Will humans need to live as space nomads to survive? Possibly, says Neil deGrasse Tyson of the American Museum of Natural History.

"It may be," says Tyson, "that our only insurance policy against extinction is to become a multi-planet, space faring species."

Worries of climate change and unexpected catastrophe on Earth, compounded with humankind's natural curiosity about what lies beyond, compel private industry and NASA alike not only to wonder "what if," but to prepare for the "when."

The video below was broadcast on ABC News' Good Morning America on February 8, 2008. Also see: ABC News.