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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."
A REAL all-out space race, open to everyone with will and a national budget, winner probably getting to own space
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.
DoggWhenever a space story is brought up, some person always brings up the argument that perhaps we should spend money on the poor instead of a useless space elevator (or whatever the space story du jour is). I don't think they are arguing correctly. Space is just as important to human advancement as feeding the hungry, curing chronic diseases, and providing a livable environment is. I don't think you can order these in importance, they are all important.
But they go hand in hand with each other. Unless we truly believe Matthew 5:5, that the weak will inherit the Earth, it will take a worldwide view of humanity to move us to the next stage of human advancement which is the eventual separation of humans from the Earth and into the galaxy. We can go this alone, leaving the world's poor to their own devices, while the space superpowers leave them behind. However, when the day comes that certain small groups of humanity take to the heavens leaving this world and venturing off into the depths of space, how will history treat those of us living now who failed to hold the hands of those unable to stand with us as we raised humanity to new heights?
The space elevator is a great achievement. Hopefully we will begin to have a true space-based space program that is not dependent upon sending rockets to the space station. This would be the largest step in the path to Earth separation since the first manned space programs.
However, taking steps only with our strongest leg means we are still limping. We must strengthen all our limbs as members of the human family, IMO.
I have been pwned because my
Two different elevators guy. One on mars and another on earth. For lauching payloads from both planets. We are going to eventually have to travel home from mars....
there are no stupid questions, but there are a lot of inquisitive idiots
Methinks Laubscher has read too much into Kim Stanley Robinson's books.
Don't get me wrong, they're great SF, but the modern designs for a space elevator don't have much in common with KSR's.
SB
It's old. The more humans I meet, the more I like my cats. At least they are honest.
If this is soon to become a reality (a large if, see my post below), than every nation on Earth is going to want to host it. Would Equador have enough standing on the world stage to pull this off?
Bouyant cables, even in the best case, can't get you out of the atmosphere, so maybe 1000 km on the top side. The space cable has to reach geostationary orbit, some 35,785 km out. You lose :)
One question : the basic plan involves transmitting power through microwaves or laser light, enough electric power to provide the kinetic energy difference to actually put a vehicle in orbit. Why not skip the development of unobtainium and skip trying to put a super long and heavy cable in orbit? Just build the power laser facility 10 times over, and build spacecraft that use a block of inert propellant, heated to millions of degrees celcius from pulses from the laser and pulsed such that the shockwave is a planer wave coming away from the spacecraft. So no nozzles, no rocket engines, no pumps, no chemicals, no fuel, no explosives...all the stuff that make spacecraft expensive and dangerous. Just a block of cheapo rock and a spacecraft built like a cheap copy of an Apollo capsule made by the Russians. Would be safer as well, since in-orbit is pretty safe (there are patches to plug small holes), launches no longer can blow up, and reentry is much simpler and less error prone that with a space shuttle. Finally, that kind of laser would make a rather fine weapon, and would help out military applications as well (so could get some of the funds from the U.S. military budget)
1/625 possibility of 'severe damage' (aka destruction) from the 2031 Leonid Shower is a pretty damn big risk, if you ask me. I imagine that every nation that might get smacked by falling debris would have an objection to this ever going up on this basis alone.
Laugh while you can, monkey-boy!
Instead of each nation trying to build it in competition, why don't we try to build it all together? Maybe this is the event we need to unite as a world, Star Trek stylee...
There are only 10 kinds of people in this world... those who understand binary and those who don't
They insist that one day there will be lots of elevators ferrying satellites, prospectors and even tourists into space.
"If the whole thing fell somehow like you cut it at the counterweight, cut it way up at the counterweight, it would wrap around the Earth a couple of times,"
These all have to be on the equator. If one breaks and wraps around the earth it would take out some others - chain reaction.
Heavily populated areas near the equator are in western Sumatra, Borneo, Celebes, Uganda and of course Ecuador.
At least if you found yourself caught with a VC in this elevator, you would finally have time to really pitch your business plan.
On a serious note, they predict it would be hit, if not moved, by a large space object around once a year. They think they can spot these objects and move it as needed. But what about smaller objects. How much damage will they do? How easily can they be detected? How often will they hit?
And worse, what about deliberately launched smaller objects, radar-invisible small objects fired by a nation that doesn't want another nation to own space.
Has it been over a year since you last donated to the Electronic Frontier Foundation
Instead, the "meek" originally intended was a word to describe a ready and willing warrior.
Can you give me a reference for this? The OED has no mention of this inversion of meaning. The closest it gets is the primary obsolete meaning, "Gentle, courteous, kind. Of a social superior: merciful, compassionate, indulgent." (see http://dictionary.oed.com, subscription required).
Probably preaching to the choir, here, but just in case someone hasn't read it... I found Robert Forward's 'Indistinguisable from Magic' to be a pretty good read. If you like the idea of a space elevator, then you'll love the rotating 'space bolo' version, kind of like a bullroarer on ubersteroids.
The earlier posts on 'space bungees' might not be so far off the mark after all.
Anti-gravity? That was *my* little secret! But I never patented it! Boy, was *that* dumb!
If i was in charge of raising funds, then i'd be damn sure that it worked... one gram of Carbon Nanotube costs around 1500$ to produce.
"Oops, we just threw 15.000.000$ out of the window, after 10Kg of it disapeared in the mail..."
On the other hand.. Just because its expencive, it doesnt mean its not worth trying. I assume they keep in mind that a project like this easily can stirr up some anger among the tax-payers, if it fails.
this is probably the most boring sig in the world
"You could use solar-powered pumps to maintain vacuum in thet floats." :)
No, they will use cold fusion instead
Yes, it sounds outrageous, but it's theoretically possible to do this with nanotubes, apparently. As I understand it, nobody has actually demonstrated a macroscopic piece of nanotube composite with this kind of strength though.
True, but the things made possible with such a material would surely attract billions of dollars worth of R&D. Can you imagine what it could do for things like aircraft design?
Any sufficiently advanced technology is indistinguishable from a rigged demo
--Andy Finkel (J. Klass?)
Cripes, these ships are probably going to be pretty small, aren't they? And there won't be much to do? And it's going to take a week?
I wonder if there's any chance that it could use a maglev system. Japan's at 581kph or so. If you could fly straight up at even 500kph that cuts the trip down to 3 days.
First of all, I would imagine the $5B stated for the Space elevator includes at least some R&D costs. At $100 million, the nanotube composite rocket contains none - in reality, the cost will be much higher.
Furthermore, consider the cost of lifting each set of cargo - just like the space shuttle is extremely expensive, the fuel for a nanotube rocket is going to be much more expensive than that of a space elevator, which doesn't need fuel to come with.
So in reality you have: Space elevator: Maybe $5B, but pay it once and you've got the bulk out of the way.
Nanotube composite rocket: Billions to start out, >$.1B per rocket (my guess), and millions for each launch. Plus a lot more inspection and stuff.
Which turns the tables a good bit.
Not speaking as a physics grad here, and possibly talking out my ass, but I was under the impression that the space end of the tether would be a little outside the balance point, such that (if not for the cable holding it down) it would continually try to fly off into space. Thus, when it's energy was sapped by the launch of a new spacecraft, it would in turn sap the rotational energy of earth to return to it's highest possible orbit.
There ain't no free ride into space: The elevator will simply replace violently exothermic chemicals with the slow sapping of earth's rotational energy.
There is one problem that doesn't seem to be addressed -- the problem of imparting the necessary angular momentum to the elevator car as it rises.
From which follows two full screens of "sky elevator is falling" whining, ending in this choice quote:
Any object lifted to the sky station is going to "steal" angular momentum from the sky station, and once you let go of anything, you will never get back that angular momentum, and there will be no way to straighten out the tether again.
Swing your yo-yo around your body. Then, swing faster. Notice how the yo-yo catches up after a few rotations?
Funny, isn't it?
The beanstalk *would* lose some angular momentum as the elevator platform rises to the top. It would tilt to an angle, and lose a bit of altitude. But, the bottom end is tied to the Earth, which would be busy pulling the whole shebang forward, back towards a balance.
Eventually, the elevator would catch up, just like your yo-yo. There'd be a very real threshold for the amount of angular momentum you could use. Also, that angular momentum would be regained when the elevator car comes back *down*...
Best bet would be to have two strings, one for cars going up and one for cars going down, say, a thousand miles apart.
Then, the equations would almost always be nearly matched, and you could start moving several cars a week, instead of just 2 cars a month. You *know* that the weight of a car would be squat compared to the weight of the string itself, so several cars at once should not be a problem.
I picture X cars climbing, X cars dropping. The two strings would be arched in a giant pointed loop, bowing away from each other.
Neat, eh?
I have no problem with your religion until you decide it's reason to deprive others of the truth.
It'll be at least a century before one of these things actually do anything useful.
What's sad is that it may well take that long.
However, the best thing we could do to promote the sky elevator is to develop and build nonotube-based structures here on Earth.
For example, if you were to rebuild the Golden-gate bridge in San Fransisco with nano-tube cables instead of steel cables, would they even be visible from the shore?
An impressive, previously infeasible structure, such as a bridge spanning the entrance to the Mediteranean, or across the English Channel would do much to get everybody used to the idea that something like this could, in fact, be done.
Also, projects like this would give us opportunities to answer questions about its durability, relability and safety in a large number of circumstances.
Building a space elevator with nanotubes as the first project is fundamentally stupid. Build something more reasonable first!
I have no problem with your religion until you decide it's reason to deprive others of the truth.
Didnt NASA experiment using a tether miles and miles long to produce electricity? What if the space elevator generate huge amount of static electricity as the "rope" move through space?
You do undergo lateral acceleration; the cable exerts lateral forces on you as you go up. Think about it: you start moving 1 Earth circumferences/24 hours at the bottom, and at the top you're moving around 5 Earth circumferences/24 hours. Somehow, while moving up a cable, you've increased your velocity.
:) At each point, you don't move much faster or slower than the piece above or below you, so the acceleration is very gradual (they're talking about hours to days to climb these things). The momentum of all the junk at the counterweight takes care of the rest.
How does this happen? It happens over a very very long piece of string.
As for catching things in orbit, it's just a matter of falling off at the right point and converting your potential energy to orbital velocity (kinetic energy). While it takes a lot of energy to climb out of a gravity well, you actually have a net gain of energy going down an energy well (although in conventional rockets, the energy is being gained by your reaction mass). That's why you can use little dinky rockets to deorbit a spacecraft; that's the easy part. It's equally easy to use a little less thrust and simply move to a lower orbit.
Geosync is approximately 22,241 miles away. Earth's circumference is about 24,000 miles. So, assuming you have a big counterweight asteroid, and not a double-length space elevator, a little less than once. Depending, of course, on where the break occurs.
The carnage that such an event would wreak absolutely beggars the imagination. Read Kim Stanley Robinson's Red Mars. Skip to the last few chapters if you just want the space elevator stuff.
Why yes, I AM a rocket scientist!
I predict that a space elevator will make the cost of the lunar landings look like peanuts. I very much doubt it'll happen in our lifetimes.
NASA is the reason space is expensive. Companies like Starchaser and Scaled Composites are the ones who will make space cheaper and will "own space".
Government of the people, by corporate executives, for corporate profits.
I've fiddled with the math for these kinds of things for decades on an old idea called the "launch loop". The dynamics of long tapered cables are not impossible, but they are nasty. Very long cables are not like a stout rope to a fixed point nearby, they are more like reaction mass that vibrates. Think "Tacoma Narrows Bridge", which fell down because 1930's engineers did not take their differential equations up to 7th order.
As a climber goes up, the surface anchoring system must pay out more cable to fill in the less tensioned region under the climber, faster and faster as the climber accelerates up the cable, proportional to the speed of the vehicle, total acceleration (including gravity) and inversely proportional to the mass per meter and the square of the propagation velocity of the material.
This is continuously changing, so forces and velocities at the surface are changing also. The problem is, this is an underconstrained and essentially undamped end-terminated system - as the cable gets very long, you develop big standing wave complexes with only two points (surface and top anchor) to remove or store the energy. Keeping the standing waves from building up is difficult, but not impossible. However, it does add an additional constraint on launch rate; you have to spend a lot of time damping out the waves, even granting that these people are more clever than I am at modelling and removing this energy.
Tapering of the cables, necessary even with magic nanotube unobtainium, makes the math even more "exciting", with the additional constraint that the through-atmosphere sections, along with the sections that dip into the atmosphere during wave motion, have to be thoroughly protected against atmospheric degradation (hint: C + O2 -> CO2 ). The portions of the system below the Van Allen belt have to be armored against atomic oxygen damage. Atomic oxygen will burn off the leading edge of ISS at rates approaching a millimeter per decade; the space elevator will be stationary in the gas field, but there are still a lot of fast moving oxygen atoms up to, and through, the radiation belt.
All motor driven systems have limits to their power-to-weight ratio. To get to GEO, we have to add about 60MJ/kg. If we take 33 hours to do so, we need to move an average of 500 watts per kg (total climber weight) through the (photovoltaic or microwave) energy collectors, motors, rollers, etc. For comparison, a 1500 kg sports car with a 300 horsepower gasoline engine uses 150 watts per kg. However, that underestimates the problem. Most of the energy will be added at the beginning of the climb, during the first 10% of the travel distance, as the climber leaves the depths of the gravity well, so expect thousands of kilowatts per kilogram in the power train during this phase. If there are unexpected variations in the power, the change in climbing acceleration will add more ripples to the cable.
I tried to avoid these problems with the launch loop (see URL below) by keeping the altitude under 100 km and the motors on the surface. Even over those "short" distances, cable propagation issues are problematic. Funny/bad things like lightning, ice buildup, fractally gusty winds, and jittery payload forces require special attention, and all reduce the capacity of the anchoring and stability cables. Everything above the atmosphere is exposed to a steady rain of the garbage that your launch system has accumulated in orbit (it all comes down, eventually). Reentry systems for human payloads (in case of failure) add weight. Problems, problems.
At the end of the day, though, the killer issue is lack of demand. The launch loop, with about the price as a space elevator (+/- 3dB) and using materials and technologies we have had for two decades, can put 80 tonnes of payload into orbit *per hour*, for less than $10/kg. Unfortunately, nobody wants that much mass in orbit, even at that miniscule price. Perhaps "if you build it, they will come", or perhaps you end up with another white elephant lik
Keith Lofstrom server-sky.com
When you are a scientist, it is always a good idea to ... well, can you give me
be a skeptic...
I'll get excited when they can grow SWNT's of 1 m length
and demonstrate no defects and high yield. Going from
1 m to 1000 m is probably not so hard once the earlier
orders of magnitude are scaled.
Fundamentally, the reson I am a skeptic is because
carbon forms bonds too readily so getting all bonds
to be aligned is hard. We are just now learning how
to make small single crystal diamonds, HOPG is not
even available in single crystal form (you always
see that mosaicity quoted next to samples) and
carbon nanotubes develop defects if you so much as
bend them too much (heptagon-heptagon defects IIRC - our group has imaged those with STM). Growing
single crystals of anything is hard, growing
large single crystals is
one example of a large (building size) single crystal
sample (and yes, man-made, not those burnt out stars).
You're right, you would have to do some serious lateral acceleration to get to the top. Luckily, this is spread out over a 1-week climb so the specific impulse required is not too great.
But actually, the lateral acceleration at the top of the elevator is one of the main selling points. By the time you reach the top of the elevator, you've got enough angular momentum that you can just let go and be thrown to the Moon or Mars for free.
I'm pretty sure the 100 GPa rating for a 1 meter wide cable already has a safety factor of 2 built in. If you wanted 3, then you could either go to 10 meters, or wait until you could manufacture a stronger (150 GPa) composite material.
The channel tunnel cost $21 billion and that's just a couple of big holes in the ground. The cost is going to have to be amortized across generations of users. I do agree with your point though.
More people fly from the UK to the continent these days because it's much cheaper, faster and more flexible.
Government of the people, by corporate executives, for corporate profits.
Space elevator doesn't need fuel? How do you think things get lifted? Magic? Then you have the interest on the billions in loans, maintenance and repairs to hundreds of km of nanotube ribbon and can you imagine the insurance bill?
The huge cost of the space shuttle has nothing to do with fuel, it's just NASA. Other countries can lift large payloads for far less. Rockets can be mass produced, space elevators can't.
Government of the people, by corporate executives, for corporate profits.
I presented at the 2nd SE conference in Santa Fe last year, offering a different way of constructing it, but my comments apply to Dr Edwards' design too.
One of the best things about space elevators is that they are inherently much safer than any other method of reaching space. In fact once a couple of them are operating one can use the exponentially increasing payload capability to builds space elevators with any desired safety factor.
-- Andrew Price
its not like we're talking about building it out of iron.
well - you asked about the wars. You might want to read James Jones works. Do a google search. I read from here to eternity when I was in grade 8 and it had quite an impact on me. If you read the books (best - do this first) then read books like the 20th century march of the dead it might give you some idea of what the war was like and why young men would be willing to throw away their lives.
Now to the rail guns.
Please consider the last shuttle disaster. Note that it took place at high elevation.
Clearly, a projectile launched at the surface must have more kinetic energy than the same projectile at the shuttle's location. Clearly at low elevation the effect of the atmosphere is many many times worse (follows an exponential in fact)
If the shuttle has a tough time protecting itself against re-entry then imagine the order of magnitude worse problem of gaining orbit from stored kinetic energy.
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Any system that is going to work has to feed energy into the launch craft on a more or less linear schedual. Given the ability to get a craft airborne using external energy feeds - then clearly we should be able to sustain the energy flow into the craft and there is a continous energy draw function and a continous energy drain function and a continuous drag/heat function and similar lift functions.
As a mathematician who has not tried to caclulate a window through these functions... my gut feeling says there is one and it is rather large.
So you can go to hyper velocities but you must choose a high elevation where you do this - where the air is rather thin.
Brute force blasting from the surface will gain a melted bullet. But - you might hide a nice little spacecraft in the wake..... agree?
It WILL be one helluva boring ride, that's for sure. Even if the thingy accelerates to like 2000km/h it'll still take like 50 hours to reach the top. Hope that elevator has a good bathroom and a nice restaurant not to mention a bed innit.
What kinda pings do you think they'll get from up there by the way?
Sigs for Nerds. Sigs that Matter.
Because there is usually a small percentage of the population with effectively total control of the populace that has no interest in letting the rest of the world help?
Imagine trying to provide healthcare, education, and the right to walk in sunlight to women of Taliban Afghanistan...
It does not bode well for you if you're measuring your self-worth by how you get modded on slashdot.
Currently: dry weight 80 tons, payload 20 tons.
;-)
After replacement: dry wt. 2 tons, payload 98 tons
(I mean, the stuff is 40 times stronger!)
Seriously though, availability of this material as a mass product would revolutionize aviation and astronautics long before anybody even mentions space elevators.
Space elevator doesn't need fuel? How do you think things get lifted? Magic?
Obviously the space elevator needs energy input and ultimately fuel, but it has two big advantages: 1) It doesn't have to carry its fuel and associated mass in the launch vehicle; 2) It uses friction rather than fluid thrust; I suspect this is much more effient else my car would have air propulsion of some sort.
They seem to have plans for maintenance and repair by automated crawlers, but obviously it's never been tested with long high-load carbon nanotube ribbons.
Rockets can be mass produced, space elevators can't.
The first one can't, but the rest can (theoretically) be manufactured in place by crawlers traversing an existing elevator.
In cost comparisons in the thread-starting post he neglects to consider at least two things: 1) The cheapening of additional elevators for higher aggregate launch capability at successively lower incremental costs; 2) the ability to slingshot vehicles far into space from the end of the elevator.