What's a space elevator? Can we build one today?
A space elevator is just what is sounds; an elevator into space. What, you were expecting something complicated?
Here's the skinny. It costs one hell of a lot to launch crap into orbit. The good ol' space shuttle costs about one billion dollars each time we fire it up (based on US dollars in 2003, for those econ geeks out there). That's why we're not living on the Moon like everyone predicted back in the 50's. We can't afford the gas.
A space elevator would solve this problem. It would be a super-long cable starting on the ground and heading all the way up to the Earth's orbit. Attached to this cable would be an elevator. People and their pets would walk in, press the "GEO" button, and take a seat for a long trip. How long? Damned if I know. It depends on several factors such as weight of the passangers or cargo, speed utilized by the elevator, and materials used to build the damn thing. How 'bout an hour?
The ultimate free ride
Yes, it would still cost a lot to get it up there but only for the first time. When it comes back from it's maiden voyage, the elevator uses no power. Gravity takes over and the sucker slides on home.
Even better is how this can be used to generate electricity. Power plants burn fuel to power turbines, which spin real fast and generate electricity. Instead of fuel, we tie the turbines to the elevator. As the elevator car drops like a rock, it spins the turbines and we have huge amounts of juice.
This electricity is then used to pull the elevator back up into orbit. It comes back down, generating enough electricity for another trip, and on and on it goes. It's like a cross between a mythical perpetual energy machine and a yo-yo. I doubt that it'll generate enough juice for a full return to orbit, but it'll be close enough to turn $1 billion into chump change.
It can also make travel to the Moon and nearby planets much more affordable. By the time the elevator reaches geostationary orbit, it's built up a lot of momentum from the Earth's spin. If we time it right, we can let the elevator slide off the end and it will shoot into a perfect orbit around Mars or whatever. The plane ticket to reach the elevator will cost more than going to the Moon.
Little problems, really. Nothing to worry about.
So why haven't we built this beautiful Tower of Babel yet? There's a lot of engineering problems, which is scientist-speak for "We don't know how to do what we said we could do." For example:
-
Even steel isn't strong enough to do the job. Since the Earth is spinning on an axis like a top pulled by a kid with ADHD, we need a material that is 100 times as strong as steel. Yikes. Carbon nanotubes might do the job, but scientists are still trying to figure them out and we're going to need 20 tons of the stuff.
-
Because of complicated reasons like centrifigal force, a space elevator needs to be built along the equator. This means rich industrial nations like the US would have to build it somewhere like Equador. Americans would love that, assuming we know where Equador is. A floating base in the Pacific Ocean is more likely, but that's going to be one hell of a raft.
-
You need something really heavy to act as a counterweight at the end sitting in geostationary orbit. We're talking an asteroid or something. Otherwise, you'd pull the end down to Earth instead of shooting the elevator upwards. That's just what the public wants in orbit just above the planet; a huge rock. But it'll never fall down. We swear.
-
The bottom needs something big and heavy, too. How big? It needs a base 31 miles tall (or 50 kilometers for you metric nuts). For comparison, the Sears Tower in Chicago is 1,450 feet tall. One mile is 5,280 feet. So we're looking at a building that's 112 times the height of the Sears Tower, if I used my calculator correctly. Which is doubtful.
So there you go. It's a nifty idea, and one that scientists are trying hard to make a reality. But there's a lot of work left to be done, some of which we don't even know how to do yet.
Think you got a good question? Prove it. Click here, fanboy.
|