The Space Elevator

[trolls' bane]

Imagine it is the year April 12, 2022. The space elevator has finally been completed and readied for climbers that will carry humans rather than satellites. Before your large ferry boat, an opaque black hairline stretches up from a gargantuan, oddly-shaped ship before you, and is lost in the haze above you. You are to be one of the people on the first climber, one of the first space tourists since the few that had visited the ISS. As the ship begins to dominate your windshield, you pull into a small dock underneath the ship. As you head up to the terminal, you notice that from one angle, you can't see the hairline cable at all: it is flat.
You take the elevator car up. Two days pass, and you enter space. Another week passes, and you're nearly three quarters of the way to the end. At this point, there's a space station, complete with a hydroponic farm and spaceport. the climber stops, and you float out.

This is a possible scenario for the twenties. A group called liftport has a countdown to the deadline for completion of a space elevator, on April 12, 2018. The cable, a slightly curved strip of a carbon nanotube/epoxy composite, though extremely small so you wouldn't be able to see it as I proposed in this scenario. The location, an area of ocean just west of the Galapagos islands, where it connects to a mobile cable base: a giant ship. Large payloads of cargo can now be lifted for a fraction of the cost it takes to lift small payloads in rockets. A whole new industry has taken hold, and businesses are booming both in nearby seaports and on the space stations. People on the stations before today have always taken space planes to the station, which are now in attendance to a large mass of spaceship parts: the manned Mars colonization mission. The first men have already been sent and returned, and now a group of forty people will be the first to colonize the planet. The rest of the parts will be brought up the cable...

The space elevator is a very real idea. A major topic of consideration among space agencies, the first space elevator could be built for less than the cost of the International Space Station. A relatively light elevator could be built of carbon nanotubes, the higher-quality version of the same carbon nanotubes that might make up the hood of your car. Nanotubes are potentially the strongest materials ever discovered, and have a relatively small tapering ratio for the elevator (1.5, as opposed to several magnitudes of ten as it is for the next best material to use). And, with our current economic standing and technology, we are ready to begin construction at any time.

[Count Comfect]

And, with our current economic standing and technology, we are ready to begin construction at any time.

According to everything I've ever seen, this isn't quite true. We've never built anything macroscopically significant out of nanotubes, and until we do, this is still way out there.

[trolls' bane]

No, we haven't. As you see, I didn't say that with our current technology we have built something macroscopically significant, but rather that we could build something macroscopically significant with our current technology. It's actually quite simple. Getting the nanotubes to stick together with the right epoxy and still be able to burn up in case of an accident or otherwise is a hurdle, but nothing we can't solve. Oh, I have a survey for all of you to take...

[durinsbane2244]

i don't think it matters if we're ready to build it or not, it's still pretty cool!!!

[trolls' bane]

I'm glad someone agrees.

[durinsbane2244]

indeed! an elevator to space...cool!!!

[Valandil]

I'm a bit confused by the duration of the trip you describe. What kind of speeds are we talking about? What kind of power moves the "cars"? It's been awhile since I've looked into this - but how far up do you need to go before you're considered to be in "space" anyway? Even with the speeds used for today's tallest skyscrapers (many of which - at least those in Chicago - were built in the 1970's) - I would think a few hours would suffice, instead of two days - to reach space.

And how far "up" does the elevator travel? Is it that one point (what's it called - "geosyncratic" or something??) (EDIT: Just looked it up - I think it's "geosynchrous") - where an object in Earth's orbit can stay over a fixed point on earth? If it takes two days to reach space, it would take a LONG time to get out that far (I believe it's on the order of 23,000 miles).

Also - should there be two elevator cables? Otherwise - you have to wait two weeks (your scenario) for a car to go up - and another two weeks for it to come back down. In other words - only one round-trip per month. With two cables, you could transfer cars from the "up" line to the "down" line - and send them as frequently as you like.

[BeardofPants]

Karl - do you mean geosynchronous? If so, a geosynchronous object only appears to be in a fixed position over earth and actually rotates around the earth in a series of periods (where 1 period = 1 day).

[Valandil]

Yeah - that's the one! Point being that it may be able to stay over the same point on the planet. To do so though, I expect it would need to be in orbit over the equator - otherwise I think it would change lattitude up and down the same longitude as it orbited, wouldn't it?

[BeardofPants]

Yes - I would imagine that if it were a tethered space elevator (vs a space fountain which is untethered) that it would have to be based over or near the equator otherwise geosynchronous orbit would not be achieved.

[Butterbeer]

it'll break down, elevators or lifts always do ... what then - step lively on the stairs? make 5 or 6 aerobic videos on the way down?

who's gonna repair that?


Space, will of course happen, though i think 2018 may be optimistic ... don't use the wembley staduim constuction team, is my advice...

[BeardofPants]

I'd be more worried about it bumping into existing satellites already in orbit than the climber breaking down up on the way up or down.

[trolls' bane]

Originally Posted by BeardofPants

I'd be more worried about it bumping into existing satellites already in orbit than the climber breaking down up on the way up or down.

Both are taken care of. Broken climbers would be followed up by working ones to pick the people up, and then detach the broken one, or in less severe cases, the climber would be able to automatically repair itself or the controller to manually repair it. Satellites are no worry at all. The elevator base is a large floating, moveable base. Any potential collisions could be avoided by simply moving the base out of the path. Some care would have to be taken to predict collisions with satellites sharing similar orbits to that of the elevator, but even my astronomy program can do that to some extent.

[Spock]

And just how would this be built?

[BeardofPants]

TB, not necessarily. The mobility is only available for ... er... mobile base stations, not stationary ones :

Originally Posted by wikipedia

Base station
The base station designs typically fall into two categories—mobile and stationary. Mobile stations are typically large oceangoing vessels, though airborne stations have been proposed as well. Stationary platforms are generally located in high-altitude locations, such as on top of high towers.
Mobile platforms have the advantage of being able to maneuver to avoid high winds, storms, and space debris. While stationary platforms don't have this, they typically have access to cheaper and more reliable power sources, and require a shorter cable. While the decrease in cable length may seem minimal (typically no more than a few kilometers), that can significantly reduce the minimal width of the cable at the center, and reduce the minimal length of cable reaching beyond geostationary orbit significantly.

[trolls' bane]

Oh, stationary base stations are feasable, but not practical. It just doesn't work on tall mountains. The situation would be different for the Mars elevator. (That, by the way, could be constructed alongside the Earth elevator and then sent to Mars.) I'm taking into consideration the most efficient, useful, and safe plan.

[trolls' bane]

Originally Posted by Spock

And just how would this be built?

Well, an "initial" cable (a few nanometers wide) would be...initially launched coiled up in a spaceship, which, upon reaching GEO above the base, would deploy the cable down. Upon touchdown, the ship would then move outward, to the 91,000 kilometers required. Then, a lightweight climber would glue another cable to the side of the first one using epoxy. This would be followed by many more climbers of increasing size until the cable became about 5 cm wide and a few nanometers thick. The climbers would be used as counterweights at the other end (to not use counterweights, the cable would have to be nearly twice as long).

[durinsbane2244]

so...a spaceship carries a cable, and pretty much just drops it to earth? what about burning in the atmosphere? what makes it fall with no gravity? what keeps the whole elevator and folks therein from burning?

[Jonathan]

Originally Posted by trolls' bane

Well, an "initial" cable (a few nanometers wide) would be...initially launched coiled up in a spaceship, which, upon reaching GEO above the base, would deploy the cable down. Upon touchdown, the ship would then move outward, to the 91,000 kilometers required. Then, a lightweight climber would glue another cable to the side of the first one using epoxy. This would be followed by many more climbers of increasing size until the cable became about 5 cm wide and a few nanometers thick. The climbers would be used as counterweights at the other end (to not use counterweights, the cable would have to be nearly twice as long).

I'm not sure I follow.
The initial cable would be "a few nanometres wide"? I mean, even if it was made of nanotubes I'm sure this cable (or "thread") would break into two if only a bird flew into it. Anything with a thickness of only a few nanometres and a lenght of tens of thousands of kilometres would break too easily.
Besides, how would we or the first climber find the cable? First of all it would be too thin to see without an electron microscope and second, the wind would sweep away such a light structure - it wouldn't just hang down vertically from the spaceship. Btw, if the spaceship climbs to 91.000, wouldn't it be leaving its GEO?

[Spock]

...you guys gotta take your meds regularly.....