Consider it a stretch of the imagination or the ultimate high-wire act. All aboard the space elevator, to be whisked above Earth in an electromagnetic-powered cable car. Taking an elevator to space has largely been in the realm of science fiction, more fanciful than engineering fact. But recent studies suggest that a melding of space tether, magnetic levitation, and carbon nanotube technologies could transform this Jack and the Beanstalk idea into a mass transit system for the 21st century space traveler.