






There’s no record of the astronauts discussing the noise with NASA or with the public. It’s unclear if the astronauts ever heard the noise on subsequent passes on the far side of the moon or if other astronauts on subsequent missions heard the sound. Young eventually flew back to the moon and walked on it as the commander of Apollo 16. Cernan commanded the Apollo 17 mission and was the last man to walk on the moon. Stafford flew in space again, but never journeyed back to the moon.

The May 1969 tapes were recorded while Stafford, Young and Cernan were on the far side of the moon, out of radio communication with Earth. The whistling sound lasted nearly the entire hour the astronauts were out of touch. Later, the recordings were sent back to Mission Control where they were transcribed, archived and classified, per protocol.

The conversation was eventually unearthed in 2008.

Some technicians have speculated the sound may have originated from interference from VHF radios on the command module and lunar module interacting with each other, according to researcher and author Andrew Chaikin.

But not everyone buys that explanation.

“The Apollo 10 crew is very used to the kind of noise that they should be hearing,” Apollo 15 Command Module Pilot Al Worden said in a clip from the episode. “Logic tells me that if there was something recorded on there, then there was something there.”