Analysis by Irene Klotz 

There are many problems to solve before we can send a spaceship to another star system. About the only thing most folks agree on is that at some point we must make the journey or eventually humans will join the dinosaurs on the species extinction list.
We don't know when that day will come, whether we will bring it on ourselves by nuclear or environmental disaster, or if Mother Nature pulls the trigger with an asteroid impact, a global natural disaster or just because the Earth is poorly positioned to outlive the eventual death of the sun.
The biggest challenge concerns interstellar travel itself. If we set off for Alpha Centauri, the nearest star system, using today's technology, we'd arrive in something like 100,000 years. The goal of a new project, called the 100 Year Starship, is to cut that time to a century or less.
There also are questions about where to go (a pale, blue world would be nice, but how to choose which one?) and whether it would be best to send people, robotic probes or future human-robot hybrids. Not to mention, how to pay for the project, sustain interest over generations and build an organization that can oversee such a mammoth, long-term undertaking.
Those issues and dozens of other knotty questions lured about 1,000 people to Orlando this weekend to discuss the 100 Year Starship project, also called 100YSS. The symposium, which was free and open to the public, drew dozens of off-duty government scientists and engineers, as well as educators, Hollywood producers, financiers, graduate students, business people, science fiction authors, astronauts and even a few lowly journalists.
The consensus of some of the best rocket scientists of our day is that there are basically two ways to cut down the transportation time to another star -- build spaceships running on thermonuclear engines, or zap vehicles across the cosmos by bouncing laser beams off their sails. But the Defense Advanced Research Projects Agency (DARPA), which is spearheading 100YSS with help from NASA, is open to new ideas, like anti-gravity engines, plasma shields and other technologies that now exist only in science fiction.
It was a fascinating gathering, both technically and culturally. Unlike previous government-organized space exploration initiatives, DARPA cast as wide a net as possible in its quest for capable minds and willing souls to nourish and evolve the idea. Symposium organizers received more than 500 submissions for paper abstracts and panel topics from people as far away as China, South Africa, The Netherlands and the United Kingdom, whose British Interplanetary Society has long studied concepts for interstellar space travel and which intends to publish papers from the symposium over the coming months.
For its part, DARPA sees plenty of potential spinoff technologies of interest to the U.S. military.

"There are definitely offshoots that are coming out of the research opportunities that were presented here and talked about that are relevant to the Department of Defense," said DARPA's director of tactical technology David Neyland.
The next step is the award of a $500,000 DARPA grant for an organization to carry the project forward. In the spirit of openness, non-U.S. entities are welcome to apply. Proposals are due Nov. 11.
Images: Top: Artist's rendering of a proposed intersteller ship called Daedalus. For fuel, it would mine helium-3 from the clouds of Jupiter. Credit © David A. Hardy/ for Discovery News. Insert: Our nearest neighbor, Alpha Centauri, a triple star system 4.22 light years away. The red star at center is Proxima Centauri, the closest of the trio. Credit: David Malin/UK Schmidt Telescope/DSS/AAO.)