A commenter here on Dean’s World recently brought up the idea of building a practical, working space elevator within the next 10-15 years. To be honest, I gave the idea the brushoff until I saw this article in IEEE Spectrum, one of the engineering world’s top journals: A Hoist to the Heavens by Bradley Carl Edwards.
It’s a very good piece by a respected researcher. IEEE Spectrum is a real engineering journal, too, not a popular magazine. (Interesting coincidence, one of our friend Harvey Bialy‘s former editorial companions at Nature, Susan Hassler, is now IEEE Spectrum’s editor). He’s done a study which suggests a single elevator-to-orbit could be built within the next 10-15 years for a cost of only about $20 billion, with subsequent elevators built at a fraction of a cost.
The most exciting thing is that it looks to be mostly an engineering challenge, and no more. Give it a read.
If they were to build a few dozen of these, it would likely completely change the world’s economy, and in ways we can barely imagine.
(Via Instapundit.)
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I’d love to see this happen. But the “engineering challenges” in this case aren’t all that easy to solve. Namely, a substance stong enough.
You’re talking about an elevator cable at least dozens of miles and up to 100 miles (space) long.
The article kind of brushes past that, In theory, at least, carbon-nanotube-based materials have the potential to be 100 times as strong as steel, at one-sixth the density.
“In theory”, “have the potential”…
Now I’m as optimistic about science as the next guy, but we’re pretty far from a material strong enough to be stretched out dozens of miles and still be strong enough to withstand weather, varying pressures and temperatures, incredible velocity as it keeps geo-synchronous orbit and still be able to carry tons of materials to the top. Maybe we could start making scrith. Or just get the material from a General Products hull.
I’m not trying to emulate the guy in one of my favorite Heinlein quotes, “I’ve told Orville and I’ve told Wilbur and now I’m telling you, that thing won’t fly.”
But… until I see a material that is more than “potential” or “in theory” (In theory Communism works. In theory) I’ll hold my enthusiasm.
Yeach, the article was interesting, and it mentioned some of the issues you raised such as the terror problem.
I’m actually skeptical it will work the first time out. I’m guessing that like the Panama Canal, the first few attempts will fail.
Actually Mike, there are already nanotube composites. They just need to boost the amount of nanotubes in the composites. It’s a failry well-understood problem.
It’s well past the sci-fi stage.
A space elevator. I love the idea. I always think of Dawn’s elevator skyscrapers. The total passion for the total height…. The Ego in the Infinite…. High…. The style….!
Has anyone dealt with the objections/problems raised by Steven Den Beste in his post The Great Chipmunk Spaceship Race? I haven’t been following closely, but so far as I can tell, they haven’t, and I agree with Steven in that the problems look insoluble.
I love the idea and I wish it could work. I don’t think it can. Read SDB’s article for why, he’s a billion times better at explaining things than I am.
If, on the other hand, these problems have been dealt with, I’d love to hear about it.
A team at U. T. Dallas recently demonstrated a device that can produce transparent carbon nanotube sheets (stronger for its weight than steel) at a rate of 7 meters per minute. Here’s a QuickTime video. The materials problem is on its way to being solved.
Yeah, the guy did not “brush past” the materials issue, he addressed it directly. Saying it hasn’t been done is like saying that no one managed to create a rocket capable of getting someone to the moon, therefore, the Saturn V was only “just theory” before they built it.
Read the article more carefully–this has moved beyond mere speculation to the realm of the probably-achievable.
I once again note: IEEE Spectrum is a respected engineering journal, not a popular science rag, and the author is a respected researcher, and if he says ESA, NASA, and the USAF are all looking at it very seriously, it’s moved beyond simple theory and into something that looks more like a big engineering challenge.
<i>The most exciting thing is that it looks to be mostly an engineering challenge, and no more. Give it a read.</i>
My semi-informed take on it is that, yes it is an engineerng challenge, but that is not the most difficult thing about building an SE system.
The most difficult thing about building one will be the legal and political issues, followed by a horde of niggly details that aren’t in the public view at the moment. Little stuff like logistics, the power system, and the one Liftport is working on now – how do you produce a car that can reliably cruise for a week at an average speed of over 200 KM/hr? And that must operate across a variety of environmental regimes? With no maintennace. Details matter.
Brian
Yes, well, Edwards produced a study that addresses all those questions, and suggests a budget of $20 billion.
This looks like a challenge about as big as the Apollo project. It also looks to be the first space project since Apollo that would actually be a giant leap forward.
“Yes, well, Edwards produced a study that addresses all those questions, and suggests a budget of $20 billion”
The NIAC work? I’ve read it – heck it’s posted on our website. Edwards did a fine job of pointing out the issues, which is not at all the same as doing the pick and shovel work. If we’re lucky it’s pick and shovel time.
I shy away from comparing this to Apollo. Apollo was all about getting there and … coming back. There were plans for instrastructure and follow-on missions, but all said and done .. more was said than done. We did get some nice lawn ornaments for JSC.
An SE is all down to infrastructure. A scalable bit of infrastructure that can send mass to space. The really (from my POV) cool part is that Apollo required 20,000 people to get what, a baker’s dozen astronauts to the moon. We might be able to do this with less than a thousand people in the core organization.
“…it looks to be mostly an engineering challenge, and no more…”
That statement appears to underestimate the complexity of this particular problem. Den Beste tackled this issue a bit here, and he’s much more eloquent than I am.
Before I take this idea at all seriously, I want someone to explain to me how, exactly, you build it.
How do you get that cable in place, connected to a major anchorage on the ground and to a large counter weight in space?
Steven, the first place to look is Edward’s NIAC study. There is a copy on Liftport’s web site, or you can google for it.
I looked at some of those studies a couple of years ago. They spent a lot of time analyzing the elevator in steady-state terms but they waved their hands really fast and walked right by the question of how you build it.
I’ll settle for someone’s 50-100 word explanation of the general approach to be used to get that cable in place. Just tell me, simply, how it’s done?
Dean,
don’t disagree with anything you’ve said here, but a quibbling point: IEEE Spectrum is not an engineering journal. It’s the magazine put out by IEEE, similar to Optics and Photonics News or Physics Today. The author is a respected researcher, but this is not a peer reviewed research article.
I personally think it’ll be more like 50 years before the space elevator thing really gets some legs under it, but really the main question is not if but when. Assuming, of course, that within the next 10-50 years no competing technology really explodes out of the gate.
If this goes beneath what you’re looking for in terms of simplicity, for deployment, I apologize.
Ribbon is delivered to orbit in several packages. How many? Edwards guess-timated 4-6 Shuttle flights. More than than for a Delta, but not many. Packages are assembled in orbit into the deployment machine. Ribbon is reeled out and down to touch down on the equator while more ribbon is reeeled out and up. The near end plops down in the ocean. The bitter end winds up in an orbit high above GEO.
At this point we have a ribbon under balanced tension but is not strong enough to put much of a load on. Lifters are attached and ascend to paste on more ribbon for added taper. Several hundred of these later we have a 20 ton ribbon.
This does not begin to address some of the glaring problems of course. Can you ‘weld’ CNT material together? Manned orbit assembly or teleoperated?
Good questions. At this point all we have is handwavium answers and the phrase ‘more study is needed’. Hand waving is not a good answer but it’s what we’ve got. Note that the amount of hand waving has gone down over the years.
If I had blue prints in hand and all the answers I’d be a rich man. I’m don’t and I’m not.
But these are important questions to answer – even a negative answer will be invaluable.
Also note I’m a systems admin, not a rocket scientists or even an engineer. I get orbital dynamics at the kidnergarten level; all of the above (in the origianl learned form) makes sense to me.
That “reel out on both sides” approach was what I came up with when I thought about it, too. But as I thought about it more, there were two big problems with it.
First, you have to reel out a lot more above than below in order for the system to remain balanced. That’s because of the nature of orbital dynamics.
Second, it is REALLY easy to disturb the orbit of the space station this way if you get it even slightly wrong, because the cable above and below affect the center of gravity of the system. In other words, you can end up with the cable reaching all the way to the ground below, but it won’t be in the right place. If you do this but end up 500 miles off, then what?
I’m also not sure I believe you can “reel” the stuff out like that. Slack propagation time becomes a serious issue when the cable has already been reeled out a few thousand miles.
Oh, and how long does all this take?
The white paper I linked answers these questions.
As Brian notes, the short answer is that you put your extruder into orbit and then start extruding a small line downward, then when you anchor that at bottom, you use further extruders to climb back up the thin line to add to and strengthen it until you get a line capable of holding 20+ ton loads reliably.
As Brian also notes, there is still handwaving involved but the amount of handwaving is reducing at a major clip. Just fifteen years ago, “we have no idea how to make a cable of the required strength” was the main hurdle. The main hurdle now appears to be getting the nanotube extruders able to produce enough of the material economically–which now appears to be an engineering challenge, not a theoretical physics problem.
Read the white paper. We’re more advanced now than we were even five years ago.
Steven,
What Dean said. And I’m a poor choice to explain all this. Servers, shell script, email: no problem. Engineering I stand back and gawk at. I get it but explaining above my level is a bit much.
I’m not sure that’s a flaw; the Edwards version of the SE (and EVSE ?) does indeed have as much above as below (or nearly so) for a counterweight.
The drawback is .. more ribbon. The plus is that you get a flinger for ‘stuff’ heading out of the Earth – Luna system.
1) Has any consideration been given to the cable stretching or shrinking in relation to temperature changes?
2) If the cable can be constructed out of nannotubing, could it not be feasible to construct the cable itself in tubular form, rather than as either a large-diameter composite strand or a flat continuous sheet?
3) Would the cable tend to act as a conductor of lightning that might automatically fry any machine climbing or descending it, along with any carried equipment or passengers? (Remember Benjamin Franklin’s almost-deadly experiment with a key on a kite-string during a thunderstorm.)
Anyway, all sucessful engineering begins with imagineering, I think.
Arnold Harris
Mount Horeb WI
The funny thing is, like Dean noted, even 10 years ago this was in the realm of sci-fi because no one had any way to produce anywhere near enough nanotubes. I mention this project to engineers I work with, and they all scoff pretty heartily until the read the white paper, and then they’re like “Wow.”
Arnold,
I believe you’ll find those questions answered in the white paper or the article.
Yeah, read the white paper. The extruder equipment starts in orbit and crawls its way down as it extrudes. Then it gets anchored, and further extruders crawl back up it, adding to the ribbon.
I’m not sure what the benefit of making the cable tube-shaped would be since a ribbon a meter thick would be able to handle 20-30 ton loads just fine.
If you read the white paper, it addresses the problem of current being generated by magnetic and other forces on the cable–basically, by luck the material is already highly resistant to electricity, so the little amount generated is easy enough to dissipate and might possibly even be put to creative use.
It appears that there are only two genuine challenges left, since we have already demonstrated in the lab that the ribbon material can be created and is more than strong enough:
1) Find a way to generate that ribbon reliably over a length of a few hundred thousand kilometers, and
2) Get a counterweight of enough mass into the proper orbital location, and keep it there.
As I say: we’re talking engineering challenges now, not theoretical physics problems. That’s an *enormous* step forward.
One challenge I don’t note addressed: wear and tear. As in, what’s the projected lifespan of one of these cables, assuming regular use over a period of years?
But once again, note that what I’ve just described is primarily an engineering problem.
Dean you might note that the Edwards SE has a counterweight – a whopping bit of ribbon extended past GEO, plus the mass of the lifters used to construct the ribbon.
I can think of more challenges as well – one immediate one is a car (lifter) that can traverse 60,000 + KMs of ribbon, undergoing a variety of environmental changes, at an average speed of 200 KPH. For a week. Without maintennance.
But the real challenge is going to be in the legal and political arenas. You thought US v. Bell Telephone or US v. Microsoft was a legal carnival of delight – you ain’t seen nothing yet.
Yeah. Military officers will tell you that strategy is useful, but logistics is a nightmare.
When I said he glossed over the materials, what I meant was that he had glossed over the fact that we can’t make the material right now. It’s all theory. “in theory”, “we think”. He stipulates a ribbon 1 meter wide and very thin and catalogues exactly the properties necessary but he admits we can’t make it yet.
That thin ribbon would have to be close to 100 miles long and able to support its own weight plus the weight of any cargo and withstand temp changes, weather patterns and flying debris. Also, the temp along the ribbon would be different at different sections so it wouldn’t be the same size throughout.
Yes, it’s just engineering. Building a building 1 mile high is “just engineering” too.
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