In 1961, an American visitor to a family gathering in the Co Antrim countryside declared to his rural cousins that "we're going to the Moon".

Shortly afterwards one local newspaper declared "Emigrant's son has become Moon Man".

Even more bizarre than the headline was the fact that Bill Fleming, whose father William left Randalstown for Michigan in 1911, was telling the truth.

What may have seemed like a tall tale to his Northern Irish cousins, in fact, came shortly after Nasa had given him just four weeks to deliver the plan to put a man on the Moon.

That year, US President John F Kennedy made his famous speech to Congress promising to achieve the impossible by the end of the decade.

The space race had already become a national obsession after the Soviet Union's Yuri Gagarin became the first man to travel into space.

Nasa still had no plan or certainty that a mission to the Moon was even physically possible and Mr Fleming, then a young aeronautical engineer, was picked to head the task force.

Speaking ahead of the 50th anniversary of the lunar landings, Mr Fleming's son Jack (69) told the Belfast Telegraph the incredible story of how 'The Fleming Report' became Nasa's blueprint for the most daring scientific project ever.

"Believe it or not, it was only after he passed away in 1999 (aged 78) when I first understood the significance," he said from his home in California.

"You have to understand my dad was an incredibly humble and modest man and never bragged or boasted about anything that happened to him at work."

This involved working directly with the German rocket scientist Wernher von Braun, who was secretly transported to the US after the war to conduct research as part of Operation Paper Clip.

The 510-page Fleming Report actually took six weeks, concluding that the goal of landing a man on the Moon could be achieved by 1967 at a cost of around $12bn provided there were no major catastrophes.

Tragically, three astronauts perished in the Apollo 1 fire which resulted in a delay of a year-and-a-half before the next manned Apollo launch.

Neil Armstrong eventually made history as the first man to walk on the Moon on July 20, 1969, but the final cost nearly doubled, with a final figure of $25.4bn reported to Congress in 1973.

The former Deputy Administrator of Nasa, Robert Seamans, who gave Mr Fleming the assignment, later said the original 1967 target could have been achieved if the Apollo fire had not occurred.

"In the years after writing this report my father was chiefly responsible for making sure it was implemented," said Jack.

"What that meant was a lot of travelling, to the space flight centre in Houston and to Huntsville Alabama where Wernher von Braun was developing the Apollo rockets with a team of German scientists. My dad would go down periodically and meet with him to make sure everything was proceeding according to plan.

"My dad didn't speak a word of German, but a typical von Braun response would be to turn and chat at length in German to all the scientists in the room.

"Eventually, he would turn round to my father and say, 'The answer to your question is yes'."

When the historic day of the lunar landing finally came, Jack said his sister vividly recalls their father's reaction.

"Whenever he would watch a rocket launch he was always very placid; it was the calm after the storm.

"The storm was doing all the prep work but once the launch took place it was like, 'OK, I'm ready to be entertained now'."

After the elation of the world watching Neil Armstrong and Buzz Aldrin walk on the Moon, Jack said his father later felt let down at Nasa.

"So much time and effort had gone into making this all happen. They went to the Moon three times and the Apollo programme ended in 1972," he said.

"My dad retired two years later and most, if not all, his colleagues did the same. There was a huge drain of personnel afterwards."

Jack said he got a rare insight into the Moon landing from his father when he visited him in Washington in the 1990s.

"By that stage, I was in my 40s and working as a lawyer in California, I had no idea about all this.

"My dad took me into his study and he pulled out this document which it turns out was the Fleming report.

"It was his personal hard copy.

"He held it up and said, 'You know, the one thing I think I'll be remembered for at Nasa is this report. I'm quite proud of this'."

He added: "It's an amazing feat - the space programme went from essentially a very fledgling operation to literally landing a man on the Moon."

Belfast Telegraph