“We were not naive, but we could not have guessed what the volume and intensity of public interest would turn out to be,” he said of his worldwide celebrity.
Over the ensuing decades, Mr. Armstrong, a solitary figure, warded off reporters’ efforts to penetrate his privacy until most gave up or lost interest. Unhappy with faculty unionism, he resigned from the university in 1979 and spent the rest of his working life in business, amassing personal wealth as an investor and a member of corporate boards.
Although he was loath to exploit his fame, Mr. Armstrong signed on as a pitchman for Chrysler in his waning months as a professor, appearing in ads for the nearly bankrupt automaker, including one that aired during the Super Bowl in January 1979.
He said he agreed to the deal mainly because it involved an engineering consultancy and because he wanted to help a beleaguered U.S. company buffeted by imports and rising foreign oil prices. The arrangement was short-lived, however, and afterward Mr. Armstrong repeatedly turned down opportunities to endorse products.
Hansen, now an aerospace historian at Auburn University, said Mr. Armstrong felt awkward taking credit for the collective success of 400,000 employees of the space agency and its Apollo contractors. In 2003, Hansen recorded 55 hours of interviews with Mr. Armstrong after years of coaxing him to cooperate on a biography.
He was not a recluse, as some labeled him. In 1986, for instance, he was vice chairman of the commission that investigated the explosion of the space shuttle Challenger.
But that was a rare step into the spotlight. As a rule, Mr. Armstrong was extremely choosey about his public appearances, limiting them mostly to aerospace-related commemorative events and to other usually low-key gatherings that piqued his interest, such as meetings of scientific and technical societies.
“The lunar Lindbergh,” he was dubbed for his refusal to grant interviews to journalists. His remoteness also irked some NASA officials, who had vainly hoped that Mr. Armstrong would become a forceful public advocate for the funding of space exploration.
“How long must it take before I can cease to be known as a spaceman?” he once pleaded. Yet by the time he retired in 2002, to leisurely travel and enjoy his grandchildren, the “First Man” finally had outlived the nation’s fascination with him, and he could often walk down a street in blissful anonymity.
His 38-year marriage to the former Janet Shearon ended in divorce in 1994. Later that year, he married Carol Knight, a widowed mother of two teenagers. Besides his wife, survivors include two sons from his first marriage, Eric and Mark; two stepchildren; a brother; a sister; and 10 grandchildren.
“Looking back, we were really very privileged to live in that thin slice of history where we changed how man looks at himself, and what he might become, and where he might go,” Mr. Armstrong said in a 2001 NASA oral history project. “So I’m very thankful.”