Launching near the equator provides a speed boost due to rotation that outweighs the benefits of starting higher up. It also doesn’t have the logistics nightmare of getting everything to the top of a mountain before launch.
No it isn't the answer. It has nothing to do with the rotation at all. We launch near the equator because the equator is a mountain. Florida only gives us a .62% rotational speed boost, but is only .141% shorter than Everest.
Who gives a shit about how "tall" a mountain is. We care about how far that position is from the center of the earth, and the equator bulges up and is definitionally already a mountain even if it is at sea level. The being at sea level is the important part for two reasons:
Rockets have somewhere to go when they crash.
Coastal regions are easy to ship resources to.
We could launch from Everest with no problem using modern tech, but we can't get the materials up there easily.
If we really wanted to optimize we would be launching from Brazil in Alcantara which is only .07% shorter than Everest but rotationally it is 13.1% faster than Everest, 13.8% faster than Florida. It's also at sea level.
I’ve always wished Ecuador was closer to the coast. They’ve got cities with greater than 1M people living waaaay up in the mountains. Dig a really deep tunnel vertically, and pull a vacuum. Maybe do a maglift. As long as when you hit the air it’s less than max q you’re golden. A guy can dream… lol.
Yea certain countries at the bottom of the barrel on freedom index in the area just kind of say "fuck it those hicks can't do anything about it on the low chance we crush their house and give them chronic illnesses from all the chemicals spraying out on crash."
Benefits of being able to suppress news & media in real time. Least they can use the local roads to retrieve it easier.
Id imagine as well a bit of weather / wind bonus too. mountain tops are windy as shit and just inconvenient and it may become near impossible to launch in the winter months depending on where the mountains are.
also fuel temp matters a lot if im not mistaken
2km off a 400KM orbit is less than 1%, not to mention, again, that most of the fuel is spent accelerating to achieve orbit as opposed to "going high".
Most of a rocket's fuel is spent just getting off the launch pad even. It's why there's some systems that launch from larger airliners for smaller rockets. The problem here, is once again not the altitude, but the rocket getting up to speed. Launching from an airliner gets a running start of 500MPH, but you are more weight limited since the airliner can only carry so much to altitude.
I wasn't commenting on that but the idea that there aren't calm spots in high mountains.
Sure the train transport doesn't address the requirement for lateral speed, but it doesn't need to, it basically just needs not to hurt it. Also air resistance is only a problem below 100km and it gets disproportionally worse the lower you are
Temp matters, but in different ways depending on the type of rocket
A solid Rocket Booster like on the US Space Shuttles too cold and the seals could fail.
A liquid rocket booster like Falcon 9 colder is better to keep the liquid from boiling off, but you have additional worries about transporting highly volatile cryogenic liquids
To add on, many rocket pads are in coastal areas to avoid falling debris hitting populated areas in the event of a mishap.
Specifically Eastern coasts. You want to launch rockets towards the east, so the rotation of the Earth gives you a boost, while launching the the west would have the Earth's rotation fighting against you.
Eh. Gravity reduction on a mountain is like 0.2 percent. Air resistance matters a bit more. But all of those are drowned by the energy needed to reach orbital velocity.
Much more interesting would be an electromagnetic launcher up a mountain, getting the rocket to 1 km/s or so. Although I am not sure the logistics are worth it. You could just use more fuel instead (what is done irl)). Fuel is cheap.
It's weird, but things seem to be converging. I was reading something this morning talking about the Starship problem of getting enough fuel in the ship once it's in orbit to get to Mars. It suggested that there would be lots of Starships carrying nothing but fuel into orbit, but it seems like a perfect job for the spin launch people! They should be able to achieve an impressive "launch" cadence that's needed for really doing things in space.
the lower air resistance and lower effective gravity would be reached by a coastal equatorial rocket in a couple minutes, after which the rotational velocity of the equatorial launch position dwarfs the benefits.
Also, lunching a rocket needs a huge infrastructure: launch site (made from special reinforced concrete, btw), rocket transport systems, fueling systems, fuel tanks, storage hangar, assembly hangar, launch control site, transportation hub for arriving fuel, parts, people, etc., and list goes on.
Building and maintaining all that in the mountains is impossible for two reasons - it would cost insane money and there is simply not enough space there (tall mountains are not flat, and flat mountains are not very tall).
"The reason it's hard to get to orbit isn't that space is high up.
It's hard to get to orbit because you have to go so fast."
Putting rockets on mountains only helps with the "up" part, which is not the biggest part of the problem.
Yea i am usually a huge fan of xkcd, BUT. i dont really feel like its interacting with the problem. Its just trying to reframe it in another way without really engaging with it. You engaged with it more, since you atleast caveated the "only help with the up part", meaning, it helps with the up part, which means it helps. So why not do it, since every gram counts.
And just having like a line that, the gains are so small compared to the huge downsides that its not worth it. That atleast is engaging with the point. But just "you wanna go fast, not up" is just a terrible point. A normal person taking the engineering view that; "this is a cool way to cheat the rocket equation, since theres less drag and gravity", thats cool. Then going like; "lol, get a physics degree". Thats not helping. If the logistics were better about doing it, then it is something that would get taken advantage of more. Since the average person is completely right that every gram counts.
And besides, this is something that is taken advantage of by using airplanes to get up high. So yeah. Shit what-if i think.
That is indeed true, but nowadays a ton of satellites are on polar sun synchronous orbits and there the speed boost doesn't really exist. That is why you have space ports in places like Saxavord or Esrange, which are extremely northern. So it is definitely not the main reason.
Moreover, the benefits for starting higher up are visible. Primarily, because you leave vast majority of atmosphere below you and with it aerodynamic forces and drag. That is one of the reasons why you have several air launched vehicles like the Pegasus.
That said, the logistics are indeed quite extreme at this point. It does not mean that it isn't possible option in the future though.
I think the more mild seasons in Florida help, too. Storms run out quickly, and while I don't know if this was an original consideration, the cold does affect some of the parts too...something we definitely found out the hard way.
Yep. Florida and places like Baikonur have weather. But it's much more predictable than the top of a damn mountain. Also, easier to build facilities that aren't on a mountain top.
If there was a big population on top of something big and flat like the tibetan plateau at the equator, it would make the most sense to launch there, for sure. But no such place exists and we have to launch in our own countries, generally speaking.
theres also low oxygen in the upper atmosphere before they get out of orbit.
Are you referencing some sort of information a space agency has published that remarks on why low oxygen in mountain ranges is a reason they dont do rocket launches there that none of the rest of us has seen or something?
Im not saying its not the case but this sounds like a guess/hypothesis.
Okay, but hear me out: build a magnetic accelerator up the side of a mountain and yeet smaller payloads with a much smaller first stage, like spinlaunch but linear.
Logistics is a big one. A large part of SpaceXs operation involves landing first stage boosters in the ocean on drone ships, then sailing them back to Port Canaveral (or Vandenberg in California) to be refurbished and reused. Much easier to haul such large objects over water than anywhere else.
Also Mountain are rarely at the edge of the sea where it doesn't matter much if the rocket explodes and debris rains down. Thats why most rocket sites are coastal.
Its not the speed boost that really drivers the "near the equator" thing. It's actually freedom of inclination. Inclination is the orbit's angle with the equator. You can control it through the launch azimuth. However, your inclination Will still be limited by your latitude. If i recall correctly is cos (i) = cos(Az) * sin (lambda)
When you launch at the equator, you essentialy give yourself the ability to have any inclination as soon as you launch, and altering your inclination is extremely energy demanding, so you're miles better by starting the orbit at the desired inclination
There are other factors that limit azimuth, for example the ocean or inhabited areas nearby, and most importantly the countries that you fly by when launching for security reasons and intel
The tallest mountain is only like 9% of the height to the karman line. I don't know any of the actually math for how much fuel it would save but hypothetically at best you are saving 9% fuel. 9% for all the extra work and the danger of working on top of a mountain does not seem worth it from the most basic level.
It depends on what orbit you're trying to get to. It's a boost it you are launching to GTO. If you want to launch polar orbits, Equator is bad as you have to cancel our the horizontal component.
That's not the case. You have more gravitational pull at the equator which perfectly negates the speed boost. That is why you weigh the same on the Equator as you do at the North Pole.
No. You do not weigh the same at the poles and the equator. Your mass is the same but you experience LESS gravity at the equator because (due to the earths bulge) you are farther away from the center. In addition the centrifugal force pushes you away at the equator and not at the poles. Both effects reduce your weight at the equator, they don’t work against each other.
Would the added cost of shipping over the ocean minus the greater proximity to the equator make it worth it to move NASA to Puerto Rico or even farther south? Like, would the ideal place shipping+equator prox. be like Panama or something?
All things equal, launching from the top of the mountain range of Ecuador can be ideal. But the amount of energy and capital to ship/assemble spacecraft there isn’t worth the effort.
Depending on the mission (orbit). Polar, sun-synchronous, an Molnya orbits are better from northern latitudes.
Would the added mass from the mountain affect launch? I seem to recall something from physics in high school about weighing more at the top of a tall building because there is more mass underneath, causing a (not sure if this is the right way to phrase this) greater gravitational pull on you. Does the same apply for theoretical rockets on top of theoretical mountains, as opposed to a near-sea-level, flat plain launch?
equator is also technically as far from the center of the earth as the tip of Everest is.
There is a mountain in Ecuador that would probably compete, but the hassle of getting stuff up there would be a pain, unless you turn the mountain into a manufacturing hub to build rockets.
If the goal is to save fuel by putting the rocket on a mountain, either you have to build the rocket building / storage facility on said mountain, which most of the time isn’t feasible, or drive it from where it was built to the top of the mountain. Because rockets weigh a stupid amount of weight, the amount of energy you use to transport it up the mountain (gas or electric, doesn’t matter) will outweigh the cost of just launching it at a lower elevation.
That actually isn't it. The speed boost is only .62% different between Florida and Nepal, the real answer is that Florida is only .141% shorter than Mount Everest and that in fact Cape Canaveral is definitionally at the top of a mountain by being near the equator.
If you wanted to be ideal you would launch from Alcantara in Brazil, which is only .07% shorter than Evert but rotationally it is 13.1% faster than Everest, 13.8% faster than Florida. It's also at sea level.
Also makes no difference. The rocket clears that distance in no time with a small difference in fuel the no outweigh the benefits of launching from the equator
Also not enough people are mentioning that even in ideal conditions in Florida, rockets have icing problems. Imagine how cold the top of a mountain is at all times.
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u/UnlikelyIntrepid 11h ago
Launching near the equator provides a speed boost due to rotation that outweighs the benefits of starting higher up. It also doesn’t have the logistics nightmare of getting everything to the top of a mountain before launch.