Space Elevator successes

[betazed]

What about the skyhook design (a rotating length of cable in Earth orbit which periodically dips into Earth's upper atmosphere to snag cargo)? Not as efficient as a true elevator, but would this require less tensile strength?

Intuitively, yes; the skyhook design would require less tensile strength primarily because we can make the hook radius as small as possible (and also less usefull too but that is another matter) as make the hook rotate as slowly as possible.

Unfortunately, for a true elevator that reaches till the ground we have no such choice. We could however, not let the elevator reach till ground. For example, we can say that the elevator reaches only till 10 km of surface (say). That would reduce the tensile strength requirement of the elevator.

 

[Abaddon]

I just keep seeing it as the ultimate terrorist's target.

Why? if they damage it, it will float on out to space, not crash back down to earth.

 

[Sahkuhnder]

Why? if they damage it, it will float on out to space, not crash back down to earth.

Not for the actual damage it causes but for the symbolic value.

Not to offend, but the 3000 or so deaths from 9/11 don't qualify as a huge number really either. During WWII that would have only been a minor skirmish and likely wouldn't have even been reported. During WWI there is a valley between Italy and Austria that about 1 million men died fighting over. How many people can even name it?

Symbolism is important.

 

[Leifmk]

If you're saying what I think you are, the centre of mass of the elevator is in geosychronous orbit, so it turns with the Earth, completing an orbit every 24 hours.

Nitpick: It is the centre of gravity needs to be in synchronous orbit (or just further out), not the centre of mass. On this scale it is no longer a good approximation to treat the Earth's gravity field as uniform, so the two will not coincide.

 

[El_Machinae]

Not for the actual damage it causes but for the symbolic value.

Once we've got the technology, won't the construction be rather cheap (relatively)? I suspect it's the bureaucracy that will be the huge expense. And once one is made, there's no reason more couldn't be made. Will it be much more expensive than an oil rig (after bureaucracy is factored out)?

 

[MrCynical]

Once we've got the technology, won't the construction be rather cheap (relatively)? I suspect it's the bureaucracy that will be the huge expense. And once one is made, there's no reason more couldn't be made. Will it be much more expensive than an oil rig (after bureaucracy is factored out)?

It's going to be a lot more expensive. Unlike most things a space elevator has to be built from the top downwards, and that needs spacecraft. Even the methods which involve lowering a 'seed' elevator from orbit, would still require at least a dozen space shuttle flights before the elevator would reach a stage where the rest of the material could be hauled up the 'seed' elevator. That's to say nothing of the expense of producing the vast amounts of carbon nanofiber, or whatever the elevator is being built out of. I'd have thought the price tag would look very similiar to that of the ISS (though an elevator would be more useful).

 

[onejayhawk]

One aspect of this that everyone seems to ignor is that you can use a one for power transmisssion. Even if it has to be dedicated for that purpose, the availability of orbital sunpower to the city on the ground will be a big benefit.

I also would expect orbital mining to pick up quickly. Asteroid prospecting is an old SF standby, because it makes so much sense. As rock, many meteorites are better ore than what we dig up, and some are almost prefined metal. Also the smelting methods you can use in space would not be wise near populations. And, since the metal would be up top, there is an energy benefit to bringing it down.

J

 

[Leonel]

I wonder what the elevator music is gonna be then?

Love in an Elevator by Aerosmith.

 

[El_Machinae]

Wiki says that we need a tether in the >65 GPa range, though this is still interesting. I've seen elsewhere that this stuff has strength at about 9 GPa.

http://www.physorg.com/news151938445.html

Long, Stretchy Carbon Nanotubes Could Make Space Elevators Possible
...
Scientists from Cambridge University have developed a light, flexible, and strong type of carbon nanotube material that may bring space elevators closer to reality. Motivated by a $4 million prize from NASA, the scientists found a way to combine multiple separate nanotubes together to form long strands. Until now, carbon nanotubes have been too brittle to be formed into such long pieces.
...
Currently, the Cambridge team can make about 1 gram of the new carbon material per day, which can stretch to 18 miles in length.
...
"The key thing is that the process essentially makes carbon into smoke, but because the smoke particles are long thin nanotubes, they entangle and hold hands," Windle said. "We are actually making elastic smoke, which we can then wind up into a fiber."
...
"The biggest problem has always been finding a material that is strong enough and lightweight enough to stretch tens of thousands of miles into space," said Winter. "This isn't going to happen probably for the next decade at least, but in theory this is now possible. The advances in materials for the tether are very exciting."

I only quoted the super-cool parts.

 

[warpus]

18 miles, huh? In 2006 we were up to 1 mile, and that was a pretty big accomplishment.

How much do we need again? 300 miles?

 

[gangleri2001]

2009 and you are still building space elevator? You're bad civ players.

 

[Abaddon]

I thought Graphene was the new kid on the block?

 

[jeps]

0.0000161290323% wow.

 

[Cheezy the Wiz]

18 miles, huh? In 2006 we were up to 1 mile, and that was a pretty big accomplishment.

How much do we need again? 300 miles?

67,000 miles or so, since the end has to be in geocentric orbit, not simply in space.

Cool stuff El Mac!

 

[El_Machinae]

I thought Graphene was the new kid on the block?

It's certainly a player. I think the current concern is electrical conductance. I don't know what's going on regarding mass-production of the stuff. That's why there are competitions!

 

[warpus]

0.0000161290323% wow.

18 is about a quarter of a % of 67,000

 

[Gooblah]

I just keep seeing it as the ultimate terrorist's target. It would have to be strongly defended.

To be most effective it should also be as close as possible to the equator to take advantage of the spin of the earth for the up-bound loads. This adds to the defense problem as most of the Western world's land holdings are nowhere near the equator.

If there is a profit in it someone will build one.

French Guiana? Close to the equator, under European control, and already the EU's spaceport.

 

[emzie]

French Guiana? Close to the equator, under European control, and already the EU's spaceport.

The problem with French Guiana is that it's really rather remote. From what I remember there's not a single road that enters the... department(?)... I think it's called a department. There's also no major sea port that could handle large volumes of traffic. And while it's true we don't send a lot into space now -- surely, nothing that couldn't be sent through French Guiana right now -- a space elevator would change that. Though the infrastructure to meet that demand could be build up along side the project, I think it might be simpler to just build the thing in Brazil.

 

[carmen510]

2009 and you are still building space elevator? You're bad civ players.

Just a little plug in, isn't this supposed to be in the Science/Technology forum?

 

[Bill3000]

Just a little plug in, isn't this supposed to be in the Science/Technology forum?

This thread was made before the Sci/Tech forum was created.