Building A Space Elevator

Okay, so I've been doing some digging, and I've found some papers that propose the construction of a non-equatorial space elevator may be possible. Now I'm not exactly fluent in physics or engineering, so I'd really appreciate it if someone could tell me if this is legit or not and how it works in a nutshell.

Upon reading your post, I immediately thought of a two-foundation elevator, going up, then meeting somewhere, then continuing upwards as a single strand, which I think might be legit physics, and a quick glance at the page you link to suggests to me that the writer is onto something similar.

So, it's probably okay, unless you want to write extremely hard science fiction. Then you ought to research further.

But as the web page implies, it's non-trivial to do it like that.

Building an equatorial space elevator is already terribly difficult. Clarke had to move Sri Lanka about a thousand kilometers(!), as I recall, in order to satisfy his own need for plausibility.

Just to pull an arbitrary number out of my ass, it might be 10 times harder to do a non-equatorial elevator compared to an equatorial one. That is (warning: more arbitrary numbers coming your way), it might be 60 years and 80 trillion euros instead of 30 years and 8 trillion euros.

I always thought the biggest problem with a Space Elevator wasn't the cost but rather that pretty much none of the industrial grade materials we have available can build one right now. The thing would be too heavy and unstable regardless of where it is located.

Carbon nanotubes were proposed, maybe a couple of decades ago, as a potential material for a space elevator.

edited 24th Sep '13 6:39:13 AM by Peter34

Graphite sheets would work too,(possibly rolled togheter like a [1]?). But space elevators have two problems. 1, Making a tether long enough out of these materials and get it up there. 2, there is a bunch of other alternatives, like hypersonic skyhooks/rotovators.

^ I'm quite partial to mass drivers like they have in the various Gundam continuities.

Why do you want a non-equatorial space elevator in the first place?

Because his City of the Future is in Japan, near Tokyo.

It's possible, given a good material. Carbon nanotubes, as stated before, has been the go-to science fiction material because of its high theoretical strength.

The cost is somewhere between 10 billion to 100 billion dollars. (USD, 2013)

The first space elevator would be built using typical rockets or space shuttles to carry payloads of single strands plus a small counterweight to be dropped down to the surface from orbit. The first space elevator will be around 10x the cost of any subsequent space elevator (since the first can be used to build the next ones). Basically, the counterweight floats in geosynchronous orbit and you hang down a strand to the surface. You attach it to a ground based (likely in the ocean) facility. Then you send a few more rockets up there to get the cable thick enough for a small elevator. Then you use the elevator to ship up more material to the top and slowly build your space elevator.

So, in short, space elevator is possible given our current understanding. We just don't have a material strong enough right now.

edited 24th Sep '13 12:01:38 AM by breadloaf

m8e, do you mean graphite or graphene?

Well both, Graphene is a single layer of Graphite.

Close, but no cigar (also, UQ Holder would have also sufficed in that joke). I need to know if space elevators could be built around major geopolitical capitals in the future, like near Russia and Japan, possibly Australia (Russia and its allies in East Asia have kind of risen as a superpower due to their growing monopoly on farming and food production thanks to climate change). Also, now I really want to use those mass drivers for something, but I'm not sure what now that I've already introduced space elevators as the primary mode of transportation into orbit...

edited 24th Sep '13 8:42:51 AM by KSPAM

It seems to me that it would be logical for the expense, and time and engneering difficulty, to increase enormously, the further you get from the equator. 3 degrees, kinda sucks, 10 degrees, ouch, 20 degrees, massive pain, and so forth.

But a Space Elevator at the axial poles would suddenly invert the cost. Relative to the Earth it no longer moves at any altitude thus making the engineering extremely simple.

My main question is, ignoring any costs or other limitations like a lack of resources or a strong enough material, is it actually physically possible (as in, do the laws of physics allow it) to build a space elevator anywhere other than the poles or the equator? The technical details don't matter (but they are appreciated), I just want to know if it's possible.

To the best of my knowledge: yes.

Isnt the counterweight effectively in orbit? How would that work anywhere except at the equator?

You adapt to the different angular velocities by putting the counterweight higher or lower. At 45 degrees north the velocity differential would be maximum compared to the poles or equator so you'd make the elevator shorter. At the pole you could make it the maximum length.

Alternative space elevator designs basically have them of the giant TV tower type where the support wires/beams/tethers/etc are anchored 100 km away from the actual tower. There's no real upper limit save the size of the Earth to build one that way. Plus it can be built at any latitude. The reason that's not usually considered is because the counterweight design floats away (like in Halo ODST) if the elevator suffers catastrophic failure meaning the damage from the resultant severing is limited. Imagine the damage if the TV tower design goes "Timber!" and it's 1000 km tall, it's a lot more than if the thing were a floating counterweight.

edited 24th Sep '13 11:47:11 PM by MajorTom

Yeah, it's physically possible to build it at non-equatorial locations. It's just... not intelligent to do so. You might want to have to point that out that someone is being real dick-ish to have caused such a situation to occur.

Also, building a tower of babel is way harder than a counterweight design space elevator. For one thing, you'll need much stronger materials.

edited 25th Sep '13 2:16:45 AM by breadloaf

So such design requires a tower that is structurally strong enough to support its own not-trivial mass (and the mass of the payload and the mass of the "station" at the top) without collapsing?

Compared with, say, an equatorial "skyhook" that relies on a geosynchronous space station in orbit (that holds itself up there by virtue of the fact it is maintaining orbital velocity around the Earth) from which is lowered a cable that need only be strong enough to not snap under the combined mass of itself and the payload. (with, of course, another cable payed out further into space on which there is a counterweight to compensate for the upward/downward motion of the payload).

Personally, I can see them overcoming the structural problems of a "strong enough cable" before those of "a strong-enough rigid structure".

edited 25th Sep '13 2:43:49 AM by Wolf1066

Damage wouldn't be so severe should the TV tower model collapse. I mean unless it's orders of magnitude more massive than it's counterweight counterpart (heh) it should just burn up in the atmosphere, no?

But... there is no stable orbit that remains at one specific latitude. What am I missing?

I'm gathering from the "TV Tower" analogy that the top is not in a stable orbit, it's merely supported by the strength of the rigid tower below it.

Which to me seems a major problem. A satellite in a stable orbit "holds itself up", so the "elevator" need only be a flexible cable - and even then it's going to have to be stronger than anything we're currently making just to support its own weight and the weight of the car/gondola - as its top end is anchored on a stable orbital platform.

A "TV Tower" would have to be strong and rigid enough to withstand a vast number of stresses beyond those that the flexible cable must withstand. It must be rigid enough to remain vertical without a distant point on which to anchor. It must support its own weight and the weight of a space station.

And it's anyone's guess how an orbiting space craft is supposed to dock with such a thing...

Assuming the tower reached up to geostationary altitude (yeah, I know), a spacecraft could simply put itself into a suitably inclined orbit and intercept it.

Er, no. The tower would be tracing out a path around the planet that does not correspond to any orbital trajectory.