As the lunar module pilot for Apollo 15, he was the eighth person to walk on the moon. He was a recipient of the NASA Distinguished Service Medal.
He received a Master's degree in aeronautical engineering from the University of Michigan in 1957.
He died of a heart attack and was buried in Arlington National Cemetery, the first of the astronauts who walked on the moon to die.
He had five children with his wife Mary Ellen.
He visited the moon like astronaut Neil Armstrong.