Slashdot Mirror
Space Elevators Going Up
MikShapi writes "CBC is running a new piece on the Space Elevator. Nothing dramatically new, as we're all still waiting for one of the many Carbon Nanotube research centers to announce they reached the famous 100GPa red line from page 10 of the NIAC Phase 2 Report, thus obtaining 'unobtainium' [pun intended], the material necessary to build the Elevator. The report predicts this will happen during the course of the next two years or so. It's then that the fun really starts - A REAL all-out space race, open to everyone with will and a national budget, winner probably getting to own space [read last paragraph]. In the meanwhile, we can all spread the word, discuss, debate and brainstorm every nook and cranny of the program here on Slashdot, and give Edwards a shoulder by giving the program every bit of mass-exposure we can."
Getting 100 GPa for carbon nanotubes composite is one thing. Getting 100 GPa on a 100000 kilometers carbon nanotube composite is another.
I'm more interested in the length of the nanotubes than in their strengh since increasing the strengh is quite easy (basically all we need is to increase the fraction of carbon nanotubes in the composite) compared to increasing the length of the composite.
Iraq: war to save the U
Almost exactly on the equator and above a lot of the weather.
When this technology finally comes into fruition, would it not basically put the ISS out of buisness ? You could basically do all of the things the space station does but also be able to lift and unload new cargo without launching rockets. And if this technology is only 2-3 years away, won't this be ready before the station is even built ?
If the dollar is an "I owe you nothing", then the Euro is a "Who owes you nothing." - Doug Casey
In the article they estimate that it would require 650 tons of material. Christ, how many kilograms have we made to date! A two year timeline is unreasonable given our current limitations. Yes, it would be nice if we did have a space elevator, however I do not see it becoming a possibility in this decade. Do we not need more expertise in manufactoring and manipulating these materials? Has anyone made any mathematical models that predict the stress etc... that an elevator would need to undergo?
Dang, over 300,000 geeks on slashdot and i'm the first to say this!
Why not create a chain of bouyant cables instead of focusing on strong and light ones made from carbon nanotubes??
I was at that NIAC conference a couple years ago when Brad Edwards presented his Phase 2 results and I have to say this was one of the most inspiring things I've ever seen.
Listening to him go through all the numbers and technical details you're left not only with the amazing scope of the thing but the feeling that, ya know, we might just be able to build this thing!
G.
Im constantly amazed how optimistic some people get about a space elevator. The main post and a lot of things other people are saying make it seem like they think technology is the deciding factor in whether or not one will get built. The only reason nobody has really spoken out against the idea is the average person thinks the scientists are smoking some good crack on this one.
This isn't a harmless piece of cable we're talking about. The real barrier is going to be whether or not it'd be dangerous if it breaks or if it's cut. If it'll burn up and IF the burnt nanotubes aren't dangerous then maybe there will be a snowballs chance in *$#@ that the public will ok such a project. You can be guaranteed that if it's dangerous though that everyone will just assume that it will break or be broken intentionally.
the top floor would move much faster than the bottom. Don't remember all my freshman physics, but it seems reasonable that to get to the top you have to undergo some serious lateral acceleration.
You'd also have a hard time interacting with any orbiting satellites (except those in a geo-stationary orbit) because they'd be flying by at 13,000 mph.
"We have to fix the satellite. Here it comes, I'll grab it with my giant catcher's mitt... WHOA! That almost took my head off! Well, at least it won't come around again for 90 minutes."
Warren Buffet often argues that since he is more productive than average, it's better for him to put his money to work than donate it to the needy. Once he dies, the argument goes, the money (a greater sum due to compounding) can be distributed. Take any discovery expedition - Columbus, Cortez, Polo - figure the aggregate value gained vs. the actual cost. This is the principle of investment.
The strength of the material is controlled by defects. In a petri dish, the carbon nanotubes have no defects, but there is no way they can make a cable that is more than a few cm long without defects. This will make the strength of carbon nano-tube much smaller. In real materials, the reductions is 3 orders of magnitude. So instead of a meter wide cable, they would need a kilometer wide cable.
One thing I really question is the claim that there will be or can be only one final winner in "owning" space. I'm sure there will eventually be wars and such but dominance by one group doesn't mean exclusion of another. There are times where one group in a particular realm is the "king of the hill" but often there is room for other players too, without the help of that "king".
...the 100 GPa number sounds ridiculous.
For context: the most common type of structural steel currently used has a yield strength of 350 Mpa. 100 GPa is 285 times stronger. And stronger isn't enough, it has to be dependable and resistant to cyclicle loading and fatigue, which isn't easy to quantify, especially under such unusual conditions.
To suggest that this can be achieved in a couple of years sounds silly to me, considering whatever material used would a lengthy term of testing and a proven track record before sinking billions of dollars into it.
Unless it breaks, it can't tip over. It's like hanging a yoyo from your finger. There's no way the string is going to tip over onto your hand.
I'm not the least bit concerned about the carbon nanotubules. I'm still trying to figure out how their going to ATTACH the damn thing. All buildings are essentially resting upon the Earth. This thing can't rest, it needs to be attached. For a cable this long, a "stupid hurricane" could set up a vibration is going to build to the point where the whole thing starts "walking" across Columbia.
Don't blame me, I didn't vote for either of them!
It'll be at least a century before one of these things actually do anything useful.
Actually, common English translations of Matthew 5:5 state that the MEEK shall inherit the Earth. Additionally, the evolution of the english word "meek" since the time of translation makes it an unfit word for the intended meaning.
A more accurate interpretation suggests that those who inherit the earth are exactly the opposite of weak. Instead, the "meek" originally intended was a word to describe a ready and willing warrior. My university's Bible professor likened it unto the steed of a knight. Eager for battle, ready at a moment's notice to aggressively and unashamedly obey its master. Christ, I think, was referring to those who put intense, unmitigated faith in his Father. That's the sort of "meek" who inherit the earth. [/theology lesson]
Anyway, I do agree with you that advancing technology like this is not necessarily at the expense of helping the poor. It can actually HELP that endeavor. I am of the personal belief that it shouldn't rest on the government's shoulders to prop up the poor. That's the sort of thing with which the compassionate members of society ought to be busying themselves.
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The only problem is that the same nanotube technology that would enable a space elevator will also enable a reusable single-stage-to-orbit spacecraft capable of putting mass into orbit at a much lower cost.
Just to pick some numbers:
Space elevator: $5B each, one 4 ton payload per day
Nanotube composite rocket: $.1B each, one 8 ton payload every two days
In other words, it will never happen.
To avoid this possibility why not take this approach:
Instead of a fixed cable that has to support it's own weight, how about a large satellite or space station in geo-syncronous orbit, with 2 cables, one that comes down to earth and one that goes the opposite direction into space as a counter balance.
Nothing would be permanently attached to earth. Instead the two cables would wind out (like a giant winch) in each direction until the earth-bound cable reaches earth.
The cable could be wide and flat, like a giant nanotube nylon webbing. Payloads may only be in the thousands of pounds, but that is OK. Even if we could only make a few trips per day it would revolutionize space travel, exploration, and research.
Larger objects like space ships could be taken up in pieces and assembled in space.
Best of all, when the 2031 Leonid Meteor Shower (and others like it) arrive the ribbons can be stowed and the satellite could be flown around to the back side of the earth and protected from meteors (if that is even necessary).
Also, if the cables break they would fall to earh in the general vicinity of the landing base on earth, causing destruction there (like the never ending chain falling on that guy in "Twins") but not wrapping around the earth twice...
Oh, and when I mentioned the "giant winch" I wasn't talking about your wife. This is slashdot, you don't have a wife. (I was talking about your mother).
article here
From the other side, the idea that exponential growth will begin immediately after an elevator is constructed is probably total nonsense. There simply won't be that much demand. In a world where cheap access to space doesn't exist, nobody invests in things that demand cheap access to space. Once cheap access to space becomes possible, investment in such things will explode (probably to bubble-like proportions), but it will take years of R&D before the new stuff that will be created will actually be ready to load on an elevator. It takes time to build entire new industries up from essentially nothing.
In any case, regardless of the economics, there are several countries which will want to have their own space elevators, simply for reasons of national security or prestige. The US would not be at all happy with the idea that China could cut of its reasonably-priced access to space, for instance. So, don't expect anyone to have an elevator monopoly for long.
This space unintentionally left unblank.
A soyuz capsule on top of a big piece of rock. Big gyroscopes for stability. Rock turns to plasma from laser heat, explodes in planar shockwave by pulsing laser at correct intervals. Spacecraft rockets in other direction. Same complexity as the crawler, no cable, much cooler takeoff, faster, and can be built starting TODAY, making space travel cheaper (no reason it wouldn't cost any more than the cable plan, probably be cheaper) in just five years.
The site doesn't actually run through the numbers or mention how long this recovery time would be. The logic does make sense -- if the tether becomes slanted relative to the surface of the earth (my objection), then by definition there is a lateral component to the centripetal force on the tether, which should allow the sky station to steal some angular momentum from the earth. at some unspecified rate.
The site doesn't actually run through the numbers or mention how long this recovery time would be. If any physics mavens are irritated enough by my parent post to actually run the numbers, I'd be genuinely interested in seeing the solution worked out.
It seems to me that attaching a large rope (for lack of a better word) to the moon and letting it 'hang' to Earth would be worth some thought. Because the moon is tidally locked to Earth, the rope would always be facing down. The distance isn't inconcievible (IIRC, twice the length as the elevator). It would be largely ballenced by the opposing gravities, and the part under most stress would be virtually weightless.
The rope could hang a large distance off the ground, and the space bound object could be raised up to the top of an Earth bound tower, hooked onto the rope, and the it could elevate itsself.
I don't know if it's feasible, or even a good idea, but it's food for discussion.
What about static electricity cause by the cable as it rub against earth atmosphere. NASA try something like the tether to generate electricity using that method
I predict that there will not be a space race, because the cost-benefit isn't acceptable yet. If this technology is only 2 years away (doubtful again), then there would be massive funding to accelerate the program if there was enough interest. Lack of interest now means that there is probably not going to be much interest when the nanotubes arrive.
One of the interesting points that Dr Edwards makes about the space elevator is the first one to build one has an exponential advantage over followers. This is primarily due to the fact that you can "spawn" off full-sized elevators off an existing one for a fraction of the cost of building a new one. If we don't have the plans and infrastructure in place to build an elevator as soon as it is a viable option, we may as well not even try - someone will have already beat us to the punch.First Falcon-1 to orbit, then Falcon-9. Then I can die a happy man.
Wouldn't that actually be four books?
Technically, yes. But in a shoot-off between the cheap Merlot I am currently drinking, and the cheap (and obvious) point you are making, YOU LOSE! (in a diplomatic sort of way, not meaning to put you down, you understand, but, like, the Merlot is getting me drunk, what are you doing to help my plight? Savvy?)
Tubal-Cain smokes the white owl.
There are some pictures of real carbon nanotubes in plexiglass containers available here, taken with my crappy digital camera at LiftPort.
Cool story: at one point some of this material, which looks more or less like soot, spilled onto the flat, seemingly smooth table top. After wiping it off, there was a permanent black smudge left on the table top that no amount of scrubbing would remove... some of the nano-scale CNTs had slipped down into the microscopic grooves and divots on the table surface!
Not to rain on the parade, however, back on earth we do still have a lot of growing up to do.
How many wars are still going on?
When will greater minds unlock puzzles like world poverty?
No biggie, Mars looks a lot like the land in the Gaza strip.
Now lets talk some sense.
Space is going to have to become cheap and safe.
Otherwise, lets go back to debating the above.
That said, why not develop current technologies better?
Rail Guns?
Potential Energy converted efficiently into Kinetic Energy using magnets, superconductors, aerodynamics and a smaller amount of safe fuel.
The idea is to create momentum and push closer towards escape velocity while still on the earth and then launch the moving mass into space and keep it going with a lot less fuel.
The example is best seen when trying to push your dead car forward for the first time.
If on flat land, it takes some effort at first to get her rolling, thereafter it takes just a little until you stop again or realize that trying to push her up a big hill was just a bad idea.
This is also seen in the fact that most of a rocket's fuel is used up in the beginning part of the launch. It takes very little to keep the mass going, especially once it sheds enough mass and starts to move farther from the gravity well.
Now on earth we are going to have problems pushing a mass to 330m/s. (air friction and ionization to name two).
So lets get our aerodynamic payload at least to Hyper Mach using a superconducting magnet rail gun, then engage the air turbines and go for some fun with the rocket once out of the stratosphere!
A plug for my really amateur space site:
www.spacecanada.org
no - I didn't read the book. But NASA has been a parasite before... this is how they put many probes into space... its called a "gravitational assist"
the idea that exponential growth will begin immediately after an elevator is constructed is probably total nonsense.
That's correct, because the exponential growth will begin several years *before* the space elevator is operational, as soon as it looks like the project might actually succeed. Do you know how airplanes, satellite launches, RAM, and other items dependent on scarce, expensive manufacturing capabilities are procured? Companies purchase options for these things decades before they actually need them. In fact, much of the manufacturing capacity is *financed* through such options. Why would the space elevator be any different?
nobody invests in things [that don't exist yet]
*Investment* is by definition in things that don't exist yet. Otherwise it's called a *purchase*. Investors are very well capable of looking years ahead and weighting risk vs. profit.
it will take years of R&D before the new stuff that will be created will actually be ready to load on an elevator.
A communications satellite that goes to GEO by space elevator differs from one that goes to GEO by rocket only insofar as the former has to suffer far less g-forces on ascent and can therefore be built more cheaply.
The US would not be at all happy with the idea that China could cut of its reasonably-priced access to space, for instance.
Like they're not at all happy that China could cut off its reasonably-priced access to clothes, shoes, and electronics, for instance?
Be faithful to your obsessions. Identify them and be faithful to them, let them guide you like a sleepwalker. JG Ballard
With a properly designed gripping mechanism, movement of the cable is irrelivent. It's not really a "space elevator". It's more like a "space suspension bridge." Bridges move all the time, indeed a healthy bridge moves a few feet at a time. Since the movement is distributed over a distance of several miles, drivers on the bridge don't notice the movement. (The narrow bridge was a combination of being not stiff enough, wide enough to spread the motion across, and exactly the wrong length.)
One possibility motivation technique is to exploit the vibrations of the cable. You can make a wooden bead "surf" a standing wave along a rope, even against gravity.
Ok, that's a little far fetched. But so was the idea of wing warping that solved problem of Roll control in aircraft. (Well, until the invention of the flap.)
"Learning is not compulsory... neither is survival."
--Dr.W.Edwards Deming
Material of this strength allows other methods of space access that may be more efficient.
Tether a platform just a few dozen or hundred kilometers up, supported by rigid hydrogen-filled inflatables. Access it by elevator (but now, the cables can be over-engineered by a factor of 100, for safety). Launch from there, either chemically (standard single stage to orbit), or electrically (linear accelerator). Either way, you are beyond the bulk of the energy stealing atmosphere.
It is possible to build a linear accelerator several hundred kilometers in length, moored to the platform, that would allow launch of living payloads, because the average acceleration would be survivable.
-- -pjk Perry Kundert perry@kundert.ca http://kundert.2y.net