In the autumn of 1976, a small committee gathered in a windowless room at Cornell University. Their task was absurd in scope and impossible in deadline: curate the sounds, images, and greetings that would represent an entire planet to whatever intelligence might someday intercept the two Voyager spacecraft. Carl Sagan chaired the group. Frank Drake calculated the odds. Ann Druyan sat in a Manhattan church, recording her own brainwaves for inclusion on the disc — converting thought into signal, signal into groove.
Binary arithmetic for an unknown reader
The aluminum cover, engraved by Sagan's team over three frantic weeks, is a masterpiece of restraint. No words — words presuppose language. Instead, a pulsar map triangulates Earth's position relative to fourteen known pulsars, each identified by its period in binary notation. Every line was checked by independent radio astronomers; a single miscalculation would render the entire artifact indecipherable.
"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."