http://www.nbcnews.com/science/area-51-its-purpose-declassified-no-ufos-lots-u-2-6C10931555 A newly declassified CIA history from 20 years ago spills the story about Nevada's Area 51 and its secret mission â€” which was not to study UFOs, but to test the U-2 and other spy planes. The CIA's story about the legendary test site is contained in "The Central Intelligence Agency and Overhead Reconnaissance: the U-2 and Oxcart Programs." The document was approved for release in June, with just a few remaining redactions, in response to a Freedom of Information request filed by George Washington University's National Security Archive back in 2005. Much of the material was already known to Area 51 aficionados. "Nearly all of the newly released information is already in my books," British author Chris Pocock said in a commentary distributed by the National Security Archive. But the fact that Area 51 is explicitly mentioned in a publicly available document is nevertheless notable. "It marks an end to official secrecy about the facts of Area 51," Jeffrey Richelson, a senior fellow with the National Security Archive, told the Las Vegas Sun. "It opens up the possibility that future accounts of this and other aerial projects will be less redacted, more fully explained in terms of their presence in Area 51." The book describes how officials involved in planning the spy-plane projects flew over the Nevada desert in a small plane in April 1955, looking for sites suitable for secret tests. "They spotted what appeared to be an airstrip by a salt flat known as Groom Lake, near the northeast corner of the Atomic Energy Commission's (AEC) Nevada Proving Ground," the book's authors wrote.