Credit: University of Texas at Dallas

NASA has released 19,000 hours of audio recordings from the Apollo 11 mission.

The collection covers communications both on-board, at mission control and between the two. It was made up of 200 tapes, each 14 hours long and made up of 30 audio tracks.

The recordings have been released under the rules that NASA’s work should be publicly available. Work began to digitise the tapes in 2012 but it’s taken so long as they were only playable on a specific machine called a SoundScriber (pictured) of which only one was available.

The machine was set up so that users had to manually turn a handle to switch track, something that would have made the digitization impractically long. Staff at the University of Texas rigged up a system to read and record all 30 tracks simultaneously.

Another reason for the slow progress was that the digital audio had to be clear enough to accurately transcribe the audio, a particular challenge as any some tracks included as many as 35 different voices. The project also involved using NASA text archives to build a dedicated language base for automated speech recognition.

The recordings have been made available on two sites: as a relatively unorganized collection on the Internet Archive and as a more attractively packaged dedicated site. The latter includes options to explore the recordings day by day, go straight to highlights, or play a random recording.