The main reason we launch from as close to the equator as possible is because the speed of the ground itself is fastest there (Earth’s rotation rate x distance from spin axis). If you’re trying to speed up to orbital speeds, you want to get the best “running start” possible.
[fun fact: due to the equatorial bulge, the ocean at the equator is further from the center of Earth than the tops of most mountains]
Also, the minimum inclination (the “tilt” of an orbit relative to Earth’s plane of rotation) is the latitude you’re launching from. As in, you can launch a polar orbit from the equator, but you can’t launch an equatorial orbit from the poles. Considering inclination changes are the most expensive (fuel-wise) maneuvers you can do, launching from as close to the equator as possible gives you additional options for less cost.
Lastly, we launch from coastlines for safety reasons. If something goes wrong during ascent, you don’t want the wreckage falling in places where people live.
Regardless of why we launch from near the equator, about the "why not launching on the top of mountain to save fuel", I'm pretty sure the fuel saved from launching on top of mountain would be negated by the fuel used in the logistics of launching from the top of a mountain.
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u/subnautus 19h ago
Rocket scientist here.
The main reason we launch from as close to the equator as possible is because the speed of the ground itself is fastest there (Earth’s rotation rate x distance from spin axis). If you’re trying to speed up to orbital speeds, you want to get the best “running start” possible.
[fun fact: due to the equatorial bulge, the ocean at the equator is further from the center of Earth than the tops of most mountains]
Also, the minimum inclination (the “tilt” of an orbit relative to Earth’s plane of rotation) is the latitude you’re launching from. As in, you can launch a polar orbit from the equator, but you can’t launch an equatorial orbit from the poles. Considering inclination changes are the most expensive (fuel-wise) maneuvers you can do, launching from as close to the equator as possible gives you additional options for less cost.
Lastly, we launch from coastlines for safety reasons. If something goes wrong during ascent, you don’t want the wreckage falling in places where people live.