It was 50 years ago that Neil Armstrong stepped out on to the surface of the moon and cemented his place in history. The mission of Apollo 11 remains the most celebrated in Nasa's history and now a new film takes viewers to the very heart of it.

Thanks for a newly discovered trove of footage, which has been digitally remastered, and more than 11,000 hours of uncatalogued audio recordings, we can see the astronauts suiting up, the crowds on the beach watching take-off, the tension inside Mission Control, and the conversation inside the rocket.

"We wanted to challenge ourselves to make a film out of all archival materials, that is how it started," director Todd Douglas Miller says.

"We had already done a short film about Apollo 17 and experimented with the form and the structure of having no talking heads and doing more of a direct cinema experience."

The effect here is the same - with nobody telling the audience what is going on or narrating the process, the film is a fully immersive experience inside those momentous days in 1969.

"We joked among the team that we wanted to make Dunkirk (the 2017 war film by director Christopher Nolan, starring Harry Styles, Tom Hardy and Kenneth Branagh) in space.

"That movie just happened to come out while we were making the film and it was relevant - it's basically the third act of a regular film and we were doing something similar."

Miller and his team worked closely with Nasa and the National Archives to locate all the existing footage of the mission and that was when archivists made an incredible discovery, an unprocessed collection of footage of the launch, the recovery and post-mission, never before seen by the public.

The huge cache of audio recordings was also a huge boon. Thousands of hours of tapings, of 60 different mission personnel throughout every moment of the launch, landing and return, offered new insights into the key events, as well as surprising moments of humour.

"Getting that email about the discoveries was probably one of the greatest days of mine and Todd's lives," says archival producer Stephen Slater.

"I know it's weird if he calls me," adds Miller.

"I work in New York, he's in Sheffield so usually it's Skype or email.

"But I was walking to work and my cell phone rings and it's a 44 area code and it's Stephen, asking, 'Did you see the email? Did you see the email?'

"Usually when you get emails from archivists it's very boring monotone, there is a lot of nuance in there, and this was filled with bolded words and exclamation points.

"The reels themselves had Apollo 11 on them, if you were lucky you got a date.

"If you were even luckier, you had a shot list that gave you some direction - but for the most part it was putting them up on this prototype scanner that the team built and seeing what was on it, and every day was just like being on holiday.

"It became more than just a film, it was an opportunity to curate and preserve this priceless, historical material."

A particularly special moment was when they discovered footage of Armstrong, Buzz Aldrin and Michael Collins putting on their space suits.

"That was amazing," acknowledges Slater.

"When we first saw that, Todd's jaw was on the floor in the scanning room.

"It's very historically important because it's seeing it for the first time like it was yesterday.

"It's a real testament to those guys, those cinematographers, that they had the foresight to capture this in such a great format."

They also had the foresight to capture a huge array of material, not just of the launch itself but of the thousands of people who gathered on the beaches near the Kennedy Space Centre in Cape Canaveral in Florida.

"It really is a time capsule," marvels Miller.

"Nasa had a couple of working camera guys through their technicolour lab that were shooting a large portion of the Apollo missions but 11 was special, the crowds were bigger, the media coverage was bigger.

"There were two cinematographers in particular capturing that footage, one they called The Bear and he was hand holding these giant cameras 40 or 50 years before Christopher Nolan and the guys at Imax were doing their thing.

"This other guy, a Finnish cinematographer, got all those great shots on the beach and the parking lots.

"They speak to how much of an event it was, that we were gong to go touch a new world for the first time and people wanted to participate in that.

"There were protesters that were down there too, who were asking why were we spending so much money on the space race.

"To Nasa's credit, the administrator Thomas Paine invited them in to a VIP area to watch.

"There was a great moment that happened afterwards, captured by the networks news at the time, of Ralph Abernathy, who took over from Martin Luther King after he was assassinated a year before, and he said, 'I think our protest can wait for a day, this is about all of us'.

"It speaks to the collective conscientiousness of the planet, all coming together to experience this miraculous event."

Apollo 11 is out now.