As Apollo 10 Passed The Dark Side Of The Moon, Its Crew Perceived Mysterious Outer-Space-Like Music

In May 1969 the Apollo 10 crew headed toward the Moon. But the astronauts’ assignment wasn’t to make a lunar landing; they were merely passing the astronomical body as observers. But then as the intrepid explorers traveled on the dark side of the Moon with no connection to mission control, the crew heard mysterious “music.”

Yes, Apollo 10 took off from Florida’s Kennedy Space Center on May 18, 1969, and its mission was to take people to the Moon. But NASA’s quest was not a lunar landing – that wouldn’t take place for another two months. Instead, the space agency had sent its crew to simply scope out the Moon and essentially lay the groundwork for the famous Apollo 11 flight.

So the Apollo 10 crew were due to watch, listen, learn and take notes ahead of Apollo 11’s historic Moon landing. But as the astronauts orbited the astronomical body, the spacecraft passed behind the Moon’s far side – and they fell out of contact with mission control. It was then, of course, that the crew heard the unexplainable sound.

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The sound was unlike anything the Apollo 10 crew had heard before – and they had no idea what its source was. Yet the noise echoed clearly in the astronauts’ headsets as they orbited out of sight and radio contact of home. Apparently, it was a “whistling sound.” Or, as a crew member later described it, “outer-space-type music.”

But with the connection to mission control lost for the moment, there was nowhere else the sound could have come from. In fact, the Apollo 10 crew were so baffled that they didn’t think anyone would believe what they had heard. It therefore became a mystery that would remain a closed secret for almost 40 years.

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By this time, though, NASA was pretty experienced with space flight. First, there had been Project Mercury – a U.S. Air Force program to send people into space, which a fledgling NASA had later adopted. Then, after Project Gemini had supported the transportation of multiple pilots into space, a new mission was announced. Yes, Project Apollo was conceived in 1960 to send a manned spacecraft to the Moon.

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The project was a highly ambitious one, however, and wasn’t without problems. Apollo 1, for example, never got off the ground – literally. It was actually due to launch on February 21, 1967. But during a dummy run around a month before the scheduled takeoff, a fire broke out in the module’s cabin, killing all three crew members.

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So in October 1968 Apollo 7 became the first manned spacecraft. That flight remained in low Earth orbit – but the mission did beam back a live TV broadcast. This was the first of its kind from a U.S. spacecraft. And while Apollo 8 became the first space flight to orbit the Moon, it was Apollo 9 that initially took the Moon landing’s full modular setup out for a spin.

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Come 1969, then, NASA felt ready to perform a full scale lunar landing. But before undertaking the mission for real, the agency sent Apollo 10 on a dummy run. So the crew were set to run through all the tasks scheduled for the Moon landing – without actually setting down on the Moon’s surface.

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Experienced astronauts Thomas P. Stafford, John W. Young and Eugene A. Cernan manned the Apollo 10 spacecraft. Their objective for the flight was to reach a certain distance from the Moon. That distance would later be the point where the expedition that followed them would begin a landing procedure. The goal was therefore to understand inconsistencies in the Moon’s gravitational pull.

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Understandably, to go through all the procedures of the Moon landing that was to follow without the glory of being the first to step on the satellite may have been difficult to swallow. And with all of the astronauts’ combined experience, it could have been tempting to break protocol and attempt the landing themselves.

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Author Craig Nelson broached the subject in his book Rocket Men: The Epic Story Of The First Men On The Moon. And astronaut Cernan said, “A lot of people thought about the kind of people we were: ‘Don’t give those guys an opportunity to land, ’cause they might!’” NASA was, however, one step ahead.

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That’s right: the brilliant minds at NASA weren’t about to be duped by underhand stunts. As Cernan described, “The ascent module, the part we [would have] lifted off the lunar surface with, was short-fueled. The fuel tanks weren’t full. So had we [actually] tried to land on the Moon, we couldn’t have gotten off.”

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So in the end, even the honor of being the first men on the Moon wouldn’t have been enough compensation for the pilots of Apollo 10 being stranded there. Unknown to the astronauts at the time, though, they would earn notoriety for another aspect of their mission. Some would even go as far as to claim that it required a NASA cover-up.

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As previously mentioned, then, the Apollo 10 mission launched on May 18, 1969, and headed toward the Moon. A Saturn V rocket performed the launch, propelling an Apollo command and service module and a lunar module onward to the astronomical body. The spacecraft then reached its destination three days after liftoff.

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Previous missions, whether manned or unmanned, had only ever gotten as close as five nautical miles from the Moon’s surface. But to test conditions for a lunar landing, Apollo 10 had to get as close as one nautical mile. This would allow the NASA experts to achieve a better understanding of the Moon’s gravitational field.

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Apollo 10 consequently executed multiple orbits of the Moon during its expedition. The command and service module itself performed a total of 31 circulations. And in preparation for the Moon landing that would follow their dress rehearsal, the Apollo 10 crew also performed other tasks central to their successors’ historic venture.

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The Apollo 10 astronauts, for instance, performed a separation of the lunar module from the command and supply module. This involved Young piloting the command and supply module, while his colleagues, Stafford and Cernan, departed in the lunar module. And it was as the spacecraft flew separately that the crew members heard that intriguingly unusual noise.

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As the two space vehicles traversed the void of space, in fact, the crew inside passed behind the Moon and out of radio contact with Earth. So the only communication that the explorers had was between the two modules. But then an unnerving noise began to emanate from the Apollo 10 crew’s headsets. And it was a sound that the astronauts couldn’t explain.

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The crew couldn’t even figure out where the noise was coming from. After all, it wasn’t from inside the modules – and it wasn’t a noise that any of the astronauts were making. And because contact with mission control had been lost as the vehicles traveled behind the Moon, it couldn’t have come from Earth.

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“Whooooooooooo,” Cernan mimicked from the lunar module when he heard the bizarre sound. But it soon transpired that the noise wasn’t confined to the vehicle he shared with Stafford. “Did you hear that whistling sound too?” Young inquired from his spacecraft. The noise was also transmitted to the command and supply module.

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Cernan went as far as to suggest that there was some structure to the sounds that the Apollo 10 crew could hear. He said, “Sounds like, you know, outer-space-type music.” And wherever the noise had emanated from, the astronauts seemed baffled by it. Young even added, “I wonder what it is.”

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“Boy, that sure is weird music,” Cernan noted. “We’re going to have to find out about that,” Young was recorded saying. The “music” that the astronauts could hear in fact played for around an hour, as they traversed the “dark side of the Moon.” And it was an occurrence that the astronauts seemed reluctant to broach with NASA.

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Indeed, as the men continued to discuss the strange music at the time, their conversation showed their reluctance to share what they were hearing. They said, “Well, that sure is weird music!” “It’s unbelievable! You know?” “Shall we tell [NASA] about it?” “I don’t know. We ought to think about it.” In fact, both Cernan and Young commented at different points that nobody would believe them.

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The noise was, then, something that none of the astronauts had ever heard before – despite their vast accumulated experience. Yet they weren’t the only ones to have ever heard it. You see, Apollo 11’s command module pilot, Michael Collins, heard an almost identical noise when he traveled by the Moon’s far side too.

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Collins recalled how he had enjoyed similar “music” in his 1974 book, Carrying the Fire. It was something that he described as being “a strange noise in a strange place.” And it was this mysterious sound that in fact landed in NASA’s classified files for nearly 40 years after the Apollo 10 mission.

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How do we know? Well, it is routine for NASA to record all cockpit conversations that occur on its space missions. These recordings last from the moment that the spacecraft takes off to the moment that the astronauts return to Earth. Yet the Data Storage Equipment, as NASA calls it, remains classified and hidden from public consumption.

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In 2016, however, the strange noise incident was the subject of an episode of the Science Channel’s NASA’s Unexplained Files. The “outer space music” was discussed in an eerie tone, giving the occurrence an added feeling of foreboding. The program asked, what had NASA been hiding? And where had the unusual noise really come from?

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One talking head on NASA’s Unexplained Files was Al Worden, who had flown on the later Apollo 15 mission. He said, “Logic tells me that if there was something recorded on there, then there was something there. NASA would withhold information if they thought it was in the public’s best interest.”

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“You don’t hear about anything like that until years after the incident occurs, and then you kind of wonder,” Worden further explained to HuffPost in February 2016. “Because it’s such an old memory… you get concerned about if they were making something up or was there something really there?”

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So what was NASA hiding for four decades? Were aliens attempting to make contact with Apollo 10? Why had previous missions not recorded the same noise? After all, it couldn’t be a coincidence that it happened only on the “dark side of the Moon” out of contact with Earth… Or could it?

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Well, the first misconception that should be debunked is that the Moon has a “dark side.” The Moon rotates just as our planet does, after all, and because a full rotation takes as long as a circulation of the Earth, we only ever see one “side.” The Moon’s far side, therefore, receives as much sunlight as the Earth-facing side.

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Yet the noises that the Apollo 10 crew heard in their headsets are real enough. But to call them “music” may be a stretch of the imagination. But if the sound that the astronauts heard had had an undulating tone, then it can be considered to be no less musical than, say, a whale’s call – which is often described as a song.

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The truth of where the “outer-space-type music” came from is far more mundane than communication from alien beings, though. NASA had developed the technology to fly man to the Moon, it seems, but the communication systems used inside these advanced aircraft were imperfect. In fact, when Apollo 8 departed for the Moon, it was unclear if the radios would even work in space.

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You see, Apollo 10’s communication system wasn’t designed for a range as long as 230,000 miles. And before Apollo 8, NASA wasn’t sure if it would work outside of the low Earth orbit, either. The Apollo 10 mission involved undertaking tasks that had never been attempted before, too, so there were many unknowns.

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Apollo 10 was also the first mission in which two manned spacecraft split near the lunar surface. So each had its own communication system transmitting through its own antenna. And although the Moon’s orbit is radio-quiet, particularly on its far side, the electromagnetic frequencies emanating from deep space can easily be picked up.

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The outer-space-type music the Apollo 10 crew heard, then, was nothing more than feedback between the two spacecraft’s radios. It was a possibility discussed by crew members during the incident too. As Young noted at the time, “Probably due to the [Very High Frequency radio] ranging, I’d guess.”

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And the NASA cover-up? Well, it was routine for cockpit recordings to remain classified simply because they contained coarse language. Yet, with the Apollo 10 crew concluding that the noise was interference, they were nevertheless reluctant to bring it up. It was a tense time, after all, and no one dared show anything less than steel.

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Transcripts of Apollo 10’s cockpit recordings have been available since 1976, though. Yet it was a bizarre noise that could have been unnerving to anyone who had never heard it before. As Michael Collins wrote in Carrying the Fire, “Had I not been warned about it, it would have scared the hell out of me.”

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Worden’s mind, however, is open. He told HuffPost, “We’d had a lot of incidents where guys who flew in space saw and heard things that they didn’t recognize… It’s somebody’s hearsay evidence. It’s only a visual or audio event, which is hard to pin down. Recollection is one thing, but actual proof is something entirely different.”

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