A killer asteroid with the power to destroy civilization is not only a science fiction, but also a scientific fact. More and more evidence supports the theory that dinosaurs were wiped out because of asteroid impacts. But unlike dinosaurs, we can do something about it. NASA just hit an asteroid in the world's first planetary defense test, and for the first time, humans moved an asteroid in space. Is the threat real? How can we defend ourselves? Today, we are honored to invite 87-year-old former NASA astronaut Rusty Schweickart, the first pilot of a human lander on another celestial body during the Apollo 9 mission and an asteroid hunter for decades. If a Hollywood plot comes true, men like him will be real world heroes saving the planet.