Dimitar Sasselov on Astrobiology

Are we alone in the universe?  Astronomer Dimitar Sasselov is leading the hunt for "super-Earths" -- rocky planets like our own that orbit other stars.  He and his colleagues believe it's only a matter of time before they discover a super-Earth that is not only habitable, but home to some form of life.  He explains that the search for extraterrestrial life takes to forms:  planet hunting, and the creation of the world's first artificial cells.