NASA Releases Recording of 'Outer-Space Type Music' From Far Side of the Moon

"Did you hear that whistling sound too?"

"Sounds like -- you know, outer-space type music."

"I wonder what it is."

This conversation, between Apollo 10 astronauts Eugene Cernan and John Young, as their craft flew around the far side of the moon, remained under wraps for over four decades.

Transcripts of the discussion were released in 2008 but this is the first time the audio of that discussion has been made public.

The sounds were so weird, the team actually debated whether to mention it or not to their superiors at NASA. They were worried it could end up affecting how people will think about their suitability for future spaceflight, according to a new Science Channel series "NASA's Unexplained Files."