We Nailed a Map to Earth on a Spacecraft — Some Scientists Think It Was Reckless
Answers: “what is the pioneer plaque?”
In 1972, NASA launched Pioneer 10 toward Jupiter — the first spacecraft that would gain enough speed to escape the solar system entirely. Journalist Eric Burgess had a thought: if it’s leaving forever, shouldn’t it carry a note?
Carl Sagan loved the idea. He and astronomer Frank Drake had just weeks to design one. The result — sketched in final form by artist Linda Salzman Sagan — is the Pioneer plaque: a gold-anodized aluminum plate, 15 by 23 centimeters, bolted to the spacecraft’s frame.
What do you tell a civilization you know nothing about? The plaque gambles that physics is the universal language:
- A diagram of the hydrogen atom, the most common thing in existence, establishing a unit of length and time
- A starburst pattern of 14 pulsars — spinning dead stars, each with its unique rhythm — triangulating the position of our Sun in the galaxy. A cosmic “you are here” map.
- Our solar system, with a little spacecraft shown departing from the third planet
- Two figures: a man with a raised hand, and a woman — drawn to scale against the spacecraft
The plaque caused two very human controversies. Newspapers of 1972 objected to the nudity — NASA was accused of “sending smut to the stars.” And later, a more serious debate took hold, one that has never gone away: was it wise to broadcast our home address? Stephen Hawking famously warned that meeting a more advanced civilization might go the way it went for less advanced civilizations on Earth.
The counterargument is disarming: our radio and TV signals have been leaking into space for a century anyway. The secret was already out.
Pioneer 10 fell silent in 2003. The plaque, though, needs no power. It’s headed in the general direction of the star Aldebaran — arriving in roughly two million years.