How did Walter Cunningham play a role in Nas is lunar moon program

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Ronnie Walter Cunningham (born March 16, 1932), (Col, USMCR, Ret.) is a retired American astronaut. In 1968, he was a Lunar Module Pilot on the Apollo 7 mission. He was NASA's third civilian astronaut (after Neil Armstrong and Elliot See), and has also been a fighter pilot, physicist, entrepreneur, venture capitalist, and author of The All-American Boys. Following the deaths of Donn F. Eisele in 1987 and Wally Schirra in 2007, Cunningham is the last surviving crew member of Apollo 7.