UFO Files - Out of this world

Are we alone in the universe? Is the earth on the brink of a cosmic catastrophe? Do aliens really exist? And if they do, how do they get here? Long before man landed on the moon, people have been asking these and other questions that are out of this world. Perhaps clues to some of these questions lie in understanding the behavior of asteroids, life on Mars, and secrets that our government may hold about UFOs and Roswell.
(Originally "Greatest History's Mysteries - Out of This World".)