The Space Elevator

[IAM]

Brazil is probably one of the most stable governments along the equator. It is also far enough South of Hurricane tracks and is fairly stable from earthquakes, volcanoes, etc.

map world equator
http://commons.wikimedia.org/wiki/File:World_map_with_equator.jpg

 

[onejayhawk]

The Pacific rim is very unstable tectonically, but the Atlantic side of South America is relatively calm. Other choices would be in the Indian Ocean, either east of Africa, south of Singapore or the Maldives atolls. All have issues, but when the push comes, I suspect Sinapore to get one of the first two. It is too natural a location--large, technically sophisticated population, major transport hub, an archepelgo to break up the worst weather.

J

 

[Evie]

And tons of population for the elevator to fall on top of

 

[onejayhawk]

And tons of population for the elevator to fall on top of

No. It is all away from the equator. Also, ribbons would flutter down. It could reach around the world, more than once, which would be annoying.

J

 

[Evie]

Ah, interesting. Having ideas for space elevators that won't fall on top of people in a destructive way is probably one of the biggest steps toward actually building them.

 

[Kyriakos]

Ah, interesting. Having ideas for space elevators that won't fall on top of people in a destructive way is probably one of the biggest steps toward actually building them.

Another issue might be the arrival of some multi-personality deity which would want to confuse the people creating the tower of Babel

 

[Leifmk]

It could reach around the world, more than once, which would be annoying.

If it broke near the top. Breaking near the bottom (as in within the atmosphere) would be far more likely in most scenarios, and in that case only the part below the break point would fall down while the rest would move into a slightly higher orbit (and might still be a pain in the butt to clean up, mind you).

 

[Phrossack]

I'm confused. Just how long is this elevator tether supposed to be? If it's long enough to reach around the world more than once, it would be tens of thousands of kilometers long, but low orbit's between 160 and 2,000 km high, innit? Does it really need to reach tens of thousands of km, or am I missing something?

Also, how would we deal with the ever-increasing amount of very high velocity space junk? Couldn't it destroy the elevator or the tether? And how easy would it be to destroy the tether or elevator in a terrorist attack with rockets or heavy gunfire?

All this space stuff hurts the brain of this simple history major.

 

[Kyriakos]

^Which was one of the reasons i asked where the space elevator would actually be leading to. Some space station in eternal orbit around our planet? Something other than that? (seems less likely it would link to the moon, for example).
I don't really see the use of it if it leads to a space station, cause obviously it would cost an enormous amount of money to make, it might not work with current technology, it could be prone to disasters, and if it gets ruined we would be stuck with a rather nasty tower orbiting our nasty little world :\

 

[Evie]

Low orbit is way too low, though. Keep in mind, you want your end point to be constantly above the same point in the world (for hopefully obvious reason), that means geostationary orbit. Which is 35 000 km above the world, give or take.

 

[Phrossack]

Low orbit is way too low, though. Keep in mind, you want your end point to be constantly above the same point in the world (for hopefully obvious reason), that means geostationary orbit. Which is 35 000 km above the world, give or take.

Good gods.

We're better off looking for more efficient rockets, a space elevator's totally impractical.

 

[onejayhawk]

If it broke near the top. Breaking near the bottom (as in within the atmosphere) would be far more likely in most scenarios, and in that case only the part below the break point would fall down while the rest would move into a slightly higher orbit (and might still be a pain in the butt to clean up, mind you).

Hence the "could."

I'm confused. Just how long is this elevator tether supposed to be? If it's long enough to reach around the world more than once, it would be tens of thousands of kilometers long, but low orbit's between 160 and 2,000 km high, innit? Does it really need to reach tens of thousands of km, or am I missing something?

Also, how would we deal with the ever-increasing amount of very high velocity space junk? Couldn't it destroy the elevator or the tether? And how easy would it be to destroy the tether or elevator in a terrorist attack with rockets or heavy gunfire?

All this space stuff hurts the brain of this simple history major.

Low orbit is often less than two hours. Higher means longer. This would be fairly high, in geo-synchronous orbit, which means one orbit every 24 hours. Since the Earth turns at the same rate, the station stays in the same place in the sky. We use this fact extensively for communication satellites. It has to be at the equator for the same reason. Any other latitude would cause an orbit that drifts north and south.

One of the interesting things is that Carbon nanotubes are electrically conductive. Potentially, much of the power could come from a solar array at the top. The climber could have enough solar cells to power itself over the top half of the climb.

Good gods.

We're better off looking for more efficient rockets, a space elevator's totally impractical.

It is now, but the necessary materials and tech are within a generation or two.

Just so we are clear, you start at the top and build down. Once a single ribbon is in place, you build bottom up, using a climber that extrudes ribbon as it goes.

J

 

[IAM]

Good gods.

We're better off looking for more efficient rockets, a space elevator's totally impractical.

Our current technological trends make it more likely for the space elevator to improve space exploration before increase in rocket efficiency. As a cost comparison using tested rocket technology can still cost $40,000 to get 1 kilogram (2.2 pounds) into space. A space elevator should cost about $220 per kilogram.

http://en.wikipedia.org/wiki/Space_elevator_economics

 

[El_Machinae]

Good gods.

We're better off looking for more efficient rockets, a space elevator's totally impractical.

That's where you differ from consensus. The SE would lower the cost of getting stuff into space by nearly an order of magnitude. Everything becomes easier.

 

[Phrossack]

That's where you differ from consensus. The SE would lower the cost of getting stuff into space by nearly an order of magnitude. Everything becomes easier.

It's not the fundamental idea of the elevator that's impractical, it's just that there are a lot of very serious issues. The truly insane length of the tether, the vulnerability to terrorism and space junk, the dangers of such a long tether falling, and so on. They seem insurmountable.

 

[El_Machinae]

Well, the insane length of the tether is not an overwhelming issue. Like, seriously, suppose it only needed to be 1/100th the length (~350 km), would that be significantly different? Yeah, the manufacturing is harder, but that difficulty doesn't scale linearly. It's basically a budgetary issue. The consequences of a 'break' are higher, yes, but those consequences ain't all that much even in a worst case scenario, and are worth any cost/benefit ratio. The vulnerability to terrorism doesn't scale. Space junk risk scales linearly, but ehn, it's a fairly definable issue.

 

[Kyriakos]

Well, the insane length of the tether is not an overwhelming issue. Like, seriously, suppose it only needed to be 1/100th the length (~350 km), would that be significantly different? Yeah, the manufacturing is harder, but that difficulty doesn't scale linearly. It's basically a budgetary issue. The consequences of a 'break' are higher, yes, but those consequences ain't all that much even in a worst case scenario, and are worth any cost/benefit ratio. The vulnerability to terrorism doesn't scale. Space junk risk scales linearly, but ehn, it's a fairly definable issue.

We can always fall back on the previous ~35000 KM buildings we have created

Moreover, while mechanical physics ('engineering physics' in english?) is fairly straightforward for buildings we create reaching up to several hundred metres now (tallest afaik being a bit less than a full KM), i have to doubt it is a simple step from that to have a building that has vast parts in very different pressure conditions to each other.
If anything it seems very unlikely we already have the tech to create such a thing, even if money was no issue (and it probably is, but nothing a new world war can't fix for its winning side...).

 

[peter grimes]

I think the term you're looking for is architectural engineering?

The Space Elevator wouldn't really have an issue with pressure. From the base to the anchor (or whatever the orbital element is called) is a difference of 1 atmosphere. That's not really anything to worry about. The tension along the length, on the other hand, is a real challenge.

I wonder if winds are also a concern. Would be pretty dicey if a harmonic vibration got going.


Link to video.

 

[Cutlass]

Wind is one issue where I question the idea of anchoring the bottom to a ship. It would take a really big ship to withstand if wind started pushing the tether around. HERE's a spot. 1000s of miles from anywhere, and just off the equator.

 

[Samez]

About cnts: in 2013 the longest carbon nanotube was about 0.5*10^0m long, for the space elevator it would have to be 3.5*10^7 m so there is still a long way to go.

About vibration:
Wind is probably of concern, also tidal effects might appear....