What NASA Bolted to a Spacecraft in 1977

Carl Sagan chaired the committee that picked the contents of the Voyager Golden Record in 1977, and the team had only six weeks to make every decision. The disc itself is a 12-inch gold-plated copper LP, sealed in an aluminum cover with engraved instructions for any technically inclined alien who might find Voyager 1 or 2 in the next billion years. The two probes are still flying.

The audio side runs about 90 minutes. It contains 27 musical pieces, including Bach's Brandenburg Concerto No. 2, a Navajo night chant, Chuck Berry's "Johnny B. Goode," Bulgarian folk singer Valya Balkanska, and a Peruvian wedding song. There are 55 spoken greetings in different languages, beginning with Akkadian — a tongue dead for 2,500 years — and a Sumerian phrase from even earlier. Whale song closes out the audio.

Greetings from Earth's leaders made it on. So did a small section the team labeled "sounds of Earth": surf, thunder, footsteps, a kiss, a mother and child, a Saturn V launch, the heartbeat and brain waves of Ann Druyan, recorded a few days after she and Sagan privately decided to get married. Druyan thought of the man she loved during the EEG, hoping that whatever a future listener could decode of her thoughts would carry that, too.

The record also includes 116 still images encoded as audio — diagrams of human anatomy, a fetus, the Great Wall, a supermarket, a sunset, a violin with a sheet of music. There are no images of war, religion, or money. Whether anyone will ever play it is beside the point. The committee was not really designing for aliens; they were designing the most ambitious self-portrait humans have ever attempted.