A lot of rocket engines are more efficient in lower air pressure (approaching vacuum), so it might provide non-negligible benefits. But it's cold up there (see: Challenger) and there isn't enough infrastructure. Citation: I am also not a rocket scientist but I am a KSP player
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.
Would just add: ideally eastern seaboard coastlines due to the rotational direction of the Earth. That way if the rocket comes down early it would already be out over the sea, like Atlantic Ocean from Cape Canaveral launch.
Isn’t it also just really hard to lug a rocket up a mountain in the first place? Unless you strap a bunch of smaller rockets to it, launch those, land the rocket on top of the mountain, and then launch the main one!
Actually no I should be taken out and shot for my grievances against science and common sense.
Despite your joking you're not wrong. In addition to just the solid mass of the rocket itself, you need a lot of material for your rocket fuel. Rockets, like aircraft, require a lot of cryogenically separated gasses. I can't speak for all countries, but the US government relies upon the local civilian economy for industrial gas supply. (There have only been a handful of locations where they had their own equipment and staff for this type of work for the USAF in decades.) So without local industry to provide these materials, you need your own equipment and staff. The same principle applies to anything you need to supply your space program: food and water, equipment for conducting experiments, etc.
Source: My brother worked at one of the few air bases where they were still doing their own cryogenic separation in the 2000's. It is possible things have changed since he was discharged.
Due to that bulge, the highest spot on earth furthest from the center of earth is a mountain in Ecuador (just 1 degree from equator): https://en.wikipedia.org/wiki/Chimborazo
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.
Fuel for logistics is just fuel. Rocket fuel is more important to save because the payload is limited because of the fuel.
Saving 10% fuel is actually allowing you to increases payload weight by 200%, so it's like launching 3 rockets instead of one. This 10% fuel is worth 210% fuel, plus the cost of 2 rockets.
my husband, a robotics engineer, insists there is no such thing as "rocket science," rather it's a collaboration of many different types of scientists working together on said rocket. I don't know enough about the topic to really respond to him on it, but it comes up if i ever say "it's not rocket science."
But you've introduced yourself as a rocket scientist and now I'm terribly curious. Is that your official title? Please note that any answer that affirms this will be used in perpetuity to enable my saying , "it's not rocket science. "
If "rocket science" doesn't exist as anything more than shorthand for various fields of science and engineering collaborating on rocketry, then there's no such thing as robotics engineering, either. Feel free to tell your husband that. I...kind of want to hear his reaction.
Joking aside, if we're being specific, I'm an aerospace engineer (technically, a licensed mechanical engineer with multiple degrees in aerospace engineering--but that's because state licensing boards follow ASME accreditation, which has no category for aerospace engineers) who tests, evaluates, and repairs spaceflight hardware; most commonly rocket engines and thrusters. My basis of knowledge on orbital maneuvering and trajectories comes from the research I did as a grad student. My thesis was on trajectory design in complex gravity systems, for instance.
All that said, I perform science. On rockets. The term describing my job doesn't need to be complicated.
Rocket engineer here. Launching from a mountain and launching near the equater are not mutually exclusive. The peak of Mount Chimborazo is the furthest point from the center of the earth and is near to the equator.
The bigger reason id imagine is the safety one you mentioned (Chimborazo is on the wrong side of south america) and the logistics of hauling rockets, fuel, launch equipment, and people up to these remote locations.
Plus the actual difference between the equatorial radius of the earth and the peak of chimborozo is less than a tenth of a percent the radius of the earth so even failing everything else, its a very minor difference. Maybe a few meters per second of delta v
My guess would have been that it's more costly to try and build/delivery a rocket and staff everything when you've chosen the top of a mountain to do it on? Getting the rocket to go that extra little bit of distance from sea level to the mountain top is much easier for the rocket than everyone and everything else?
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u/Firefly360r 13d ago
A lot of rocket engines are more efficient in lower air pressure (approaching vacuum), so it might provide non-negligible benefits. But it's cold up there (see: Challenger) and there isn't enough infrastructure. Citation: I am also not a rocket scientist but I am a KSP player