It's not easy to forget the moon. The images of NASA's celebrated lunar landings are lasered onto the national retina, and perhaps no two things are better remembered than the sister ships that made the trips: the cone-shaped Apollo command module and the leggy lunar lander. If NASA has its way, those kinds of spacecraft will be flying again soon. They will not, however, be your daddy's moonships.
In January 2004 President Bush announced his plan to send Americans back to the moon and onto Mars. Those bold goals—which NASA estimates it could achieve by 2018 and 2030, respectively—would at last...