# Building a space elevator would stimulate the economy **URL:** \ **Category:** Great Debates\ **Created:** [March 4, 2009, 6:13pm UTC](https://boards.straightdope.com/t/building-a-space-elevator-would-stimulate-the-economy/488299 "2009-03-04T18:13:56Z")\ **Posts on this page:** 20\ **Page:** 4
**Author:** ![Tenebras](https://avatars.discourse-cdn.com/v4/letter/t/977dab/32.png) [@Tenebras](https://boards.straightdope.com/u/Tenebras)\ **Post date:** [March 6, 2009, 2:58am UTC](https://boards.straightdope.com/t/building-a-space-elevator-would-stimulate-the-economy/488299/61 "2009-03-06T02:58:45Z")
> [@Chronos](#): > > I don’t think that “unstable” means what you think it means. Most orbits are _not_ unstable, unless you’re talking about things like gravitational radiation which would take longer than the lifetime of the Universe to bring a satellite down. Unstable does not mean that there are perturbations on the orbit; there’s perturbations on everything. The question of stability is how a system responds to those perturbations. If a system is unstable, then the perturbations will grow exponentially; if it’s stable, then the perturbations will be damped out or reversed. Geosynchronous orbits are stable, which means that the effects of the perturbations will not be significantly larger than the perturbations themselves, which is to say small. A space elevator is even more stable than a standard geosynchronous orbit, since it’s further stabilized by being anchored to the Earth at the bottom. Yeah, that’s what I meant.\* The problem with geosyncronous orbits is that once perturbed, they are no longer geosynchronous. Not a big deal if you’re a free floating satellite because if you get a bit off from where you’re supposed to be, you fire up the main thrusters and you cruise on back to where you oughta be. (more or less) If you anchor the elevator to the ground and then it starts drifting, you’re going to have serious problems, because the ground isn’t drifting, too. Even the people who think the space elevator is possible recognize that you have to be very careful about maintaining the orbit, they just handwave away the difficulty of moving a ginormous diamond ribbon back where you want it to be. - I’m actually teaching Differential Equations this semester. I know that internet appeals to authority are not worth the paper they’re printed on, but I feel like it’s worth pointing out. I started reading about this stuff because I thought it might be a fun project for my students to work out the details of how a space elevator would work. Unfortunately, most of the equations don’t have elementary solutions, so I think it’s a project better suited to a numerical methods class. I’m still planning to use this as an “interesting real world example” though. ---
**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\ **Post date:** [March 6, 2009, 3:02am UTC](https://boards.straightdope.com/t/building-a-space-elevator-would-stimulate-the-economy/488299/62 "2009-03-06T03:02:15Z")
> [@Tenebras](#): > > Unfortunately, most of the equations don’t have elementary solutions, so I think it’s a project better suited to a numerical methods class. I’m still planning to use this as an “interesting \*\*real world \*\*example” though. [/SIZE] Given your recent posts I just love irony of that part. You work in academia dont you ?🙂 ---
**Author:** ![Tenebras](https://avatars.discourse-cdn.com/v4/letter/t/977dab/32.png) [@Tenebras](https://boards.straightdope.com/u/Tenebras)\ **Post date:** [March 6, 2009, 3:20am UTC](https://boards.straightdope.com/t/building-a-space-elevator-would-stimulate-the-economy/488299/63 "2009-03-06T03:20:10Z")
Also, because the Earth is flattened in the polar direction, if the inclination of an orbit is not exactly 0, it will drift. Then there’s also the issue of the ellipticity of the equator and… yeah. Not going to get into it. But the upshot is, you can’t just hang a ribbon off the actual Earth and expect it to stay put without giving it little pushes. ---
**Author:** ![Tenebras](https://avatars.discourse-cdn.com/v4/letter/t/977dab/32.png) [@Tenebras](https://boards.straightdope.com/u/Tenebras)\ **Post date:** [March 6, 2009, 4:19am UTC](https://boards.straightdope.com/t/building-a-space-elevator-would-stimulate-the-economy/488299/64 "2009-03-06T04:19:22Z")
> [@billfish678](#): > > Given your recent posts I just love irony of that part. For certain values of real world. > [@](#): > > You work in academia dont you ?🙂 Does it show? ---
**Author:** ![Sage\_Rat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sage_rat/32/399_2.png) [@Sage\_Rat](https://boards.straightdope.com/u/Sage_Rat)\ **Post date:** [March 6, 2009, 5:00am UTC](https://boards.straightdope.com/t/building-a-space-elevator-would-stimulate-the-economy/488299/65 "2009-03-06T05:00:22Z")
To add some economic talk to this discussion, I’ll just note that a space elevator or space fountain would likely be a poor means of stimulus. 1. It could spend a decade just in planning. Economic stimuli are things that effect the economy _now_, not ten years from now. 2. A “good” economy is one in which there is **growth**. The way you create growth is by figuring out some project that, if completed, will earn more money than it cost to make within a short enough period of time to be worthwhile (i.e. before you go bankrupt.) Some infrastructure programs can help to improve trade and so, even though there is no toll to use the infrastructure, the money spent on the infrastructure is made back via the increase in trade. A space elevator, though, is essentially the world’s biggest Bridge to Nowhere. Getting into space is entirely about coolness until such a time as we have the speed capabilities to take advantage of the resources and land available in space. So essentially it would just be a big money sink on the economy, not a boon. The only way it would help the economy would be via the creation of the materials used. But you could build a bridge connecting Europe and North America instead of a space elevator and get those same materials, plus something useful. ---
**Author:** ![mswas](https://avatars.discourse-cdn.com/v4/letter/m/e99b99/32.png) [@mswas](https://boards.straightdope.com/u/mswas)\ **Post date:** [March 6, 2009, 5:04am UTC](https://boards.straightdope.com/t/building-a-space-elevator-would-stimulate-the-economy/488299/66 "2009-03-06T05:04:06Z")
> [@Chronos](#): > > We already have a material which is plenty light and strong enough to build rockets out of… It’s called aluminum. The weight of the hull of any rocket is negligible compared to the weight of the fuel-- That’s the reason it costs so much to launch anything into orbit on a rocket. A space elevator bypasses that requirement. > > The cost estimates I’ve seen are in the vicinity of 50 billion dollars. A government could easily afford that. > > Oh, and as for the “what if it breaks” argument, in that case it would burn up in the atmosphere before hitting anything on the ground. We’d be out our initial investment, of course, but it wouldn’t be a cataclysmic global apocalypse. Umm the top part would, not all of it would burn up on re-entry. ---
**Author:** ![wevets](https://avatars.discourse-cdn.com/v4/letter/w/e9a140/32.png) [@wevets](https://boards.straightdope.com/u/wevets)\ **Post date:** [March 6, 2009, 5:10am UTC](https://boards.straightdope.com/t/building-a-space-elevator-would-stimulate-the-economy/488299/67 "2009-03-06T05:10:48Z")
So is it safe to assume the Kim Stanley Robinson scenarios in his _Mars_ books have no basis in reality? How much of the space elevator would survive re-entry? ---
**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\ **Post date:** [March 6, 2009, 5:13am UTC](https://boards.straightdope.com/t/building-a-space-elevator-would-stimulate-the-economy/488299/68 "2009-03-06T05:13:19Z")
> [@mswas](#): > > Umm the top part would, not all of it would burn up on re-entry. Anything more than about 50-100 miles up would most likely burn up. That much of the cable would weigh something in the tons range. A falling plane is just as dangerous, if not more so. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [March 6, 2009, 6:10am UTC](https://boards.straightdope.com/t/building-a-space-elevator-would-stimulate-the-economy/488299/69 "2009-03-06T06:10:50Z")
> [@](#): > > But the upshot is, you can’t just hang a ribbon off the actual Earth and expect it to stay put without giving it little pushes. …Or little pulls. Which is really easy, given that it’s a cable and that it’s anchored to a point on the Earth. ---
**Author:** ![Diz](https://avatars.discourse-cdn.com/v4/letter/d/87869e/32.png) [@Diz](https://boards.straightdope.com/u/Diz)\ **Post date:** [March 6, 2009, 6:49am UTC](https://boards.straightdope.com/t/building-a-space-elevator-would-stimulate-the-economy/488299/70 "2009-03-06T06:49:16Z")
> [@wevets](#): > > So is it safe to assume the Kim Stanley Robinson scenarios in his _Mars_ books have no basis in reality? How much of the space elevator would survive re-entry? I have no idea if his idea is realistic or not, but in his favor is the fact that Mars has significantly less atmosphere for the cable to burn up in. I also seem to remember the cable in his story being quite a bit larger than anything proposed in this thread. ---
**Author:** ![E-Sabbath](https://avatars.discourse-cdn.com/v4/letter/e/e19adc/32.png) [@E-Sabbath](https://boards.straightdope.com/u/E-Sabbath)\ **Post date:** [March 6, 2009, 11:34am UTC](https://boards.straightdope.com/t/building-a-space-elevator-would-stimulate-the-economy/488299/71 "2009-03-06T11:34:40Z")
Once again, the ‘space fountain’ manages to ignore pretty much _all_ of these issues. It just requires a bit more power. Nice trick, huh? ---
**Author:** ![Tenebras](https://avatars.discourse-cdn.com/v4/letter/t/977dab/32.png) [@Tenebras](https://boards.straightdope.com/u/Tenebras)\ **Post date:** [March 6, 2009, 3:14pm UTC](https://boards.straightdope.com/t/building-a-space-elevator-would-stimulate-the-economy/488299/72 "2009-03-06T15:14:24Z")
> [@Chronos](#): > > …Or little pulls. Which is really easy, given that it’s a cable and that it’s anchored to a point on the Earth. What, exactly, do you envision when you say “anchored”? What kind of tension are we talking about at the bottom of the cable? Will this be on land or at sea? How do you imagine the “little pulls” might be accomplished? ---
**Author:** ![Tenebras](https://avatars.discourse-cdn.com/v4/letter/t/977dab/32.png) [@Tenebras](https://boards.straightdope.com/u/Tenebras)\ **Post date:** [March 6, 2009, 3:19pm UTC](https://boards.straightdope.com/t/building-a-space-elevator-would-stimulate-the-economy/488299/73 "2009-03-06T15:19:06Z")
> [@E-Sabbath](#): > > Once again, the ‘space fountain’ manages to ignore pretty much _all_ of these issues. It just requires a bit more power. Nice trick, huh? A “space fountain” is a railgun you can never turn off, firing constantly at a station in the sky, which shoots them back down at you. It has all of the practicality of a space elevator with the extra added bonus of being a superweapon. Oh, and if you ever do need to turn it off, it falls down. Just checked wikipedia to refresh my memory on the idea and… you need to build an airtight tower 100km tall? For reference, the tallest structure ever built, when they finish it, will be the Burj Dubai tower which has a TV antenna that’s 818m high. Make that airtight and you’re 0.8% of the way there! ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [March 6, 2009, 3:25pm UTC](https://boards.straightdope.com/t/building-a-space-elevator-would-stimulate-the-economy/488299/74 "2009-03-06T15:25:00Z")
> [@billfish678](#): > > Anything more than about 50-100 miles up would most likely burn up. That much of the cable would weigh something in the tons range. Why would it burn up? It’s not moving at orbital speed, so the cable has very little kinetic energy when it hits the atmosphere. Only what it acquires during the fall. ---
**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\ **Post date:** [March 6, 2009, 3:30pm UTC](https://boards.straightdope.com/t/building-a-space-elevator-would-stimulate-the-economy/488299/75 "2009-03-06T15:30:28Z")
> [@scr4](#): > > Why would it burn up? It’s not moving at orbital speed, so the cable has very little kinetic energy when it hits the atmosphere. Only what it acquires during the fall. you fall 50 miles and see how much kinetic energy YOU have 🙂 Burt Rutan’s Space Ship One “only” went up and down about 50 miles and reentry heat wasnt something they could just shrugg off. It certainly did not have anywhere near orbital velocity. Hence, my 50 to 100 mile WAG. ---
**Author:** ![SteveG1](https://avatars.discourse-cdn.com/v4/letter/s/bb73d2/32.png) [@SteveG1](https://boards.straightdope.com/u/SteveG1)\ **Post date:** [March 6, 2009, 4:10pm UTC](https://boards.straightdope.com/t/building-a-space-elevator-would-stimulate-the-economy/488299/76 "2009-03-06T16:10:45Z")
> [@RickJay](#): > > There isn’t enough money in the world to build a space elevator, and half the technology to construct and operate it isn’t worked out yet. > > Since there’s really no chance at all that such a thing could be constructed in our lifetimes - sorry, **Chronos** , it is not going to happen - you would probably get much more effective stimulus by simply dropping bales of money out of helicopters flying over low-income neighborhoods. Agree. the whole idea is unsound. We don’t have the money, the materials, the technology. If we did, we still have to buck up against laws of physics dealing with orbital speeds vs earth rotational speed, altitude, tension, gravity, voltage build up on the cable (the voltages will be gigantic), etc etc etc. Let’s go with better “conventional” launch systems instead. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [March 6, 2009, 5:00pm UTC](https://boards.straightdope.com/t/building-a-space-elevator-would-stimulate-the-economy/488299/77 "2009-03-06T17:00:50Z")
> [@](#): > > Agree. the whole idea is unsound. We don’t have the money, the materials, the technology. If we did, we still have to buck up against laws of physics dealing with orbital speeds vs earth rotational speed, altitude, tension, gravity, voltage build up on the cable (the voltages will be gigantic), etc etc etc. Let’s go with better “conventional” launch systems instead. The technology we don’t have _is_ the materials, and the lack of money is just because we don’t have the materials yet. So that’s really only one objection, which I’ve already explained why I think it will be resolved in the not-too-distant future. And there is nothing in the laws of physics which presents an obstacle: The physics all works out just fine, provided you have the material available. ---
**Author:** ![E-Sabbath](https://avatars.discourse-cdn.com/v4/letter/e/e19adc/32.png) [@E-Sabbath](https://boards.straightdope.com/u/E-Sabbath)\ **Post date:** [March 6, 2009, 5:19pm UTC](https://boards.straightdope.com/t/building-a-space-elevator-would-stimulate-the-economy/488299/78 "2009-03-06T17:19:09Z")
Tenebras, one of the nice things about the fountain is that the things being shot up it help keep it up. … it’s still easier to build than the elevator. Another variant I like that I forget the name of is the pinwheel. Central body in space, rotating arms, no attachment to the earth. You board as it passes. ---
**Author:** ![Tenebras](https://avatars.discourse-cdn.com/v4/letter/t/977dab/32.png) [@Tenebras](https://boards.straightdope.com/u/Tenebras)\ **Post date:** [March 6, 2009, 5:34pm UTC](https://boards.straightdope.com/t/building-a-space-elevator-would-stimulate-the-economy/488299/79 "2009-03-06T17:34:22Z")
> [@E-Sabbath](#): > > Tenebras, one of the nice things about the fountain is that the things being shot up it help keep it up. > … it’s still easier to build than the elevator. > > Another variant I like that I forget the name of is the pinwheel. Central body in space, rotating arms, no attachment to the earth. You board as it passes. The things being shot up are the _only_ thing keeping the station up. The space fountain is a continuously running railgun launcher. So the first thing you have to do is build a railgun launcher that works one time, and then just hold down the trigger. Again, the people who think it will work admit that one part of the process is to build a tower 100 times taller than any structure on Earth, and then pump all the air out. It’s just not going to happen. ---
**Author:** ![Tenebras](https://avatars.discourse-cdn.com/v4/letter/t/977dab/32.png) [@Tenebras](https://boards.straightdope.com/u/Tenebras)\ **Post date:** [March 6, 2009, 5:40pm UTC](https://boards.straightdope.com/t/building-a-space-elevator-would-stimulate-the-economy/488299/80 "2009-03-06T17:40:26Z")
> [@Chronos](#): > > The technology we don’t have _is_ the materials, and the lack of money is just because we don’t have the materials yet. So that’s really only one objection, which I’ve already explained why I think it will be resolved in the not-too-distant future. And there is nothing in the laws of physics which presents an obstacle: The physics all works out just fine, provided you have the material available. Even if you discovered a _scrith_ mine, it still wouldn’t happen. Even if you get an army of wizards to cast Wish spells until the thing is in place, and then a second army of clerics all cast Miracle to hold it there, it gets hit with a piece of garbage and goes kaplooie. And the physics don’t work out fine. Try this: ignore the moon, sun and every other body in the universe. Assume that the Earth is an ellipsoid, flattened through the poles. What orbit are you going to put this in, and how are you going to keep it there? [Previous page](https://boards.straightdope.com/t/building-a-space-elevator-would-stimulate-the-economy/488299.md?page=3) [Next page](https://boards.straightdope.com/t/building-a-space-elevator-would-stimulate-the-economy/488299.md?page=5)