The most audacious time capsule ever created is not underground, but in interstellar space. In 1977, NASA launched two space probes — Voyager 1 and Voyager 2 — each carrying a gold-plated copper phonograph record 30 cm in diameter. This disc, named the Golden Record, is arguably the most poetic object ever conceived by humanity: a cosmic message in a bottle, intended for potential extraterrestrial civilizations or for humans of the distant future.
The Context: The Voyager Program and a Rare Planetary Alignment
The Voyager program was designed to take advantage of a rare planetary alignment, occurring approximately every 176 years, that would allow a single probe to fly by all four giant planets — Jupiter, Saturn, Uranus, and Neptune — using the gravitational assist of each. This alignment, called the "Grand Tour," will not recur until the mid-22nd century.
Voyager 2 was launched on August 20, 1977, followed by Voyager 1 on September 5, 1977. Despite its later launch, Voyager 1, placed on a faster and more direct trajectory toward Jupiter, overtook its twin en route. The primary scientific mission was the detailed study of the Jupiter and Saturn systems — their atmospheres, rings, and moons. Voyager 2, benefiting from the favorable alignment, continued on to Uranus (flyby in January 1986) and Neptune (flyby in August 1989), becoming the only probe to have visited these two planets.
But from the design phase of the project, astrophysicist Carl Sagan, then a professor at Cornell University, proposed to NASA that a message be included for any intelligent beings who might one day intercept the probes. Sagan had already designed the plaques carried by the Pioneer probes in 1972 and 1973, but he wanted to go much further. NASA agreed and entrusted him with leading a committee tasked with composing this message.
The Design of the Golden Record: Six Weeks to Represent Humanity
Carl Sagan assembled a small committee of individuals with complementary skills to select the disc's contents. Among the key members: Ann Druyan, creative director of the project, responsible for the music selection and the collection of Earth sounds; Frank Drake, pioneer astronomer in the search for extraterrestrial intelligence and creator of the famous Drake equation estimating the number of communicating civilizations in the galaxy; Timothy Ferris, science journalist at Rolling Stone, who supervised the disc's technical production; Jon Lomberg, artist and scientific illustrator, who designed the diagrams engraved on the protective cover; and Linda Salzman Sagan, artist who had already drawn the human figures on the Pioneer plaques.
The committee had approximately six weeks to assemble the contents — an extremely tight deadline for a project whose ambition was to represent all of human civilization. The final result is a copper phonograph record, plated with gold, designed to be played at 16 2/3 revolutions per minute (not 33 rpm like a standard vinyl, in order to maximize recording time). The disc is protected in an electroplated aluminum cover, accompanied by a stylus and a playback cartridge. The cover bears instructions engraved in symbolic language, using the hyperfine transition of the hydrogen atom (a universal physical phenomenon) as a fundamental unit of time and length, to explain how to play the disc and locate the vessel's origin.
The Contents: A Sonic and Visual Portrait of Earth
The Golden Record contains a remarkably diverse sample of human civilization and planet Earth, organized in several sections.
116 images encoded in analog on the disc. Among them: a diagram of the solar system, the structure of DNA, representations of human anatomy, photographs of terrestrial landscapes (mountains, deserts, oceans, forests), animals, cities, monuments, scenes of daily life in different cultures, and images of scientific instruments and human technology.
Recorded greetings in 55 different languages, from ancient Sumerian (a language dead for millennia) to Wu Chinese, including French, English, Arabic, Hindi, Zulu, and Thai. The message in French simply says: "Bonjour tout le monde" (Hello everyone). A child's voice in English, recorded by Carl Sagan's six-year-old son Nick, says: "Hello from the children of planet Earth."
Natural sounds of Earth forming a soundscape of our planet: wind blowing across plains, the thunder of a storm, the songs of various birds, the haunting cry of humpback whales, ocean waves, an earthquake, the crunch of footsteps on gravel, and a kiss.
90 minutes of music from cultures around the world, carefully selected by Ann Druyan and Timothy Ferris. The selection includes the first movement of Bach's Second Brandenburg Concerto (performed by the Munich Bach Orchestra conducted by Karl Richter), "Dark Was the Night, Cold Was the Ground" by Blind Willie Johnson, Javanese gamelan music (Puspawarna, performed by the court of the Sultan of Yogyakarta), an Indian raga performed by Kesarbai Kerkar, Senegalese percussion, and "Johnny B. Goode" by Chuck Berry. The committee would also have liked to include a Beatles song, but EMI, the copyright holder, refused permission.
A Touching Detail: Ann Druyan's Brainwaves
One of the most intimate elements of the disc is a one-hour recording of Ann Druyan's brainwaves (EEG) and heartbeat, made on June 3, 1977, at New York Hospital. What makes this recording extraordinary is its context. Two days before the session, on June 1, 1977, during a work phone call, Druyan and Sagan declared their mutual love, after months of professional collaboration on the Golden Record project. Druyan recounted in later interviews that she had meditated during the recording on the history of civilization, on the human condition, on war and peace, and on what it meant to fall in love. These thoughts and emotions, compressed as electrical brain signals, are now navigating through interstellar space.
United States President Jimmy Carter also contributed an official message dated June 16, 1977, evoking Earth and its inhabitants with hope. United Nations Secretary-General Kurt Waldheim recorded a message on behalf of the peoples of the world.
The Precedents: The Pioneer Plaques
The Golden Record was not NASA's first attempt to send a message to the stars. The Pioneer 10 (launched March 2, 1972) and Pioneer 11 (launched April 5, 1973) probes each carried a gold-anodized aluminum plaque measuring 15 x 23 cm. Designed by Carl Sagan, Frank Drake, and Linda Salzman Sagan, these plaques show the nude silhouettes of a man and a woman in front of the probe (drawn to scale to indicate our size), a diagram of the hyperfine transition of hydrogen, the position of the Sun relative to 14 pulsars (serving as galactic landmarks), and a diagram of the solar system indicating the probe's trajectory. The publication of these plaques had sparked controversy in the United States: some criticized the depiction of nude human figures being sent into space.
The Golden Record represented a considerable qualitative leap: where the Pioneer plaques were a simple engraved diagram, the Voyager disc offered a true multimedia portrait of terrestrial civilization, with music, voices, images, and sounds.
Where Are the Probes Today?
Voyager 1 crossed the heliopause — the boundary where the solar wind gives way to the interstellar medium — on August 25, 2012, becoming the first human-made object to reach interstellar space. This discovery was confirmed and announced by NASA on September 12, 2013. Voyager 2 crossed the heliopause in turn on November 5, 2018. Both probes are now more than 20 billion kilometers from Earth and continue to move away at approximately 17 km/s for Voyager 1 and 15 km/s for Voyager 2.
Both probes still communicate with Earth via NASA's Deep Space Network (DSN), a network of large parabolic antennas distributed at Goldstone (California), Madrid (Spain), and Canberra (Australia). Their Radioisotope Thermoelectric Generators (RTGs), powered by the decay of plutonium-238, weaken by approximately 4 watts per year. NASA is progressively deactivating scientific instruments to conserve energy and estimates that the last scientific data will be received around 2025-2030. But the probes themselves, and their Golden Records, will continue to drift silently through the galaxy for hundreds of millions of years.
In approximately 40,000 years, Voyager 1 will pass within about 1.6 light-years of the star Gliese 445, in the constellation Camelopardalis. Voyager 2 will pass within about 1.7 light-years of the star Ross 248.
The Cultural and Philosophical Legacy of the Golden Record
The Golden Record has become one of the most iconic objects in space history and popular culture. In 2017, for the 40th anniversary of the probes' launch, the Ozma Records label (co-founded by Timothy Ferris and David Pescovitz) released a vinyl edition of the disc's audio content, funded by a Kickstarter campaign that raised more than $1.3 million, well beyond the initial goal of $198,000.
The disc embodies a profoundly optimistic and universalist idea: that humanity deserves to be known, that our music, our voices, and our images are worth sharing with the entire universe. It is also a philosophical exercise: deciding what to put on the disc meant deciding how we wanted to be perceived by beings who know nothing about us. A mirror held up to infinity.
On our own scale, every capsule we create for our loved ones proceeds from the same impulse: projecting a fragment of who we are into the future, with the conviction that it will be received and understood. Capsul carries on this gesture on a human scale — not toward the stars, but toward those who matter.
Sources
- NASA Jet Propulsion Laboratory, "Voyager – The Golden Record," voyager.jpl.nasa.gov - Sagan, Carl et al., "Murmurs of Earth: The Voyager Interstellar Record," Random House, 1978 - NASA, "Voyager 1 Enters Interstellar Space," press release, September 12, 2013 - NASA Jet Propulsion Laboratory, "Voyager Mission Status" - Ozma Records, "Voyager Golden Record: 40th Anniversary Edition," Kickstarter, 2017