Video footage of the aftermath of the 9/11 attacks on New York which was filmed from space is to be broadcast in full on British TV for the first time.
The footage, in which a huge plume of smoke is seen stretching from the site of the devastated World Trade Centre towers, was captured from the International Space Station by astronaut Frank Culbertson.
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Hours after the attack Mr Culbertson went on to discover his friend Chic Burlingame was one of the pilots killed during the 2001 attacks when his airliner was hijacked by terrorists.
In the Channel 4 film, part of a season of programmes about space which detail the realities of astronauts' lives, he is shown playing the Taps bugle call - which signals the end of the day for US military personnel - on a trumpet in tribute to his friend later that day.
The channel's Live From Space season next week will feature documentaries about astronauts, building up to a two-and-a-half-hour live broadcast from the ISS and Mission Control in Houston, Texas, which will feature a full 90-minute orbit of Earth.
Short clips from the film of the attacks on New York were released by Nasa to mark the tenth anniversary in 2011, but the film has not been seen in full with Mr Culbertson's commentary and his bugle call.
The creative director of the Channel 4 project, Tom Brisley, said: "Not every frame has been seen before, so every frame that was shot on that day is in the show."
Executive producer Sally Dixon said: "It's the first time we have had it in that form with Frank talking us through it. If that had been in a movie you'd have gone, 'oh come on, that guy's got a trumpet?'. But reality is stranger than fiction sometimes."
It will feature in the documentary Astronauts: Houston We Have A Problem for which programme-makers have been given access to Nasa footage of some of the difficulties in space over the years.
They include film of Italian astronaut Luca Parmitano, who was close to drowning when his helmet filled with water during a space walk and he had to feel his way back to the airlock to decompress before he was able to remove the helmet, causing colleagues to fear for his life.
During other filming for the documentary - to be screened on Thursday March 13 - there was a real-life emergency on the station when a cooling system failed, forcing the crew to make two space walks to fix it.
Ms Dixon said: "Suddenly a valve went on a coolant pump outside and they had to shut down power to half the station to power down a lot of equipment, so we were there filming our general stuff and they let us in on meetings of all these various teams.
"They work out how will they do the space walk, people are practising in the big pool with a model of the space station underwater because it's very like microgravity.
"It was just an amazing coincidence that we happened to be filming - no space walks were filmed for Rick (Mastracchio), Koichi (Wakata) and Mike's (Hopkins) mission. It was incredible to see the teamwork that went on to work out what needed to be done and how they would do it.
Another film, Living In Space, to be shown on Wednesday, looks at the impact on the astronauts and their families and how they cope.
The live programme, Live From Space: Lap Of the Planet, will be screened on Sunday March 16, presented by Dermot O'Leary and veteran astronaut Mike Massimino, whose achievements have included fixing the Hubble telescope.
Mr Brisley, the executive producer for production company Arrow Media, said of the season: "We'd seen our early images of space from the 60s and this felt like a real opportunity to do something fresh and different and to show the warts and all approach to living in space.
"What's it really like to be living on a space station where, in a totally alien world, it's the most extreme place that humans inhabit? It would be fascinating to lift the lid and show what it was really like living in space."
He added: "When it became clear that the space station makes an orbit of Earth every 92 minutes it just felt like a perfect journey for a two-hour live programme."