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Rockets: So Old School?

11/08/2012 01:15 pm ET | Updated Jan 08, 2013

Could rocket scientists be an endangered species?

You're probably betting "no," given the contemporary efforts to hurl hardware to the moon, to Mars, and to a passel of other unearthly locales. The rocket biz is busy, and it's diversifying. An enthusiastic troupe of private companies is also getting into the act, hoping to cash in by lifting off.

It seems that "rocket scientist" is a job category that's here for the long haul, like "mortician." But all this activity masks an important point: rockets are not a terribly efficient way to lift things into space. For every pound of payload, there are typically 25 pounds of rocket and fuel, and in some cases the vehicle is just thrown away after use. Rockets also suffer from a heavy foot on the accelerator, subjecting payloads and passengers to G-forces that warp faces into Botox ads. In addition, and despite nearly a hundred years of building these flame-belching devices, they're still vulnerable to colorful self-destruction. This is probably not a list of features you would accept in your next family car.

However, there's an intriguing alternative to traditional reaction technology that could beat rockets at their own game. It's called the space elevator.

What's a space elevator? Simply described, it's a thin ribbon, about 3 feet wide and 60 thousand miles long, stretching upwards from the surface of the Earth. The lower end is bolted to a heavy anchor (think of an oil drilling platform), and the top is capped with a counterweight. It's all arranged so that the center of mass falls at the geosynchronous orbital point, about 22,000 miles up. Like a rock on a string swung 'round your head, the ribbon is under tension, stays straight, and rotates with the Earth. Consequently, it can serve as a "track" for solar-powered motorized climbers that leisurely lift satellites, people, or other payloads into space. No combustion required.

The physics for this was noodled out a long time ago, and despite your intuition, it would work. Sure, it might take a week to crawl your way up to orbit, but if you're a telecommunications satellite, you won't get bored en route. The cost would be 100 times less than using a rocket, and you wouldn't have the usual constraints that rockets make on payload size or shape. You could also avoid the "shake, rattle and roll" of a launch - heading skyward would be a slow and steady affair, not a shuddering blast of smoke and fire. Countdowns might become déclassé.

Clearly the space elevator could grab a lot of the space transport business. So why is it still on the drawing boards, and not hauling satellites or tourists into orbit?

The answer is that the technology to build the ribbon is not yet in hand. To withstand the forces that keep the ribbon taught, the material used to make it must be a thousand times stronger than steel.

There's only one known material boasting that kind of tensile strength: carbon nanotubes, which are cylindrical molecules built of atoms holding hands with strong, covalent bonds. But a factory that can turn carbon nanotubes into a sheet a yard wide and long enough to stretch one-fourth of the way to the moon is not something you'll find at your local industrial park.

That's the show-stopper for the space elevator. The ribbon.

The good news is that engineers think they've tamed the other technical problems. These include easily envisioned mishaps that could break the ribbon, such as meteors, space junk, terrorists and lightning. These threats (and more) have been considered, and the elevator crowd figures that with careful operational procedures, together with a design that can take abuse and mechanisms to occasionally move the ribbon out of harm's way, they're all solvable.

So when does it happen? How long will it be until you can reach orbit while sitting quietly in a capsule eating sandwiches and listening to Muzak?

According to space systems engineer Peter Swan, Director of the International Space Elevator Consortium, this device is about three to four decades away. That's a long time, although breakthroughs could always shorten the wait. As for the price, Swan reckons it to be about $13 to $15 billion. Mind you, these are best guesses, but the elevator promises to be comfortably profitable, given that the launch business should generate revenues of at least a billion dollars a year.

Sure, this is a project that will be a long time in coming, similar to practical nuclear fusion. But like fusion, the space elevator would be a true game changer. Imagine the effect of knocking down the expense of getting anything into space by a factor of a hundred. When railroads were introduced, they brought down the cost of sending goods hundreds or thousands of miles by comparable amounts, and economic activity exploded. The space elevator's not just another competitive technology, promoted by people who simply like the idea of diminishing the luster of the thrusters. It would open wide the doors to space.

That includes far cheaper rides to the solar system, practical solar power satellites, orbiting habitats, and -- of course -- that weekend vacation in a hotel with a killer view.

And while the space elevator is now merely a good idea awaiting some important new technology, it's easy to foresee a time only a generation away when people will cross the final frontier with a lift, instead of a lift off.

MORE:

Space, Rockets

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