The American space agency NASA is organizing several events to celebrate the 50th anniversary of Apollo 11, the mission that first put a man on the moon. Recently, three astronauts who were part of the space program in the 1960s and 1970s gathered at the Paris Air Show to talk about their own experiences. Walter Cunningham, 87, was part of the Apollo 7 mission. Al Worden, 87, flew with Apollo 15 and Charlie Duke, 83, walked on the moon with Apollo 16. Worden orbited the moon alone for days in 1971. He holds the record of having been the world’s most isolated human. Cunningham was part of a team that, in 1968, tried to go against orders from Mission Control. The team members asked if they could reenter the atmosphere without their helmets. They were told “no” and were not permitted to go on future flights. Still, Cunningham remembers his experiences with great pride. “Five hundred years from now there is only going to be one thing they remember about Apollo, and that is that man landed on the moon,” he told the crowd at the air show.