Space elevators a fantastic idea that maybe someday could be reality?

[TheGeoninja]

Actually our technology would support building one on Mars the only issue would be getting it to Mars.

[Tinyboss]

Actually our technology would support building one on Mars the only issue would be getting it to Mars.

And then sending something to Mars to launch with it. ;-)

[Nibb31]

Actually our technology would support building one on Mars the only issue would be getting it to Mars.

Not really.

It would be "feasible" to build one on the Moon, but to say that we have the technology when the TRL is <2 is pushing it.

[Aghanim]

But... Why??? Moon is useless for a space elevator

[SargeRho]

A lunar space elevator could make bringing things into orbit around it easier, and down from orbit.

[Nibb31]

But... Why??? Moon is useless for a space elevator

Of course it is. It's useless for Earth too in the real world.

However, if you could set up an ISRU facility on the Moon and find a cheap launch method to send propellant to EML-2, then you might be able to design an interplanetary gateway infrastructure. This isn't happening in our lifetimes of course, but neither is an Earth-based space elevator.

[KvickFlygarn87]

Theoretically, it's possible. In practice, the requirements for the tether are too huge.

[peadar1987]

A lunar space elevator could make bringing things into orbit around it easier, and down from orbit.

Although the moon has no atmosphere either, and lower gravity, so it could be more effective to fire stuff into orbit with a railgun of some description, either a return trajectory to earth, or something with a small amount of delta-v so it can circularise.

[Winter Man]

Theoretically, it's possible. In practice, the requirements for the tether are too huge.

If you ignore carbyne, yeah. Other than that though, the main issue is cost. Who's going to invest in a space elevator when SpaceX is throwing stuff into orbit for a fraction of the price using proven tech?

[Science-Recon]

It's useless for Earth too in the real world.

Not really, it is very expensive to get things into orbit and, once the space elevator is built, it would cost almost nothing. Of course, as we dont have the materials or the finding to make it, SkyLon is the alternative.

[Nibb31]

Not really, it is very expensive to get things into orbit and, once the space elevator is built, it would cost almost nothing. Of course, as we dont have the materials or the finding to make it, SkyLon is the alternative.

Why do you assume that riding on a space elevator would be cheap? How do you know how much it would cost to develop and build one? How do you know the payload capacity of one? How do you know the energy requirements for lifting those payloads to GEO? Without the engineering problems fully figured out, there is no way to estimate how much it will cost.

And similarly, what makes you think that Skylon is ever going to be economically viable either?

It will always be expensive to get things to orbit. This is because the amount of energy needed to accelerate any mass to orbital speed is huge, and because huge amounts of energy will always be potentially dangerous and expensive to play with.

[Science-Recon]

Firstly, the space elevator is completely hypothetical and the spec would differ depending on a multitude of factors. And secondly, SkyLon is reusable and more efficient at getting things to orbit. The entire point of a space elevator is to get things to orbit both cheaply and be reusable.

[Nibb31]

Firstly, the space elevator is completely hypothetical and the spec would differ depending on a multitude of factors.

If you don't know the spec, you can't determine whether it would be cheaper or not.

SkyLon is reusable and more efficient at getting things to orbit.

Skylon is also hypothetical. Nobody knows how reusable it can be or how efficient it can be. Reusability doesn't necessarily mean that it will be cheaper. You also have to include the initial development cost, the production cost, and the operational cost. Are glass cups cheaper than paper cups? Why does McDonald's choose to use paper cups?

In all likeliness Skylon will never fly because nobody is willing to pay for it. Please look at the other threads about Skylon and let's not start another off-topic debate in this one.

[Bean]

I think given time we will have space elevators, it just makes sense to me in terms of we are going to become a spacefaring species or die, and there's no easy way to get to space with stuff without boatloads of energy or a space elevator. Perhaps a drive based on fusion?

[Moar Boosters]

If you don't know the spec, you can't determine whether it would be cheaper or not.

Well It's basic physics/engineering. A system involving pulleys and counterweights is always going to be cheaper (in energy) than one that uses a motor to do all the work.

Whether that translates to viable system economically is questionable, just because the cost of setting up a system is likely to be extremely high and it may never recoup the losses through the saving it achieves through energy efficient travel.

Space elevators aren't likely to be the ultimate from of transportation into orbit anyway. The laws of physics don't appear to rule out teleportation as being possible, so eventually we'll have a guy called Scotty sending stuff into orbit with the push of a button.

[magnemoe]

If you don't know the spec, you can't determine whether it would be cheaper or not.

Skylon is also hypothetical. Nobody knows how reusable it can be or how efficient it can be. Reusability doesn't necessarily mean that it will be cheaper. You also have to include the initial development cost, the production cost, and the operational cost. Are glass cups cheaper than paper cups? Why does McDonald's choose to use paper cups?

In all likeliness Skylon will never fly because nobody is willing to pay for it. Please look at the other threads about Skylon and let's not start another off-topic debate in this one.

My guess is that Science-Recon says that an Skylon type SSTO would be more economical than a space elevator.

Skylon don't make much economic sense today, neither do an space elevator, that is unless you can make huge quantities of perfect nano-tubes for other uses.

[magnemoe]

Well It's basic physics/engineering. A system involving pulleys and counterweights is always going to be cheaper (in energy) than one that uses a motor to do all the work.

Whether that translates to viable system economically is questionable, just because the cost of setting up a system is likely to be extremely high and it may never recoup the losses through the saving it achieves through energy efficient travel.

Space elevators aren't likely to be the ultimate from of transportation into orbit anyway. The laws of physics don't appear to rule out teleportation as being possible, so eventually we'll have a guy called Scotty sending stuff into orbit with the push of a button.

Teleportation has so large problems it makes making an warp drive child play.

Yes the star trek type don't breaks so many physical laws but has some engineering problems

[Mazon Del]

You see, building such a huge infrastructure only makes sense in there is massive demand for transportation. Right now, and until there is some hypothetical breakthrough in space business, there simply isn't any demand for mass transportation.

And as I have already said, the space elevator is not really a mass transportation system. Its payload capacity is poor, with a very limiting bottleneck.

That's pure conjecture. We don't even have any idea of the material cost for building one because the material simply doesn't exist. No do we have a power source for the climbers or any idea of the payload capacity or the speed of the climbers. How can you have any idea "dollar for dollar" of what a space elevator would cost compared to a launch vehicle that would use the same superlight superstrong material or the same magical power source?

But that is the thing, there IS already a large demand for transportation to space. Currently mostly of cargo (because manned flight is too expensive). A space elevator IS the hypothetical breakthrough. We'd totally be doing a bunch more in space if we could get there cheaply.

It sounds like you believe that the space elevator can only carry one payload at a time. I have never actually seen a proposal that has assumed this. Every proposal I've ever seen envisions having the capability to have dozens of carts going up at a time. I've heard of some (though admittedly have no source for this) predictions envisioning a cart beginning its ascent every hour or so. So no, there really isn't a bottleneck, which drops down price by quite a lot.

Correct, we do not have the ability to produce multiwalled carbon nanotubes of the sufficient arbitrary length necessary just yet, but we are getting better at it. Some company in Isreal figured out how to produce arbitrarily long carbon nanotube "yarn". It is nowhere close to being good enough to do the job in terms of strength, but to be fair, their system is a prototype technology demonstrator put together with random castoff parts in a lab.

I have seen NASA funded estimates of how much it would cost per lbs for a "launch" using a space elevator. Last one I saw was something around roughly $15-25 per lbs. Now of course this IS pure conjecture, but it is conjecture coming from the people with the most authority to provide said conjecture.

Powering the climbers honestly is amongst the easiest problems of the whole darn system. There are dozens of ways to do this, it really just ends up being what they can afford in the great tradeoff game of mass, volume, effort, and cost.

But... Why??? Moon is useless for a space elevator

A space elevator on the Moon is certainly NOT useless. I almost ended up working for the company that is attempting to place a space elevator on the Moon (currently talking to the FAA about testing locations for the current model of the ribbon climber). Something around 1/3rd of your total mass on a Moon mission is JUST fuel to land safely and take off from the Moon again. If you have a space elevator, you can cut out almost that whole fuel alotment (some would be needed for matching orbits and docking of course).

A lunar space elevator is also possible with current technology in materials science.

Yes, a linear accelerator like a maglev cannon or something similar would be cheaper to get things OFF the moon, they don't help you land. Likely you would have a lunar elevator for destinations you expect frequent traffic to and from, a colony for example. Mining stations would likely just go with the accelerator. Of course, one big issue is people on Earth would be quite worried about the possibility of the accelerator being used to lob tons of metal like giant bullets at the Earth, so it is possible this could become legally infeasable (ex: An international law is put into place limiting the delta-V offered by a linear accelerator cannon to something that can never threaten Earth. If this limit prevents the cargo from getting somewhere practical, then the accelerator may not be used.)

This isn't happening in our lifetimes of course, but neither is an Earth-based space elevator.

It is quite certainly possible for this to happen in our lifetimes. NASA is watching the team I mentioned quite closely. Considering how cheap a launch from a Falcon Heavy is likely to be compared with something else, it is quite possible that NASA would foot the bill for this, or even an experimental setup.

[rtxoff]

In "Star Trek Voyager - 3.19 - Rise" the secret star of that episode is the space elevator :-)

[Nibb31]

But that is the thing, there IS already a large demand for transportation to space. Currently mostly of cargo (because manned flight is too expensive). A space elevator IS the hypothetical breakthrough. We'd totally be doing a bunch more in space if we could get there cheaply.

There is more offer than demand. The current launch market is saturated. Global launch capability is in overcapacity. To the point where some launch providers are having trouble remaining competitive.

It sounds like you believe that the space elevator can only carry one payload at a time. I have never actually seen a proposal that has assumed this. Every proposal I've ever seen envisions having the capability to have dozens of carts going up at a time. I've heard of some (though admittedly have no source for this) predictions envisioning a cart beginning its ascent every hour or so. So no, there really isn't a bottleneck, which drops down price by quite a lot.

You can't have dozens of carts going up and dozens going down at the same time on the same tether.

The space elevator is a theoretical construct. Nobody knows the exact operational constraints because we don't know the weight, strength, or cost specifications of materials that don't exist yet.

[SargeRho]

Of course you can have multiple carts going up and down at the same time. You'd just need a way for one cart to "climb" over the other, and that honestly isn't a very hard thing to do - I've built such systems in Lego before.

[magnemoe]

Of course you can have multiple carts going up and down at the same time. You'd just need a way for one cart to "climb" over the other, and that honestly isn't a very hard thing to do - I've built such systems in Lego before.

A bit harder than they move in hightway speed, you need an decent speed to get some capasity, probably better to store up the wagons and send up a bunch, then send down. If they mostly go down empty you can send them closer.

Other option is to build two and shuttle the wagons to the down elevator.

[SargeRho]

They would have to slow down whenever they meet, but I don't think that would be much of a problem. Another solution would be to build multiple elevators with shuttles moving between them.

[Everten P.]

Why is the picture in the O.P. In Indonesia?

Anyway I know how to make one, just get a satellite to orbit in Geosynchronous orbit and have it carry special graphene wire 390km of it, when the wire hits the ground carbon nanotubes would go through the side cables to reinforce it and keep it up. Send stuff up and build a station. Also it should be stronger if the cables supported a circular cart.

C'mon guys you heard one lets mothatruckin' build one who needs to wait for NASA? I just need someone to set up a website for it!

Edited July 3, 2014 by Everten P.

[SargeRho]

Why is the picture in the O.P. In Indonesia?

Could be concept art of the Front Mission franchise. Has a Space Elevator around there.

Anyway I know how to make one, just get a satellite to orbit in Geosynchronous orbit and have it carry special graphene wire 390km of it,.

Geosynchronous Orbit is 35,786 km above sea level, not 390km. Two orders of magnitude off.