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.

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.

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.

The Moon stabilizes Earth's obliquity. Well, almost. The tilt actually varies between 22 and 24.5 degrees - and the variation is enough to induce such environmental inconveniences as the occasional ice age. Without the Moon, it might be much worse.

If you're going to go to the moon, you don't shoot the rocket right at the moon. You have to go at it obliquely.

That's no moon. It's a space station.