Filed under: Transportation If the third time is the charm, yet you botch that attempt just like the earlier two, then what? That's the problem facing NASA and its Space Elevator Challenge, which has for three successive years failed to live up to the vision of Arthur C. Clarke. Japan isn't waiting for a fourth, announcing plans to spend $7.3 billion on its own lift to whisk passengers (and cargo) 22,000 miles aloft on composite cables. It's the cables that are the problem, as they need to be 180 times stronger than
