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Kris_J writes "Seattle PI appear to have been the first to pickup the story that a former member of Highlift ("Space Elevator") Systems has split off to form Liftport. The new company has the impressive aim of a space lift by July 1st, 2018. Competition is supposed to be good, right? If you want to know more they've got a messageboard where you can ask questions."
I'll be willing to forgive it all if you make this your pet project and provide cheap space access, by the pound, to everyone. Just... please... don't use Windows NT to control the ground station boat, OK?
The gist of the article is that the carbon ribbon material they'll be using is strong enough for the 62,000 miles length needed to reach geosynch and the counterbalance beyond.
Of course, the article also points out that the exact material has yet to be made...
You should really read about the system, before you denounce it as impossible and ridiculous with statements that demonstrate clearly that you don't understand the concept.
you still have to accelerate to orbital velocity after the lift, unless they plan to build it all the way out to the distance of a geosynchronous orbit.
They are going way past the geosynchronous point; they *have* to because the lift's center-of-mass has to be at the geosynchronous altitude.
Nothing is strong enough to support that kind of weight. With today's best engineering, they haven't even managed to build a building 1/2 of a mile high.
You shouldn't think of it in terms of a weight-bearing structure like a building. The lift ribbon will not need to support the weight of the whole system; on the contrary, centrifugal force will hold it aloft (i.e., the whole thing is effectively in orbit).
So, the material needs tensile strength, not weight-bearing capacity. Think carbon nanotubes, not "diamond beams".
But right now it's ridiculous and any venture capitalist who gives them money would have to be borderline retarded.
Ignorance has a cure: RTFA
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. . . or that it would cost hundreds of billions of dollars. Ahem. Take the money and run!
You're missing something here: the difference between science and engineering. Space elevator advocates often point out that most of the remaining problems are not in the realm of science but instead tech and financing. So progress is not dependent on some long haired genius in a basement lab having a brainwave. You can make confident predictions that technology will improve and that the material with the required tensile strength will be constructed soon in the future. And hey, considering that these guys are trying to accomplish the mind-boggling, optimism is the only way.
Hrm. That seems so far, yet so soon. That's only a couple months over fifteen years. Will we have everything necessary to make a useable space elevator? I would personally like to see it, just because the idea of an elevator into space interests me. But, I don't know if we'll have it by 2018...
Ah am not a crook! (\(-__-)/)
Companies that are more interested in attracting attention than in getting tangible results are usually interested either in attracting investments or overcoming opposition. Since there is no widescale opposition to a high lift operation yet, they are probably at the investment stage.
Seeing as they are going to the general public, I guess that they don't have stable long term institutional investors for their long term project. That means they are searching for lots of piece-meal investments to keep a capital intensive project going for fifteen years. That sounds pretty hopeless to me.
I'd guess that what they're really after is money, in the name of the project. Perhaps the other partners saw this and that is why they left the original coalition.
I hope they have a good relationship with Highlift Systems, because their FAQ is a copy of Highlift's .
I feel fantastic, and I'm still alive.
A hanging steel rod or fibre will break under its own weight already at a length of about 10 km. The article mentions that the carbon nanofibers are 30x stronger than steel, which means that you get 300 km. Maybe they meant 30x stronger by volume, not by mass, in which case it adds another factor 8 for the difference in density between carbon and steel, resulting in 2400 km before this hypothetical material collapses under its own weight. The geostationary orbit is around 30,000 km above the earth, so I don't see how this is supposed to work, even in theory.
Another problem is that 100,000 km of cable represents quite a large surface. Suppose that the cable is 1 mm thick; that is a total surface of 100,000 square meters. Just one microscopically small dust particle that hits the cable at 10 km/s can break the cable. With such a big surface, the chance of that happening is quite large. Oops, there goes the space elevator!
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You missed the point. There will be no breakage "under its own weight" with the space elevator, because there won't be any weight pulling the elevator down to earth. They're not talking about building a tall tower here. They're talking about tying a heavy rock up in orbit to the ground and climbing up the rope. Ever play tether-ball when you were in elementary school? It's the same principle.
That's why the grandparent post mentioned *tensile* strength rather than *load-bearing* capabilities; you need something that's going to flex outwards rather than something that has to stay rigid yet flexible enough to handle the occasional tremor like conventional buildings.
Furthermore, the suggested material will not be solid, like a steel beam. It will be a mesh... a rope. You can get tremendous strength from meshes, much more than from a single solid beam. That's why, for example, the cables that hold suspension bridges aloft are twisted ropes rather than a single solid strand of material -- it's simply much stronger that way.
True, to get the tensile strength they need for this they require a stronger more exotic material than normal cables and ropes are made of, but the principle is the same.
"Times have not become more violent. They have just become more televised."
-Marilyn Manson
Sounds like the only way to *deploy* the tower is to build it from orbit both up and down, otherwise you still have the weight problem while you're building it, until you reach the height of geosynchronouse orbit, at which point the "weight" of continuing to build upward starts to lessen.
Anybody heard any mention of the launch vehicle to get into orbit to build the tower? Not to mention, where do you plan on storing all of the pieces in orbit? Sounds like a pretty expensive proposition just to launch enough pieces to even start building the tower.
You're missing something here: the difference between science and engineering. Space elevator advocates often point out that most of the remaining problems are not in the realm of science but instead tech and financing. So progress is not dependent on some long haired genius in a basement lab having a brainwave. You can make confident predictions that technology will improve and that the material with the required tensile strength will be constructed soon in the future.
I agree except for the "soon" part.
You can make exactly the same arguments about whisker fibers, which have been around for quite some time and would be a wonderful material if we could solve the degradation and production problems.
You can also make the same argument about controlled fusion. Few doubt that it's possible; there's just been a history of very optimistic estimates for when we'll finally have all of the engineering problems solved.
If we have nanotubes in quantity tomorrow, I'll be the first to cheer, because you can do many interesting things with them on a smaller scale than building space elevators. However, I'm not holding my breath.
It is NOT a tower - It is a CABLE and that is all
READ before you troll
I am pretty excited about this. With this in place, space will be accessible to all at a reasonable price. Travel will be so much safer as well. No more tying yourself to a stick of dynamite with a hole at one end and lighting the fuse.
I wonder what kind of industries will spring from this. People may be able to get on an elevator, climb to several miles in the sky, strap on a parachute and jump off. Others may try to see how high they can climb under their own strength. Of course, the higher you go, the easier it will be to climb!
The radical sect of Islam would either see you dead or "reverted" to Islam.
Maybe they could build the whole thing on the ground, as a long, long coil of nanotube rope, then unwind it from GEO.
All it takes is nukes and nerves.
A.C. Clarke has confidently predicted that in the year 2001, we will have a commercial space station, regular manned flights to the moon, and manned expeditions to Jupiter.
"I'm so moist I'm sticking to the leather." -Kermit the Frog on The Late Late Show
Unless one is wearing ruby slippers, that is considered a rather menacing gesture by many, in particular when accompanied by unintelligible toasts and an extended arm (holding a glass softens the effect, I suppose).
- That the historical rate of improvement will continue.
- That energy storage will become a great deal cheaper as well.
The first assumption is debatable, and the history of batteries shows that the second is extremely suspect. The suitability of a solar-electric energy supply for our whole economy cannot be taken for granted at any particular time; all we can do is use it where it works today, and let the market for better products push the improvements.Solar falling on roofs imposes a limit on the amount of power which can be supplied for use on Earth. Depending on the exact challenges which face humanity in the future (e.g. having to remove a lot of CO2 from the atmosphere in a BIG hurry), we may need power at a quantity or price which rooftop PV cannot match, if only due to the cost of the real estate it sits on. For that, we'd have to go upward.
All the Tethered Satellite System did was convert some of the Shuttle's kinetic energy of motion into electricity; it wasn't supplying any energy that hadn't originally come from rocket motors (a very inefficient way to power something). Besides, a geosynchronous skyhook would not be moving relative to the Earth, and therefore would not be moving relative to Earth's magnetic field; conductivity or no conductivity, there would be no V-cross-B to create a potential difference.Scientists restrict study to entire physical universe; creationist
Who needs batteries?
It is currently cost effective to put solar panels on your roof, and generate enough power to run your electric meter backwards feeding the grid. The break-even period is less than 10 years for a system that has a 30 year warrantee.
At the end of the month, you have generated more power into the grid than you took out.
How the grid chooses to store that power is quite flexible. It can simply offset the power that would otherwise be used from hydroelectric dams, allowing those to be run only at night, saving up the water behind the dam during the day.
I never mentioned using solar power to supply "the entire economy", and neither did the web site for the elevator. The question is whether the solar power satellites make sense economically, or whether they have some of the same problems that nuclear power plants have -- the tremendous costs of the financing of huge projects makes them less practical than simply making something more efficient.
The cost of the real estate on my roof is cheap. I have already paid for the roof. If putting solar cloth on top of it generates more power than my house uses, and is as cheap as it looks like it will be, then it will simply become a part of building a house, like the rest of the roofing business.
The cost of real estate in geosynchronous orbit is "astronomical", even with the elevator.
The tethered satellite used a different mechanism than the one mentioned on the elevator web site. The elevator connects the earth to the ionosphere, where there are some pretty decent currents. The voltage difference between the top of the cable and the bottom (if the cable were doped to be conductive or superconductive) would be useful.
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The present problem is the old "how do they stick the teflon to the pan" problem; getting them to play nicely in composites, and finding ways to manufacture the composites.
-- MarkusQ
Not to nitpick here, but we're talking about compression strength here, not tensile strength. Steel's strength to weight ratio is only good enough to ideally go about a mile up, unless you use a pyramid shape. Synthetic diamond beams will probably never be a viable option, which leaves you with things like silicon-carbon compound crystals that are less than 1/10 as strong, and more dense, or even worse, that hypothetical carbon-nanotube composite material that is only 30 times stronger than steel and would be atrociously difficult to manufacture. IMO they should try using the carmon-silicon compound crystals instead (same structure as a daimond except every other atom is silicon instead, and 1/10 as strong which is like 100 times stronger than steel)
Repeal the DMCA!
Incorrect reasoning. Suppose that you have your rock locked in a geostationary orbit. Then you unwind the cable: the cable hangs down from the GS orbit. (the roundtrip time for an orbit decreases with decreasing altitude; since everything is forced into a 24-h roundtrip time, the cable does HANG or otherwise it will fall down). In other words, the cable needs at least to support its own weight, which is quite challenging with the 30,000 km that are below the GS orbit, even if the gravity is not that strong at the higher altitudes.
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And why are we talking about compression strength? These things are not built from the ground up, but from orbit down. They hang.
Ahh, I see what you meant by the breakage. I thought you were talking about stacked up and topling like a building, not hanging weight.
Still, I don't think it's too hard to believe that the cable will be capable of withstanding the tensile forces of its own weight pulling on it. Individually, a nanofiber might break under its own weight, but collectively, as a woven mesh / rope, it will have a much higher tensile strength.
"Times have not become more violent. They have just become more televised."
-Marilyn Manson
I would say that the enforcing effect of a cable instead of a single beam is that
1. a local rupture cannot propagate; just one fiber breaks, but not the whole cable.
2. the system gets some elasticity such that shocks are absorbed.
3. the tensile force is evenly distributed over the cross-section of the cable.
These effects result in a cable that is more robust against typical causes of failure, but I don't see why the total tensile strength would increase.
Another issue is how to cope with shockwaves in the cable. When you change the force on the cable because you're trying to lift something heavy, this increase in tension will propagate with a finite velocity along the cable. A few hours later, the wave arrives at the satellite, causes damage, and reflects such that the wave can inflict damage onto the elevator cabin. I recall a documentary on Discovery about the lifting of a wreck on the ocean floor where that was a serious problem.
Avantslash: low-bandwidth mobile slashdot.
I'd almost have to wonder whether we might actually GROW the lift, as in a genetically engineered tree (like Mr Niven's "Integral Trees") grown from silicon,carbon, and whatever else we could throw at the composter bin.
"Troll -- ... This is a prank comment intended to provoke indignant (or just confused) responses. A Troll might mix up vital facts or otherwise distort reality, to make other readers react with helpful "corrections." ...." -timothy
It was not my intention to provoke indignant or confused responses. I did not mix up vital facts or distort reality: I used elements from the plot of a famous movie. It is my strongly held opinion that whoever modded me Troll has an economic interest in one of the two corporations mentioned in the article on space elevators, or is a rabid Arthur C. Clarke fan. Either way, that moderator is the Troll.
"I'm so moist I'm sticking to the leather." -Kermit the Frog on The Late Late Show
Some even hope the system might someday lift people to space.
Wow, those crazy optimistic people. Given the existance of a working commercial cargo elevator, those hopeless romantic optimists will go even further and begin dreaming anew of "someday" using it to lift a real live person. Kooky guys indeed.
Karma police, I've given all I can, it's not enough, I've given all I can, but we're still on the payroll.
Theoretically, you could build a beanstalk out of any material just by varying the thickness in exact propotion to the amount of force exerted by the portion below (multiplied by some safety factor). If you solve the differential equations for it, you get an exponentially increasing thickness as you go up from the bottom to geostationary orbit. (The shape of the counterweight that goes up from geosynchronous orbit is much less restrained as it does not have to reach a particular point or become particularly thin.)
I don't have the equations in front of me, but I vaguely recall that a beanstalk that was 1 millimeter in diameter at the surface of the earth would have to be many kilometers wide at geostationary orbit if made of steel, and many meters wide if made of kevlar. This 1981 Omni Article by Robert L. Forward and Hans Moravec suggests that a beanstalk made of "crystaline graphite" would have a taper factor of 10:1 (presumably a cross sectional area ratio of 100:1). Presumably, it is hoped that if carbon nanontube cables ever become practical, that they will have even greater tensile strength, allowing a smaller taper factor.
... about spaceborne solar.
:)
You know, that whole thing with collecting energy in space and blasting it to Earth in the form of tight-beam microwaves?
Thankfully, this sort of system does not require one to depend on roofs.
+++ATH0
I am a big fan of HighLift and the tiny nanotube thread, but I'm just not convinced that a steel tower is impossible given the right geometry. (Note, I'm not suggesting the ascii below is such a geometry, it's just to illustrate the point)
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Sure, maybe a steel cable could never work, but at some scale it must be possible to build up a tower or, alternately, to build down a beam of of interconnected steel tubes.
Building down it seems we could use steel beams made of elaborate geometries like we see in some space frame construction. The members could be spring loaded to distribute stresses therby adding vast amounts of tensile strength. Just because the material itself lacks tensile strength over a given length, that doesn't mean all structures composed of that material would share that property.
A mass of steel triangles or other geometries is not not as elegant as using a single strand of nanotube composites, but it uses existing materials in plentiful supply at a good price.
At some scale a steel mesh tower must be capable of reaching into the edges of the atmosphere. They're building 500 meter buildings left front and center all over Asia. It would only be necessary to stack up a few hundred of them in an octet "truss" type formation to make a nice dent in a trip to orbit.
|X|
|X|
|X|
|X|
|X|
|X|
|X|
|X|
|X|
|X
Now this rather homely ASCII art is not meant to be a prototype, but you get the idea. Replace each leg of an X with a 500meter steel tower and you could easily imagine a ten kilometer tower. Sure, that's not even close to orbit, but it's higher than Everest. At some scale this has to make a dent in the cost of launching to orbit if you build up from the ground.
Of course coming down from space instead of builduing up you have the issue of materials transport. But I think it's got to be possible even with steel.
What part of "For that, we'd have to go upward" didn't you understand?
Scientists restrict study to entire physical universe; creationist