The Voyager Golden Records are phonograph records which were included aboard both Voyager spacecraft, which were launched in 1977. They contain sounds and images selected to portray the diversity of life and culture on Earth, and are intended for any intelligent extraterrestrial life form, or for future humans, who may find them. The Voyager spacecraft are not heading towards any particular star, but Voyager 1 will be within 1.6 light years of the star AC+79 3888 in the Ophiuchus constellation in about 40,000 years.[1]
As the probes are extremely small compared to the vastness of interstellar space, the probability of a space faring civilization encountering them is very small, especially since the probes will eventually stop emitting any kind of electromagnetic radiation. If they are ever found by an alien species, it will most likely be far in the future as the nearest star on Voyager 1's trajectory will only be reached in 40,000 years.
Carl Sagan noted that "The spacecraft will be encountered and the record played only if there are advanced space-faring civilizations in interstellar space. But the launching of this 'bottle' into the cosmic 'ocean' says something very hopeful about life on this planet."[2] Thus the record is best seen as a time capsule or a symbolic statement rather than a serious attempt to communicate with extraterrestrial life.
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As of 2008[update], the two Voyager spacecraft became the third and fourth human artifacts to escape entirely from the solar system. Pioneers 10 and 11, which were launched in 1972 and 1973 and preceded Voyager in outstripping the gravitational attraction of the Sun, both carried small metal plaques identifying their time and place of origin for the benefit of any other spacefarers that might find them in the distant future.
With this example before them, NASA placed a more comprehensive message aboard Voyager 1 and 2—a kind of time capsule, intended to communicate a story of our world to extraterrestrials.
| “ | This is a present from a small, distant world, a token of our sounds, our science, our images, our music, our thoughts and our feelings. We are attempting to survive our time so we may live into yours. | ” |
The contents of the record were selected for NASA by a committee chaired by Carl Sagan of Cornell University. Sagan and his associates assembled 116 images and a variety of natural sounds, such as those made by surf, wind, and thunder, and animal sounds, including the songs of birds and whales. To this they added musical selections from different cultures and eras, spoken greetings in fifty-five languages, and printed messages from President Jimmy Carter and U.N. Secretary-General Kurt Waldheim.
The collection of images includes many photographs and diagrams both in black and white and color. The first images are of scientific interest, showing mathematical and physical quantities, the solar system and its planets, DNA, and human anatomy and reproduction. Care was taken to include not only pictures of humanity, but also some of animals, insects, plants and landscapes. Images of humanity depict a broad range of cultures. These images show food, architecture, and humans in portraits as well as going about their day to day lives. Many pictures are annotated with one or more indications of scales of time, size, or mass. Some images contain indications of chemical composition. All measures used on the pictures are defined in the first few images using physical references that are likely to be consistent anywhere in the universe.
The musical selection is also varied, featuring artists such as Beethoven, Guan Pinghu, Mozart, Stravinsky and Chuck Berry.
After NASA had received criticism over the nudity on the Pioneer plaque (line drawings of a naked man and woman), the agency chose not to allow Sagan and his colleagues to include a photograph of a nude man and woman on the record. Instead, only a silhouette of the couple was included.[3]
The pulsar map and hydrogen molecule diagram are shared in common with the Pioneer plaque.
The 116 images are encoded in analogue form and composed of 512 vertical lines. The remainder of the record is audio, designed to be played at 16⅔ revolutions per minute.
In the upper left-hand corner is an easily recognized drawing of the phonograph record and the stylus carried with it. The stylus is in the correct position to play the record from the beginning. Written around it in binary arithmetic is the correct time of one rotation of the record, 3.6 seconds, expressed in time units of 0.70 billionths of a second, the time period associated with a fundamental transition of the hydrogen atom. The drawing indicates that the record should be played from the outside in. Below this drawing is a side view of the record and stylus, with a binary number giving the time to play one side of the record - about an hour.
The information in the upper right-hand portion of the cover is designed to show how pictures are to be constructed from the recorded signals. The top drawing shows the typical signal that occurs at the start of a picture. The picture is made from this signal, which traces the picture as a series of vertical lines, similar to ordinary television (in which the picture is a series of horizontal lines). Picture lines 1, 2 and 3 are noted in binary numbers, and the duration of one of the "picture lines," about 8 milliseconds, is noted. The drawing immediately below shows how these lines are to be drawn vertically, with staggered "interlace" to give the correct picture rendition. Immediately below this is a drawing of an entire picture raster, showing that there are 512 (29) vertical lines in a complete picture. Immediately below this is a replica of the first picture on the record to permit the recipients to verify that they are decoding the signals correctly. A circle was used in this picture to ensure that the recipients use the correct ratio of horizontal to vertical height in picture reconstruction.
The drawing in the lower left-hand corner of the cover is the pulsar map previously sent as part of the plaques on Pioneers 10 and 11. It shows the location of the solar system with respect to 14 pulsars, whose precise periods are given. The drawing containing two circles in the lower right-hand corner is a drawing of the hydrogen atom in its two lowest states, with a connecting line and digit 1 to indicate that the time interval associated with the transition from one state to the other is to be used as the fundamental time scale, both for the time given on the cover and in the decoded pictures.[4]
The record is constructed of gold-plated copper. The record's cover is aluminium and electroplated upon it is an ultra-pure sample of the isotope uranium-238. Uranium-238 has a half-life of 4.51 billion years. It is possible that a civilization that encounters the record will be able to use the ratio of remaining uranium to daughter elements to determine the age of the record.
The records also had the sentence "To the makers of music — all worlds, all times" handwritten on them. Since this was not in the original disc specification, it almost caused their rejection.[5]
Voyager 1 was launched in 1977, passed the orbit of Pluto in 1990, and left the solar system (in the sense of passing the termination shock) in November 2004. It is now in the Kuiper Belt. In about 40,000 years, it and Voyager 2 will each come to within about 1.7 light-years of two separate stars: Voyager 1 will have approached star AC+79 3888, located in the constellation Ophiuchus; and Voyager 2 will have approached star Ross 248, located in the constellation of Andromeda.
In August 2009, Voyager 1 was over 16.5 billion km from the Sun and traveling at a speed of 3.5 AU per year (approximately 61,000 km/h, or 38,000 mph) while Voyager 2 was well over 13 billion km away and moving at about 3.3 AU per year (approximately 56,000 km/h, or 35,000 mph).
Voyager 1 has entered the heliosheath, the region beyond the termination shock. The termination shock is where the solar wind, a thin stream of electrically charged gas blowing continuously outward from the Sun, is slowed by pressure from gas between the stars. At the termination shock, the solar wind slows abruptly from its average speed of 300-700 km per second (700,000–1,500,000 miles per hour) and becomes denser and hotter.[6]
Most of the images used on the record (reproduced in black and white), together with information about its compilation, can be found in the 1978 book Murmurs of Earth: The Voyager Interstellar Record by Carl Sagan, F.D. Drake, Ann Druyan, Timothy Ferris, Jon Lomberg, and Linda Salzman.[8] A CD-ROM version was issued by Warner New Media in 1992.[9] The CD-ROM was the result of Sagan's diligence in obtaining copyright clearances for many of the numerous musical passages and photographs that the original Golden Record contained, to allow for their inclusion in the Warner New Media release. (The copyright owners for the images and music on the actual record signed agreements which only permitted the replay of their works outside of the solar system.) Because copyright clearances could not be obtained one image in the book and a different image on the CD-ROM are not included. Both the book and the companion CD-ROM are no longer published, although used copies may still be found in many libraries. Further information is available at: http://voyager.jpl.nasa.gov/faq.html
In July, 1983, BBC Radio 4 broadcast the 45-minute documentary Music from a Small Planet, in which Sagan and Druyan explained the process of selecting music for the record and introduced excerpts. It was not clear whether this was an original BBC documentary or an imported NPR production.
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