Can’t you place a space elevator below or above the equator? The tether would leave the ground at an angle but it would be parallel to the centrifugal force from the planet’s spin.
In: Physics
You’ve gotten a lot of imperfect replies here, let’s see if I can do better or just add one more.
Think of the simplest and most commonly envisioned type of space elevator, from the perspective of the ground. I’m not talking about material, size, anything like that, but the direction. It goes straight up, and it always goes straight up. That means that the station/anchor of the elevator is always directly above the ground location. The only way that that can occur is on the equator.
The reason for this is that objects orbit the center of mass of an object. Take a ground location at around a latitude of 30 degrees (southern US). A point far above that location (space elevator anchors need to be very far away, a lot closer than the moon but way farther out than lower earth orbit) would be even more “north” than 30 degrees. Honestly it would probably be way higher than the Earth, but lets say that it was around 80 degrees. If this anchor was fixed there so that it was always straight above the ground at 30 degrees it would be making a big circle around the North Pole, nowhere near the center of mass of the Earth, that’s not an actual orbit.
For an actual orbit whatever the highest latitude the object passes over, it also needs to pass over the same exact value south of the equator, so a satellite that went as far North as 30 degrees would also have to go 30 degrees South.
That said perhaps the elevator doesn’t need to be going straight up. If the Anchor was still orbiting at the Equator (or very slightly below it technically, because our forces are about to be weird) then maybe it could attach to that point in the Southern US, but instead of the elevator going straight up it would only being going 60 degrees up, with a slope of 30 degrees to the South. The most extreme example of this would be an elevator at the poles, which would actually go out almost perfectly horizontally.
This has a couple ramifications though. First off your are spending a lot more time and distance in the Earth’s atmosphere, which isn’t great, that’s where the wind and weather that most of the hazard to a operating space elevator is. (I’m ignoring how the heck you’d build it, and assuming that at this point space has been mostly cleaned so that cutting the tether is a minimal risk, I feel like those need to be solved problems in order to even get to an operating space elevator).
Once again I’m not going to do the math (especially considering that this math is actually way more difficult) but I suspect that many examples of a system like this would be much less stable than a typical space elevator. For example if a normal space elevator would be expected to wiggle half a degree in any direction over the course of multiple orbits, the ground location of something like this may be expected to move a handful of degrees north and south, and a different handful of degrees east and west.
Another downside is that no point on the cable would be in a real orbit. With a typical space elevator you have an anchor way out past geostationary orbit, but the location at geosynchronous distance is at a real geostationary orbit point. This means it’s basically weightless, that means that the station can grow very, very large with minimal strain added to the cable there. That means that vehicles or cargo coming and going has very little effect on the cable. That also makes attaching to the station very easy, or at least a similar level of difficulty to docking with any other non-accelerating object in space.
None of that is true with an angled elevator, the non-symmetrical force from the tension of the ground point always pulling the system north means (I’m almost positive) that every single location on the cable on the way to the anchor is going to be under some sort of active acceleration, meaning that mass would indeed have weight. I’m sure at some point that acceleration would be very low, maybe even less than a percent of Earth gravity, but I’m pretty sure that (at least for something as far from the equator as 30 degrees) it would be orders of magnitude more than the microgravity you’d see on a “vertical” space elevator, and enough to be an issue in many ways.
It may be important to note that the challenges to building a Space Elevator on Earth are significantly larger than on many other bodies, because our gravitational well is so strong and our atmosphere is so dense. That means that scenarios like this that may have enormous challenges on top of the the already incredibly difficult task of making a vertical Earth space elevator, may have far less difficult ramifications on a body where space elevators are easier to handle. I suspect that humanity will create Space Elevators on the Moon, and then on Mars, many dozens of years before it’s ever done on Earth. Kevlar is plenty strong enough for a Lunar space elevator. Hell if someone wanted to spend dozens and dozens of billions of dollars I bet humanity could have a lunar space elevator within 20 years (I am not anticipating that happening, but my point is that nothing about a lunar space elevator seems to require any technology or materials that humans don’t have, and indeed have had for decades. It would “only” be one of the most difficult engineering challenges that humans have ever accomplished. (Maybe the hardest one, not really sure how you would rate the comparative engineering difficulty of that compared to, say, the Saturn V or the Large Hadron Collider, for example).
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