Why am I such a strong supporter of human spaceflight? Is it the thrill of a launch, the adventure of spacewalking, the advancement of science or national pride? All of those things are nice, and by themselves probably worth the $0.06 of each tax dollar we spend on NASA (which does a lot more than just manned spaceflight). Those who say we could do more by abandoning human spaceflight and concentrating exclusively on robotic exploration may be right, but exploration is only step to the ultimate goal - the expansion of human life throughout the solar system, and then to the stars.
You see, I support human spaceflight because it's absolutely required for our survival. There is only one way humans might survive an extinction event:, and that's not to be there when it happens. Only viable, self-sustaining offworld colonies can insure the survival of our species. Think of it as having an off-site backup of civilization.
For this reason, I'm ecstatic that DARPA is working to put together an organization which will span generations, dedicated to working on all aspects of long-distance spaceflight.
The 100-Year Starship is about more than building a spacecraft or any one specific technology. Through this effort, DARPA seeks to inspire several generations to commit to the research and development of breakthrough technologies and cross-cutting innovations across myriad disciplines such as physics, mathematics, engineering, biology, economics, and psychological, social, political and cultural sciences. The goal is to pursue long-distance space travel while delivering ancillary results along the way that will benefit mankind.
This endeavor will require an understanding of questions such as: how do organizations evolve and maintain focus and momentum for 100 years or more; what models have supported long term technology development; what resources and financial structures have initiated and sustained prior settlements of "new worlds?"