Leap of Faith: An Astronaut's Journey into the Unknown

Gordon Cooper's memoir, written with the journalist Bruce Henderson, covers his years as an Air Force pilot, test pilot and Mercury and Gemini astronaut, and his conviction that the government concealed evidence of UFOs. It includes his accounts of seeing UFOs over West Germany in 1951 and of the 1957 Edwards Air Force Base photographs, which he says showed a craft landing.

The space historian Robert Pearlman, reviewing it, found it hard to understand how someone so connected with groundbreaking technology could embrace extraterrestrial visits on little more than anecdotal evidence. The witnesses to the Edwards case describe a disc photographed in flight, with no landing.

Sources: Wikipedia — Gordon Cooper