How far from the equator can a space elevator be built?

[The Disintegrator]

So with space elevators staying up based on centrifugal force, it's pretty well figured that the equator is the ideal location to build one. This puts places like Ecuador, Indonesia, and Kenya pretty high up on the list of places for a land based space elevator. But let's say that you're a country that's a bit of a ways from the equator, and for political and/or logistical reasons you're unable to set one up outside your borders. What I'm wondering is just how far from the equator can one be built and still be usable? For the purposes of the story I'm writing I'm specifically curious as to whether or not it's even possible to build a working space elevator at about 38 degrees. But any insight as to farther locations would be interesting since I'm sure places like Russia would eventually want in on space elevators.

Now in an interview with PBS' NOVA, physicist Brad Edwards is asked "Q: Would the space elevators have to be placed exactly on the equatorial line, like a satellite in a geosynchronous orbit, to maximize the centripetal force of the Earth's rotation to stiffen the elevator cable? Or would they work equally well anywhere on the surface of the Earth? What would be the "orbital physics 101" considerations here?"

To which he responds "The elevator can be placed anywhere within 20 degrees of the equator due to the dynamics, but the performance is best at the equator. As you get off the equator, the ribbon goes up at an angle and eventually is lying close to the ground and is unusable."

- http://www.pbs.org/wgbh/nova/space/edwa ... vator.html

This certainly sounds like a problem for countries that don't have access to territory outside their own borders, particularly if they're landlocked. As he mentions, the further off you go the more of an angle it goes up at. What kind of an angle would a space elevator built at the 38th parallel go up at, and can a space elevator be usable above or below 20 degrees? And assuming it isn't, which appears to be the case, does anyone have any ideas as to how this might be rectified? Or are space elevators going to be a game left solely for the states closest to the equator or good access to international waters?

[Borgholio]

There is no limit how far north you can build one, really. It is just a question of how long you have to make the cable so you get adequate centrifugal force to keep the thing in orbit. Even at the poles you can build one, but you'd have to make it absurdly long since you'd be depending on precession to swing it around and not the Earth's rotation

[Darth Tanner]

As said its still possible your just adding horribly to your costs... you could have it offshore however so if you want Norway to have a space elevator for instance just have Norwegian offshore platform or floating facility be the base that is moored up at the equator.

I think the general idea is that it should be a floating facility so you can move it around to avoid space junk ect.

[Simon_Jester]

This certainly sounds like a problem for countries that don't have access to territory outside their own borders, particularly if they're landlocked. As he mentions, the further off you go the more of an angle it goes up at. What kind of an angle would a space elevator built at the 38th parallel go up at...

38 degrees.

[Elheru Aran]

This certainly sounds like a problem for countries that don't have access to territory outside their own borders, particularly if they're landlocked. As he mentions, the further off you go the more of an angle it goes up at. What kind of an angle would a space elevator built at the 38th parallel go up at...

38 degrees.

Is that 38 degrees from the horizontal or from the vertical?

[phred]

This certainly sounds like a problem for countries that don't have access to territory outside their own borders, particularly if they're landlocked. As he mentions, the further off you go the more of an angle it goes up at. What kind of an angle would a space elevator built at the 38th parallel go up at...

38 degrees.

Is that 38 degrees from the horizontal or from the vertical?

I would assume vertical, but that's still quite a lean.

As a point of reference the Leaning Tower of Pisa only leans 3.9 degrees, and is a hell of a lot shorter.

[Elheru Aran]

I would assume vertical, but that's still quite a lean.

As a point of reference the Leaning Tower of Pisa only leans 3.9 degrees, and is a hell of a lot shorter.

If one assumes 'vertical' to be 90 degrees, with the horizon being from 0 to 180 degrees, then 38 degrees off is either 52 degrees or 128 (depends on which side of the equator your 38 degrees is at). That is definitely a pretty serious tilt and would be introducing quite some lateral forces as well as the straight up-and-down forces along the elevator.

It would basically look like a giant straight line going diagonally into the sky... be one heck of a scenic ride, though.

[The Disintegrator]

That's for the input everyone! Not sure which direction I'll take this in terms of writing, but it does give me a lot to think about.

[andrewgpaul]

I found this site a few years ago, which discusses non-equatorial beanstalks.

[Simon_Jester]

Is that 38 degrees from the horizontal or from the vertical?

From the vertical.

It's a straightforward exercise in geometry of similar triangles.

One thing about a space elevator is that it isn't resting on its own 'foundation' anchor point at the ground level. On the other hand, the further from the vertical you 'hang' it, the greater the tension force required to hold it up against its own weight gets, at least for the part that is close to the Earth's surface.

EDIT: The article linked above discusses this.