Since the launch of the manned space program more than 50 years ago, cameras aboard NASA spacecraft have captured thousands of images. Many show stars, views of Earth and other expected sights. However, hundreds of these pictures reveal imagery that leave scientists scratching their heads. Unexplained transmissions on the far side of the moon and NASA's plan B for a catastrophic failure of the first moon landing are just some of the mysterious encounters, unusual discoveries and strange sightings featured in the third season of NASA's Unexplained Files.