“You hear that, that whistling sound?”
“Yes.”
“Whooooooo...”
Two months before astronauts landed on the Moon for the first time in 1969, they circled around it in orbit during the Apollo 10 mission for reconnaissance.
On the far side of the moon, cut off from contact with the NASA base on earth, the astronauts heard haunting “space music” on their radio transmission.
Although the audio files have been available in the National Archive since the early ‘70s, they were publicized for the first time this week on the Science Channel’s series, “NASA’s Unexplained Files.” (The music comes in around the 2:04 mark).

NASA