Back in ninth grade, I raised my hand in Physical Science and asked my teacher if it would be possible to build a pole extending from the earth into space. I had seen a reference to such a structure on television. The kids loved it when he replied, "Don't be an idiot, LeeMichael." It actually became the class motto for some time.
Flash to ten years later: NASA researchers are considering the construction of a 'space elevator.' Laugh all you want, I can't hear you through the magazine.
Based on discussions during the Advanced Space Infrastructure Workshop held last year at the Marshall Space Flight Center, David Smitherman of Marshall's Advanced Projects Office compiled a paper in which he describes the limitations and possibilities of space elevators. What we need:
A base tower approximately 50 km tall (did someone say Babel?)
A few tons of carbon nanotube materials to extend a cable from the tower into space
Some developments in space tether technologies and lightweight composite structural materials
Approximately six high-speed electromagnetic propulsion-based vehicles to ride vertically along the nanotube cable
A space station for docking and unloading
And one giant asteroid to counter-balance the whole sha-bang in geostationary orbit.
OK, it sounds expensive. But it is possible. According to Smitherman, today's construction materials could be used to make a building several kilometers high. An engineer at Otis Elevator Co., who claims to have the know-how to build elevators for a five-mile-high tower, supports that fact. Carbon nanotubes, and other wondrous materials—while not available in your local hardware store—are in existence. And electromagnetic propulsion-based mass transportation systems? It could happen!
Now, you know what they say. Location, location, location. If you're going to have a catastrophic failure, and a few tons of cable and some space vehicles are going to rain down on Earth, the best place to build this thing would probably be in the middle of the ocean. This will also help you avoid paying property taxes. Somewhere near the equator would be nice—less stormy there.
Why go through all this trouble? Some calculations price a one way ticket on the elevator at $222 per 150-kg person (with luggage). Compared to today's cost prohibitive space travel, that's a savings of hundreds of thousands of dollars per payload delivery.
When I spoke to Smitherman, he stressed that clever engineers and innovative engineering would be crucial in designing the 22,000-mile-high structure. He says, " Advancing technology to produce continuous carbon nanotube strands is perhaps the most important development needed to make the space elevator possible."
Are there any drawbacks? According to Smitherman, those necessary advances are 50 or more years away. Given that, it doesn't make much sense to get over excited. Besides, who knows what other forms of travel engineers will come up with in the next century? I saw something on television the other night called a transporter that can beam you where no man has gone before.
Who's the idiot now?
Check out this story on www.designnews.com for a link to David Smitherman's "Space Elevator" paper.
The velocity of a satellite in a circular orbit radius r about the earth is proportional to:
B) r 2
D) 1/r 2
E) 1/r 1/2
Source: Adapted from The Fundamentals of Engineering Examination, Eugene L. Boronow, Prentice Hall Press, 1986.