2
$\begingroup$

For context, my story is quite far in the future(not sure quite how far), and space is quite developed at this point, so elevators are a thing that have been made, although only a few. Essentially, this country is located at a high latitude(I was thinking 50-60 degrees at the southernmost point), and wants to make its elevator, and for political reasons needs to build it in its territory. I know an elevator at such a high latitude is way harder to make than an equatorial elevator, but would it still be feasible? If not, is there anything else that can fill a similar role?

$\endgroup$
2
  • 1
    $\begingroup$ you would have to consider a lot more issues if you want to build it that way. Mainly because the earths spin and gravitational field is not going to be very kind to this kind of construction on a place that is not the equator. $\endgroup$ Commented Apr 14 at 14:04
  • $\begingroup$ Not only has this been asked before, it's been asked multiple times before with minor changes in perspective. [1], [2], [3] and others. It's worth searching the Stack before posting questions. $\endgroup$
    – JBH
    Commented Apr 14 at 19:16

3 Answers 3

3
$\begingroup$

You could have a Rotating Skyhook.

Imagine a tether with a hook on either end rotating end-over-end. For a special relationship between the rotation speed and the tether length, the hooks at the end will describe a cycloid. If you are flying in the upper atmosphere in the right direction, this would look like a hook on a vertical line coming down, then going back up again. Your craft might be travelling at 3 Km/s at a height of 100 Km. This is feasible with something like Skylon. And things would mostly balance out if you unhooked an equal mass coming down.

This could work in a non-equatorial orbit. The hooks stay above almost all of the atmosphere, so there is no need to match the velocity of the atmosphere.

$\endgroup$
1
$\begingroup$

Given the required phlebotinum cables (or stade chains), it is possible, with some caveats. Which might go against the original requirements.

In your country, gravity will pull downwards, but the centripetal force which ought to balance it, and is perpendicular to the rotation axis, will be directed at an angle equal to the latitude: 0° from the vertical at the Equator, but in your country it will be 60° from the vertical. So, the cable near Earth will be subject to its own weight, counterbalanced by the vertical component only of a "slanted" traction, and will bend. You can imagine it as being "lowered" axis-wards towards a point on the rotation axis at the same distance from the equatorial plane as the skyhook base: it will be deflected south, towards the center of the Earth.

The terminal will be subject to cable tension, centrifugal force and gravity, at three different angles. The "vertical" (axis-parallel) components will balance, keeping the terminal off from the equatorial plane. How much off, I couldn't say; the actual equation would need to take into account tension and weight of each elementary cable segment, dl/dt.

enter image description here

Depending on the cable's mass per unit length ratio, and the country's "height", you might have a sufficiently rigid cable bend gently enough to stay initially vertical-ish and still be inside the country's airspace all the way up to the Karman limit. But the elevator terminal will never be "straight above" the country (that would be the green line), it will be on a plane parallel to the equatorial plane that passes for the country, at a latitude lower than the base's. The far end will also need to be farther than an equatorial skyhook's to generate the extra tension.

enter image description here

The terminal, wherever you place it, will not be in a stable (geostationary) orbit, so it will need a launcher of some kind for payloads to reach orbit. This might not matter for vessels going somewhere else.

$\endgroup$
7
  • 1
    $\begingroup$ as far as i am concerned building a space elevator near the earths poles is a bad idea. From what i know a space elevator needs to be near the equator to balance out the entire infrastructure with the earths spin and some other things. Any structure near the north pole would be crushed and lead to disastrous consequences. @LSerni $\endgroup$ Commented Apr 14 at 14:00
  • $\begingroup$ I am a bit confused with the red line(cable) in your picture, as the end of that where an anchor would be also doesn't seem to be in a stable orbit. So how does that work? Or is there something I am missing? $\endgroup$
    – Bubbles
    Commented Apr 14 at 16:11
  • $\begingroup$ The depicted curvature is impossible. A non-equatorial elevator would connect to the ground at a steeper and steeper angle with increasing distance from the equator, becoming tangent at some point dependent on its tension. $\endgroup$ Commented Apr 14 at 16:20
  • 1
    $\begingroup$ Aside from what was mentioned, a space-elevator (well, a space zip line, at this altitude) that does not go directly up by scythes through the atmosphere at a shallow angle would do interesting and disastrous things to the atmosphere itself. $\endgroup$ Commented Apr 14 at 21:45
  • 1
    $\begingroup$ @Fallenspacerock you're right, of course. That was just to make an example. And anyway, a space elevator at the North Pole would have its base under water. $\endgroup$
    – LSerni
    Commented Apr 14 at 22:32
0
$\begingroup$

Not feasible.

Try by yourself spinning something with a wire at an angle other than 0 with respect to the centripetal force and experience failure.

You can only do it by using a rod, but at the lengths involved in a space elevator anything which doesn't crumble under its own weight is a wire.

$\endgroup$
2
  • 4
    $\begingroup$ While the counterweight does indeed have to be in the equatorial plane, the tether can be anchored just about anywhere. The cable will be slanted, of course. The theoretical limit is 81° latitude, because further north or south the geostationary orbit is below the horizon. True, the material properties of the cable become more and more outrageous the further away from the Equator the anchor point is, but that's not particulary relevant, because the cable anchoring a space elevator on Earth has to be made of unobtainium anyway. $\endgroup$
    – AlexP
    Commented Apr 14 at 9:16
  • $\begingroup$ @AlexP if you set a counterweight far enough, the extra tension should develop a force pulling the counterweight outwards from the equatorial plane, much like a weight spun at the end of a string at constant speed rises the more string is paid out. $\endgroup$
    – LSerni
    Commented Apr 14 at 22:48

Not the answer you're looking for? Browse other questions tagged .