Is a space elevator a real possibility?

[cjp]

Another problem is where to build it. A project of this magnitude and expense would of course be run by the US or EU, but it needs to be built at the equator. What countries occupy the equator? Kenya, Congo, Indonesia, Brasil, Columbia, Ecuador...

We'd have to pay those people for the land, the right to build, and whatever tax they decide to levy against goods going to and from orbit. It's a political nightmare.

Actually, some designs are connected to a floating 'oil platform' or ship. It also adds maneuverability to the elevator, so that it can sling the cable to avoid space debris. And it is good to have some uninhabited ocean around the cable.

I wonder: would it be necessary to extend the cable all the way down to the ground? What if it would only extend down to LEO altitudes? Launching towards the 'first floor' would be possible with relatively cheap devices like Spaceship One. Would this solve any real problem? Would it add problems? I guess the (now free-floating) structure would lose orbital energy over time if cargo is pulled upwards on it. What sort of forces would prevent this from happening if the construction is attached to the surface?

 

[Ghostrider]

Much as I think that the concept of a space elevator is cool, there would be some real problems with it.
Like, what happens when it's out of order? Because climbing 36'000 km of stairs is a major pain in the netherparts.

 

[anemazoso]

This is always a funny topic when discussed. There are always some nay-sayers that want to point out this reason or that why a space elevator won't work. In my (admittedly layman) opinion the concept is very doable. All the issues can be engineered away. The real issue is cost. Why should we spend billions of dollars to build a space elevator some might say, but we have this question already with space exploration as it exists today. Anyone is welcome to fill in there favorite answer for that one :thumbup:

But I will repete as clear as I can, building a space elevator IS technically possible.

So, lets examine the major issues with building it:

1. What would the cable be made of?
So far bucky carbon or "Carbon Nanotubes" looks like the right stuff. Although there need to be much more study of the material I have not read about any issues that disqualifies this material. The typical design envisioned using Carbon Nanotubes is a ribbon about a meter wide.

2. Where would the elevator be anchored?
As cjp stated, an oil platform seams to me the best solution. It can help in manuvering the ribbon out of the way of any orbital objects and will not be subject to any potential territorial issues.

3. What about objects in earth orbit striking the elevator?
I think this is the most problematic issue but it is not without solutions although they might be costly. If we (humans) really wanted to clean up the lower orbits we could launch a hand full of automated spacecraft that would collect and de-orbit objects or send them to a higher orbit where they would be less of a risk. Meanwhile establish stricked manuverability requirments for future spacecraft. If we can co-ordinte 2000 commercial aircrat in the skies at any given time why not spacecraft to avoid collision?

4. What if the ribbon is severed and falls back to earth?
Well, it the ribbon is cut within the atmosphere the the whole elevator will fly away from the earth whcih would suck for people on the ribbon but life boat type spacecraft would solve that problem. If the counter weight was severed and the ribbon fell back to earth the ribbon is not substatial enough to do any damage and most of it would burn up on re-entry.

5. How would the space elevator be built?
My favorite solution is to capture a NEO, bring it into earth orbit, land nanotube manufacturing equipment and start spinning a ribbon using the asteroid as feed-stock, slowly droping the ribbon down to earth.
This is also a tricky part because most people i think will have serious issues with deliberatly bringing an asteroid near the earth.

So those are the major questions that I can think of. I am sure their are others but I know they can be adressed. As I said, it is technically possible. The real question is if the general public could be convinced.

 

[SpaceShaft]

A different space elevator approach

Hello,

I wanted to share some ideas that will fuel even more your interest on space elevators.

As you all probably know there are other proposed space elevators, namely a skyhook, pneumatic space tower by Prof. Quine, the launch loop, etc.. Let me introduce yet another concept for a “non carbon nanotube” space elevator; the system goes by the name of a SpaceShaft, (we needed a name for it,) and is described in more detail at http://spaceshaft.org. It basically uses common, everyday technologies. Some of the components do use the cumulated potential energy of the atmospheric mass of the planet, yes good old buoyancy!

The other important factor is the method of construction; as we all know, when we construct a building by using mortar and brick we stack bricks on top of each other generating a lot of weight with the cumulated mass. With the SpaceShaft method the thing happens the other way around; the stacking activity is done upside-down, i.e. stacking is done at the base and stays at the base! It goes like this; special buoyant blocks, (or helium balloons in the shape of cubes to keep things simple,) are inserted at the base after some existing ones are permitted to levitate in a controlled manner.

The resulting effect of this method of construction is that it generates the counterpart of weight, i.e. upthrust! This upthrust can be quickly estimate the reader after a little math and he/she will see tat the system can generate thousands of tons of upthrust. For a buoyant building of a few tenths of kilometers height and therefore a space elevator of 100 km, or more, is be reasonably deployable.

When discussing timelines that will take for the development of technologies related to a CNT tether space elevator we must take into account the political environment in which the CNT tether community needs to work, (or better said survive). NASA did put out the challenge, and yes they know what was at stake, i.e. the interests of the large industrial complex that builds expensive rockets, whom, of course, do not want to relinquish the achieved monopoly of space access. At the SpaceShaft Endeavor we do feel the weight of these companies, and that of the CNT tether groups as well, which sometimes do try to dismiss the SpaceShaft method. Correction, l will be fair; not all of those guys.

Life is not without ironies: “The Space out there does not seem to be that infinite for such a small community of inventors!”

 

[PhantomCruiser]

"Red Mars" anybody? It has a pretty good explanation of a space elevator, plus some ramifications should something happen to the counterweight. I agree with Artlav, possible but not practical (or cheap until we've got nano-machines to build it for us). Science, but still science-fiction...
Streb2001's mention of "Fountains..." is a good read too, I forgot all about it...

 

[2552]

A random and probably impossible question, but:

What if you somehow made a space elevator on the equator of a neutron star with a rotation period of 1 millisecond; if you extend it high enough, and rode it to the top, could you then travel faster than the speed of light?

 

[anemazoso]

A random and probably impossible question, but:

What if you somehow made a space elevator on the equator of a neutron star with a rotation period of 1 millisecond; if you extend it high enough, and rode it to the top, could you then travel faster than the speed of light?

No because you can not travel faster than the speed of light. :tiphat:

 

[Andy44]

The relativistic effects would be a sight to behold, though!

 

[tblaxland]

For a buoyant building of a few tenths of kilometers height and therefore a space elevator of 100 km, or more, is be reasonably deployable.

Such a structure solves only a small portion of getting an object into space. Any payload delivered to the top will only have a fraction of the energy required to achieve orbit. A true space elevator has the advantage that it will accelerate its payloads to orbital velocity or greater.

 

[Eagle]

It's like when you explain how gravitational slingshots rob the planet of a small amount of momentum around the sun, and people go "OMG, the year's gonna be longer!!!!" :beathead:

Actually the year's going to be shorter as the minute losses lower Earth's orbit around the Sun. Immeasurably slow of course, it would be interesting to find out how many slingshots (with arbitrary parameters) it would take to make the Earth uninhabitable.

 

[JamesG]

A random and probably impossible question, but:

What if you somehow made a space elevator on the equator of a neutron star with a rotation period of 1 millisecond; if you extend it high enough, and rode it to the top, could you then travel faster than the speed of light?

Discounting all of the problems with building and attaching something on the surface of a neutron star, I think the sheer forces from the drag of colliding with interstellar radiation would make it impossible unless you borrow some of the Avatar "unobtainium". :lol:


Ser'sly.
Probably the Moon or Mars will be the first place that a space elevator is tried. Lower gravity so the tether will be of much smaller scale, less atmosphereic effects, plus none or few people on the ground to sue you for ruining thier view or whatever.

 

[tblaxland]

Probably the Moon or Mars will be the first place that a space elevator is tried.

The Moon rotates too slowly.

Mars is a possibility but I expect you would want a well established colony there first and it will be quite sometime before that happens. You also have the issue of avoiding collisions with Mars' moons. Phobos is well inside ares-synchronous orbit and Deimos is just outside but within the reach of the cable extending out. Whether that is any harder than dealing with the Earth problems of higher cable tension and weather in a dense atmosphere, I don't know.

 

[T.Neo]

You might get sandblasting in the lower atmosphere.

I doubt it'd be as severe as effects from the Terran atmosphere though.

 

[JamesG]

The Moon rotates too slowly.

Not if you take advantage of tidal (gravitational) forces from Earth.

Mar's moons would probably get moved to become the anchor and/or become the building materials for the tether.


Its kind of interesting the overwhelmingly negative waves on this topic. As if all the "rocket people" on this board find the idea of a space elevator a threat. lol....

 

[T.Neo]

Right. So now we have to move moons that are up to 20km across...

As if all the "rocket people" on this board find the idea of a space elevator a threat. lol....

Nope- we find it annoying.

 

[JamesG]

Right. So now we have to move moons that are up to 20km across...

By the time the materials and engineering for a orbital tether are ready, and there is enough economic or otherwise reason for it, moving a potato shaped mountain ought to be pretty easy.

 

[george7378]

I don't know how this would work, primarily because of the fact that as the elevator pulls on the cable to ascend, the cable will pull on the satellite or upper tether, causing it to descend. I suppose this can be avoided by firing engines against the pull of the elevator, or creating a cable which essentially acts as a 100KM-high skyscraper, i.e.- it isn't flexible, but rather acts as a pedestal on which the satellite at the top sits.

 

[Nerull]

I don't know how this would work, primarily because of the fact that as the elevator pulls on the cable to ascend, the cable will pull on the satellite or upper tether, causing it to descend. I suppose this can be avoided by firing engines against the pull of the elevator, or creating a cable which essentially acts as a 100KM-high skyscraper, i.e.- it isn't flexible, but rather acts as a pedestal on which the satellite at the top sits.

Perhaps you should look up how a space elevator actually works?

 

[tblaxland]

Not if you take advantage of tidal (gravitational) forces from Earth.

Which means locating the elevator centre of mass at an unstable L1 point 60,000 km from the Moon. That's doable, I guess, but its quite debatable that it is easier than building a shorter elevator for Earth.

There is also the important issue of demand - demand for a space elevator is much higher on Earth and even if it was easier to build one for Mars or the Moon, would it be so much easier to be offset by the lower demand?

Mar's moons would probably get moved to become the anchor and/or become the building materials for the tether.

I agree. That is certainly more feasible than shipping the materials all the from anywhere else.

Its kind of interesting the overwhelmingly negative waves on this topic. As if all the "rocket people" on this board find the idea of a space elevator a threat. lol....

If that criticism was directed at me, to be clear, I was not being negative against space elevators at all. I love the idea. Rather, I thought we were debating the relative prospects of a space elevator being built on Earth vs Moon/Mars. BTW, I don't see my self as a "rocket person" at all: http://www.orbiterwiki.org/wiki/ZTC_Tether-Sling_Transportation_System

 

[Ark]

I don't know how this would work, primarily because of the fact that as the elevator pulls on the cable to ascend, the cable will pull on the satellite or upper tether, causing it to descend. I suppose this can be avoided by firing engines against the pull of the elevator, or creating a cable which essentially acts as a 100KM-high skyscraper, i.e.- it isn't flexible, but rather acts as a pedestal on which the satellite at the top sits.

I don't think the force of an elevator car pulling itself up the tether is going to outdo the tension on the tether provided by the counterweight.