Over 45 years after Apollo 10 years after the astronauts of NASA's Apollo 10 mission circled the moon, audio recordings from the mission have been released that were previously marked "classified" and archived. In these recording, made when the Apollo 10 space craft lost radio contact with NASA while traveling around the dark side of the moon, the astronauts claim to hear sounds that they describe as "space music", a source of which they can not determine.

The unidentified sounds began almost as soon as Thomas Stafford, John Young and Gene Cernan lost radio contact with Mission Control. For the hour that the command module, better know as "Peanuts" past behind the moon, they picked up "tones" that they could only describe as music. Not knowing what exactly they were hearing, and not wanting Mission Control to think they were suffering from "cabin fever", the crew members debated whether or not to further discuss their previous hour for fear they would be accused of hallucinating. Cockpit recorders downloaded tape of the "down time" when the module came back around the moon. When the mission was completed, the audio of the event was labelled "classified" and archived, and for the most part, forgotten. The three astronauts did not talk about the incident after returning to Earth, and have never spoken publicly about what they may or may not of heard.

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Apollo 10 never landed on the moon, but it would be known for being the mission that set up Neil Armstrong's famous small step and leap, practicing many of the maneuvers that were used by Apollo 11 when it landed on the moon. The mission is also know as the mission that traveled the furthest from home, more than 220,820 miles from NASA Mission Control. Because of the Earth's rotation and the moon being at its furthest point during its month's orbit around the earth, when they module passed behind the moon, the three crew members were further into space than any earthling before or since. Was it a coincidence that it was at this point they heard the unidentified signals?

For years, NASA denied the existence of the audio, NASA claims the audio was "declassified" in 1982, transcripts of the capsule incident were published online, and that the actual audio was posted in 2012. But to this day, while NASA claims there has never been a "cover-up" of the incident, yet there has never been a satisfactory, definitive explanation of what the three astronauts heard either.

Photo By Nasa/Getty Images

Barely 2 months later, Apollo 11, headed by Neil Armstrong would "boldly go where no man has gone before", landing on the moon's surface. Michael Collins, who was the command module pilot for that mission, later stated in his biography that he had been warned before the mission about "whistling noises". Some believe it was VHF interference, some believe the module passed through a magnetic field on the far side of the moon, and the conspiracy theorists claim NASA covered up evidence of extraterrestrial contact until they could dummy up an explanation.

The truth is out there...somewhere!