Tense moments before the touchdown
A dramatic recording of the first manned landing on the Moon has been rediscovered at Nasa's Johnson Space Center in Texas.
The tape covers the crucial few minutes as the Apollo 11 lander touches down on the surface of the Earth's satellite in July 1969.
The recording is of the flight director, Gene Kranz, and his "white team" of mission controllers. Each member of the team was responsible for one aspect of the landing, such as fuel, altitude, orientation, crew health, etc.
The rescued recording of the perilous descent combines the flight director/controller loop with the astronaut loop. It also covers the decision about whether the astronauts should remain on the Moon following the landing - or immediately lift off.
The impetus to locate the tape came from Kipp Teague, who runs an online resource of data on the Apollo Moon landings.
'Bad tape'
It was found in the audio library at Nasa's space centre in Houston. The recording had been labelled "bad tape" because it was in a very poor condition.
Initially, it could not be played, being so poorly tensioned on its spool. It was also starting to disintegrate, shedding metal oxide particles from its recording surface.
The tape frequently adhered to itself as it was played. Nasa technicians said they were lucky to get the tape to play at all.
As well as astronauts Neil Armstrong and Buzz Aldrin, the most prominent voice is that of Gene Kranz, the flight director, who was overseeing the landing.
He can be heard consulting with his mission controllers and passing information on to Charlie Duke, the so-called capcom, who talked directly with the astronauts.
Of particular interest is the "T1" decision. After landing, the flight controller had to decide whether to remain on the Moon or to leave after one minute.
You can listen to the tape by clicking on the audio box at the top-right of this page.