocket explode on the pad or fail shortly after liftoff. This was especially important given the somewhat spotty track record of the Zenit. It would also allow launches from near the Earth’s equator, which imparts greater tangential velocity on the vehicle during ascent and directly translates into increased payload capacity.
The initial boost provided by the Earth’s rotation can be approximated by taking the planet’s rotational speed at the equator and multiplying it by the cosine of the launch site’s latitude:
- Baikonur Cosmodrome - 320m/s
- Cape Canaveral - 408m/s
- Sea Launch - 460m/s
While the gains offered by equatorial sea launch might seem small compared to orbital velocity (roughly 28,000 km/h), the rocket equation is exceptionally unforgiving. Even a tiny reduction in the acceleration required to reach orbit allows more of the vehicle’s mass to be devoted to payload instead of propellant. Additionally, it means that payloads destined for equatorial orbits, such as geosynchronous communication satellites, don’t need to adjust their inclination after separation from the booster. This further reduces propellant requirements and gets the satellite into its final operational orbit faster, which results in a longer useful lifetime.
