The CIA has officially acknowledged the secret US test site known as Area 51, in a newly unclassified internal history of the U-2 spy plane programme."> The CIA has officially acknowledged the secret US test site known as Area 51, in a newly unclassified internal history of the U-2 spy plane programme.">
Area 51, so-named for its designation on a 1950s
era map, surrounds a dry lake bed, Groom Lake
The CIA has officially acknowledged the secret US test site known as Area 51, in a newly unclassified internal history of the U-2 spy plane programme.
The document obtained by a US university describes the 1955 acquisition of the Nevada site for testing of the secret spy plane.
It also explains the site's lingering association with UFOs and aliens.
The remote patch of desert surrounding Groom Lake was chosen because it was adjacent to a nuclear testing facility.
"The U-2 was absolutely top secret," Chris Pocock, a British defence journalist and author of histories of the programme, told the BBC.
"They had to hide everything about it."
The U-2 plane, developed to spy on the Soviet Union during the Cold War, is still flown by the US Air Force.
Reports of UFOs
The document, a secret 1992 internal CIA history of the U-2 programme, was originally declassified in 1998 with heavy redactions.
Many of the blacked-out details were revealed this month after a public records request by the National Security Archive at the George Washington University in Washington DC.
While a lengthy account of the development of the U-2 spy plane programme, the history also attempts to shed light on the public's fascination with the Area 51 site and its lingering associations with extra-terrestrials and UFOs.
It notes that testing of the U-2 plane in the 1950s - at altitudes much higher than commercial aeroplanes flew then - provoked "a tremendous increase in reports of unidentified flying objects (UFOs)".
"At this time, no one believed manned flight was possible about 60,000 feet, so no one expected to see an object so high in the sky," note authors Gregory Pedlow and Donald Welzenbach.
The original request for the reacted portions of the history was made in 2005. It was released to the National Security Archive several weeks ago.