Poll: Should America Go Back to the Moon Soon—or Set Sail for Mars?

The space shuttle Discovery landed for the final time Tuesday—piggybacking a jumbo jet.  Destined for the Smithsonian Air and Space Museum’s Udvar-Hazy Center in Chantilly, VA, Discovery thrilled Washington-area observers. But where is the thrill of space exploration now that the shuttle program is over? Where should NASA take us now? You tell us.