- Audio from far side of the Moon from May 1969 space mission resurfaces
- Astronauts heard saying the whistling noise sounds like "outer space music"
- NASA says the audio was only radio interference sounds
The story behind the unusual whistling noises was showcased last night on the US cable channel Discovery, and sparked reports the audio has only just been released.
But NASA has denied the reports, releasing a statement saying: "While listed as 'confidential' in 1969 at the height of the Space Race, Apollo 10 mission transcripts and audio have been publicly available since 1973."
"Since the internet did not exist in the Apollo era, we have only recently provided digital files for some of those earlier missions," NASA said.
"The Apollo 10 audio clips were uploaded in 2012, but the mission's audio recordings have been available at the National Archives since the early 1970s."
The sounds, which lasted about an hour, were recorded and transmitted to mission control in Houston.
"You hear that? That whistling sound?" asks Mr Cernan, describing it as "outer-space-type music".
Mr Cernan told NASA he did not take the sounds seriously and never gave them another thought.
"I don't remember that incident exciting me enough to take it seriously," Mr Cernan said.
"It was probably just radio interference. Had we thought it was something other than that we would have briefed everyone after the flight. We never gave it another thought."
Noises explained as radio interferenceNASA says the sounds could not have been alien music.
An engineer from the US space agency said the noises likely came from interference caused by radios that were close to each other in the lunar module and the command module.
Michael Collins, the pilot of Apollo 11, who became the first person to fly around the far side of the Moon by himself while Buzz Aldrin and Neil Armstrong were walking on the surface, said he too heard "an eerie woo-woo sound" but accepted the explanation of radio interference.
In fact, he had been warned ahead of time, he wrote in his book, Carrying the Fire: An Astronaut's Journeys.
"Had I not been warned about it, it would have scared the hell out of me," he wrote.
"Fortunately the radio technicians (rather than the UFO fans) had a ready explanation for it: it was interference between the LM's and Command Module's VHF radios."
abc.net.au 26 Feb 2016