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The concept of a space elevator unfortunately still seems like one confined to fiction, at least for now. However, I've heard some sources claim that carbon nanotubes could be the first material strong enough to construct one.

Is this the case, or are they still not strong enough? And if so, is the material the only real technological barrier to constructing such a structure, or are there other major issues that need to be overcome as well?

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(with considerable help from "Why we'll probably never build a space elevator")

You have laid out a good foundation, for the first, and largest challenge, namely the material for the cable itself. Carbon Nanbotubes are the best substance we know of to build a Space Elevator. In their purest form, they have a tensile strength of over 100 GPa. The exact number varies, but the general consensus is 130 GPa would result in a safe elevator. The next challenge beyond that is to build one that is the required length, and combine them into a workable cable, which isn't an easy task.

The second significant obstacle is how to keep the cable stable. It would vibrate with time, which could make managing the cable quite difficult. Add in space debris already in orbit (a ton), and it would be extremely challenging. Keeping the cable steady while climbing would take a considerable amount of time, perhaps up to a month for the trip to orbit.

Then there are the issues of where to build the space elevator, security, and other related issues. It's an extremely challenging problem.

There is some hope, principally in constructing an elevator at the Moon, Mars, or similar locations. In fact, one could be built around the Moon using technology easily available, and there are far fewer societal issues with that than would exist around the Earth. Around Earth would be quite difficult, at least, in the foreseeable future.

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  • $\begingroup$ Not to mention the risk of space debris. I think this is by bar the biggest barrier to the space elevator. Personally, I don't believe it's a viable technological idea at all. $\endgroup$ – Carl Dec 19 '13 at 10:49
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The technological barriers to building a space elevator are utterly dependent on the site selected. By this I mean which planet or moon you are "elevating" from. This is directly related to the mass of the body and its diameter.

So, building a terrestrial space elevator is probably several decades off - at least. But, the technologies exist today to build a lunar space elevator. Unlike a terrestrial space elevator, a lunar space elevator has much lower tensile strength requirements that are well within today's technologies limits.

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    $\begingroup$ Of course, a lunar space elevator also has much smaller advantages compared to rockets. $\endgroup$ – gerrit Mar 15 '17 at 8:54
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The issues at hand, at least tensile strength, can be lessened by building something else, which is also cool and sufficiently spacey. The Spaceshaft.

I mean, I like it, but again, what we're probably going to be looking at in the next ten years is more like a railgun launch. Sadly, There is quite a consensus that carbon nanotubes aren't strong enough, that the space debris is terrifying (I wonder why?), and that in general, it could unbalance the rotation of the earth(pfft, totally worth it)

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  • $\begingroup$ Because space debris could hit the elevator easily and a small impact would be enough to damage it, so you have to repair it at tremendous cost. A bit bigger impact and the whole structure could collapse. Where did you hear the unbalance of rotation thing? I never heard about it. (I'm really curious) $\endgroup$ – Bounce Dec 29 '15 at 12:47
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    $\begingroup$ I'm also very skeptical of the the bit about the rotation of the earth unbalancing without a source. A space elevator that was at all feasible would have an insignificant mass/angular momentum compared to the rest of the Earth. I would imagine that a single mountain has far more of an effect. While it's true that the space elevator would slightly shift Earth's center of rotation, so do a person who stands up. I can't imagine the effect would be noticeable or perhaps even measurable. $\endgroup$ – Shufflepants Oct 14 '16 at 15:39
  • $\begingroup$ @Shufflepants I honestly don't remember saying that. I suspect that what I meant was the consequences of changing the earth's center of balance. $\endgroup$ – jaked122 Oct 15 '16 at 19:05
  • $\begingroup$ @jaked122 And my point is that it will change it so slightly that it will be immeasurable to the point that it's not worth mentioning. The way you have it worded makes it sound like some great catastrophe; but compared with the actual affect it will have, you might have well said that driving a dump truck to the site where the elevator will be built will unbalance the rotation of the Earth. It's misleading. $\endgroup$ – Shufflepants Oct 17 '16 at 16:01
  • $\begingroup$ @Shufflepants I realize that now, but I wonder why I thought that back then. $\endgroup$ – jaked122 Oct 19 '16 at 19:33

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