Image copyright NASA/SCIENCE PHOTO LIBRARY Image caption Neil Armstrong: An enigma until recently

Neil Armstrong is one of the most famous people in human history.

When he returned from the Moon, he was feted by kings and queens, presidents and prime ministers. He was Captains America and Kirk rolled into one - with a touch of President John F Kennedy.

He had the world at his feet, but instead of embracing his celebrity status he retreated from public life.

The public knew little about this enigmatic man. But now we are gaining a glimpse of the real Neil.

There was a sense that he was reclusive. Perhaps the experience of the lunar mission had left him somehow traumatised, because life on Earth seemed an anticlimax after the heights of reaching the Moon.

He did not enjoy giving interviews, so his silence gave space for such rumours to grow and be recycled each decadal anniversary of the first Moon landing.

I was one of the few journalists lucky enough to have met Neil. And he seemed to me to be the sanest person I had ever met.

I was a young reporter working for BBC Look East. He was receiving an honorary degree from Cranfield University and I was invited to interview him.

I was nervous and star-struck. He was smiley and friendly. He was the first man to have set foot on the Moon yet he was gracious, putting me at my ease and answering my questions thoughtfully and thoroughly.

And he sensed my pain when I confessed to having felt disappointed that the Apollo programme was cancelled - ruining my young boy's dream of one day travelling through space myself.

I asked him: "Whatever happened to the Armstrong dream?"

"The dream is still there," he replied with a twinkle in his eye. "The reality may have faded, but it will come back in time," he continued.

Image copyright Emily Selvadurai Image caption Neil Armstrong and the BBC News team in 2010. He declined an interview but agreed to chat to us.

His answer was an act of kindness to reawaken a young man's optimistic spirit of the Moon landings, rather than to provide a reporter with a story.

I met him again 16 years later. He was in the UK with his fellow Apollo astronauts Gene Cernan and Jim Lovell as part of a world tour to commemorate the Moon landing's 40th anniversary.

We were invited to interview them at a not-so-splendid hotel near Heathrow airport under strict conditions of secrecy.

The astronauts were booked in under false names, and when the hotel staff asked what the interview was about I said it was to do with golf. This seemed plausible given the astronauts' attire.

I reminded Neil Armstrong that we had met long ago. To my surprise, he gave me that same warm reassuring smile and said he did remember and spoke fondly of that day.

Media playback is unsupported on your device Media caption Mark Armstrong, son of Neil Armstrong talks about his father.

We made small talk over a sandwich and chatted about his tour. But he declined a request for another interview, saying that he did not wish to take the limelight away from his fellow astronauts.

This view of him is now emerging from the documentary film, Armstrong, which was released on Friday to coincide with the 50th anniversary of the Moon landing.

His youngest son Mark and his granddaughter Kali, both musicians, came to the BBC News studios to tell us about it.

We showed them highlights of Nasa footage of the mission to get them into the mood.

Watching her grandfather walk to the launch pad, Kali was struck by the resemblance of 39-year-old Armstrong with her youthful 56-year-old father.

And they both smiled, unable to contain their glee of what they so obviously felt to be their great good fortune.

And even though it was a story Mark and Kali knew so well, they were gripped. "This never gets old," Mark told her.

Dad and daughter watched in awe as Neil stepped off the lunar module and uttered the words that would forever resonate through history: "That's one small step for man, one giant leap for mankind."

Image copyright BBC News/Nasa Image caption Mark Armstrong bears an uncanny resemblance to his father

"Good job grandpa!" whispered Kali, under her breath, her eyes full of emotion as if she was watching it live.

Mark told me that the impression of his dad as a recluse were wrong.

"I think my father was mischaracterised by the media," he told us.

"He was thoughtful, had a great sense of humour and he was musical. He'd sometimes walk down the hall and open up with a song from Oklahoma!

"And he wasn't the kind of dad that would tell you what to do all the time. He was more a professor type who would show you different options and urge you to think carefully about your choices and pick the right one, just as he did by example throughout his life."

For Kali, Neil was simply "grandpa" who didn't talk about his Moon landing very much. But he did once tell her that the greatest impact the mission had on him was seeing the Earth rise from the lunar surface.

"In 1969, he was looking back at the Earth and seeing it from space as a fragile resource and hoping that people would care for it," she said.

Image caption Rick Armstrong: As self-effacing as his dad

I also caught up with Neil's eldest son, Rick, while he was visiting the UK to take part in Moon landing celebrations. Now a software engineer, he loves being his father's son but admitted that at times his legend was sometimes hard to live up to.

"There is an expectation," he told me. "Everyone expects to be judged by their own merits and being the son of someone famous can override that sometimes.

"I would like to have been an astronaut in the shuttle programme, and maybe I didn't because I didn't want to face the comparison."

Asked what he thought Neil's legacy was, Rick said: "When I think of a legacy I don't think of dad. I think of the Apollo programme where you had a team of thousands of people committed to a goal.

"When you work to that goal, you can achieve amazing things.

"And there is the inspiration it gave people. So many people have come up to me and said that they became a scientist or an engineer or doctor or whatever, because they were inspired by what happened in the 60s. You can't calculate the value that has."

In a sense, those who were around for the Moon landing are all Neil's children. It was a moment that millions across the world shared, which raised our spirits and made us realise we could all in our own way reach for the Moon.

For many of us, the experience showed anything was possible and spurred us on in our endeavours.

For me, the most heroic part of Neil's story is that, having played his part in that incredible cultural transformation of humanity, he had the humility to walk away and be the man he truly was: the professor, the musician, the father, the engineer - the real Neil Armstrong.

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