The Pioneer plaque, a message for other worlds
The account
A metal plaque would carry a map to Earth for any civilization that found it.
What investigators found
The message exists and is traveling through space, but the odds of anyone finding it are minimal, and it is more of a symbol for humanity itself.
The story
When the Pioneer 10 probe launched in March 1972, it carried a small gold-anodized aluminum plaque attached to its frame. The idea, from Carl Sagan and Frank Drake, with artwork by Linda Salzman Sagan, was to leave a message in case the spacecraft was someday found by another intelligence. Pioneer 11, launched the following year, carried a copy.
The plaque shows a man and a woman, the outline of the probe for scale, a diagram of the Solar System indicating the planet of origin, and a map that uses pulsars to pinpoint the Sun's position in the galaxy. At the time, some criticized the nudity of the figures, and others questioned whether it was wise to reveal where we are. Neither probe communicates with Earth anymore, but both keep traveling out of the Solar System.