Space Elevator A Real Possibility

The space elevator may be a very real possibility within our lifetimes. Previously the stuff of science fiction novels, scientists and engineers around the world will continue their discussion at a conference in Japan this November. The space elevator’s basic design would include a cable that is anchored to the Earth’s surface, and on the other end, tens of thousands of kilometers away, a counterweight for balance. The space elevator could be used to solve many different problems, from nuclear waste disposal to powering homes with solar panels.

The technology driving the development of the space elevator is the carbon nanotube. Its lightweight properties and tensile strength, over 180 times stronger than steel cable, make it the ideal cable for the space elevator. Currently there are several logistical problems, which range from designing a carbon nanotube strong enough to support the elevator to finding an ideal site to design and build the elevator, which would require international consensus and input. Several organizations are working on space elevator designs, and NASA is holding a $4 million Space Elevator Challenge to encourage designs.

55 thoughts on “Space Elevator A Real Possibility

  1. “and NASA is holding a $4 million Space Elevator Challenge to encourage designs.”

    Didn’t we just approve some kind of bailout package for around $700 billion?

    I think a space elevator would be much more useful than a bank bailout.

    I vote to divert some funding to NASA.

  2. Mark my words… “The Space Elevator will *NEVER* work!” Signed Almost_There 2008/10/07

    The biggest problem they had was a 20 mph wind flapping a 100 foot cable around during a contest (they almost had to cancel the contest.) What do you think will happen to a cable that is 10’s of thousands of kilometers long? When a Storm hits – You can’t real it in, the counter weight will crash to earth who knows where; you can’t let it go, it cost billions to build and launch.

  3. Fountians of Paradise I believe was the title of the book by Arthur C Clarke published in 1979. The main character was Morgan Vannevar or something close to that. The design was very similar using a carbon (diamond) filament and a geostationary satelite above what would now be Sri Lanka.

  4. Fountians of Paradise by Arthur C. Clarke Pub 1979
    This book was about one mans life work to develope a space elevator.

    A mountain top in a place resembling Sri Lanka connected to a geostationary satelite by a carbon filiment.

  5. Great, a planet-scale garbage chute into space.

    We used to think that the land was good for garbage disposal – big enough so that no noticeable impact would be felt. Not so any more.

    We used to think that the sea was good for garbage disposal – big enough so that no noticeable impact would be felt. Not so any more.

    We used to think that the atmosphere was good for garbage disposal – big enough so that no noticeable impact would be felt. Not so any more.

    We presently think that developing countries are good for garbage disposal – big (or far away) enough so that no noticeable impact would be felt. Not so any more.

    Let’s try space. Yeah, there’ll be no consequences for that one. It’s big enough.

    How many centuries (years?) until such foolishness is evident?

  6. the likelihood of space junk hitting the cable is ridiculously low, and they can prevent plane collision (well, unintentional collision) by establishing a large no-fly zone around it, perhaps event protected by surface-to-air missiles in case of “emergency”.

  7. This is one of those things that the physics says will work, but it is just hard to believe. Yes, there are issues to be resolved. Eventually, we’ll look back on this just like we look back at nuclear energy and powered flight.

    Placement of the Earth end point would need to be movable near the equator and hopefully far from populations for when (not if) the cable falls to earth.

    The Red Mars series of books describe many of the issues in some depth AND they are fairly good reads. Two won Hugo Awards.

  8. That’s why one of the possible earth end points is in Western Australia. When the average driveway to a cattle station is about 70Km long and the population of sheep outnumbers humans 1000 to 1, it’s the perfect place to put it.

  9. I don’t think you guys get it, this cable is 180 times the strength of steel, it will be quite fine from all but the worst impacts. Especially since the vast majority of space debris is very tiny, smaller than a golf ball from what I’ve heard.

  10. almost_there –

    we are talking about a cable at least a meter in diameter (most likely many times larger), harder than steel, tensioned by millions of tonnes of force (130 GPa = 14 million tons of force in 1 square meter of cable) where weather only effects the bottom 0.0017% of the length. I doubt even a powerful tornado with its funnel at the base could sway it.

    I have a hunch that whatever contest was held probably didn’t fairly represent the atmospheric effect on the cable – not even close.

    Also, the fact that the 0.0017% of the cable potentially affected by weather will likely be located along the equatorial doldrums means the chances of seeing a storm or even a breeze for that matter is remote. No pun intended.

    As far as space junk goes… that is a much bigger threat although it would take a fairly massive asteroid, traveling a decent rate to completely snap the cable. I think the greatest threat to the cable would be the fatigue-wear due to the crawlers (transporters) and a lot of little things hitting it over time.

  11. I really hope this happens. I’ve been saying this will happen for years. This will make anything we do in space easier. Imagine being able to make Ships and probes for other planets in space so they are no longer restricted to the size-weight limit of our ground based rockets.

    As for location, I believe it was once said on the science channel that an oil rig moved to the equator would make a good base for something like this. That or a land based base in either Brazil, The republic of Congo, or Indonesia.

    I say ocean base.

  12. >we are talking about a cable at least a meter in
    >diameter (most likely many times larger), harder
    >than steel, tensioned by millions of tonnes of force

    Sounds like the world’s largest bass guitar string to me.

    (ain’t no way that a string that is 10,000,000 longer than it is wide with millions of tons of tension on it is going to oscillate!)

  13. The space shuttle has a special coating on the belly and a special angle of approach to breach the atmosphere. Could we just drag this cable through the atmosphere at the speed of the earth rotating and not worry about the friction? I am not sure exactly how friction effects the whole situation but I am sure that someone here is. The speed of the cable at the terminal end (just before it leaves the atmosphere) would be incredible. Anybody more motivated want to calculate it? Certainly far greater than our fastest aircraft. Maybe we could shape the cable like a bullet? :-)

  14. jehu,
    If the cable is to be geosynchronous, the earth end of the cable must be located on the equator. We don’t get to pick sites in Australia or the United States.

    If the cable is not geosynchronous, then the earth end will float around in an orbit above the planet’s surface, and it must be kept high enough to avoid all mountains. The only access to it would then be via high altitude aircraft or LEO spacecraft (like the shuttles.) This has a couple of interesting properties: accessing the cable would be limited to organizations capable of flying to it, and if it’s high enough it wouldn’t be subject to atmospheric conditions like the jet stream or storms.

    If the cable is in a geosynchronous orbit, it still isn’t actually attached to the earth. Like the Dish Network satellites, the cable’s geosynchronous orbit has exactly the same period as the earth’s rotation, so the earth end appears stationary to us. In reality, they would hover it over a designated terminal area located exactly on the equator, and they’d probably have to steer it with jet engines to keep it lined up with the earth terminal in case of winds.

  15. I call vapour-ware. I’ve bee hearing about this thing for many years and Arthur Clarke wrote about it some 40 years ago. I’ll believe it when I see it, in the meanwhile, I’m hoping for more commercial space flights.

  16. imagine the scaffolding needed to build it. but seriously if this cable existed, how would you put it up? It is too big.
    That plus “NASA has conducted several experiments with Plasma Motor Generator (PMG) tethers in space. An early experiment used a 500 meter conducting tether. In 1996, NASA conducted an experiment with a 20,000-meter conducting tether. When the tether was fully deployed during this test, the orbiting tether generated a potential of 3,500 volts. This conducting single-line tether was severed after five hours of deployment. It is believed that the failure was caused by an electric arc generated by the conductive tether’s movement through the Earth’s magnetic field.”

  17. >(ain’t no way that a string that is 10,000,000 >longer than it is wide with millions of tons of >tension on it is going to oscillate!)

    Actually, physicist working on this project predict a small amount of oscillation induced by the Coriolis effect, and the imperfect rotation of the Earth about its axis. From the research I’ve seen, both are these can be accounted for.

    >I am not sure exactly how friction effects the >whole situation but I am sure that someone here >is. The speed of the cable at the terminal end >(just before it leaves the atmosphere) would be >incredible.

    You have to imagine this problem from the reference frame of the Earth. If the cable is lowered from a satellite in geosynchronous orbit (which is how its planned), the cable will have zero motion relative to Earth’s surface and atmosphere. The only frictional forces created would be due to relative wind resistance (the wind you feel on your face).

    >imagine the scaffolding needed to build it. but >seriously if this cable existed, how would you >put it up? It is too big.

    Is this sarcasm? I can’t tell. That has never been the plan. So far, most science/engineering minds believe the best building strategy is to launch a pair of spools into geosynchronous orbit and then simultaneously extend one cable towards the earth and one out into space so that the center of mass remains in GEO. After that, I’ve heard many strategies in which to continue constructing/reinforcing/strengthening the cable.

    >20,000-meter conducting tether. When the tether >was fully deployed during this test, the orbiting >tether generated a potential of 3,500 volts. This >conducting single-line tether was severed after >five hours of deployment. It is believed that the >failure was caused by an electric arc generated >by the conductive tether’s movement through the >Earth’s magnetic field.

    This is very interesting. While I’m positive NASA did not have a tether made of CNT in 1996, I am not sure about the electro conductive properties of the cable they are proposing. A powerful arc could destroy anything. If it is a good conductor, then I am confident that magnetic fields have been accounted for. Time for some more research.

    …on the other hand, if your hypothesis is that a current is induced by a wire hanging from the ionosphere to the earth due to the earths magnetic fields, that is even more interesting. Can anyone say “free energy?” :)

  18. think of the speed the end most point would be traveling. the center of a record and the outer most edge travel at different speeds.
    the thing would bend like a fishing pole. Halo 3 anyone..

    @ryan rodd “free energy?” totally cool!
    what about some sort of turbine that would fall arount the earths orbit… a neo with a twist

    1. Even though the outside and inside edges travel at a different velocity, they travel at the same number of revolutions per time period. Think about drawing a line on a record and playing it, the line doesn’t bend…from the record’s frame of reference the the outside and inside edges are always synchronized, otherwise a record would twist itself apart.

  19. I just can’t help but think, where will all the raw materials for this come from? Will there be a giant, noticeable chunk of the earth’s crust missing? Are they gonna dig up Australia or something?

  20. Well, think about it. If they are going to make it out of carbon nano tubes, they can use anything. The go green people using bio-matter to power cars are already taking advantage of the carbon based-ness of everything on our planet. The only real formidable structure that will have to be built is the anchor facility, and when you think about it, just think about how many huge structures have we already built.

  21. @ kevin bane

    “think of the speed the end most point would be traveling. the center of a record and the outer most edge travel at different speeds.”

    WTF are you talking about? They are going the same speed. If they weren’t the record would tear itself apart. That’s like saying the top floor of the sears tower is going faster than the lobby.

  22. @ spinner
    “Wouldn’t having objects hanging off the planet and into space cause some sort of slowing down of earth’s rotation?
    Like a skater spreading out her arms?”

    not enough mass to cause any noticeable change. technically there shouldn’t be any weight pushing down on the planet at all. it’s going to be the same as if you were spinning around holding a rope. centripetal force will keep it straight, the counter balance mass out on the other end will counter gravity to keep the tether “floating”.

  23. Well, since the cable will be in geosynchronous orbit and not being drug through the atmosphere like the NASA experiment the charge being generated by wind friction should be minimal. Less than that of a helicopter rotor in dense ocean air (which can still knock the poop out of you).

    In Alastair Reynolds’ book Chasm City the space elevator is one long string of grown diamond, which we all know is carbon just arranged into a crystal.

    As for the anchor location on earth, they will have to pick some place with little or no geologic activity. Even a small oscillation at one end can propagate to disastrous proportions if not checked quickly. Since the cable would be “hanging” from its space anchor by way of centripetal force generated by gravity a central pacific location is probably best.

    Getting the thing up is going to be the real engineering problem. If they do decided on an ocean location then they can break the sea water up into hydrogen and use ridiculously large balloon clusters. No one has to ride the thing up so if one goes boom, the cable falls in the water and no one burns to death. Lower the other end from space and your good to go.

  24. Not a good idea. A significantly sized and anchored cable could possibly effect earth’s orbit, you want to talk about global warming, start screwing with our position relative to the sun.

    Also, PRIME target for attack, and whichever country had it would rapidly gain a huge economical advantage.

    Why not, instead of ejecting the nuclear waste, find a way to directly convert radiation into electricity? Seems like it’d be much more practical, and not likely used by the stupid and the greedy.

    Darn environmentalists. “Hey, let’s stop progress and instead of a small boo-boo that requires a few years to fix, COMPLETELY screw everyone over when an alien planet gets hit by garbage, gets pissed, and invades us!”

  25. @Spinner & @Barry & @k_aud: The cable would not be “anchored” to the earth. It’s not like a rock tied to the end of a string. It’s just a very long, straight string in orbit around the earth, rotating at the same speed we are, held in place by the earth’s gravitational field. It floats in space exactly the same way any other satellite floats, except it’s a lot longer.

    As far as making it, it has to be produced in space and lowered to earth. It cannot be pushed up from earth. You can do it in two ways: you can create an elevator-rope-factory and place it in the geosynchronous orbit over where the earth’s terminal will be. Start ejecting rope in the direction of earth, and simultaneously start ejecting the same amount of rope in the opposite direction away from earth (as a counterweight). The other way is to start farther away from earth and find an asteroid that has as much mass as the counterweight end of the rope will need. Start ejecting rope, and then rocket the whole thing into its geosynchronous orbit. Harder to do, but it may be easier or cheaper to make only half as much rope.

    To anybody who thinks it’ll be traveling fast, that’s only relative when viewed from outside the earth. From the earth’s point of view, we will see a stationary rod, like a psychotically tall radio tower. Look at a satellite dish mounted on a house: the satellite 22,000 km away is moving awfully fast when viewed from the moon, but the dish here on earth doesn’t move at all to track it. The cable is the exact same thing, it’s a satellite, only the satellite is very very long and skinny.

  26. @markps2: the 20km tether that NASA experimented with was made out of Spectra line — kite string. And the Young Engineers Satellite (YES2) deployed 32km of .5mm Dyneema (a chemically similar material) for their record-setting tether experiment. The stuff is really strong, (two lines can drag my big carcass across a plowed field) but .5mm is very thin, and I’ve never flown more than 100m of it. I can’t really imagine how fragile 31,700m of it would be.

    The space cable would be made of a meters-thick-bundle of carbon nanotubes. Crazy strong stuff.

    A terrorist could likely only attack the last few km of it (they could fly a plane into the cable, but only in the atmosphere.) It’s much harder to fly a rocket to attack the middle of the cable. A plane crash likely wouldn’t sever the cable, but let’s just say it does. So 10km of cable falls to the earth. Big deal. The factory in orbit just spits out another 10km, and spits out an appropriate offsetting amount of counterweight cable, then uses rockets to manoeuver the orbiting cable back into position over its terminal. Only those people unfortunate enough to be in a car in the bottom 10km would feel the pain, as would anyone the falling cable fragment landed on. The rest of the cable would remain undamaged.

  27. @ barry99705
    read this. and indeed the top of the tower and the lobby are traveling at diff speeds.
    As a record spins on the player, an object placed near its edge will travel at a faster speed than an object placed nearer to its center. …
    btw, your pretty smart ;p

  28. To go along with what jaded is saying about terrorists, Its likely that something this expensive will have one of the most powerful defense systems ever used. I mean, do you really think anything larger than a small bird will be able to come within 75 miles without being identified and if necessary, shot down?

    As for it slowing down the earth’s rotation, consider what the earth weighs and what this would weigh. Unless it was high enough to risk colliding with the moon, it shouldn’t have a noticeable effect on the earth.
    To add to that, the cable won’t be tight enough to hold the station down because the cable would drag it out of orbit

  29. Dear NASA,
    I have just figured out how to go to space without rocket engine. I’ve started building my ladder to space(like in south park). Don’t worry it’s a great idea. I just need lots of some kind of cable(UTP would be great).
    Thanks in advance.

    Isn’t space shuttle kind of an elevator to the space. What’s the point of having space in a tube. Why don’t they just thow the rope from the space(oh yeah, if you have tube, the equation E=MxGxH doesn’t exist, you need less energy or what) and lift space shuttle with it(joking).

  30. You people do realize that as convenient shuttles are, they are unsafe and very expensive right? They take too much fuel just to get into a low earth orbit. An orbital elevator may seem a bit extreme if you are just thinking about it like the ISS or a port to launch satellites, but consider how much easier it will become to go to the moon, mars, or anything else. More complex probes and ships can be built and launched from space.

    I think that once one has been built here, we can move to mars and the asteroid belt. We use materials from the belt to make one over mars and begin colonizing.

  31. If my calculations are correct, a trebuchet with a 270.3 mile long boom and a 979.3 million ton counterweight should just barely get 300 pounds (a 150 pound human in a 150 pound space suit, or a small satellite) to reach escape Velocity.

    It could be built rather inexpensively with parts bought on E-Bay (mostly the shipping costs for the counterweight.)

  32. 4 Mil won’t even buy you the tail of a boeing 747 (total cost of boeing 747 = 216 Mil). Human beings are too shortsighted for this kind of achievement, no matter how benificial it would be to mankind. Nobody is willing to take the risks, financial or otherwise, that are necessary for the success of a project of this magnitude. Hadron took forever, it took a small eternity for man to get to the moon (assuming that actually happened). If people are expecting an endeavor like this to succeed the first time… on 4 million dollars, then they would see much more benifit, paying me 2 Mil to kiss the fattest part of my black ass.

  33. Imagine though…reducing the per-pound cost to send things into space so drastically, that mankind could finally get out into the solar system…We could build solar plants above the clouds…We could build factories that make things that are impossible to make in a high gravity environment like that on the earth’s surface…. we could build more elevators at less cost than the first.. using the first.. we could build and assemble telescopes, using modern technology, that could see everything that’s out there waiting for us….We could stop squabbling amongst ourselves for the resources on this planet and devote our time to exploring the infinite resources that surround us just beyond this wonderful blue and green prison that has entrapped us since that fateful day when stinking bits of slime first crawled from the sea and shouted to the cold stars, “I am man.”

  34. I know that it won’t be physically anchored to the earth. Considering plate tectonics its just a bad idea. Again that’s why a lot of people advocate an ocean placed facility some where on the equator. I used the term “anchor” loosely to mean the earth end. I guess in the case of a space elevator the anchor is in space and the terminus in on earth.

    And to all those that say it can’t be done, well the same thing was said about manned flight. Besides the shuttle is over 30 years old and is a prototype every time it flies because of the sheer number of modifications made between flights. Not to mention it costs 10k just to send up one pound of cargo.

    As for the terrorists, well, nothing risked nothing gained. Also, I think the security will be a bit tighter than at airports. I mean have you been to a shuttle launch?!? They’ve got gunships flying around and inspecting anyone who even looks remotely suspicious.

  35. @spinner

    Geostationary orbits are about 22,000 miles from earth — that’s just a fact of the mass of the earth and the length of a day. Every single geostationary satellite, from the DirecTV constellation to the Telstars and Echostars, is 22,000 miles from earth.

    It’s important to note that the 22,000 mile distance is to the “Center of Gravity” (CG) of the satellite, not just to the nearest edge.

    So the cable is just another satellite in a geostationary orbit. That means that the CG of the cable must be 22,000 miles up, too. With a traditional satellite, they’re only about 50 feet long, so the CG is right there with the rest of the satellite, and we don’t think about it much. The cable, however, has to be long enough to reach the ground, which is 22,000 miles away. That’s a heavy satellite. And if the cable was only 22,000 miles long, it’s center of gravity would be only 11,000 miles up — nowhere near the altitude required to stay in a geostationary orbit.

    Something must be offsetting the mass of all that earthbound cable to keep the CG 22,000 miles up. Either you have an identical length and mass of cable reaching out further into space (that’s 44,000 total miles of cable), or you have a giant counterweight somewhere beyond 22,000 miles away. The cable won’t “stay put” on the earth end unless its CG remains in the precise geostationary orbit.

  36. Ooh! My mistake!
    One assumes a “counterweight” to be on the “other side” or in this case, I thought the “other side” of earth.

    So, to have an elevator going up and down to earth, one needs a counterweight going up further into space?
    Now, you really need extra cable!

  37. @spinner

    Think of it like this

    [ ] <–counterweight
    { } <- hub/’rope’ factory (also cg) in geosync orbit
    | <–cable
    O <- Earth(probably not to scale)

  38. Actually the cable falling wouldn’t be at all dangerous, because of the incredible materials needed to build it, the cable would weigh the same as a sheet of paper for the same area, so it would just float down to earth.

    There are a load of problems with it though, space junk IS a very large problem, even tiny flecks of paint colliding at such high speeds can have massive consequences. Another is radiation, parts of the cable would need to be heavily shielded to prevent them breaking down from a variety of effects.

  39. One thing I don’t understand about the concept is how do you just drop the cable from GEO orbit down to the surface? The only way I know how is to use a rocket the burn retrograde and decrease orbital energy. This will lower your PeA, but it would take a hell of a rocket to decrease Ecc to 1. Even at that the cable would be half way wrapped around the Earth by the time in hits the atmosphere, right? Also, the logistics of burning retrograde from GEO while towing a cable with you sounds insane. So, what is the tonnage payload capability of these elevators per run?

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