Archaeology through the keyhole: the serendipity effect of aerial reconnaissance revisited

Recently declassified US intelligence satellite photographs dating from the Cold War have been found to be a valuable source of historical overhead imagery for use in archaeological and other studies. Such civilian uses of material that was originally acquired for intelligence purposes represent salient examples of the ‘serendipity effect’ of aerial reconnaissance, whereby photographs taken for one purpose find, years later, a new value or use. This review describes the nature of declassified intelligence satellite photographs and the uses to which they have been put in archaeological and other scientific studies, and demonstrates the great scientific potential of this archive of historical material that has lain dormant for over thirty years.