40 years of Voyaging - Part 2

The Voyagers both contained a record of sounds and voices from Earth. No other probe sent out did. This was because it would eventually leave the solar system, and travel onwards, barring accidents, until the end of time. Here is the story of that record.

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.

Electroplated onto the record's cover is an ultra-pure source of uranium-238 with a radioactivity of about 0.00026 microcuries. The steady decay of the uranium source into its daughter isotopes makes it a kind of radioactive clock. Half of the uranium-238 will decay in 4.51 billion years. Thus, by examining this two-centimeter diameter area on the record plate and measuring the amount of daughter elements to the remaining uranium-238, an extraterrestrial recipient of the Voyager spacecraft could calculate the time elapsed since a spot of uranium was placed aboard the spacecraft. This should be a check on the epoch of launch, which is also described by the pulsar map on the record cover.

Each record is encased in a protective aluminum jacket, together with a cartridge and a needle. Instructions, in symbolic language, explain the origin of the spacecraft and indicate how the record is to be played. The 115 images are encoded in analog form.

The remainder of the record is in audio, designed to be played at 16-2/3 revolutions per minute. It contains the spoken greetings, beginning with Akkadian, which was spoken in Sumer about six thousand years ago, and ending with Wu, a modern Chinese dialect. Following the section on the sounds of Earth, there is an eclectic 90-minute selection of music, including both Eastern and Western classics and a variety of ethnic music.

As Carl Sagan has noted, "The spacecraft will be encountered and the record played only if there are advanced spacefaring civilizations in interstellar space. But the launching of this bottle into the cosmic ocean says something very hopeful about life on this planet.“

The records also had the inscription "To the makers of music – all worlds, all times" hand-etched on its surface.

Many people were instrumental in the design, development and manufacturing of the golden record. Blank records were provided by the Pyral S.A. of Creteil, France. CBS Records contracted the JVC Cutting Center in Boulder, Colorado to cut the lacquer masters which were then sent to the James G. Lee Record Processing center in Gardena, California to cut and gold plate eight Voyager records. Gold plating took place on August 23, 1977; afterward, the records were mounted in aluminum containers and delivered to JPL.

References:
https://voyager.jpl.nasa.gov/golden-record/golden-record-cover/
https://en.wikipedia.org/wiki/Voyager_Golden_Record
https://voyager.jpl.nasa.gov/golden-record/