Ryan Smith, writing at World of Indie:
Fifty years ago, 5 unmanned lunar orbiters circled the moon, taking extremely high resolution photos of the surface. They were trying to find the perfect landing site for the Apollo missions. They would be good enough to blow up to 40 x 54ft images that the astronauts would walk across looking for the great spot. After their use, the images were locked away from the public until after the bulk of the moon landings, as at the time they would have revealed the superior technology of the USA’s spy satellite cameras, which the orbiters cameras were designed from. The main worry was the USSR gaining valuable information about landing sites that the US wanted to use.