Countless mysterious objects have been caught on camera by NASA. Many NASA astronauts have reported seeing unidentified flying objects. In this special, we reveal NASA's top ten unexplained encounters using original footage and revealing interviews with astronauts and scientists. Can these phenomena be explained away through science and detective work? Or have NASA's cameras captured signs of extra-terrestrial life?

NASA's Unexplained Files features in-depth interviews with, among others, astronauts Story Musgrave and Alan Bean, physics professor Dr Jack Kasher and NASA space flight operations expert Jim Oberg.