There was a whole program just on the elevator cars alone, all the different types, how they work, how they're constructed inside, how they're connected to the tracks. The bigger cars have longer carriages and they stand away from the cable more. They're mounted at the tops and bottoms, so they look like handles with windows in them sliding up and down the Line.
It's all done with magnetic induction. The car never even touches the cable unless it has to stop, in which case there are contact brakes, because the track-riding mechanisms aren't really designed for slowing and stopping; they're designed for moving a thousand miles an hour. You can't just slow an elevator down and hold it in place because magnetics don't work like that, so that's why there are contact brakes; but even contact brakes have to be specially designed, because the cars are moving so fast that to try to stop one, the brakes would generate enough heat to permanently weaken the cable. So stopping a car isn't a simple operation.
If the car is going up, they just turn off the magnetics and let the car coast for a bit until it burns off most of its speed. When it's still going about fifty miles an hour upward, that's when the contact brakes grab hold. But stopping the car when it's going down is a whole other story; they have to reverse the magnetic inductors and slow the car, and that takes a whole lot longer to reduce its speed.
Restarting a car is easier going down, but almost impossible going up, because the magnetic inductors are spaced too far apart for an easy start. They don't really expect cars to stop and start on the cable anyway. Weird said that in the event of a real problem, the Line engineers would rather pop the car off and either let it parachute down if it's low enough, or catch it somewhere in orbit if it's too high to land.
The most interesting show we saw was a rerun of the Nova episode called "Breakaway Revisited" about what would happen if the cable snapped. First they showed clips from the movie Breakaway which supposedly depicted everything that would happen in such an accident. They showed all the best shots, of the cable falling and falling and falling and finally wrapping itself around the Earth, slicing across continents, jungles, deserts, oceans, mountains. They extrapolated all the damage that could occur. It was pretty scary stuff—I was surprised they were even showing it on the cable channels.
The most likely place for the Line to break would be low Earth orbit, around the 1000-kilometer point, because that's where the most and fastest orbital junk is—and the most ionized gas too, which also has a corrosive effect. But the part that fell back to Earth would be relatively short and thin. And it would fall almost vertically. A break at the 1000-kilometer point would result in the broken end arriving at ground level about eight minutes later, at a speed of nearly 4 km/sec, about 25 km west of Terminus Station—the foothills of the Andes.
A break higher up, though, would be much more serious. If the beanstalk snapped at Geostationary, the upper half would fly away into space, but the lower half would be 40,000 kilometers long. It would wrap itself around the planet—all the way around the planet!
It would be like detonating nuclear weapons along every inch of the equator. The destruction could be as bad as the asteroid that killed the dinosaurs. When you calculate mass and impact, you're talking about an object 40,000 kilometers long, circling the Earth and hitting the ground with the equivalent force of twenty times its own weight in TNT. It's an extinction-level event.
We would lose millions of lives, first from the immediate destruction around the equator and vicinity, then millions more from all the after-effects. Slumbering volcanoes might be shaken back to life. Earthquakes would very likely be triggered along fault lines. Uncontrollable firestorms would be started across the Amazon and the heart of Africa. A gigantic wall of ash would climb into the atmosphere—at least as bad as anything caused by an asteroid impact—and all that soot in the air would create a nuclear autumn and probably a decade-long disruption of the seasons, maybe longer. The impact of the cable across the Atlantic and Pacific oceans would cause immediate tsunamis on every coastline, and noticeable heating of tropical water temperatures as well—enough to trigger super-hurricanes. After that, the real disaster would begin: the inevitable extinction of many species; the disruption of rainfall, migration patterns on land and sea, and crop-growing seasons; long-term famines.
Oh, and one other thing. If one Line failed in a big way, enough to wrap around the Earth, it would very likely knock down all the others with it—the one in Africa, and the one at Christmas Island. And each of those failures would have equally disastrous effects.
Of smaller import, but equally significant to human beings, would be the near-total collapse of the global economy.
The Line represents such an enormous part of the wealth of the planet that its destruction and the destruction of property on land and in space would essentially bankrupt every insurance company in the world. The loss of capital would also bankrupt every investment company. The interconnectedness of everything would pull down everything.
The failure of the beanstalk would also maroon many people in space with no safe way to return, simply because there wouldn't be the spacecraft available. Without regular supplies, the folks in the asteroids, the Lagrange colonies, and other bases would run out of food, water, and air. Only Luna and Mars were anywhere near self-sufficiency. The death toll in space would be proportionally more severe than the death toll on the ground. Three out of every five. As many as six million people.
But then the show started examining all of the movie's premises and took each one apart to show that for all of the events in the movie to actually happen, the cable would have had to have been designed to fail. They showed how the individual fibers of the cable were manufactured out of superlong molecules, how they were braided, strengthened, linked, and energized by superpowerful currents—so that even if a terrorist were to succeed in planting a strong enough bomb on an elevator car, it still wouldn't destroy the beanstalk. All three cables were now cross-linked every hundred klicks, and those linkages were designed to provide enough support so that a broken cable would stay in place until a repair crew could arrive to secure it. In fact, any single one of the cables was thick enough and strong enough to hold the other two in place if a break occurred. They showed that even if all three cables were broken at different places, the beanstalk would still survive long enough to be repaired. The only way a terrorist could destroy it, he'd have to snap all three cables at the same place, which just wasn't possible because the cables were held far enough apart from each other to put them well out of each other's blast radius. Even a piece of orbiting space junk colliding with the Line could only take out one cable, not all three, because they were spaced farther apart than the size of any known piece of junk. Anything short of a nuclear device would be insufficient to snap the Line.
Part of the show talked about some of the proposals to add self-destruct mechanisms to the beanstalk. One guy wanted to mine the entire length of each cable with binary explosives, so if the cable snapped, the whole thing would be blown to bits and all the bits would vaporize on the way down through the atmosphere, so nobody on the ground would get hurt. But the analysis of that plan showed that it was not only too expensive, but even if you could do it, and even if all the cables snapped, it still wouldn't work. The resultant meteor showers would do almost as much damage as a falling cable, and the radius of destruction would be far wider. And besides, there was more chance of one of those self-destruct units failing and blasting the Line apart than there was of a terrorist snapping all three cables at once. So much for that idea.