"Humans will become a multi-planet species by making it to Mars, but no farther. That is, they will never travel beyond Mars."
Keith's note: While Planetary Society Co-founder Lou Friedman proclaims that humans will never go beyond Mars, a stunning video, posthumously narrated by Planetary Society Co-founder Carl Sagan, certainly suggests otherwise. I'm with Sagan on this one. Watch this video full screen with the sound turned up. Ad astra, y'all.
The Planetary Society Is Against Human Space Flight, earlier post