From the first foot on the moon to the first robots on Mars, NASA has long led the human race into the great unknown, fulfilling man's ancient imperative to understand the worlds beyond this one. WHEN WE LEFT EARTH chronicles the amazing achievements--and heartwrenching disasters--of the space agency's first 50 years. The series includes intimate, candid interviews with the astronauts, mission control personnel, engineers, and politicians who had a front row seat for the first half-century of America's space exploration.