当危机降临，星际航行是人类的唯一出路。僵尸世界大战2在线观看完整版免费

　　If we faced a countdown to destruction, could we build a spacecraft to take us to new and habitable worlds? Can we Evacuate Earth? NGC's two-hour special examines this terrifying but scientifically plausible scenario by exploring how we could unite to ensure the survival of the human race.