With the cameras rolling, and microphones in place, National Geographic documentary producers hope to retrace the final 24 hours of President John F. Kennedy.
The president's speech outside at Brooks Air Force Base in San Antonio was planned, but his visit to a hyperbaric chamber at the military facility was not.
We didn't know he was coming right away, said Phillip Jameson, one of four airmen who lived in the chamber for 42 days as an experiment for the Apollo moon project.
Jameson spent his 18th birthday inside that chamber.
"They gave us hospital pajamas, so to speak, and had us clean up our act a little bit," he recalled. "All of a sudden we heard, 'Here he comes!
It was an impromptu appearance by President Kennedy himself.
"There he was, big as life, the President of the United States -- this man was Camelot, Jameson said.
People were mesmerized by this man, even people who didn't agree with him, said National Geographic producer Robert Erickson, who added that JFK's final celebrations were overshadowed by tragedy.
"We're trying to show the celebration, joy and excitement that Kennedy brought to Texas in the last 24 hours," he said. "It's a different take, with endless stories of people touched by the president's character. We're focusing in on people who heard him speak, who shook his hand for the last time.
Jameson said Kennedy asked where he was from, how he was feeling... even joked around.
You didn't feel like you were speaking to the president," he said. "We felt such closeness to him the way he spoke to us."
And in an atmosphere where a single spark could kill all four airmen, Kennedy applauded them for accepting his challenge to help send an American to the moon and back.
From his inaugural speech, that we were the perfect model of 'Ask not what your country can do for you, but what you can do for your country.' That was a very exciting moment, Jameson said.
The two-hour documentary will be broadcast on the National Geographic Channel this November. An exact date hasn't been set.