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NASA Still Wants Space Elevator
Jerry Smith writes "The Guardian reports 'Each of the groups that will gather in New Mexico is competing to win a NASA prize set up to encourage entrepreneurs to start development work on the technology needed to create a space elevator.' It still might take a while though, progress is slow, so slow."
when a plane runs into the elevator? It only takes one crazy pilot.
I know a man named Otis who invented a room,
And his heart was filled with pride.
I said to Mr. Otis, "What does your room do?"
He said, "It goes from side to side."
So I said, "Mr. Otis, if you take my advice,
You'll be the richest man in place.
You gotta take that room that goes from side to side,
And make it go to outer space."
And that was good advice, good advice.
Good advice costs nothing, and it may win a prize.
NASA offered me
Four-hundred-thousand dollars, whee!
For good advice.
Have you read my journal today?
FTA: As New Scientist magazine reported last week, the best performing robot last year managed an ascent of only 12 metres up a cable before it stalled, while no material came close to meeting the standards needed for building a space elevator.
Hopefully won't be too hard beating that, my mindstorm robot can do better!
It still might take a while though, progress is slow, so slow.
There is of course truth in that statement, especially considering the effective infancy of CNT materials science. Many gains have been made in the past 15 years or so, but it takes time...and thus the quote from the summary. We are today seemingly obsessed with instancy; however, this is to our detriment. Patience, patience!
They won't waste time and resources to create a folly, this principle is a worthwhile venture (if it can be pulled off).
Once you get one tether you can send runners down it with additional strands.
It would be strengthened and grow like a pearl from an initial seed.
The problem is getting that seed line up there.
liqbase
The same technologies used to build a space elevator from earth would be usable for building other things: space elevators for other planets, for one, since every body in the system that could use a space elevator has a shallower gravity well than Earth; inter-orbital elevators; rotating tether slingshots; ...
I just don't understand what would take a long time about developing a nanotube ribbon countless miles long, and then suspending it in space... what's so hard about that? I think I have enough leftover cables from old pc's to about get there, if only they were thinner.
stuff |
If they want a space elevator, they'll have to earn it the old fashioned way: buy enough candy bars to get a golden ticket, and by all means RESIST all temptation to snack on that scrum-diddly-umptious confectionary cornucopia when touring the factory.
Where were you when the voynix came?
If we are some day able to create this elevator, the distance involved means it will take several days to complete a journey from ground to earth orbit.
I have a hard enough time avoiding contact with "other people" in elevator cars -- but the real tragedy will be the music. Girl from Impenema for 72 hours straight?
Aaaraargh.
The only way I could see this working is if they piped in aerosol (-)-delta9-trans-Tetrahydrocannabinol and phillip glass...
Tornado's, earthquakes, hurricanes, flooding... Mother nature probably poses a very large threat to this thing. And it isn't like you can just let it float or move it around as the need arises, it has to be firmly attached to the planet. Granted a flood doesn't threaten it much, but high winds (hurricane, tornado) could damage the strand. An earthquake could damage the foundation that keeps it there in the first place.
And yes, an aircraft could just aim for it - though I'm sure there would be a lot of restricted airspace within miles of this strand, likely under the watch of the military, so you'd need a fast aircraft to make it there before getting blasted out of the sky. If they use this to launch satellites, you can bet access will be tightly controlled.
I'm still waiting for a giant slingshot. Something the size of an aircraft carrier. Muah!
In geostationary orbit, a LED ZEPPELIN will be holding up this STAIRWAY TO HEAVEN. They will probably outsource much of the work to KASHMIR. I hope the isn't a COMMUNICATION BREAKDOWN that makes the whole thing come crashing down OVER THE HILLS AND FAR AWAY.
How ya like dat?
The variables that need to be addressed are vast. Aside from the material needs I wonder if they are addressing the IT needs. The quickly changing variables such as adjustments from the moon gravity to atmospheric disturbances to maintenance and repair will require great models and this thing will need an amazing nervous system to detect problems before they bocome disasters. BTW: Where will the lower parts of this thing fall when there is a disaster?....
Don't forget GPS. And satellite TV. And high-speed intercontinental data backbones. And weather forecasts based on satellite imagery. Even 'failed' missions such as Beagle 2 resulted in significant scientific advances (in that particular case, reducing the size of a mass spectrometer from the size of two desks to something the size of a Kirk-era tricorder prop).
"Tornado's, earthquakes, hurricanes, flooding... Mother nature probably poses a very large threat to this thing"
History shows again and again how nature points up the folly of man. You know that once Godzilla gets a bus caught between two gargantuan fangs that he just can't pick out with his silly T-Rex claws, he's going to be looking for some good dental floss.....
Where were you when the voynix came?
"The same technologies used to build a space elevator from earth would be usable for building other things: space elevators for other planets"
Got enough rubber to mix in with the nanotubes? That space elevator to Mars is going to need a LOT of stretch.
Where were you when the voynix came?
Well, fortunately the NASA can use US Dollars, which are somewhat cheaper than Euros, or even British Pounds.
The Tao of math: The numbers you can count are not the real numbers.
Build a 40,000 km cable out of nano-parts that haven't quite been invented yet, and then stand the entire thing straight up.
Yeah, I'm not going to hold my breath on this one.
You see? You see? Your stupid minds! Stupid! Stupid!
I doubt we will ever see a space elevator. Not only is it incredibly difficult to create. The article clearly states that this technology is nowhere near and it would probably take at least a decade to create, if not two. By the time this is actually a reality - which is unlikely going to happen within 30 years - we will probably have way more efficient space travels as even commercial space tourism has started to kick in as well.
Point is, it would probably not take long before such elevator would be completely useless due to its slow speed and low capacity.
Full Tilt
the tension on the initial cable is going to be extremely high, and this is an application where microfractures of the nanotubes will introduce unacceptable points of failure. modern ropes and wires are constructed by a weaving process, of sorts, that take shorter strands and weave them together to make a longer piece. that weaving process creates micro failure points. so, not only does the space elevator project have to create a ribbon that is at least 100 miles long, it's very likely they're going to need to make it as one continuous strand of nanotubes 100 miles long. making a dozen strands, each 10 miles long, and connecting them is likely not going to work, as the connection points won't withstand the tension that's going to be on the ribbon. so, that's a major manufacturing problem that has to get resolved. also, there are logistic problems out the wazoo with getting all the pieces put together properly. unlike a skyscraper, or an elevator, which exist within one basic inertial reference field, the space elevator would exist in it's own reference field. if you don't believe me, take a look at the math and try to calculate the tension of a strand of nanotubes as it extends outside the gravity well of a planet. the math is based on our previous understanding of astronautics and physics, but it definately would extend our operational knowledge into new areas, thus requiring it's own learning curve. consider the amount of time, energy, and research that was spent developing our current operational knowledge of launching spacecraft, connecting spaceships with spacestations, and the like. we would be doing all of that over again, in the context of space elevators and superstructures which extend out of the gravity well. when you dock at the one end of space elevator, what happens to the tension at the other end? operationally, how do you deal with that? operationally, what do you do with a docked spaceship when a hurricane is entering the elevator earthside location? there are a zillion operational details which need to be worked out in both the construction and operation of a space elevator.
The government just prints more money when it needs some. Simple... Ok it's not that simple, really they usually borrow it, that's why you're 8.5 trillion USD in debt.
Deleted
Are they too lazy to take the stairs?
Stupidity is like nuclear power, it can be used for good or evil. And you don't want to get any on you.
The initial seed ribbon will not support very much, obviously. Beyond that though, even the early ribbons are expected to lift up to 200 tons. This is by no means a limit, merely what is expected to be the safest and most economical course of development. Once the initial ribbon goes up, it is pretty much inevitable that much larger ones will follow.
Moreover, even the first ribbon is expected to have a payload capacity of 13 tons, and a trip to GEO will take about a week. The useable capacity is *far* greater than with any existing means of launch. (The shuttle can deliver less than 4 tons to GEO, and it certain can't launch 50 times a year.)
This is a bit too simplistic however, for two reasons. As things go up the ribbon, they get lighter. In actuality, you can get much more out of the ribbon by sending multiple climbers up at appropriately spaced intervals. Second, many things only need to go to LEO, so the frequency of "launches" could be much greater.
I have been following this for some time... Here are a few links for ya.l Study
http://www.isr.us/Downloads/niac_pdf/contents.htm
LiftPort Group. Company wants to beat NASA.
Reference Site
Place a curse on the RIAA/MPAA
and a rather good image (I use it as my wallpaper)
http://www.mondolithic.com/06Gallery08.htm
Won't be cheap getting something like 23000 mi up.
Actually, all you need is a space elevator that can bring up a few pounds - then you keep running it, loading the mass at the counterweight. Then build a bigger cable, wash/rinse/repeat. Soon you are sending tons up at a time. Yes, it is expensive, but compared to blasting the stuff up into orbit, greatly cheaper.
No, I don't trust in god. He'll have to pay up front, like everybody else.
Someone asked, what about planes hitting the space elevator? Well screw planes, what about satellites in low orbits? It would be a long shot, but if one hit it would hit hard.
Finally, what's this thing supposed to sit on? I know a lot of it isn't supposed to weigh much (even though I'm too ignorant to understand why not, only the far endpoint is actually in orbit, the rest is going the wrong speed for its altitude), but the first few miles sure would. You can't just pour a concrete footing and then put near-infinite weight on it, it'll just drill itself into the Earth's surface. We'll be lucky if the Earth doesn't crack open like an egg! Well I guess we could spread the load out, maybe build a frame all the way around and balance it with another space elevator on the flip side of the world. I mean we didn't even get the Big Dig right and we're talking about this, might as well think big since we know we're kidding ourselves (except for the part about blowing our tax money, that's real).
At least that's the conclusion of Nicola M. Pugno:
the megacable strength will be reduced by a factor at least of ~70% with respect to the theoretical nanotube strength, today (erroneously) assumed in the cable design.
For this reason I've become quite skeptical. But please, prove me wrong, boy would that be cool.
Any sufficiently advanced libertarian utopia is indistinguishable from government.
Im not a rocket scientist, my name isnt Otis and Im not feeling that smart today. However here is my two pence idea: From what I understand the major hurdle in Space Elavator design is the weight of the cable. The longer it is, the heavier it gets, and it reaches a point when the material used for the cable is not strong enough to hold its own weight. I read carbon nanotubes are a great leap forward, but not good enough yet. So if weight is the problem. Lets lay supports along the way up, just like we do electricty pylons. Of course we can not have them down to the ground, so instead, why not at regular intervals, huge circular platforms with large gas envelops filled with hydrogen, (explosive but could be replenished all the time by elotrolizing water vapour making it self sufficant). These lighter than air blimpy things could take cable weight, lighening the load, and provide a cool viewing platform. If anyone things this would work and wins the contract, my only request is use of platform two and five to put an office and an apartment on so i can live in the sky. - Tristan
I don't understand why you think loading or unloading would take weeks, unless you're comparing it to the current processes which involve special packaging to handle the vibrations of rocket liftoff, which would be largely unnecessary with an elevator.
With an average speed of 50km per hour, it would take about ten hours to get to 500km, which could be a waypoint for transfers to other LEO objects. Getting out to 35,000km would take much longer at that velocity (about a month), but even if the cars were limited to such speeds in the atmosphere the speed could probably be accelerated once at least past LEO since friction and turbulence from the atmosphere are no longer any significant issue. At 500km per hour, it would take about a three days, and I'm sure there would be plenty to do along the way. If they can pull off 500km per hour average from the base to LEO, that keeps the travel time to about 40 minutes, which while twice as long as my commute is something I can handle on a frequent basis.
As to powering the unit, a nuclear plant would probably be used to start, and then eventually large solar arrays at differing points along the stretch would come into use, taking over the primary power duties while the nuclear plant remained as a backup.
Finally, the cost comparisons are hard to do. VoidEngineer threw out a trillion dollars as a construction price, but there are some estimates that come in much, much lower, especially since construction would take place at or near the equator -- as little as $20 billion, once the cable technology is there. I don't buy into something that low at this point, but I doubt it would be as high as the price VoidEngineer tossed out, which he said was an arbitrary number. Launch costs right now are significant; for LEO, a Russian Proton can put 44,000 pounds for ~$2000 per pound, the shuttle costs about $8000 per pound, and a Pegasus can cost $15,000 per pound. It's believed by some that it will be nearly impossible to get rocket-based costs below $1000 per pound to LEO with even the biggest launch vehicles. OTOH, a space elevator may be able to take loads into orbit for $100 per pound or less, with eventually dozens of trips per day depending on how it's built.
So let's say it's $100 billion to build, and $10 billion to maintain per year. For the first ten years ($200 billion), it would need to move 200 million pounds to make $1000 per pound. That's an average of about 55,000 pounds per day, or one fully-stocked shuttle launch. But that's not necessarily just putting things up; it can also bring things down, including rotating crews, satellites in need of maintenance that can't be done in space, retrieval of scientific experiments, and perhaps eventually even raw materials from the moon. However, the more trips that are made, the more infrastructure is in space, and the more there will be to do, including adding to the elevator's schedule, further depressing the price. The numbers here are, as with VoidEngineer's, completely arbitrary, but they show how quickly the costs can flatten out.
You can never go home again... but I guess you can shop there.
Hey guys, somebody better call up NASA and ESA real quick! They think they're going to build one of these fancy "space elevators", right? Well I'll have you know that some guy on the internet uncovered a fatal flaw in their plans. And he got modded informative! Alert your Congresscritters everyone, we don't want to be wasting time on an idea that's obviously flawed.
"When we do get strong enough carbon fiber filaments (or diamondoid nanotech or whatever) to produce a space elevator, then we can start building it."
Call me crazy, but I think thats the whole fucking point or R&D.
We dont have the tech now, so we go and try to invent it.
How amazing boring would human society be if we simply waited around for new technologies to fall from the heavens instead of actively searching them out?
When we do get a strong enough carbon nanotube rope to build the elevator, we will. And there's nothing like trying to build something to ensure that your materials are up to the task
Come read my stupid blagablog. Rants and Giggles
It seems to me that the problems of building a Space Elevator would be significantly reduced if be built one from the lunar surface. With one-sixth of the gravity of the earth, would it be practical to build a space elevator to the lunar surface with currently available materials?
Might this not be a useful exercise to demonstrate the feasibility of the "Space Elevator" concept, while also giving us relatively easy access to the lunar surface?
In terms of energy losses, the elevators are generally accepted to be more effecient (admittedly this is theoretical).
It takes enourmous amounts of energy to put anything in orbit. Period. Future technology, in whatever form it takes, will face the same physical limits.
Rocket fuels aren't cheap, and aren't going to get cheaper. Moreover, rockets have a very low weight limit - those commercial launches you mention put up tiny satellites, and even then they cost through the nose.
Show me the advanced launch tech that can put something heavy in orbit today. Oh, right, it's that model of effeciency the space shuttle. Trust me, if that's the cost per pound that a space elevator has to beat, we could make it out of pure gold and still come out ahead.
We don't have anything that can do what a space elevator can. Unless you can show me an example of a launch system (existing or theoretical) that can carry the same weight, then your arguement that "by the time we can build the space elevator, we'll have better tech", is invalid. Seriously, go take a look at stuff like the X-prize craft - these are the "spaceships of tommorow" and they still carry very little payload, to no higher than LEO, for a hefty price.
Erotic is when you use a feather. Exotic is when you use the whole chicken.
In the last discussion we had. You're getting very close to troll territory my friend.
REPOST:
With all the talk lately about a space elevator, I got to thinking after recent slashdot discussion, just what advantages would a space elevator offer over a tower launch? I contacted the man responsible for a similar idea, the skyramp, (warning: hideous javascript menu may break firefox), Carlton Meyer, and had a dialogue in which he pointed me to the tower launch archive.
The ideas I see bandied about there are similar to what I had in mind, which would be essentially an 11km tall tower (think pylons rather than skyscrapers, based at sea), with evacuated airless launch tubes, using nuclear reactors to power a maglev or pulley system to accelerate vessels to escape velocity. These would then emerge above the end of the troposphere [gatech.edu], with it's associated weather and air pressure, and have little to no fuel needed to escape the earth's gravity, meaning you could do a lot more while you were up there. At normal launch accelerations you can get to LEO with very little external propulsion.
Not only would this enable multiple launches daily, it is, unlike the space elevator, readily achievable with today's technology, and financially viable as well. Given NASA had an annual budget of $16.2 billion for 2005 [space.com], and a nuclear power plant costs a cool billion to build, give or take, we could have this up and running in a few years.
Space has got vast, essentially unlimited resources. One recent story pointed out the trillion dollar iron asteroid up there. The thing has about 5 tons of steel for every man, woman and child on earth. And thats just one of god knows how many... billions more?
Once we leap the cost to escape hurdle (as I think I have managed), we can proceed to use these resources. There are several obstacles in the way of this, first of which is zero gee mining, we have no idea how to do it. We can either mine the ore out there, or bring the asteroid back into orbit and slice it up there. Or slice it up and send it back to orbit. I would be opposed to moving it back into orbit for processing, purely for the debris issue. Perhaps a lunar base would have some merit there.
So we set up a mining and processing operation either on the moon or in deep orbit, and start cutting and processing one of those bad boys. Whats the first thing we build? A bigger processing and mining operation. Space exploration, much like the internet, has to be a largely incestuous affair at first, existing solely for its own benefit.
Once we have that mastered, we can move to algae pods in orbit for food production, oxygen refining, and fuel production (biodiesel or chemical engines), all of which can be powered by the immense energy of the sun, and use the raw materials abundantly available in space. Whether you ship that stuff back to earth or use it for further colonisation, its a vital step.
The production of automated scouts is also a high priority; a vast amount of surveyor and prospector drones to sweep and map every square inch of every rock and gas in the system, out to the Oort cloud, and figure out what they are made of. I'd err on the side of quantity rather than quality, still no reason not to have either. This could be combined with deep space observatories that would make hubble look like the end of a coke bottle.
So now we have a manufacturing bridgehead, a good idea of what's interesting out there, and a cheap means to launch to orbit. Actual manned system ships would come next, to either colonise or investigate the system. The rest, as they say, is (future) history.
A lot of this would require automation, robotics, right up to the point when we build a larger manufactory from the orginal small one. Robots would als
What he can't kill, he has sex on. Trent.
The SE is a rock on the end of a very, very long string, being whirled around by the Earth's rotation. That's what keeps it up -- what's sometimes called centrifugal force. Pulling inward/downward on the string doesn't cause the rock to fall; if the rock is whirling fast enough, it won't even be pulled down, and when you stop pulling, the rock is still there. There's no real notion of "center of mass" of the SE as a whole. The majority of the mass is well above GEO.
The "rock" will actually be all the construction machinery that was used to build the SE, a few hundred machines that climb it and add a tiny bit of material all along its length while they're going up. They will have a total mass of about 650 tons and be at an altitude of 100,000 km. The CNT ribbon will have a mass of about 950 tons. We'll be able to send up a 20-ton climber with a 13-ton payload every four days, or a 10-ton climber with a 6.5-ton payload every day. (Gravity falls off so quickly that a given climber is down to 50% of its weight when it's 2600 km up. That's what makes it possible to send up smaller climbers more often than you'd expect.)
If you accelerate something to escape velocity, it does exactly that: escapes the gravitational attraction of the Earth and never comes back, unless it's decelerated by some unspecified means. And escape velocity at 11km height means it will be burned to ashes very quickly, remember the Columbia. With our current technology level, building a ship that can fly at escape velocity at 11km height is much more difficult than building a space elevator.
OTOH, if you want to put something in orbit around the Earth, then you should give it orbital velocity, which means it should have a very high tangential velocity around the Earth. You cannot do that with a vertical tower, unless that tower reaches the synchronous orbit altitude of 36000km, which is the whole idea of a space elevator. Remember, velocity is a vector. It has both magnitude and direction. If you want to reach orbit, it's useless to throw something straight up with a high speed, because it will fall straight down.
Well, you may say, let's make the top of the tower curved, so the ship will be accelerated tangentially. Do the math. Find out how big the curvature radius must be so that the ship isn't subjected to deadly accelerations in order to convert that vertical velocity to orbital, i.e. tangential, velocity. That math has been done even before artificial satellites reached orbit. I have an old book, "Flight in Cosmic Space", written in 1952 by Russian scientist Ari Sternfeld, where he analyzes, among other concepts, the idea you have proposed. A practical accelerator to send a ship into space would have to reach a 100km height and have a curvature radius so great that it would be several thousands kilometers in length.
Seeing as how the price to Geosynchronous orbit will be measured in cents - the price of getting cargo to an equatorial base is negligible.
Storm are not problem either - because you do NOT build the thing and attach it to an island. You build it on a floating platform, and the platform is powered. When a storm comes, you simply drive the thing in the opposite direction. The platform can move a coupel of hundred miles to avoid bad weather. This has already been thought of - and the math/engineering works just fine.
How many escape pods are there? "NONE,SIR!" You counted them? "TWICE, SIR!"
Um. All the first order research was done by the military. In particular the German military.
I'm going to assume you're including the efficiency of the electricity generation in that calculation. i.e. Start at around 35% efficient and get worse from there. It will almost certainly require a dedicated nuclear power station to run.
Rocket fuel is not the expensive part of the operation, the fuel cost is negligible compared to the cost of the administration and infrastructure. i.e. the NASA bureaucracy. The shuttle should of course have been scrapped decades ago and replaced by an unmanned heavy lifter, but that's NASA for you. Atlas V, Proton etc can both handle payloads about as big as the shuttle and for a tiny fraction of the price.
Um, I haven't made that argument. My argument is that by the time a space elevator comes around, rockets and rocket launches will be on a production line and their costs will be amortised over far more launches than currently. Commercialising the launch business will bring cheap space flight, NASA never will.
Deleted
The climbers going up the SE will be the size of a small bus, about 10 tons, and will go up one per day. It's unlikely any will come down the SE; standard reentry procedures are much cheaper for that. The very first thing we'll do with an SE is build another, and then another; after a decade or two, there'll probably be a dozen SEs sticking out from the Equator. The first one may cost $10 billion, but the second will be 20% of that.
This is only tangentially related, but I thought /.ers would enjoy seeing this space elevator concept video, made by my friend Alan Chan. He's done special effects for LOTR and Harry Potter, so the production values on this video are much nicer than your standard NASA flick.
There is also a very good companion article on IEEE Spectrum, and a fun interview explaining how it was made (short answer: lots and lots of Lightwave).
No, I'm not getting paid to promote this or anything, I just enjoy sharing it with friends/family, and thought a few of you would like it as well. Alan Chan's a ridiculously cool guy, I mean anyone who could make a short film entitled 12 Hot Women and get people to play it at pretentious movie festivals... wow.
It still might take a while though, progress is slow, so slow."
It's not slow, it's incremental.
This is an important distinction. Incremental advances allow for a stable and mature system to emerge.
Stable and mature are good things in this environment.
Display some adaptability.
Well, I can think of two reasons: (1) an elevator would be more fail-safe... i.e. if you ever need to shut down the lasers, your elevator car comes to a halt, puts on the brakes, and waits for the lasers to start again, whereas a free-flying vehicles would fall to its destruction. But more importantly, (2) it's not clear to me how a free-flying externally powered craft would work. How is the received laser power to be converted into upward acceleration? If it's done by boiling reaction mass off the bottom of the craft and shooting particles towards Earth somehow (i.e. rocket-style), then we're back to the original scaling problem of having to lift additional mass. A Space elevator solves the problem by giving the craft something to pull against, so it can just use an electric motor to lift itself. I'm not saying it can't be done -- as you say, the energy is there -- I just don't see how.
Why the hell would we lift raw mass out of our gravity well when there is so much of it available in much shallower wells?
Seems like there is a bit of a chicken-and-egg problem there: you need large manufacturing facilities in space in order to make all that stuff from raw materials up there, but the large manufacturing facilities are far too heavy to lift into space.
I don't care if it's 90,000 hectares. That lake was not my doing.
The laws of physics work just as well for any nation.
I am convinced that Man will conquer space. Whether the dominant language is American-accented English, Mandarin, Spanish or Japanese is still uncertain, but your capability remains.
You have a brilliant track record, and a wonderful people. Your achievements have inspired me to a thousand times greater use of my potential, my career, than I would have ever reached without them.
However, from across the Pacific it looks like you're in a kind of perpetual Saturday afternoon over there. Might I diffidently suggest that you, as a country, get up off your arses and start doing what you were best known for again? Your beer is terrible, your automobiles are awful, your cuisine apalling, and your politicians are worse than the French.
But your aerospace engineering is utterly superb, and the hope of the race. Don't let the rest of us down.
Do not mock my vision of impractical footwear
I am feeling SO disappointed with my fellow slashdotters.
I've read through every comment on this thread that is scored 2 or above, and every one of you is seeing less than half of the space elevator's potential. You are all so one-way in your thinking.
Let me try to prime the pump of your imaginations...
Visualize a one pound iron ball, sitting in your hand. How much energy would that ball release on impact if you are on an airplane at 5,000 feet and you drop it out the window? Do you think it might break a car's windshield? Do you think it might put a heck of a dent in a car's roof?
Now drop it from 23,000 miles....
So long as we move enough mass down the space elevator, we can capture enough energy using existing regenerative braking technologies to power lifting side. If we move more mass down than that, the space elevator becomes a power generator. And the beauty of this is, it isn't important what we move downward, so long as we can put some kind regenerative braking on it.
As we begin to explore space elevator technologies, we should also begin to think about how to start nudging a near Earth asteroid into a position where we can get at it easily when we are ready to start dropping things down the elevator shaft. Ion engines might be the ticket. At first it won't matter much what we drop down the shaft, but eventually we'll get more picky.
At some point we'll want to build a solar powered distillery at the end of our string, so we can deliver bottled water mined from comets or icy asteroids to the thirsty. We'd do the bottling at the surface, after running the water through 23,000 miles of water wheels and turbines. And we'd probably build a solar furnace at Strings End to reduce nickel iron asteroids to ingots that would fit special drop tubes.
Well, that's it. I'm tired of playing Heinlein. Somebody else can imagine the distribution system for the surplus power.
There's the idea of laser launch - instead of providing the energy to vapourize propellant with chemical reactions, you aim a laser at the spacecraft to do the job.
Secondly, there's a variety of space tether schemes that don't go all the way down to the surface; instead, they dip down to an altitude and relative velocity where they could be met by hypersonic rockets. These have the rather large advantage of not requiring super-nanotubes. here is a NASA-funded study on the idea.
And, of course, there's always Project Orion - explode nuclear bombs beneath a gargantuan steel plate to push the thing along...but somehow I don't see that one getting approved any time soon
Any sufficiently advanced technology is indistinguishable from a rigged demo
--Andy Finkel (J. Klass?)
Here's a no-duh sort of idea: Why not attach an inflatable ring to the payload when climbing the ribbon and fill it with helium? I mean really, is there some limitation on the contest for climber robot designs that says you can't send your robot zooming up the first quarter of the distance into space using helium to lift the payload? Your climber, for that distance, is really just tasked with keeping a firm grip on the ribbon so it doesn't float away. When the climber gets to the point where it's carrying the balloon instead of the other way around, it would deflate and stow the balloon, or send it back down, and continue on its merry way. A whole lot of lift on the cheap.
Just thinking out loud....
*** *** You're just jealous 'cause the voices talk to me... ***
Energetically, the elevator really starts paying for itself once you bring an asteroid or three into orbit and start using the potential energy stored in them (and their raw and barely refined materials - including fresh water) to raise things like people, finished goods, and supplies into orbit. As long as someone wants those raw materials on the earth enough for it to be worth getting them into GSO, that energy is free for the taking.
As The Man (Heinlein) said, "Low Earth Orbit is halfway to anywhere" (meaning that it's very high in our gravity well, such that you've got about half of the energy you need for escape velocity). Geosynchronous is much further out than LEO is - it's most of the way to anywhere, and that works both ways.
"It is our blasphemy which has made us great, and will sustain us, and which the gods secretly admire in us." - Zelazny