NASA announced on Tuesday that it has released the audio recordings included in the first and second Voyager missions launched during the 1970s.
The audio samples, known as the "golden record," feature greetings spoken in several different languages and other sounds, which are meant to introduce Earthling culture to extraterrestrials that might pick the satellites up in space.
The idea behind the golden record came to be after scientists decided to place small metal plaques on the Pioneer 10 and Pioneer 11, two space missions that preceded the Voyagers. The plaques included information on the time and place of origin of the satellites for the benefit of potential space travelers in the future.
For the Voyager missions, NASA researchers, led by Cornell University astronomer Carl Sagan, placed a phonograph record on each capsule. The 12-inch disk, which was covered in gold-plated copper, contained several images and audio samples that portray what the culture and life on planet Earth is like.
Sagan and his colleagues selected the 115 analog-encoded images and a collection of natural sounds, including the sound of surf, thunder, wind, whales, birds and other animals.
They also placed musical selections gathered from different eras and cultures, as well as greetings from Earthlings spoken in 55 different languages arranged in alphabetical order. Recorded greetings begin with one spoken in the six-thousand-year-old language of ancient Sumerians known as Akkadian and end with the modern-day dialect in China known as Wu.
There were also messages in print from United States President Jimmy Carter and United Nations Secretary General Kurt Waldheim.
Each Voyager record was encased in an aluminum jacket for protection along with a needle and a cartridge. There were also instructions, written in symbolic language, that indicate the spacecraft's origin and how to play the recording.
"The spacecraft will be encountered and the record played only if there is advanced spacefaring civilizations in interstellar space," Sagan noted during the launching of the Voyager space missions in 1977.
"But the launching of this bottle into the cosmic ocean says something very hopeful about life on this planet."