In May 1969, the Apollo 10 mission marked a milestone in space exploration by conducting a dress rehearsal for the first human landing on the lunar surface.
During this historic mission, the three astronauts managed to orbit the Moon for more than 10 hours and carry out important maneuvers, including separating from and reuniting with a lunar lander.
However, while on the far side of the Moon, in a lonely and enigmatic environment, the astronauts claimed to have heard a mysterious “whistling”.
One of them described this sound as coming from music from outer space. This statement sparked speculation that the Apollo 10 astronauts had heard alien music from outer space during their lunar orbit in 1969.
Did the Apollo 10 astronauts then hear alien music while orbiting the Moon in 1969? The answer is no. However, it is true that the Apollo 10 astronauts heard strange whistling noises that they described at the time as “music from outer space.” So the real question is: what did the astronauts actually hear that day?
The true story behind the strange whistles
In the audio recordings of the Apollo 10 mission you can see an interesting dialogue between astronauts Gene Cernan and John Young. During the flight, Cernan, who was in command of the lunar module, asks Young, command module pilot, if he hears “that whistle…”. Cernan describes the sound as music and mentions that it even seems to come from outer space.
Later, both astronauts ask Tom Stafford, who is in the lunar module with Cernan, if he can hear it too. They agree that it’s something really weird, and Young mentions, “We’ll have to find out. No one will believe us.”
Later, as reported Space.com, During the Apollo 11 mission, NASA warned the crew, including Michael Collins, about the possibility of hearing unusual sounds. Collins, who was left alone in the command module as Neil Armstrong and Buzz Aldrin headed for the lunar surface, noticed a strange and disturbing sound in his headphones, describing it as a “woo-woo” in his book “Carrying the Fire: The voyages of an astronaut. Fortunately, NASA had already provided an explanation for it.
“Radio technicians (rather than UFO fanatics) had a ready explanation for it,” Collins wrote. “It was interference between the VHF (very high frequency) radios of the Lunar Module and the Command Module.”
“If they hadn’t warned me, I would have been scared to death,” Collins added.
NASA put the transcripts of the Apollo 10 transmissions online in 2008, though the documents themselves say they would have been declassified in 1982. NASA also put the audio files online in 2012, according to the NASA History Office.
Interference between the VHF radios of the two vehicles
To understand how the sounds could have originated and settle the different versions with nods to stranger phenomena, you have to understand a bit about how radio works and how electromagnetic interference is created and mitigated. As Paul D. Spudis, a scientist at the Lunar and Planetary Institute in Houston, explained in an article in the Smithsonian Magazine As of 2016, these sounds can be explained by the interaction of radio signals and the generation of beat frequencies.
According to Spudis, on the Apollo missions, multiple radio links were used for various communications, such as telemetry, biomedical data, and navigation. The radio takes a high frequency signal and modulates the amplitude or frequency to carry information.
The production of radio waves can generate unwanted harmonics, so engineers must minimize them and limit the emission of parasitic radio signals. When two radio signals interact, they can mix together and generate a beat frequency.
In a complex environment such as a spacecraft, with many components operating simultaneously, radio frequency interference is likely to occur.
Thus, according to Spudis, the sounds described by the Apollo 10 astronauts and other missions resemble the tones generated by beat frequencies. These sounds can come and go due to systems only partially turning on.
In short, the mysterious appearance and disappearance of sounds is related to this phenomenon of radio frequency interference.
Although the technical explanation eliminated the possibility that they were alien songs, much to the contrary of those who want to believe otherwise, the experience of the astronauts is still fascinating.
In their exploration of the unknown, they were exposed to unexpected phenomena that, for a brief moment, defied their comprehension. But luckily for everyone, science was there to investigate and provide a real answer to what the Apollo 10 astronauts experienced that day.
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