Slashdot Mirror
Space Elevator Update
TheMadReaper writes "The 2005 edition of the Space Exploration Conference in Albuquerque, NM came to a conclusion earlier this week. A large fraction of the conference was devoted to the Space Elevator. Surprisingly, there hasn't been much news coverage of this conference, perhaps because it doesn't have Space Elevator in its name. The most interesting fact I got from the conference is that money is really starting to exist in the space elevator world mainly thanks to the work of Dr. Bradley Edwards at ISR and at Carbon Designs, Inc. The strong nanotube talk was also more promising than last year."
Update: Still on ground floor.
What if you happen to get stuck at some weird altitude out of reach of help? If you're stuck high and above, you might have the space shuttle come and rescue you. If you're stuck low, you might have a helicopter come and help you. At other altitudes, you're pretty much fucked.
In the interest of promoting more enlightened discussion, a lot of good information concerning space elevators can be found here.
____
~ |rip/\/\aster /\/\onkey
The music in normal elevators is already driving me crazy...
Imagine going upwards for hundred sof miles while having to listen to Julio Iglesias' songs, performed by some guy on a synthesizer. NOOOOOO!
Jeez, try to imagine the havoc if the cable comes loose from its orbital anchor. Thousands of miles of pure splat! Whatever safeguards the builders promise, the NIMBY factor is so huge, it has no chance of happening.
A "space elevator" is totally unlike anything ever done before. As I read in a Slashdot post some years ago (referring to nanotubes, the favorite among space-elevator aficionados), "When somebody has built a 40,000 millimeter bridge across a creek on campus, then we can start to talk about a 40,000 kilometer bridge straight up".
The fact that we have not yet achieved one millionth of the task (and in fact fall several orders of magnitude for that) suggests to me that, much as I would love to see a space elevator in place, the job today belongs to materials scientists who are looking at shorter-term goals.
An eye to the future is great, but experimenting on climbers is like practicing the high jump: if you're jumping twice as high today as last year, I wouldn't start drawing any exponential curves. The ribbon is the really, really hard part, and we're currently so far away from it that research energy is better spent elsewhere for a while. 2010 is way, way too close.
Maybe with enough motivation we could get that 40,000 mm bridge by 2010, but somehow I doubt you're going to raise $10 million to build a bridge. The X-prize shot somebody into space for that kind of money.
I'm prepared to be wrong. I'm a software developer, and I've learned that as a consultant I can say, "Your project is doomed" with 95% accuracy before I've even heard your name. Being a nay-sayer is easy. But the real trick is being able to spot the 5% that will actually be profitable, and there are a lot of projects more immediately deserving of this kind of money.
Operating costs estimated at 100 kg/lb, ready in 15 years at most optimistic.
Kilograms per pound? What is that?
Now I know, anything is possible with technology. Science fiction of the 50's is science reality of today. But let's stop the conversation of "is it possible" with that. The question of if the Space Elevator CAN be made seems irrelevant to me.
When it comes to this whole Space Elevator business, the relevant question in my opinion is "would we WANT to make something like that?" To me, it's a novelty idea and nothing more. If people want to get serious about space travel, we need to invest more into the building of in-orbit construction yards (IMHO). Once we get the infrastructure in space to produce the vehicles, we'll find that occasional trips to the "Drydock" from Earth to supply it with raw materials will be far more practical than some 21,700+ mile long elevator reaching into the sky.
-Vendal Thornheart
How about creating a simulator for a space elevator? It would be great to mess around with values to see how possible this thing really is. The closest thing to a simulator I've seen is this but its sadly lacking.
http://spaceelevator.sourceforge.net, anyone?
As long as youre wearing a spacesuit theres no reason why you couldn't base jump off to escape... ...Or for the fainter of heart - atmospheric bungee jumping!
Man what a rush.
------
beware he who would deny you access to information, for in his mind he dreams himself your master
My first thought upon hearing of the space elevator was "what happens if it breaks?" Who cares if science suggests it won't be a catastrophe? Most terrorists do not exactly subscribe to the latest scientific journals. A lightbulb will go off in one of their dim minds and they'll try to ram a plane into the cable, or the tower, or whatever, hoping it will somehow dislodge the asteroid from orbit and send it crashing into Washington D.C. or something. It'd make a great scifi action movie, wouldn't it?
And don't forget it'd be a tremendous icon of Western achievement. You'd better believe everyone in the US, or whatever country eventually builds one, would be proud as hell of it. The media would be going on and on about how it'll usher in a new age for mankind, and so on, and so forth. If terrorists could somehow take it out, wouldn't that have tremendous psychological value? Remember that they chose the World Trade Center and Pentagon to strike at us, two (or three) buildings that symbolized, to them, everything that's wrong with the US. Wouldn't a tower that reaches into the heavens (hello, Tower of Babel?) symbolize that even more?
It's quite reasonable to take terrorism into consideration when designing a structure. While I may be obsessing over the whole "living in fear" deal, its definitely something that needs to be considered.
Before this gets too far, somebody should call NORAD and ask them how many of the 2500+ satellites and other odd bits of junk traveling at 17551mph (LEO) cross the Equator (ascending and descending nodes) and might present a collision hazard. I could be wrong, but shouldn't the answer should be "Almost all of them."
This reminds me of the asteroid/comet problem, the probability of a significant impact might be low, but it only takes one.
A warning label you won't see on the space elevator:
In emergency, USE STAIRS.
Aside from which, manufacturing spacecraft is perhaps one of the most industrially complex things we do. Trying to replicate that in a place more remote, and with far more environmental challenges than, say, Antarctica, would have gargantuan capital costs dwarfing the elevator. In fact, the only way you could probably get the infrastructure up there would be an elevator or something equivalently cheap.
Any sufficiently advanced technology is indistinguishable from a rigged demo
--Andy Finkel (J. Klass?)
This is a space elevator we are talking about. Might as well have the sign say "In case of emergency, use stars."
Don't blame Durga. I voted for Centauri.
Humans could and would travel on such an elevator. It would probably be much safer than sitting on top of a bomb that is a rocket, and much, much cheaper. It wouldn't be the most pleasant ride, but there's no reason it couldn't or shouldn't be done.
Professor of Astronomy, Author of Spider Star & Star Dragon (Tor)
A space elevator, or beanstalk, has two big problems for construction: 1) materials that are strong enough, and 2) getting it to stay up.
The first we're getting close to being able to handle. The second is just a matter of having a counterweight that balances the 22,500 miles of cable from the equator (more on that later) to the top. Without the counterweight, the ground end drags it down.
That means that we really need to build this sucker from the middle out: extend equal masses out and in (or up and down, if you prefer) from geosynchronous orbit. That's a very expensive proposition. Whether it's cheaper to ship carbon for nanotubes up or go and fetch some carbonaceous asteroids down to our orbit I'll leave as an exercise for the reader.
A poster above was concerned about the terrorist target of something like this. The one consolation in this one is that you can't build it on US or European soil: it needs to be at the equator. At least one SF author (I forget which) posited an elevator whose ground-level terminus was an upside-down Y to two islands straddling the equator some hundreds of miles apart. Not the silliest thing I've ever read, but I'm not sure it makes much sense. Tethering one end down will be tricky enough.
So it won't be Imperialist America that's building it... but that's not to say it won't have protestors. It'll cast a shadow pretty much across the entire planet. It will likely change weather patterns in the region.
It will create the most valuable real estate in the world.
It's going to end up in some place where technology and resources are accessible: Brazil, Equador, Congo, Somalia, The Maldives, Indonesia, Malaysia, or some Pacific Island are all candidates, my money is on a spot just south of Singapore -- there's enough high-tech industrial nations close enough to justify it there. Brazil is my second guess.
And who knows, maybe we'll find Saddam building WMDs up there. (obligatory Funny whoring)
Design for Use, not Construction!
Ground-breaking is right! Mr. Wonka's ingenious solution to base the elevator on a weave of microchocolate fibres is to be applauded. However, once the sun shone on this, the chocolate string melted and the elevator hit like a meteor.
Next time, Mr. Wonka, consider using Oompa-Loompa hair fibers. Or maybe you can beam astronauts into space with that TV ray. Who cares if they come back from their mission 1 inch high?
Don't blame Durga. I voted for Centauri.
Your objections are very leaky.
It is a single point of failure. If any one of the millions of potential problems with a space cable turns out to be a show-stopper, the whole investment is lost.
It's possible to "prove" the space shuttle can't fly based on the number of parts and the failure rate in those parts. Yet it flies. It isn't like we've spent a fraction of the GNP on it. This argument comes down to "I don't think it will work because it seems complicated." It's actually much simpler than riding a bomb into space which is what astronauts currently do.
The benefits are small. The energy needed to shift a payload from the bottom to the top remains the same with or without the structure. The amount of money and energy spent on building the structure needs to be recovered in improved efficiency, and that seems unlikely.
This is just wrong. The benefits are huge! This would reduce cost to orbit by orders of magnitude. When you put material into space, you're not paying for the energy. It actually doesn't take all that much energy to put something into space. The calculation is easy. It's about 60 million Joules per kg (1/2 mv^2 with v=escape velocity). You can take a day to lift (which is 86400 seconds). That gives you about 700 J/s (which is the same as 700 Watts). It's the same energy you need to run 7 100 Watt light bulbs for 24 hours.
All of the investment is up front. There is no incremental benefit to this - the elevator does not become useful until it's complete. Any return on investment (including to governments in the form of kudos or re-election benefit) is delayed until long after completion of the project.
This objection is correct, but trivial. Edwards and Westling, the only ones who have done a realistic design study, put the cost at around $10 billion. That's less than the NASA budget for 1 year. That's much less than building a successor to the shuttle. That's factors of several less than the defunct superconducting supercolidor, and similarly less than the space station. Heck, Bill Gates could in theory build it for fun. Given the international nature of the problem, issues about security, the need for some additional bits of engineering/research, it is a government project. But not an outrageously expensive one.
Professor of Astronomy, Author of Spider Star & Star Dragon (Tor)
Look the longest Nanotube is about 2 mm. (I've seen them and know the student making them.) Nanotube fibers are made but they are tough to do. The amount of MWNT (the easy stuff!) made in the US is small. There is no way to make a massive amount of the stuff. Certainly not the amount needed for an 'elevator'. Now let's consider the minor factoid that you will have to drop something heavier than you are lifting. (Or at least of similar mass.) I have single word that this space elevator project does not consider - physics
This message was brought to you by "Lack of Sleep."
Oh you've got to be kidding me. Name one Adam Sandler movie that has not been a disaster.
Two main points are:
Geostationary orbit is a long way up.
We don't know yet if carbon nanotubes have the strength require to be able to handle their own mass over such a distance - or half it if you have an asteroid keeping station at the other end.
Call back when we have the technology to bridge from Singapore to Mexico City in a single span - we'll be a small fraction of the way there.
I see this whole concept as just being another aspect of people getting too influenced by Biblical sound bites - they want to build a tower of Bable for the sake of it, while similar ludrous schemes for launch like building a mass driver circling the equator would be orders of magnitude cheaper. Keep your religeon and your science seperate guys. People would argue this came from SF, from people that have heard of geostationary orbit but don't have a clue, but it gets rooted in our heads from Sunday School and the Bable story.
Anyone who wants to build another Tower of Babel because they read about it in the Bible clearly didn't finish reading it.
English is easier said than done.
Catastrophe. Yes Bad Things can happen. The amount of damage done is less than might be expected.
IS less? So this has been tested, has it?
I'll tell you what I'd expect. I'd expect if something went wrong and a "load" plummeted to earth from 5km up it would be pretty difficult to predict what sort of damage it would do... There's one of many possible catastrophes we'd like to hear whay you'd expect the damage to be
Terrorism. The thing is less a target than might be expected.
Again, IS less? This fact comes from where? A poll of known terrorists, or off the top of your head?
Yes, I know... people were executed for suggesting that the world wasn't flat, etc etc... but please - if you want a rational discussion on this thing pushing "facts" like these at us is hardly likely to sway any opinion.
I used to hang out on their forum a while back. One solution that was proposed was to "maypole" the tether when it enters the atmosphere - i.e., have it split and have a number of anchor points.
Edwards already had discussed several issues: one, the potential site, has almost no thunderstorms. Also, depending on the type of CNTs that you use, many are very resistive, and would not be the easiest route to the ground, but the most difficult. A risk factor, however, would be water streaming down the tether making a more conductive path.
sed "s/SJW.*$/... never mind. I was about to say something stupid, and also, I'm a troglodyte./Ig"
You might find it surprising, then, to hear that I'm very excited about the possibility of a space elevator, despite being a lifelong atheist.
It's true that the space elevator relies on technology that doesn't exist yet. But that technology is rapidly advancing, and there have been extensive studies of the material properties of carbon nanotubes in the context of use in a space elevator. Of course, you'll have to wade through pages of Biblical references to get to the actual science, but that's something you'll just have to get used to if you want to read about space elevator technology.
In addition, a mass driver is simply NOT a substitute for a space elevator. Even if a practical electromagnetic mass driver could be built, each launch would require a large amount of energy that would never be recovered. The space elevator uses less energy to send each ton of matter to GEO than any other proposed system, but that's not the really cool part. You see, each ton of matter that is returned from GEO effectively recovers the energy required to send that matter up in the first place via regenerative braking.
This is also where I should mention that, energy concerns aside, the space elevator removes one of the largest risks from space flight - reentry. Mass drivers help you get into orbit, but they don't help you return from orbit at all. In a space elevator, though, you just press the "down" button. Simple as that.
Now, if you'll excuse me, I have to go do my religion homework. Oops, I meant to say science homework. I have such a hard time keeping those two subjects separate... but you can't really blame us clueless space elevator kooks for that, right?
It seems likely that the estimates of 12 years are a little optimistic for something of this scale, but I would certainly like to be wrong on that count. However, if we spend 5 billion dollars on this and we end up developing the technology to cheaply produce super-strong cables out of carbon nanotubes, I say it is money well spent, even if there is no space elevator.
If it works, a space elevator is THE best way to get things in and out of orbit. Also, I am sure you realize it, but your bridge analogy is specious at best. Building long bridges and tall elevators are not comprable projects.
I didn't mean to imply that I'd found some magical way around the 2nd law. What I meant was that all existing launch systems recover 0% of the energy expended to send objects into space, whereas the space elevator has the potential to recover at least some of the energy spent to send mass into space. All physical devices will have inefficiencies, but those inefficiencies will diminish as technology improves.
As for the current re-entry method, it's the cheap way of slowing down without using fuel, it doesn't have to happen but it is a carefully calculated risk.
True, it's the best we have at the moment. What I'm saying is that it is (a) dangerous and (b) wastes energy by shedding it as heat instead of reclaiming that energy for the next launch.
I'm not a practising materials scientist anymore, but from what I've read of carbon nanotubes they have a possible potential to be strong enough someday - but since we don't know how much it's going to cost us per unit volume to make the stuff or how much we'll need it is way to early to make up numbers from nowhere.
That's true, but it doesn't mean that we shouldn't invest in some relatively cheap studies of what carbon nanotubes could do when we finally get them working. In addition, I sincerely doubt that economics of carbon nanotubes will be a large problem because there are a huge variety of applications for nanotubes that don't involve spaceflight at all. Economies of scale and all that. Plus, the whole point of a space elevator is that the costs associated with each launch are miniscule- it's only the initial construction that is expensive. A large initial investment will prove less expensive over the long haul than continuously wasting energy by sending small payloads into orbit and then wasting all their orbital energy in re-entry.
It's hype - and from the way people in the west have been brought up it strikes a Biblical chord.
I agree that the people who think an elevator can be up and running within 15 years are probably overoptimistic to the point that you could call it "hype", but I've honestly never seen anyone besides you compare the space elevator to a biblical story. Most of the discussions I've had with colleagues regarding the space elevator, and most of the articles I've read about it have been concerned with the technical challenges involved and the incomparable riches it could provide to the human race if we ever manage to construct one. It's an engineering project, albeit an ambitious one, which is fundamentally no different from, say, the moon shot.
If we are going to ship millions of tonnes into space it could either be an elevator or infrastructure to get stuff from places that are not in such a deep gravity well.
Mining near earth asteroids is definitely a good way to jumpstart the human presence in the solar system, but it doesn't address the fact that some things need to be taken into space from the surface of the Earth. For instance: people, any technology that requires large factories to be constructed (such as computers), and food (at least until greenhouses can be constructed in orbit). In addition, mining near earth asteroids may be a way to reduce the amount of mass that needs to be lifted into orbit for a space elevator. If we can manage to capture an asteroid of the right size and put it into GEO to act as a counterweight, the cable length can be shortened considerably, from 143,000km to 36,000km.
The Space Tethers will be built far sooner and are really much better. These can toss you into space fast so you don't fry in the radiation belts, recycle the energy from payloads going down into payloads going up, and be built with materials we have today.