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THE MAGLEV CARRIAGE IN [#61 RISE] |
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There's been a lot of talk in the News recently about a space elevator. This was something that we featured on a [Voyager] episode called [Rise].
Neelix makes a proposal to Tuvok and the group of Nezu |
the maglev carriage rises |
Neelix: "I saw what appeared to be an orbital tether anchored nearby."
Dr Vatm: "Yes, we use those to lift cargo from the surface to the orbital supply stations."
Neelix: "May I assume it uses magnetic leverage to lift the carriage?"
Dr Vatm: "Yes."
Tuvok: "What is your point?"
Neelix: "What if we use that carriage to climb the tether?"
Sklar: "That tether's over 300 kilometres long. It takes 12 hours to reach the station."
Neelix: "Well, we wouldn't have to go all the way to the station. We just have to leave the ionosphere. Once we get above all this interference we can contact Voyager; they'll beam us aboard."
The idea behind it is basically if you went up to high orbit, geosynchronous orbit, and ran a cable all the way down to the surface of the Earth, you could attach payloads and even a pressurised vessel containing people to any orbit between the Earth and geosynchronous orbit. A gentle push is all that would be needed to
put that object into its own orbit around the Earth. It's an idea that's been around for decades. It was a Russian scientist named Y.N. Artsutanov who proposed this back in 1960. In the late 1970s, Arthur C. Clarke wrote a novel called 'The Fountains of Paradise' that talked about the construction of a space elevator.
Neelix calls: "Hang on! We're breaking through the ionosphere!"
The mag-lev carriage hurtles upwards. At the right moment Neelix reports: "Engaging induction dampers." The carriage halts. "We did it. We made it!"
The column itself would essentially be a long cable
or tether. An anchor would be placed at the far end of the tether
to maintain tension. The anchor could be a near-Earth asteroid
corralled into orbit by thrusters strategically placed on the asteroid's surface. Once completed, pressurized cabins would be
attached to the column that would rise, like Jack climbing the
beanstalk, to the geosynchronous altitude. Spacecraft rising all
the way to the anchor at the far end of the tether could be
"flung" into other orbits, using the tether as a kind of stingshot.
Once the tether and supporting systems are built, the only cost associated
with getting into orbit is the cost of the electricity needed to raise the pressurised cabins. Most of that electricity could actually be regenerated when the cabin returns to Earth.
The biggest engineering challenge in building a space elevator would
be to create a cable that had enough tensile strength to support its own weight plus the weight of the cable car. If you've ever tried to lift a big coil of heavy rope, like the rope used to moor a ship to a dock, you know just how heavy a strong rope can be. The big problem with trying to build a space elevator is you need to construct this huge cable that's tens of thousands of kilometres long. The cable or column would need to be twice as tall as the distance from the Earth's surface to orbit, plus the radius of the Earth, or about eighty thousand kilometres. And the thing has to not only be able to serve as a kind of elevator for the cargo and the people which you might want to take up into orbit and back down eventually, but it also has to be strong enough to support its own weight. And even a relatively thin cable thousands of kilometres long is extraordinarily heavy.
And the question is always is there a material which is strong to pull this off? And now we know that there is. The breakthrough that could make this possible is a new kind of material called a carbon nanotube. Carbon nanotubes are basically fibres that are comprised of carbon 60 molecules. In the 1980s, several researchers independently discovered a molecule that consists of sixty carbon atoms arranged in a closed, soccerball-like sphere. The carbon 6o molecules are called Buckminsterfullerenes, or Bucky Balls, after the inventor of the geodesic dome, Buckminster Fuller.
carbon nanotubes |
carbon nanotubes |
And they're extraordinarily strong. They have a greater tensile strength than steel. It looks like these carbon nanotubes might be strong enough to pull this off. A carbonaceous asteroid a couple of kilometres in diameter, brought to Earth to serve as a tether anchor, could probably provide all of the carbon necessary to construct an orbital tether. The tether could be created by automated machines on the asteroid and slowly spun down, like Rapunzel's hair, to the Earth's surface.
Dr. Richard Smalley, a researcher at Rice University, has recently discovered a way to assemble Bucky Balls into tubular structures that have enough tensile strength to support their own weight, and then some, even at lengths reaching thousands of kitometres. So far, these carbon 6o "nanotubes" can only be produced in very small quantities in the laboratory. But if engineers develop a technique to manufacture this material on a large scale, it may only be a matter of time before space elevators become a reality.
carbon nanotubes |
carbon nanotubes |
The hardest part about exploring space is really that first 150 miles. Getting up into Earth orbit is the hardest part of any space endeavour. Once you get into Earth orbit* it's relatively easy to get from orbit to the Moon or to Mars or the outer planets.
* Although the USSR was the first nation state to get a man into space, scientists recognise that the USA had a natural advantage over the USSR in terms of shifting the huge payload required for getting the first man onto the moon, because of the location of the USA on Earth due to coriolis forces, and this factor will of course continue to dog space ventures launched from certain parts of the world unless a better launch method can be devised.
space shuttle launch, heading for the International Space Station
Mir space station in Earth orbit
So if we can figure out a way to inexpensively get people and payloads up into Earth orbit, that opens up the whole solar system to space exploration. It would drop the cost eventually to pennies per pound; the cost of getting a pound of payload to low-Earth's orbit on the space shuttle is currently about $10,000. The space elevator is one of the technologies that could make that far easier, far less expensive, than conventional rockets.
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