OUR SOLAR SYSTEM

Ribbon of carbon nanotubes the cable for elevator into space

As long as man has been able to stare at the stars the idea has been there, in Jacob's ladder, in the Tower of Babel. It was a mystical dream of something tall enough to reach into the heavens.
What if there were a way, a ribbon slicing through the atmosphere that spacecraft could climb? An extreme version of an elevator that's right out of science fiction by writers like Arthur C. Clarke.
The space elevator starts with a basic platform in the ocean, near the equator. Attached to the platform is a paper-thin ribbon no more than a metre wide that stretches 100,000 kilometres into space, about one-quarter of the way to the moon. There it's tied to a satellite that pulls the ribbon taut and keeps it straight as it orbits in synch with the Earth's rotation.
Spacecraft would ride up the cable on an electrically powered climber that would be fuelled by ground-based lasers shining onto solar panels.
Once above the Earth's atmosphere the spacecraft would be released to orbit the Earth and do whatever business it was sent to do. Or it could ride the elevator right to the end and be thrown toward Mars or Venus.

[Until 1991, scientists were forced to fantasize about a space elevator built with a magic material they called "unobtainium". Then carbon nanotubes were discovered -- hollow carbon tubes 100 times stronger than steel yet so tiny 50,000 of them would fit inside a human hair. Scientists are trying to figure out a way to stretch carbon nanotubes. Right now the longest one they can make is just 1.5 centimetres.]