# Scientist Says Space Elevator Running 15 Years **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [June 26, 2004, 4:54pm UTC](https://boards.straightdope.com/t/scientist-says-space-elevator-running-15-years/252328 "2004-06-26T16:54:11Z")\ **Posts on this page:** 15\ **Page:** 4
**Author:** ![Exgineer](https://avatars.discourse-cdn.com/v4/letter/e/a88e4f/32.png) [@Exgineer](https://boards.straightdope.com/u/Exgineer)\ **Post date:** [June 30, 2004, 1:43pm UTC](https://boards.straightdope.com/t/scientist-says-space-elevator-running-15-years/252328/61 "2004-06-30T13:43:32Z")
> [@Gest](#): > > I’m not sure about the physics of it either. Whether it would necessarily change the orbit of the station at the top of the cable or not (which would necessitate the release of more cable) I don’t know. I do know that much of this stuff is counterintuitive to someone used to gravity and so a physicist would be of more help. Orbital mechanics isn’t that complicated. Changing the orbit of the high station is not an option. It has to be where it is for the thing to work at all and it can’t be moved, even if moving it were a trivial matter to begin with, which it isn’t. For similar reasons the ground station must remain stationary as well. Even if you could move it without boffing everything up tidal forces would tend to stabilize the thing. The whole article just reeks of BS. ---
**Author:** ![Sam\_Stone](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Sam\_Stone](https://boards.straightdope.com/u/Sam_Stone)\ **Post date:** [June 30, 2004, 2:55pm UTC](https://boards.straightdope.com/t/scientist-says-space-elevator-running-15-years/252328/62 "2004-06-30T14:55:30Z")
You’re not going to move this thing out of the way of storm. Isn’t going to happen. This thing will make an oil platform look tiny, and you don’t see those things moving out of the way of storms. Plus, if you moved the bottom part, if would cause the entire structure to oscillate. And we’re not talking about moving it a mile or so - if you’re going to dodge storms, you’d better be ready to move it hundreds of miles. Not going to happen. But I think this is a misplaced concern. If a lousy atmospheric storm can hurt this thing, it’s useless anyway. The forces acting on it will positively dwarf the forces a storm could put on it. Remember, storms exist only in about the bottom 30,000 feet of the atmosphere, which is a very, very tiny portion of the elevator. Besides, it’s going to have to have to survive constant winds as high as a powerful storm anyway, because it will penetrate through the jet stream. But look at all the handwaving still going on here. What about oscillations? “We’ll need some kind of active damping system.” Think about that. An active damping system that is going to smooth out oscillations in a structure 60,000 miles long? We haven’t even begun to consider how to build something like that. That alone could take far more than 10 billion dollars and 15 years to figure out. I don’t think a space elevator is impossible. I just think it requires SO MANY new engineering practices that the estimate of 15 years/10 billion dollars is insane. If I had to guess, I’d say more like 75 years, and 200 billion. For comparison, the English Channel tunnel cost $21 billion and took six years to build. And that’s in 1988 dollars. Does anyone think this project would be _smaller_? ---
**Author:** ![Epimetheus](https://avatars.discourse-cdn.com/v4/letter/e/c4cdca/32.png) [@Epimetheus](https://boards.straightdope.com/u/Epimetheus)\ **Post date:** [June 30, 2004, 3:21pm UTC](https://boards.straightdope.com/t/scientist-says-space-elevator-running-15-years/252328/63 "2004-06-30T15:21:14Z")
I don’t think it will happen anytime soon either. I think 50 years is way too optimistic. I do think it is possible mind you, just not very probable. I would LOVE to see something like this happen, I am a space geek at heart, but at some point one has to admit that reason should trump fantasy and hopefullness. Personally I don’t see us doing much in space for the next century or two. That is an IMHO of course. Of course, I consider that within my lifetime. 😃 ---
**Author:** ![Ale](https://avatars.discourse-cdn.com/v4/letter/a/f19dbf/32.png) [@Ale](https://boards.straightdope.com/u/Ale)\ **Post date:** [June 30, 2004, 4:16pm UTC](https://boards.straightdope.com/t/scientist-says-space-elevator-running-15-years/252328/64 "2004-06-30T16:16:34Z")
> [@Gest](#): > > I can imagine it. What are you basing your _at best_ guess on? How fast can aircraft carriers move? Most of my objections to nuclear power would be eliminated with the cheap, safe disposal option presented by a space elevator. Particularly since the waste wouldn’t need to be shipped long distances to the platform. Meet the [Troll A](http://www.shell.com/home/Framework?siteId=no-no&FC1=&FC2=%2FLeftHandNav%3FLeftNavState%3D10%2C8%2C2&FC3=%2Fno-no%2Fhtml%2Fiwgen%2Fundersokelseproduks%2Ftrollgassutbyggingen%2Fphotoarchive%2Ftrollontowoverview_10101036.html&FC4=&FC5=) Follow the link at the bottom for some facts about it´s towing: > [@](#): > > **Ten of the world’s largest and most advanced tugs towed the huge Troll platform** from its construction site at Vats in Nord-Rogaland to the Troll field (174 kilometres of which 34 nautical miles were inshore) Eight of the vessels towed the platform while two vessels were situated to sheer the tow. Each vessel had a bollard pull of 150-200 tons, and approx. 13,00 hp, a total of approx.130,000 hp. > [@](#): > > **The average speed under tow was 1 knot.** And they didn´t have to worry about pulling a 60.000 mile long and an orbiting counterweight along with it… :dubious: ---
**Author:** ![Diceman](https://avatars.discourse-cdn.com/v4/letter/d/22d042/32.png) [@Diceman](https://boards.straightdope.com/u/Diceman)\ **Post date:** [June 30, 2004, 4:54pm UTC](https://boards.straightdope.com/t/scientist-says-space-elevator-running-15-years/252328/65 "2004-06-30T16:54:47Z")
Getting back the question of what happens if the cable breaks: I did a quick and highly simplified force balance on the cable, and I figure that if the cable broke at or near the base, it would accelerate upward at about 30x the force of gravity. Also, considering how long this cable would be, I suspect that its mass would dwarf the mass of the space station at the top. So if the cable broke at or near the top, the space station would be doomed, but the cable might stay up thru its own centrifugal force. They could try to build another station, or just cut the cable loose. But no way in hell are we going to do anything like this in the next few decades. Maybe in the 22nd century, but not in the 2010’s. ---
**Author:** ![Exgineer](https://avatars.discourse-cdn.com/v4/letter/e/a88e4f/32.png) [@Exgineer](https://boards.straightdope.com/u/Exgineer)\ **Post date:** [June 30, 2004, 5:14pm UTC](https://boards.straightdope.com/t/scientist-says-space-elevator-running-15-years/252328/66 "2004-06-30T17:14:46Z")
We need to stop speculating, especially since that article was conspiculously short of facts. I’ve seen a few schemes for something like this, and they’re all impractical. The most common one involves parking a mucking huge asteriod at geostationary orbit for the top anchor and suspending the station “under” it, along the cable. There’s also some sort of “counterweight” attached to the outward side of the asteroid to balance the cable. > [@Diceman](#): > > Also, considering how long this cable would be, I suspect that its mass would dwarf the mass of the space station at the top. So if the cable broke at or near the top, the space station would be doomed, but the cable might stay up thru its own centrifugal force. They could try to build another station, or just cut the cable loose. The station might survive, but that cable is coming down. It has to. Nowhere along its length is it going fast enough to maintain orbit. “Centrifugal force” isn’t exactly the right concept here, so it’s difficult to explain in those terms. I’m more comfortable thinking in terms of energy. ---
**Author:** ![spingears](https://avatars.discourse-cdn.com/v4/letter/s/ebca7d/32.png) [@spingears](https://boards.straightdope.com/u/spingears)\ **Post date:** [June 30, 2004, 8:12pm UTC](https://boards.straightdope.com/t/scientist-says-space-elevator-running-15-years/252328/67 "2004-06-30T20:12:03Z")
To provide a solid footing for the space elevator the bottom end should be stuck in the “Mohole.” Hopefully the Mohole will be ready by then too. ---
**Author:** ![msmith537](https://avatars.discourse-cdn.com/v4/letter/m/d9b06d/32.png) [@msmith537](https://boards.straightdope.com/u/msmith537)\ **Post date:** [June 30, 2004, 8:37pm UTC](https://boards.straightdope.com/t/scientist-says-space-elevator-running-15-years/252328/68 "2004-06-30T20:37:09Z")
> [@Gest](#): > > You know how difficult it is to build a terrestrial skyskraper? > > Not a clue. The answer is “very”. Although it would probably be more similar to a suspension bridge than a skyscraper in terms of construction. Someone explain again how this would be built? A satelite or shuttle or something is placed in geosyncronous orbit, right? And then cables are played out at either end until the Earth-sided one hits the ground and then they tie it off? The question I have is what happens as the end is lowered? To reach a lower orbit, the end of the cable has to somehow decelerate to a lower orbital speed than the platform, doesn’t it? And how do they catch it at the bottom? I can imagine several miles of atmospheric winds would make the end whip around pretty badly, not to mention sending oscillations up the length of the cable. ---
**Author:** ![Tuckerfan](https://avatars.discourse-cdn.com/v4/letter/t/eada6e/32.png) [@Tuckerfan](https://boards.straightdope.com/u/Tuckerfan)\ **Post date:** [June 30, 2004, 9:20pm UTC](https://boards.straightdope.com/t/scientist-says-space-elevator-running-15-years/252328/69 "2004-06-30T21:20:57Z")
> [@msmith537](#): > > Someone explain again how this would be built? A satelite or shuttle or something is placed in geosyncronous orbit, right? And then cables are played out at either end until the Earth-sided one hits the ground and then they tie it off? > > The question I have is what happens as the end is lowered? To reach a lower orbit, the end of the cable has to somehow decelerate to a lower orbital speed than the platform, doesn’t it? And how do they catch it at the bottom? I can imagine several miles of atmospheric winds would make the end whip around pretty badly, not to mention sending oscillations up the length of the cable. You’ve pretty much got it. The only addition I’ve seen is that when the cable gets down low in the atmosphere, a helicopter hooks up to it, and brings it all the way down. (I’ll note that NASA’s planning on doing something similar with a returning space probe.) [Here’s](http://www.guardian.co.uk/international/story/0,3604,1041210,00.html) [every](http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=169721) [single](http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=212089) [bloody](http://www.isr.us/SEHome.asp) [link](http://boards.straightdope.com/sdmb/showthread.php?t=166286) on space elevators that I have, which haven’t been posted as of yet in this thread. ---
**Author:** ![Exgineer](https://avatars.discourse-cdn.com/v4/letter/e/a88e4f/32.png) [@Exgineer](https://boards.straightdope.com/u/Exgineer)\ **Post date:** [June 30, 2004, 9:42pm UTC](https://boards.straightdope.com/t/scientist-says-space-elevator-running-15-years/252328/70 "2004-06-30T21:42:58Z")
I’m still boggled by the idea that the response to impact hazards from orbital debris is “we’ll just move it out of the way.” ---
**Author:** ![Ale](https://avatars.discourse-cdn.com/v4/letter/a/f19dbf/32.png) [@Ale](https://boards.straightdope.com/u/Ale)\ **Post date:** [July 1, 2004, 12:52am UTC](https://boards.straightdope.com/t/scientist-says-space-elevator-running-15-years/252328/71 "2004-07-01T00:52:31Z")
> [@Exgineer](#): > > I’m still boggled by the idea that the response to impact hazards from orbital debris is “we’ll just move it out of the way.” Forget about carbon nanotubes, what we need is fairy-dust. 😃 ---
**Author:** ![Loopydude](https://avatars.discourse-cdn.com/v4/letter/l/e56c9b/32.png) [@Loopydude](https://boards.straightdope.com/u/Loopydude)\ **Post date:** [July 1, 2004, 1:11am UTC](https://boards.straightdope.com/t/scientist-says-space-elevator-running-15-years/252328/72 "2004-07-01T01:11:09Z")
I’ve read a lot about this lately, and it appears to be not as nuts as one might think. Seems to me the only really major stumbling block is the elevator cable itself. It’s one thing to say “Let’s spin out 62,000 miles of ribbon with these properties” and quite another indeed to actually manufacture such a thing. The fact is, nothing with the needed tensile strength over the needed length exists, and untill it does, all bets are off. Nanotubes would work, but they need to be something like a meter long apiece, and must be produced under those specifications with vast yields to provide a ribbon that long with something like the needed 50% nanotube content. I’m guessing we won’t be seeing buckytube factories churning out carbon nanofibers by the kiloton for quite some time. The best in the field can barely get them over a cm or so, and the best prototype specimine of ribbon I’ve read about is about 1% nanotube (each of much shorter length per tube than necessary). The chemists have a long way to go. But once we have the ribbon, sure, why not? Nothing in the laws of physics forbids it at all. In fact, most of the needed technology we already have. Hell, if we can build such a thing, we can probably take care of some of the orbital debris too, if we put our minds to it. Orbital cleanup has already been proposed, and it would be of benefit elevator or no elevator. Spacejunk is a menace to what’s already up there, and it’s getting so prolific it’s a serious concern to operating orbital spacecraft as it is. Someday we’re going to have to confront the orbital debris issue head-on. It’s a good idea. But I’m not holding my breath, that’s for sure. Fifty years from now, minimum. ---
**Author:** ![Tuckerfan](https://avatars.discourse-cdn.com/v4/letter/t/eada6e/32.png) [@Tuckerfan](https://boards.straightdope.com/u/Tuckerfan)\ **Post date:** [July 1, 2004, 1:20am UTC](https://boards.straightdope.com/t/scientist-says-space-elevator-running-15-years/252328/73 "2004-07-01T01:20:20Z")
> [@Loopydude](#): > > Seems to me the only really major stumbling block is the elevator cable itself. It’s one thing to say “Let’s spin out 62,000 miles of ribbon with these properties” and quite another indeed to actually manufacture such a thing. The fact is, nothing with the needed tensile strength over the needed length exists, and untill it does, all bets are off. Nanotubes would work, but they need to be something like a meter long apiece, and must be produced under those specifications with vast yields to provide a ribbon that long with something like the needed 50% nanotube content. I’m guessing we won’t be seeing buckytube factories churning out carbon nanofibers by the kiloton for quite some time. The best in the field can barely get them over a cm or so, and the best prototype specimine of ribbon I’ve read about is about 1% nanotube (each of much shorter length per tube than necessary). The chemists have a long way to go. Not that long, did you miss my post on the previous page which linked to the article where the researchers had managed to get a 100 meter nanotube thread? [Here’s the link in case you missed it.](http://www.newscientist.com/news/news.jsp?id=ns99994769) ---
**Author:** ![Gest](https://avatars.discourse-cdn.com/v4/letter/g/9d8465/32.png) [@Gest](https://boards.straightdope.com/u/Gest)\ **Post date:** [July 1, 2004, 1:25am UTC](https://boards.straightdope.com/t/scientist-says-space-elevator-running-15-years/252328/74 "2004-07-01T01:25:13Z")
> [@Exgineer](#): > > I’m still boggled by the idea that the response to impact hazards from orbital debris is “we’ll just move it out of the way.” I, perhaps naively :D, only suggested that for moving out of the way of storm systems. Different strategies would be necessary for the debris at higher altitudes which has already possibly caused trouble for things like Mir. ---
**Author:** ![Wearia](https://avatars.discourse-cdn.com/v4/letter/w/13edae/32.png) [@Wearia](https://boards.straightdope.com/u/Wearia)\ **Post date:** [July 1, 2004, 3:36am UTC](https://boards.straightdope.com/t/scientist-says-space-elevator-running-15-years/252328/75 "2004-07-01T03:36:40Z")
Even if the space elevator proves to be impossible there is one aspect of it that will still be world changing. And that of course is the nanotubes. Maybe we’ll find that a 62,000 mile cord of these things will only be possible in another 50 years. But the process for manufacturing small amounts of those things has limitless applications. [Previous page](https://boards.straightdope.com/t/scientist-says-space-elevator-running-15-years/252328.md?page=3)