President Bush wants to return to the moon and put a man on Mars. But scientist Bradley C. Edwards has an idea that’s really out of this world: an elevator that climbs 62,000 miles into space. Edwards thinks an initial version could be operating in 15 years, a year earlier than Bush’s 2020 timetable for a return to the moon. He pegs the cost at $10 billion, a pittance compared with other space endeavors.