Recorded 19,000 hours of negotiations during the Apollo 11 lunar expedition

One of the computer printouts of the track list from a 30-channel Apollo film reel. Information about each of the 30 tracks is given.

Many heard the sound recording of the legendary words of Neil Armstrong when he left the Apollo 11 LM Eagle lunar module and set foot on the Sea of ​​Calm during the Apollo 11 lunar expedition: “One small step for a man and a huge leap for humanity. " He pronounced them on July 20, 1969.

But this historical event would never have been possible if it were not for all the other members of the mission. In addition to the three astronauts who rose into space on the Saturn-5 rocket, these are dozens of engineers, experts, analysts and operators at monitoring stations around the world, and not only them. They all maintained continuous communication throughout the expedition: from beginning to end. And now for the first time we have the opportunity to hear these talks.

Yes, the legendary words about “a small step for a man” or the phrase “The Eagle has landed”, when the lunar module sat on the surface of the Moon - these are incredibly important moments of history that were heard on all radio and television channels on Earth. But after decades, it is very interesting to listen to all the other conversations of the members of that lunar expedition.

These sound recordings have been stored intact on reels of film for several decades - and no one heard them. To date. Researchers from the University of Texas at Dallas in 2012 received a scientific grant to develop a technique for analyzing thousands of hours of NASA sound recordings.


Four developers of a speech processing computer system for restoring and transforming sound recordings made during NASA's lunar missions pose next to an astronaut model at the Johnson Space Center in Houston.

In 2017, researchers launched the Explore Apollo website, opening up access to digitized audio recordings for everyone. In addition to the full archive of negotiations with the Apollo 11 mission, the project includes most of the records of negotiations from other missions: Apollo 13, Apollo 1 and Gemini 8.

The archive includes digitized sound recordings from more than two hundred fourteen hourly analogue films, each with 30 sound tracks. Digitizing sound recordings included decoding conversations with distorted speech, technical noise, and overlapping sound circuits. The project was led by the founder and director of the Center for Reliable Speech Systems , Dr. John HL Hansen, a researcher at the same center Abhijeet Sangwan. They were helped by a group of doctoral students. Scientists have developed algorithms for processing, recognition and analysis of the audio signal. A scientific article describing the algorithms was published in IEEE / ACM Transactions on Audio, Speech, and Language Processing for November 2017.

The project lasted five years. During this time, researchers were able to fully recognize the text and analyze who speaks with whom on each record. The authors of the study say that the project has stimulated significant progress in machine learning and knowledge extraction systems.


Dr. John Hansen is standing next to the SoundScriber device - the only device that can play back audio recordings from NASA moon missions. The device reads one track, after which it is necessary to mechanically move the read head to the next track. Hansen estimated that digitizing all sound recordings in this way would have taken 170 years.

To digitize sound recordings, Dr. Hansen and his colleagues developed a new device with a magnetic head that reads 30 tracks simultaneously. This reduced the digitization process to several months. After that, software was developed for diarization , that is, the separation of the incoming audio stream into homogeneous segments in accordance with the ownership of the audio stream to one or another speaker. It was also necessary to move the records in chronological order.

In the end, this great work was successfully completed - and 19,000 hours of sound recordings of the Apollo 11 mission were published on the Internet. In addition to the aforementioned university site, they were also posted in the Apollo 11 collection on Archive.org.