The Voyager Golden Record: A Message With No Expected Reader

In August and September 1977, NASA launched Voyager 2 and Voyager 1 toward the outer solar system. Bolted to the side of each was a gold-plated copper phonograph record, with a cartridge and needle, and cover instructions etched in symbols.

The committee assembling it, chaired by Carl Sagan, had roughly six weeks and no precedent whatsoever.

The problem they were solving

The brief was to compose a message for a recipient with nothing at all in common with the sender. No shared language. No shared biology. No shared assumptions about how information is encoded, or which senses exist to receive it.

The only common ground available is physics and mathematics, and everything on the record's cover proceeds from that.

The etched diagram shows how to play the record — the required rotation speed given not in minutes but as a multiple of the fundamental transition period of the hydrogen atom, the most abundant substance in the universe and a unit any technological civilisation would recognise. It shows how to reconstruct the encoded images. And it includes a pulsar map: the position of the Sun relative to fourteen pulsars, each identified by its precise rotation period.

That map is the most ingenious element. Pulsars are individually identifiable by their timing, and their periods change in a predictable way, so the map encodes both where the record came from and when it was made. It is a coordinate in space and time, readable by anyone with radio telescopes, using no language at all.

A uranium-238 sample was also included on the cover. Its known half-life allows the elapsed time since launch to be determined from how much has decayed.

What is on it

115 images, encoded as analogue waveforms: mathematical definitions, the solar system, human anatomy, DNA structure, landscapes, animals, people eating, a mother nursing a child, buildings, a supermarket, an astronaut in space.

Greetings in 55 languages, from Akkadian and Hittite to Mandarin and Wu. The Amoy greeting reads, with some accuracy about the whole enterprise, "Friends of space, how are you all? Have you eaten yet? Come visit us if you have time."

Sounds of Earth: thunder, wind, surf, birds, whales, a heartbeat, laughter, a kiss, footsteps, a train, a tractor, Morse code.

Ninety minutes of music from across the world and across history. Bach's Brandenburg Concerto No. 2 opens it. Also included: Beethoven, Mozart, Stravinsky, Blind Willie Johnson's Dark Was the Night, Cold Was the Ground, Chuck Berry's Johnny B. Goode, Senegalese percussion, Javanese gamelan, Navajo night chant, an Aboriginal Australian song, a Peruvian wedding song, Indian raga Jaat Kahan Ho sung by Kesarbai Kerkar, Bulgarian folk song, Azerbaijani balaban.

And one item nobody would guess: an hour-long recording of the brainwaves and other biological signals of Ann Druyan, the record's creative director, taken while she meditated on Earth's history and human ideas. She and Sagan had become engaged days earlier, and she has said her thoughts during the recording included what it felt like to be in love. Compressed into audio, it is on both records, travelling out of the solar system indefinitely.

What was left out

The omissions are as revealing as the contents.

War, disease, poverty and cruelty do not appear. The selection is deliberately, unabashedly a curated best impression. Whether that is honest is a fair question, and it was debated at the time.

A proposed photograph of a nude man and woman, intended to convey human anatomy and reproduction, was rejected by NASA as too controversial. A silhouette diagram was substituted. The Beatles reportedly wanted Here Comes the Sun included, and it did not happen due to rights complications with the record label.

Where the spacecraft are now

Both Voyagers have left the heliosphere and are in interstellar space — Voyager 1 crossed in 2012, Voyager 2 in 2018. They are the most distant human-made objects, over 20 billion kilometres out, with radio signals taking around a day each way.

They are also running down. Their plutonium power sources decay steadily, and instruments have been switched off one by one to conserve what remains. Sometime in the 2030s the last instrument will go dark and the spacecraft will fall permanently silent.

The records will continue regardless. Neither Voyager is aimed at anything — they are simply drifting outward. Voyager 1 will pass within about 1.6 light-years of the star Gliese 445 in roughly 40,000 years. Voyager 2 will pass Ross 248 at a similar remove. "Pass near" at that distance means nothing will detect them.

In interstellar space there is no weather, no oxygen, and essentially no erosion. Current estimates suggest the records could remain readable for a billion years or more — long outlasting the Earth's biosphere, and possibly the Earth itself.

The honest assessment

The probability that anyone will ever play these records is negligible. Space is overwhelmingly empty, the spacecraft are tiny and dark, and they are not headed anywhere in particular.

Sagan understood this perfectly well. He wrote that the record's launch "says something very hopeful about life on this planet" — and that was the point. The Golden Record is best understood not as a message sent, but as a statement made: a civilisation deciding what it would want to be remembered for, and committing that decision to a physical object durable enough to outlast every other trace of itself.

Whatever else happens to us, two gold records carrying Bach, whale song, greetings in fifty-five languages and the recorded brainwaves of a woman thinking about love will be moving through the galaxy for longer than the Earth will exist.