Thursday, November 11, 2004

Me and the Beanstalk

I was reviewing my posts on this blog so far, and came to the disspiriting conclusion that many, upon reading them, my get the impression that I am of a singularly misanthropic disposition.

This is true.

However, I feel like rambling on about something positive, so here's my monologue of beanstalks.

Not the kind that you grow beans on; more like the kind that you grow hyperindustrial economies on. They're otherwise known as skyhooks, space ladders, space tethers or space elevators (okay, so skyhooks are slightly different.) For those not amongst the initiate in the weird world of speculative technologies, a beanstalk can be thought of as a railway that goes all the way into space. The current model, the one most likely to be constructed for a variety of reasons, is a ribbon, roughly a micron thick, ten centimeters wide, and, something like ninety thousand kilometres in length. Construction cost, roughly US $15 billion; time, two years.

Here's how its done. The first length of ribbon, constructed from carbon nanotube composites, is sent up in a rocket, which inserts itself into geosynchronous orbit. A second, smaller rocket then fires back down to the ground, attached to one end of the ribbon; the other end is anchored to the original rocket. The return rocket is recovered and the groundside ribbon attached to a platform in the ocean. The ribbon is winched tight. An unmanned crawler then proceeds to climb the ribbon, laying a second ribbon down on top of the first, and then adding its own mass to the counterweight in geosynchronous orbit. Bottom to top, the climb takes two weeks. After two years, the resulting ribbon is roughly 100 times as strong as it was when first deployed, and is now ready to start taking cargo.

Now, why go to all this trouble? Simple: cost-to-orbit goes down to about $500/kg. That means a ticket to orbit would cost me around $45 000. And I'm a big guy. Odds are, it would cost you even less. Now, in practice, a one-way orbital ticket would of course be more expensive. I'd be surprised to see them go for less than a million, myself, given the bulk of machinery that must be shipped up to keep one more person alive.

I'm geussing you're still saying, wow, that's expensive. Consider this: the current cost-to-orbit is, oh, something like $20 000/kg. Space elevators would thus perform a function in the 21st century very similar to that played by railroads in the 19th by providing a drastically reduced cost to access the solar system (once you're in orbit, after all, you're halfway to anywhere), just as railways opened up North America's West.

Initially, of course, the space elevator would serve fairly prosaic functions. Satellites first, to be followed by the machinery necessary to build orbital factories and the raw materials necessary to feed them. Much of this will be unmanned.


People would climb the ladder, too, following the machines. Hotels for the rich are a near-certainty; habitats to house the workers needed to build such structures as solar power satellites (something so useful and frankly necessary that we'd be fools not to build it.) Communities would grow, up there, living int he harshest environment men have ever entered, straddling the edge of an endless frontier. Testing themselves and their memes against this void will put human ingenuity to the hardest test it has yet to endure.

With time, more will emigrate, smelling profit or fleeing politics. The communities will become permanent. And then the day will come when those Left Behind will look up and realise that giants really do live at the top of the beanstalk.


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