There are a few moments in history that every American alive at the time remembers in crisp detail. The assassination of President John F. Kennedy. The first moon landing. The terrorist attacks of September 11. 

All three bore significance during astronaut Charlie Duke’s visit to Western Carolina University last week, on the 18th anniversary of the twin towers’ collapse. Two years before his death in November 1963, Kennedy changed the course of American history when he pledged during a May 1961 speech that the United States would put a man on the moon by the end of the decade. NASA met that challenge with just over four months to spare when Neil Armstrong and Buzz Aldrin became the first people to set foot on the lunar surface, on July 20, 1969.