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Everyone recognizes “One small step for man,” Neil Armstrong’s quote from July 21, 1969, as he stepped off of the steps of the lunar lander for the first time and onto the dusty regolith of the Moon’s surface.

What’s been lost over the years, however, are the hours and hours of conversations, commands, and quips passed from the Apollo 11 astronauts and Houston. Now, the public can hear all of it: Researchers, along with NASA, just released over 19,000 hours (or more than two years) of audio from Apollo 11, including Armstrong, Michael Collins, and Buzz Aldrin.

If you’re picking through the collection at random on NASA’s archive, much of the audio is dead air, waiting for someone to say something, and then someone on mission control sparking up the radio with a “roger” or a set of numbers and directions. But even the mundane passes back-and-forth from earth to the astronauts seem momentous. You’re listening through time and, literally, space—to conversations held nearly five decades ago, between three men floating 238,000 million miles from home.

University of Texas Dallas researchers developed a technique for analyzing and recognizing the massive archive of sound from the Apollo missions: more than 200 14-hour analog tapes in all, each with 30 tracks of audio. Adding to the challenge, the original tapes can only be played on a piece of equipment from the 60s called a SoundScriber, located in the NASA Johnson Space Center in Houston.

John H.L. Hansen and research scientist Dr. Abhijeet Sangwan led the team on digitizing the audio and developing algorithms to parse and transcribe it all.

The researchers describe the laborious process of digitizing the tapes:

The device could read only one track at a time. The user had to mechanically rotate a handle to move the tape read head from one track to another. By Hansen’s estimate, it would take at least 170 years to digitize just the Apollo 11 mission audio using the technology.

“We couldn’t use that system, so we had to design a new one,” Hansen said in the UT Dallas blog. “We designed our own 30-track read head, and built a parallel solution to capture all 30 tracks at one time. This is the only solution that exists on the planet.”

You can listen yourself at NASA’s archival page or the much easier to use UT Dallas “Explore Apollo” website.

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