instruction.” In other words, the CIA considered no other spot on Earth to be as sensitive as Groom Lake, and the astronauts had just taken a picture of it. In November 2007, Day published an article containing the photograph that the Skylab 4 astronauts took of Groom Lake, the first time this photo appeared in a public document. Selected bibliography Eye in the Sky: Story of the Corona Spy Satellites, Lightning Rod: A History of the Air Force Chief Scientist's Office, References Living people Year of birth missing (living people)