Space elevator, is it possible?

[Stclaim]

It has been suggested that a strong enough cable (carbon nanotubes?)should enable a space elevator to be built.

However, surely, as the cable is lowered from space there would be a static build up so great that when it discharges close to the earth, it would be like an atom bomb?

Also the cable would be like a super conductor and transfer earths heat into space. Another ice age anyone?

[John Cuthber]

It's a fairly thin wire so corona discharge would remove most static slowly and safely. Also, the capacitance is fairly small( again, because it's thin)

 

There's no good reason to imagine that it would be that goos a conductor. Also, again, since it's thin there's not much area for it to loose heat from so loss to space would be small.

[EdEarl]

It is plausible but not possible at this time because no current material is strong enough to support its own weight, much less an elevator. Although carbon nanotubes may be strong enough, we cannot make them long enough at this time.

[dimreepr]

It has been suggested that a strong enough cable (carbon nanotubes?)should enable a space elevator to be built.

However, surely, as the cable is lowered from space there would be a static build up so great that when it discharges close to the earth, it would be like an atom bomb?

Also the cable would be like a super conductor and transfer earths heat into space. Another ice age anyone?

 

 

Yes, it might be possible at some point in the future, the possible problems should be addressed then; ford the stream when you get there.

[Mr Monkeybat]

Space elevator is just about posible with carbon nanotubes and graphene at their top strength.

 

More feasible with current materials are Orbital Rings and Lofstrom Loops. Mass is accelerated above orbital velocity keeping the static structure with magnetic track suspended above the Earth by centripetal force. The mass driver 80km up in the vacuum of space accelerates the cargo and passengers up to orbital velocity. This is quicker and actually more energy efficient than the Space Elevator. I recommend Isaac Arthurs videos on the subject:

[wayne_m]

I've pondered this while driving long distances. I'm odd, that way.

There really is no reason that it should be impossible. Insanely expensive, sure. But not impossible.

Lower some strands from your geosynchronous station, and support a secondary platform, while extending a counterweight. Then from the lower station, lower a smaller number of strands to a smaller platform, and so on, until it reaches the ground. Once you have a functional elevator, use it to haul more building materials to the station, and begin making it stronger.

There is no real reason a cable has to extend the entire distance.

This could work with just about any material, but obviously, the station and its cables would have to be a great deal larger (and thus heavier) to support the weight as the elevator gets longer. The reasons we haven't done something like this are 1) it would be hideously expensive, and 2) the cables would oscillate, and without some way of damping that oscillation, it would eventually tear itself apart and/or yank the station out of orbit.

 

If such a thing could be started, then it might even be a good idea to transport the building materials up through a pipe, as a liquid, and make the cables on the station.

All sorts of materials could be carried up suspended in a liquid medium - we could even use magnetic medium in the liquid and an electromagnetic driver to act as a "pump" to move the fluid. The magnetic particles would be pulled along much like the mag-lev trains already in use. They would drag the fluid - water, perhaps - along with them. Letting it fall down another pipe after the payload is separated would provide some return energy. Then you'd only be spending energy to overcome the effect of gravity on the payload and the fluid resistance from the pipeline - unless you could separate the liquid from the walls of the pipe, in which case, it would flow much faster, as an added bonus. Using a flow of gas instead of a liquid could work, too.

You could even put stations on the platforms that would reduce the lifting medium at each step, as gravity becomes less of a hindrance. Then the concentration of the payload would increase each time. Or maybe an osmotic pipe could let it happen gradually, with better efficiency.

[Raider5678]

I've pondered this while driving long distances. I'm odd, that way.

 

There really is no reason that it should be impossible. Insanely expensive, sure. But not impossible.

Lower some strands from your geosynchronous station, and support a secondary platform, while extending a counterweight. Then from the lower station, lower a smaller number of strands to a smaller platform, and so on, until it reaches the ground. Once you have a functional elevator, use it to haul more building materials to the station, and begin making it stronger.

There is no real reason a cable has to extend the entire distance.

This could work with just about any material, but obviously, the station and its cables would have to be a great deal larger (and thus heavier) to support the weight as the elevator gets longer. The reasons we haven't done something like this are 1) it would be hideously expensive, and 2) the cables would oscillate, and without some way of damping that oscillation, it would eventually tear itself apart and/or yank the station out of orbit.

 

If such a thing could be started, then it might even be a good idea to transport the building materials up through a pipe, as a liquid, and make the cables on the station.

All sorts of materials could be carried up suspended in a liquid medium - we could even use magnetic medium in the liquid and an electromagnetic driver to act as a "pump" to move the fluid. The magnetic particles would be pulled along much like the mag-lev trains already in use. They would drag the fluid - water, perhaps - along with them. Letting it fall down another pipe after the payload is separated would provide some return energy. Then you'd only be spending energy to overcome the effect of gravity on the payload and the fluid resistance from the pipeline - unless you could separate the liquid from the walls of the pipe, in which case, it would flow much faster, as an added bonus. Using a flow of gas instead of a liquid could work, too.

You could even put stations on the platforms that would reduce the lifting medium at each step, as gravity becomes less of a hindrance. Then the concentration of the payload would increase each time. Or maybe an osmotic pipe could let it happen gradually, with better efficiency.

Then tension is still there, even if you make the cable in segments. Adding platforms will only increase the tensile stress.

[Ken Fabian]

I think this kind of engineering needs to have large safety margins built into it - so if the currently available materials are only just sufficient for the structure to support itself that won't be nearly good enough.

 

I doubt static charge or heat conduction are likely to be real problems. I don't know if carbon nano-tubes are tolerant of heat and cold - certainly they are good heat conductors - but whatever is proposed needs to consider the heat differences between full sun and Earth shadow which are, by ordinary standards, extreme. Exceptional heat conductivity may be an asset.

 

Vacuum diffusion and erosion from charged particles may be issues. Weather will affect the parts in the lower atmosphere and add sideways stresses that may be severe during extreme weather events. It may be that there won't be any solid materials good enough, but perhaps some kind of chained electromagnets that achieve greater tension than a physical material? (I don't even know if that is even theoretically possible - probably not, if the electromagnets themselves get torn apart by the tension!) That then introduces a whole new set of problems, including power supply that absolutely cannot ever fail. Then there is the actual construction and installation - during which there may be additional stresses, such as if the bottom end were dropped down (flown?) from orbit and anchored.

 

As a thought experiment it's interesting. As an engineering project it's not feasible and it may well prove to be forever unachievable - unless we see some extraordinary technological advances of course. And I suspect that technological advancement, despite the achievements I've seen in my nearing 60 years, ultimately will approach physical limits that aren't going to be amenable to techological workarounds or allow exceptions.

Edited October 12, 2016 by Ken Fabian

[Ken Fabian]

I suppose we should add safe deconstruction and disposal to the essential project specifications.

[HB of CJ]

Perhaps the Moon first? Then perhaps maybe Mars?

[johnmusic]

A waste of time and money. But then whoever funds stuff like this is not out to save the world or do anything for the good of humans. Like make drinkable water for everyone which will never happen because water is cash crop. And technology is used to entertain the wealthy.

 

it is more important to create a million pixle tv monitor than feed poor people.