premise: Alan Shepard was POTUS from November 1963 to July 1969.
hypothesis: Rear Admiral Alan Bartlett Shepard Jr. ( November 18 , 1923 -- July 21 , 1998 ) was an American astronaut , naval aviator , test pilot , and businessman . He was Chief of the Astronaut Office from November 1963 to July 1969 ( the approximate period of his grounding ) , and from June 1971 until his retirement from the United States Navy and NASA on August 1 , 1974 .