The world’s space programs are vertically challenged. What’s needed is a revolutionary low-cost way to move payloads and people into Earth orbit and then outward to the asteroids, Mars and beyond. Now an upstart company of enterprising engineers and investment strategists want to tackle the ultimate high-rise project for the 21st century: the space elevator. They are on the ground floor of putting calculations to paper and wrestling with the toughest challenges. The message from the First International Space Elevator Conference, held here August 12-13, is that the concept is an idea whose time has come