A Secret Love Letter Encoded in Brainwaves Is Hurtling Through Interstellar Space

The Most Personal Object Ever Launched Into Space

The Voyager Golden Record is usually described as a message from Earth to the unknown — but that description is incomplete. Tucked inside its catalogue of greetings, music, animal sounds, and scientific diagrams is something far more intimate: a compressed recording of Ann Druyan's brainwaves and heartbeat, made in 1977, shortly after she and Carl Sagan had decided to marry. It is, by any measure, the most personal object humanity has ever sent into space — and almost nobody knew it was there.

The recording was made on June 3, 1977, at Bellevue Hospital in New York City. Druyan had asked Sagan whether, if she recorded her brainwaves with an electroencephalogram and electrocardiogram, aliens could eventually read her mind. Sagan and the others liked the idea and volunteered Druyan to provide the brainwaves. She prepared a script to guide her thoughts — "a mental itinerary of the ideas and individuals of history" whose memory she hoped to preserve.

A Phone Call That Changed Everything

What changed the recording was a phone call on June 1. Druyan and Sagan had been working together intensely on the record when they realized, without a date or a conventional courtship scene, that they were in love. Druyan later described the moment: "We both hung up the phone, and I just screamed out loud. It was like a scientific discovery."

The session captured Druyan's brainwaves via EEG, her heartbeat through an electrocardiogram, and other vital signs while she contemplated topics including the history of Earth, the evolution of life and civilizations, and her recent feelings for Sagan. Those signals were analog-encoded and electronically compressed into a one-minute audio track, producing a sound resembling rapid bursts or firecrackers when played. The compression is extreme enough that the resulting audio bears no obvious resemblance to thought. To any listener, it sounds like electrical weather — crackling and abstract, carrying no obvious secret. But the secret is there.

The capacity to track brainwaves and turn them into sound was a new technology at the time, and Druyan and Sagan wondered if they might someday be resurrected to reveal her thoughts. Maybe, one billion years from now, some alien civilization might be able to turn that data back into thoughts. It was a wild, romantic gamble — and they took it.

What's Actually on the Record

Each Voyager spacecraft carries a 12-inch gold-plated copper phonograph record containing sounds and images chosen to portray the diversity of life and culture on Earth. The records were not designed for radio transmission — they are physical objects attached to the spacecraft, time capsules for any distant finder capable of recovering and decoding them. The team assembled music, greetings in 55 languages, natural sounds, and 115 images intended to give a possible finder some compressed account of Earth. Among the musical selections: Bach, Beethoven, a Navajo night chant, and Chuck Berry.

Carl Sagan and Ann Druyan married in 1981. They later worked together on Cosmos, Contact, and several books about science, skepticism, and the human place in the universe. Sagan died in 1996 at age 62. Druyan has spoken and written about the recording many times since, never quite letting go of the thought that a trace of that afternoon in New York is still moving away from Earth.

A Journey With No End

Voyager 1 launched from Cape Canaveral on September 5, 1977. It is now more than 15 billion miles — or more than 25 billion kilometers — from Earth, according to NASA's Voyager mission tracker. The signal takes more than 23 hours to travel one way. It is moving at roughly 38,000 miles per hour and will keep drifting long after its transmitter falls silent. In about 40,000 years, Voyager 1 will pass within about 1.6 light-years of the star Gliese 445 in the constellation Camelopardalis.

NASA expects Voyager's remaining science and engineering life to narrow through the late 2020s and into the 2030s. But when the spacecraft finally goes quiet, it will not stop moving. It will keep carrying the greetings in 55 languages, the music, the pulsar map, the uranium clock, and the compressed minute of Ann Druyan's brainwaves and heartbeat. The instruments will fall silent first. The record will remain bolted to the spacecraft, still moving through the dark, still carrying the electrical weather of one afternoon in New York. A young woman's heartbeat, recorded two days after the best phone call of her life, drifting forever through the cosmos — waiting for a listener who may never come, but might.