NASA releases recording of...

NASA releases recording of 'outer-space type music' from far side of the moonBy James Griffiths, CNN Updated 0518 GMT (1318 HKT) February 22, 2016

1968: Moon view gives special gift (26 Videos) <img alt="jerusalem blood moon stewart pkg_00000806.jpg" class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/150928034643-jerusalem-blood-moon-stewart-pkg00000806-large-169.jpg">

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<img alt="jerusalem blood moon stewart pkg_00000806.jpg" class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/150928034643-jerusalem-blood-moon-stewart-pkg00000806-large-169.jpg"> 

Recordings of sounds heard on the far side of the moon have been released

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Apollo 11 astronauts heard "outer-space type music" while out of contact with Earth

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The eerie noises have an earthly explanation, however

(CNN)"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.

While transcripts were released in 2008, audio of the discussion, and the sounds that the astronauts were referencing, is only just being made public.

Read More

<img alt="The Apollo 10 crew discuss strange noises heard on the far side of the moon" class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160222102310-apollo-10transcript-large-169.jpg"> The Apollo 10 crew discuss strange noises heard on the far side of the moon Scott Kelly from space: Earth's atmosphere 'looks very, very fragile'

'Weird music' Out of radio contact with Earth and all alone on the far side of the moon, the astronauts were clearly not expecting to hear anything on their instruments.

"You hear that? That whistling sound? Whoooooo," says Cernan on the recording.

"That sure is weird music."

It was so weird that the team debated whether or not to mention it to their superiors at NASA, out of fear that it could cast doubt on their suitability for future spaceflight, according to a new Science Channel series "NASA's Unexplained Files."

Read more CNN Space + Science coverage

Unexplained? Not quite However, while the trailers for the series (and accompanying media coverage) make great store of the "unexplained" nature of the sounds, the truth is likely more scientific than sci-fi.

A NASA technician on the TV show explains that the "radios in the two spacecraft [the lunar module and the command module] were interfering with each other."

This explanation is disputed by the ponderous TV voiceover and astronaut Al Worden, who says on the show that "logic tells me that if there was something recorded on there, then there's something there."

Worden's assertion that the sounds are unexplained is not one shared by his fellow astronauts, however.

&lt;img alt="The crew members of Apollo 13 -- from left, Fred Haise, James Lovell and John Swigert -- are seen after splashdown in April 1970. Apollo 13 was scheduled to be the third lunar landing mission. The crew launched on April 11, 1970, but two days later and about 205,000 miles from Earth, the service module oxygen tank ruptured, crippling the spacecraft. &amp;amp;quot;Houston, we&amp;amp;#39;ve had a problem,&amp;amp;quot; Lovell said. Instead of landing, the crew did a flyby and came home, safely splashing down on April 17. Lovell&amp;amp;#39;s book &amp;amp;quot;Lost Moon&amp;amp;quot; became the basis for the motion picture &amp;amp;quot;Apollo 13.&amp;amp;quot;" class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207001825-apollo-13-crewportrait-after-splashdown-super-169.jpg"&gt; 25 photos: The American men who went to the moon The crew members of Apollo 13 -- from left, Fred Haise, James Lovell and John Swigert -- are seen after splashdown in April 1970. Apollo 13 was scheduled to be the third lunar landing mission. The crew launched on April 11, 1970, but two days later and about 205,000 miles from Earth, the service module oxygen tank ruptured, crippling the spacecraft. "Houston, we've had a problem," Lovell said. Instead of landing, the crew did a flyby and came home, safely splashing down on April 17. Lovell's book "Lost Moon" became the basis for the motion picture "Apollo 13."

Hide Caption 13 of 25 &lt;img alt="The crew of Apollo 14: from left, Stuart Roosa, Alan Shepard and Edgar Mitchell. The mission launched January 31, 1971, landed on the moon February 5 and returned to Earth on February 9. Shepard and Mitchell conducted moonwalks while Roosa orbited in the command module. " class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207002004-apollo-14-crew-photo-super-169.jpg"&gt; 25 photos: The American men who went to the moon The crew of Apollo 14: from left, Stuart Roosa, Alan Shepard and Edgar Mitchell. The mission launched January 31, 1971, landed on the moon February 5 and returned to Earth on February 9. Shepard and Mitchell conducted moonwalks while Roosa orbited in the command module.

Hide Caption 14 of 25 &lt;img alt="Shepard stands beside a portable workbench set up on the moon." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207002110-alan-shepard-walks-on-the-moon-super169.jpg"&gt;

25 photos: The American men who went to the moon Shepard stands beside a portable workbench set up on the moon.

Hide Caption 15 of 25 &lt;img alt="Mitchell stands by the U.S. flag during his mission&amp;amp;#39;s first spacewalk. " class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207002327-edgar-mitchellwalks-on-the-moon-super-169.jpg"&gt; 25 photos: The American men who went to the moon Mitchell stands by the U.S. flag during his mission's first spacewalk.

Hide Caption 16 of 25 &lt;img alt="Apollo 15 was the first mission capable of a longer stay on the moon, and the crew had its own rover. From left are Jim Irwin, David Scott and Alfred Worden. Irwin and Scott walked on the moon while Worden kept watch in the command module. The mission launched July 26, 1971, landed on the moon July 30 and returned to Earth on August 7." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207002435-apollo-15-crew-photo-super-169.jpg"&gt; 25 photos: The American men who went to the moon Apollo 15 was the first mission capable of a longer stay on the moon, and the crew had its own rover. From left are Jim Irwin, David Scott and Alfred Worden. Irwin and Scott walked on the moon while Worden kept watch in the command module. The mission launched July 26, 1971, landed on the moon July 30 and returned to Earth on August 7.

Hide Caption 17 of 25 &lt;img alt="Scott salutes the U.S. flag during an Apollo 15 moonwalk." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207002550-david-scott-walks-on-the-moon-super169.jpg"&gt; 25 photos: The American men who went to the moon Scott salutes the U.S. flag during an Apollo 15 moonwalk.

Hide Caption 18 of 25 &lt;img alt="Irwin works near the lunar rover." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207002653-jim-irwin-walks-on-the-moon-super169.jpg"&gt; 25 photos: The American men who went to the moon Irwin works near the lunar rover.

Hide Caption 19 of 25 &lt;img alt="The Apollo 16 crew, from left: Thomas Mattingly, John Young and Charles Duke. Young and Duke walked on the moon while Mattingly stayed in the command module. The mission launched on April 16, 1972, landed on the moon April 20 and returned to Earth on April 27." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207002819-apollo-16-crew-photo-super-169.jpg"&gt; 25 photos: The American men who went to the moon The Apollo 16 crew, from left: Thomas Mattingly, John Young and Charles Duke. Young and Duke walked on the moon while Mattingly stayed in the command module. The mission launched on April 16, 1972, landed on the moon April 20 and returned to Earth on April 27.

Hide Caption

20 of 25 &lt;img alt="Young leaps from the surface of the moon as he salutes the U.S. flag." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207002938-john-young-walks-on-the-moon-super169.jpg"&gt; 25 photos: The American men who went to the moon Young leaps from the surface of the moon as he salutes the U.S. flag.

Hide Caption 21 of 25 &lt;img alt="Duke collects lunar samples." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207003124-charles-duke-walks-on-the-moon-super169.jpg"&gt; 25 photos: The American men who went to the moon Duke collects lunar samples.

Hide Caption 22 of 25 &lt;img alt="Apollo 17 was NASA&amp;amp;#39;s last manned mission to the moon. It launched on December 7, 1972, landed on the moon December 11 and splashed down on Earth on December 19. From left are Harrison Schmitt, Gene Cernan and Ronald Evans. Schmitt and Cernan walked on the moon while Evans orbited in the command module. The crew stayed on the surface 75 hours and collected 243 pounds of lunar material. " class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207003322apollo-17-crew-photo-super-169.jpg"&gt; 25 photos: The American men who went to the moon Apollo 17 was NASA's last manned mission to the moon. It launched on December 7, 1972, landed on the moon December 11 and splashed down on Earth on December 19. From left are Harrison Schmitt, Gene Cernan and Ronald Evans. Schmitt and Cernan walked on the moon while Evans orbited in the command module. The crew stayed on the surface 75 hours and collected 243 pounds of lunar material.

Hide Caption 23 of 25 &lt;img alt="Schmitt stands next to a huge lunar boulder during an Apollo 17 moonwalk. The lunar rover is in the background. Schmitt was the 12th man to set foot on the moon, but Cernan was the last to leave." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207003524-harrison-schmittwalks-on-the-moon-super-169.jpg"&gt; 25 photos: The American men who went to the moon Schmitt stands next to a huge lunar boulder during an Apollo 17 moonwalk. The lunar rover is in the background. Schmitt was the 12th man to set foot on the moon, but Cernan was the last to leave.

Hide Caption 24 of 25 &lt;img alt="Cernan holds a corner of the American flag during the first Apollo 17 moonwalk. Cernan, the last man on the moon, had these parting words as he left: &amp;amp;quot;We leave as we came and, God willing, as we shall return -- with peace, and hope for all mankind.&amp;amp;quot;" class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207003705-gene-cernan-walks-on-the-moon-super169.jpg"&gt; 25 photos: The American men who went to the moon Cernan holds a corner of the American flag during the first Apollo 17 moonwalk. Cernan, the last man on the moon, had these parting words as he left: "We leave as we came and, God willing, as we shall return -with peace, and hope for all mankind."

Hide Caption 25 of 25

<img alt="The Apollo program included 12 manned missions that launched in the late 1960s and early &amp;#39;70s. Three missions orbited the Earth: Apollo 7, Apollo 9 and Apollo-Soyuz. Two missions orbited the moon: Apollos 8 and 10. Apollo 13 made a lunar swingby -- a malfunction forced NASA to cancel the landing. Six missions actually landed on the moon: Apollos 11, 12, 14, 15, 16 and 17." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160206211449-full-moon-fromapollo-11-super-169.jpg"> 25 photos: The American men who went to the moon The Apollo program included 12 manned missions that launched in the late 1960s and early '70s. Three missions orbited the Earth: Apollo 7, Apollo 9 and Apollo-Soyuz. Two missions orbited the moon: Apollos 8 and 10. Apollo 13 made a lunar swingby -- a malfunction forced NASA to cancel the landing. Six missions actually landed on the moon: Apollos 11, 12, 14, 15, 16 and 17.

Hide Caption 1 of 25 <img alt="The Apollo 11 lunar module Eagle prepares to land men on the moon for the first time. During each of the six Apollo missions that landed on the moon, two astronauts walked on the lunar surface." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160206211717-the-eagle-preparesto-land-super-169.jpg"> 25 photos: The American men who went to the moon The Apollo 11 lunar module Eagle prepares to land men on the moon for the first time. During each of the six Apollo missions that landed on the moon, two astronauts walked on the lunar surface.

Hide Caption 2 of 25 <img alt="Apollo 8 was the first manned spacecraft to reach the moon. The mission was designed to test the spacecraft and crew, but it did not include a lunar landing. From left are crew members James Lovell, William Anders and Frank Borman." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160206211908-apollo-8-crew-super-169.jpg">

25 photos: The American men who went to the moon Apollo 8 was the first manned spacecraft to reach the moon. The mission was designed to test the spacecraft and crew, but it did not include a lunar landing. From left are crew members James Lovell, William Anders and Frank Borman.

Hide Caption 3 of 25 <img alt="Apollo 8 launched on December 21, 1968, and entered lunar orbit on Christmas Eve. That night, the crew held a live broadcast and showed pictures of the Earth from their spacecraft. &amp;quot;The vast loneliness is awe-inspiring and it makes you realize just what you have back there on Earth,&amp;quot; Lovell said. They ended the broadcast taking turns reading from the Book of Genesis." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160206212028-apollo-8-earthrisesuper-169.jpg"> 25 photos: The American men who went to the moon Apollo 8 launched on December 21, 1968, and entered lunar orbit on Christmas Eve. That night, the crew held a live broadcast and showed pictures of the Earth from their spacecraft. "The vast loneliness is aweinspiring and it makes you realize just what you have back there on Earth," Lovell said. They ended the broadcast taking turns reading from the Book of Genesis.

Hide Caption 4 of 25 <img alt="The Apollo 10 mission was just like a lunar landing missing -- but without the landing. Crew members, from left, are Gene Cernan, John Young and Thomas Stafford. They launched on May 18, 1969, made 31 orbits of the moon and splashed down in the Pacific on May 26." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160206212229-apollo-10-crew-super-169.jpg"> 25 photos: The American men who went to the moon The Apollo 10 mission was just like a lunar landing missing -- but without the landing. Crew members, from left, are Gene Cernan, John Young and Thomas Stafford. They launched on May 18, 1969, made 31 orbits of the moon and splashed down in the Pacific on May 26.

Hide Caption 5 of 25 <img alt="Apollo 11 was the first manned mission to land on the moon. The crew members, from left, were Neil Armstrong, Michael Collins and Edwin &amp;quot;Buzz&amp;quot; Aldrin. The mission launched on July 16, 1969." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160206212502apollo-11-crew-photo-super-169.jpg"> 25 photos: The American men who went to the moon Apollo 11 was the first manned mission to land on the moon. The crew members, from left, were Neil Armstrong, Michael Collins and Edwin "Buzz" Aldrin. The mission launched on July 16, 1969.

Hide Caption 6 of 25 <img alt="On July 20, 1969, Armstrong became the first human to set foot on another world. NASA says more than half a billion people watched on television as Armstrong climbed down the ladder to the moon and proclaimed: &amp;quot;That&amp;#39;s one small step for a man, one giant leap for mankind.&amp;quot; " class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160206235924-armstrong-steps-on-the-moon-super169.jpg"> 25 photos: The American men who went to the moon On July 20, 1969, Armstrong became the first human to set foot on another world. NASA says more than half a billion people watched on television as Armstrong climbed down the ladder to the moon and proclaimed: "That's one small step for a man, one giant leap for mankind."

Hide Caption 7 of 25 <img alt="Armstrong took most of the photographs during his historic moonwalk, so you don&amp;#39;t see many pictures of him -- this was before the age of the selfie. This rare shot from Aldrin shows Armstrong near the lunar module Eagle." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207000129-armstrong-on-lunar-surface-super169.jpg"> 25 photos: The American men who went to the moon Armstrong took most of the photographs during his historic moonwalk, so you don't see many pictures of him -- this was before the age of the selfie. This rare shot from Aldrin shows Armstrong near the lunar module Eagle.

Hide Caption 8 of 25 <img alt="Aldrin was lunar module pilot and the second man to walk on the moon. On each lunar landing mission, one crew member stayed in orbit in the command module. On this mission that was Collins." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207000558-buzz-aldrin-walkson-the-moon-super-169.jpg"> 25 photos: The American men who went to the moon Aldrin was lunar module pilot and the second man to walk on the moon. On each lunar landing mission, one crew member stayed in orbit in the command module. On this mission that was Collins.

Hide Caption 9 of 25 <img alt="The crew of Apollo 12, from left, were Charles Conrad, Richard Gordon and Alan Bean. Conrad and Bean walked on the moon. Gordon stayed on the command module. The mission launched November 14, 1969, landed on the moon November 19 and returned to Earth on November 24." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207000802-apollo-12-crew-photo-super-169.jpg"> 25 photos: The American men who went to the moon The crew of Apollo 12, from left, were Charles Conrad, Richard Gordon and Alan Bean. Conrad and Bean walked on the moon. Gordon stayed on the command module. The mission launched November 14, 1969, landed on the moon November 19 and returned to Earth on November 24.

Hide Caption 10 of 25 <img alt="Bean carries equipment on the moon during the Apollo 12 mission." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207000936-alan-bean-walks-on-the-mon-super169.jpg"> 25 photos: The American men who went to the moon Bean carries equipment on the moon during the Apollo 12 mission.

Hide Caption 11 of 25 <img alt="Conrad examines the Surveyor 3, a spacecraft that landed on the moon in 1967. The Apollo 12 crew touched down about 600 feet from the older spacecraft. They collected its television camera and several other pieces and brought them back to Earth." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207001142-charles-conrad-walks-on-the-moon-super169.jpg"> 25 photos: The American men who went to the moon

Conrad examines the Surveyor 3, a spacecraft that landed on the moon in 1967. The Apollo 12 crew touched down about 600 feet from the older spacecraft. They collected its television camera and several other pieces and brought them back to Earth.

Hide Caption 12 of 25 <img alt="The crew members of Apollo 13 -- from left, Fred Haise, James Lovell and John Swigert -- are seen after splashdown in April 1970. Apollo 13 was scheduled to be the third lunar landing mission. The crew launched on April 11, 1970, but two days later and about 205,000 miles from Earth, the service module oxygen tank ruptured, crippling the spacecraft. &amp;quot;Houston, we&amp;#39;ve had a problem,&amp;quot; Lovell said. Instead of landing, the crew did a flyby and came home, safely splashing down on April 17. Lovell&amp;#39;s book &amp;quot;Lost Moon&amp;quot; became the basis for the motion picture &amp;quot;Apollo 13.&amp;quot;" class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207001825-apollo-13-crew-portrait-after-splashdownsuper-169.jpg"> 25 photos: The American men who went to the moon The crew members of Apollo 13 -- from left, Fred Haise, James Lovell and John Swigert -- are seen after splashdown in April 1970. Apollo 13 was scheduled to be the third lunar landing mission. The crew launched on April 11, 1970, but two days later and about 205,000 miles from Earth, the service module oxygen tank ruptured, crippling the spacecraft. "Houston, we've had a problem," Lovell said. Instead of landing, the crew did a flyby and came home, safely splashing down on April 17. Lovell's book "Lost Moon" became the basis for the motion picture "Apollo 13."

Hide Caption 13 of 25 <img alt="The crew of Apollo 14: from left, Stuart Roosa, Alan Shepard and Edgar Mitchell. The mission launched January 31, 1971, landed on the moon February 5 and returned to Earth on February 9. Shepard and Mitchell conducted moonwalks while Roosa orbited in the command module. " class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207002004-apollo-14-crew-photo-super-169.jpg"> 25 photos: The American men who went to the moon The crew of Apollo 14: from left, Stuart Roosa, Alan Shepard and Edgar Mitchell. The mission launched January 31, 1971, landed on the moon February 5 and returned to Earth on February 9. Shepard and Mitchell conducted moonwalks while Roosa orbited in the command module.

Hide Caption 14 of 25 <img alt="Shepard stands beside a portable workbench set up on the moon." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207002110-alan-shepard-walks-on-the-moon-super169.jpg"> 25 photos: The American men who went to the moon Shepard stands beside a portable workbench set up on the moon.

Hide Caption 15 of 25 <img alt="Mitchell stands by the U.S. flag during his mission&amp;#39;s first spacewalk. " class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207002327-edgar-mitchellwalks-on-the-moon-super-169.jpg"> 25 photos: The American men who went to the moon Mitchell stands by the U.S. flag during his mission's first spacewalk.

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<img alt="Apollo 15 was the first mission capable of a longer stay on the moon, and the crew had its own rover. From left are Jim Irwin, David Scott and Alfred Worden. Irwin and Scott walked on the moon while Worden kept watch in the command module. The mission launched July 26, 1971, landed on the moon July 30 and returned to Earth on August 7." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207002435-apollo-15-crew-photo-super-169.jpg"> 25 photos: The American men who went to the moon Apollo 15 was the first mission capable of a longer stay on the moon, and the crew had its own rover. From left are Jim Irwin, David Scott and Alfred Worden. Irwin and Scott walked on the moon while Worden kept watch in the command module. The mission launched July 26, 1971, landed on the moon July 30 and returned to Earth on August 7.

Hide Caption 17 of 25 <img alt="Scott salutes the U.S. flag during an Apollo 15 moonwalk." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207002550-david-scott-walks-on-the-moon-super169.jpg"> 25 photos: The American men who went to the moon Scott salutes the U.S. flag during an Apollo 15 moonwalk.

Hide Caption 18 of 25 <img alt="Irwin works near the lunar rover." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207002653-jim-irwin-walks-on-the-moon-super169.jpg"> 25 photos: The American men who went to the moon Irwin works near the lunar rover.

Hide Caption 19 of 25 <img alt="The Apollo 16 crew, from left: Thomas Mattingly, John Young and Charles Duke. Young and Duke walked on the moon while Mattingly stayed in the command module. The mission launched on April 16, 1972, landed on the moon April 20 and returned to Earth on April 27." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207002819-apollo-16-crew-photo-super-169.jpg"> 25 photos: The American men who went to the moon The Apollo 16 crew, from left: Thomas Mattingly, John Young and Charles Duke. Young and Duke walked on the moon while Mattingly stayed in the command module. The mission launched on April 16, 1972, landed on the moon April 20 and returned to Earth on April 27.

Hide Caption 20 of 25 <img alt="Young leaps from the surface of the moon as he salutes the U.S. flag." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207002938-john-young-walks-on-the-moon-super169.jpg"> 25 photos: The American men who went to the moon Young leaps from the surface of the moon as he salutes the U.S. flag.

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<img alt="Duke collects lunar samples." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207003124-charles-duke-walks-on-the-moon-super169.jpg"> 25 photos: The American men who went to the moon Duke collects lunar samples.

Hide Caption 22 of 25 <img alt="Apollo 17 was NASA&amp;#39;s last manned mission to the moon. It launched on December 7, 1972, landed on the moon December 11 and splashed down on Earth on December 19. From left are Harrison Schmitt, Gene Cernan and Ronald Evans. Schmitt and Cernan walked on the moon while Evans orbited in the command module. The crew stayed on the surface 75 hours and collected 243 pounds of lunar material. " class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207003322-apollo17-crew-photo-super-169.jpg"> 25 photos: The American men who went to the moon Apollo 17 was NASA's last manned mission to the moon. It launched on December 7, 1972, landed on the moon December 11 and splashed down on Earth on December 19. From left are Harrison Schmitt, Gene Cernan and Ronald Evans. Schmitt and Cernan walked on the moon while Evans orbited in the command module. The crew stayed on the surface 75 hours and collected 243 pounds of lunar material.

Hide Caption 23 of 25 <img alt="Schmitt stands next to a huge lunar boulder during an Apollo 17 moonwalk. The lunar rover is in the background. Schmitt was the 12th man to set foot on the moon, but Cernan was the last to leave." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207003524-harrison-schmittwalks-on-the-moon-super-169.jpg"> 25 photos: The American men who went to the moon Schmitt stands next to a huge lunar boulder during an Apollo 17 moonwalk. The lunar rover is in the background. Schmitt was the 12th man to set foot on the moon, but Cernan was the last to leave.

Hide Caption 24 of 25 <img alt="Cernan holds a corner of the American flag during the first Apollo 17 moonwalk. Cernan, the last man on the moon, had these parting words as he left: &amp;quot;We leave as we came and, God willing, as we shall return -- with peace, and hope for all mankind.&amp;quot;" class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207003705-gene-cernan-walks-on-the-moon-super169.jpg"> 25 photos: The American men who went to the moon Cernan holds a corner of the American flag during the first Apollo 17 moonwalk. Cernan, the last man on the moon, had these parting words as he left: "We leave as we came and, God willing, as we shall return -with peace, and hope for all mankind."

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&lt;img alt="The Apollo program included 12 manned missions that launched in the late 1960s and early &amp;amp;#39;70s. Three missions orbited the Earth: Apollo 7, Apollo 9 and Apollo-Soyuz. Two missions orbited the moon: Apollos 8 and 10. Apollo 13 made a lunar swingby -- a malfunction forced NASA to cancel the landing. Six missions actually landed on the moon: Apollos 11, 12, 14, 15, 16 and 17." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160206211449-full-moon-fromapollo-11-super-169.jpg"&gt; 25 photos: The American men who went to the moon The Apollo program included 12 manned missions that launched in the late 1960s and early '70s. Three missions orbited the Earth: Apollo 7, Apollo 9 and Apollo-Soyuz. Two missions orbited the moon: Apollos 8 and 10. Apollo 13 made a lunar swingby -- a malfunction forced NASA to cancel the landing. Six missions actually landed on the moon: Apollos 11, 12, 14, 15, 16 and 17.

Hide Caption 1 of 25 &lt;img alt="The Apollo 11 lunar module Eagle prepares to land men on the moon for the first time. During each of the six Apollo missions that landed on the moon, two astronauts walked on the lunar surface." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160206211717-the-eagle-preparesto-land-super-169.jpg"&gt; 25 photos: The American men who went to the moon The Apollo 11 lunar module Eagle prepares to land men on the moon for the first time. During each of the six Apollo missions that landed on the moon, two astronauts walked on the lunar surface.

Hide Caption 2 of 25 &lt;img alt="Apollo 8 was the first manned spacecraft to reach the moon. The mission was designed to test the spacecraft and crew, but it did not include a lunar landing. From left are crew members James Lovell, William Anders and Frank Borman." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160206211908-apollo-8-crew-super-169.jpg"&gt; 25 photos: The American men who went to the moon

Apollo 8 was the first manned spacecraft to reach the moon. The mission was designed to test the spacecraft and crew, but it did not include a lunar landing. From left are crew members James Lovell, William Anders and Frank Borman.

Hide Caption 3 of 25 &lt;img alt="Apollo 8 launched on December 21, 1968, and entered lunar orbit on Christmas Eve. That night, the crew held a live broadcast and showed pictures of the Earth from their spacecraft. &amp;amp;quot;The vast loneliness is awe-inspiring and it makes you realize just what you have back there on Earth,&amp;amp;quot; Lovell said. They ended the broadcast taking turns reading from the Book of Genesis." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160206212028-apollo-8earthrise-super-169.jpg"&gt; 25 photos: The American men who went to the moon Apollo 8 launched on December 21, 1968, and entered lunar orbit on Christmas Eve. That night, the crew held a live broadcast and showed pictures of the Earth from their spacecraft. "The vast loneliness is aweinspiring and it makes you realize just what you have back there on Earth," Lovell said. They ended the broadcast taking turns reading from the Book of Genesis.

Hide Caption 4 of 25 &lt;img alt="The Apollo 10 mission was just like a lunar landing missing -- but without the landing. Crew members, from left, are Gene Cernan, John Young and Thomas Stafford. They launched on May 18, 1969, made 31 orbits of the moon and splashed down in the Pacific on May 26." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160206212229-apollo-10-crew-super-169.jpg"&gt; 25 photos: The American men who went to the moon The Apollo 10 mission was just like a lunar landing missing -- but without the landing. Crew members, from left, are Gene Cernan, John Young and Thomas Stafford. They launched on May 18, 1969, made 31 orbits of the moon and splashed down in the Pacific on May 26.

Hide Caption 5 of 25 &lt;img alt="Apollo 11 was the first manned mission to land on the moon. The crew members, from left, were Neil Armstrong, Michael Collins and Edwin &amp;amp;quot;Buzz&amp;amp;quot; Aldrin. The mission launched on July 16, 1969." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160206212502-apollo-11-crew-photo-super-169.jpg"&gt; 25 photos: The American men who went to the moon Apollo 11 was the first manned mission to land on the moon. The crew members, from left, were Neil Armstrong, Michael Collins and Edwin "Buzz" Aldrin. The mission launched on July 16, 1969.

Hide Caption 6 of 25 &lt;img alt="On July 20, 1969, Armstrong became the first human to set foot on another world. NASA says more than half a billion people watched on television as Armstrong climbed down the ladder to the moon and proclaimed: &amp;amp;quot;That&amp;amp;#39;s one small step for a man, one giant leap for mankind.&amp;amp;quot; " class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160206235924-armstrong-steps-on-the-moon-super169.jpg"&gt; 25 photos: The American men who went to the moon On July 20, 1969, Armstrong became the first human to set foot on another world. NASA says more than half a billion people watched on television as Armstrong climbed down the ladder to the moon and proclaimed: "That's one small step for a man, one giant leap for mankind."

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7 of 25 &lt;img alt="Armstrong took most of the photographs during his historic moonwalk, so you don&amp;amp;#39;t see many pictures of him -- this was before the age of the selfie. This rare shot from Aldrin shows Armstrong near the lunar module Eagle." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207000129-armstrong-on-lunar-surface-super169.jpg"&gt; 25 photos: The American men who went to the moon Armstrong took most of the photographs during his historic moonwalk, so you don't see many pictures of him -- this was before the age of the selfie. This rare shot from Aldrin shows Armstrong near the lunar module Eagle.

Hide Caption 8 of 25 &lt;img alt="Aldrin was lunar module pilot and the second man to walk on the moon. On each lunar landing mission, one crew member stayed in orbit in the command module. On this mission that was Collins." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207000558-buzz-aldrin-walkson-the-moon-super-169.jpg"&gt; 25 photos: The American men who went to the moon Aldrin was lunar module pilot and the second man to walk on the moon. On each lunar landing mission, one crew member stayed in orbit in the command module. On this mission that was Collins.

Hide Caption 9 of 25 &lt;img alt="The crew of Apollo 12, from left, were Charles Conrad, Richard Gordon and Alan Bean.

Conrad and Bean walked on the moon. Gordon stayed on the command module. The mission launched November 14, 1969, landed on the moon November 19 and returned to Earth on November 24." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207000802-apollo-12-crewphoto-super-169.jpg"&gt; 25 photos: The American men who went to the moon The crew of Apollo 12, from left, were Charles Conrad, Richard Gordon and Alan Bean. Conrad and Bean walked on the moon. Gordon stayed on the command module. The mission launched November 14, 1969, landed on the moon November 19 and returned to Earth on November 24.

Hide Caption 10 of 25 &lt;img alt="Bean carries equipment on the moon during the Apollo 12 mission." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207000936-alan-bean-walks-on-the-mon-super169.jpg"&gt; 25 photos: The American men who went to the moon Bean carries equipment on the moon during the Apollo 12 mission.

Hide Caption 11 of 25 &lt;img alt="Conrad examines the Surveyor 3, a spacecraft that landed on the moon in 1967. The Apollo 12 crew touched down about 600 feet from the older spacecraft. They collected its television camera and several other pieces and brought them back to Earth." class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207001142-charles-conrad-walks-on-the-moon-super169.jpg"&gt; 25 photos: The American men who went to the moon

Conrad examines the Surveyor 3, a spacecraft that landed on the moon in 1967. The Apollo 12 crew touched down about 600 feet from the older spacecraft. They collected its television camera and several other pieces and brought them back to Earth.

Hide Caption 12 of 25 &lt;img alt="The crew members of Apollo 13 -- from left, Fred Haise, James Lovell and John Swigert -- are seen after splashdown in April 1970. Apollo 13 was scheduled to be the third lunar landing mission. The crew launched on April 11, 1970, but two days later and about 205,000 miles from Earth, the service module oxygen tank ruptured, crippling the spacecraft. &amp;amp;quot;Houston, we&amp;amp;#39;ve had a problem,&amp;amp;quot; Lovell said. Instead of landing, the crew did a flyby and came home, safely splashing down on April 17. Lovell&amp;amp;#39;s book &amp;amp;quot;Lost Moon&amp;amp;quot; became the basis for the motion picture &amp;amp;quot;Apollo 13.&amp;amp;quot;" class="media__image" src="http://i2.cdn.turner.com/cnnnext/dam/assets/160207001825-apollo-13-crewportrait-after-splashdown-super-169.jpg"&gt; 25 photos: The American men who went to the moon The crew members of Apollo 13 -- from left, Fred Haise, James Lovell and John Swigert -- are seen after splashdown in April 1970. Apollo 13 was scheduled to be the third lunar landing mission. The crew launched on April 11, 1970, but two days later and about 205,000 miles from Earth, the service module oxygen tank ruptured, crippling the spacecraft. "Houston, we've had a problem," Lovell said. Instead of landing, the crew did a flyby and came home, safely splashing down on April 17. Lovell's book "Lost Moon" became the basis for the motion picture "Apollo 13."

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Michael Collins, the pilot of Apollo 11 and the first person to fly around the far side of the moon by himself (while teammates Buzz Aldrin and Neil Armstrong were exploring the Lunar surface), also recalled hearing strange sounds, but did not think too much of it.

"There is a strange noise in my headset now, an eerie woo-woo sound," 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 (...) 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."

Edgar Mitchell, Apollo 14 astronaut who walked on moon, dies at 85 Collins explained that the noise began when the radios in the two vehicles were both turned on and in close proximity to each other.

Unlike Apollo 10, the Apollo 11 lunar module did land on the moon's service, after which the "woo-woo" noises stopped.

So much for "outer-space music."