They are seen as bearers of eternal truths and were designed to survive for more than 500 million years and/or outlast humanity. One is the Nebra sky disk, which was made in the Bronze Age, the other comes from our era of space travel, and is the Voyager Golden Record. After the Nebra sky disk was dug out of the earth by looters in 1999, a long clarification process and court case began surrounding the question of the artefact’s genuineness. Other artefacts found with it suggest that it is 3,600 years old. The bronze disk is seen worldwide as the oldest reproduction of the heavens and its uses as a calendar, for symbolic or religious purposes is the subject of much speculation. 

Before the American aerospace agency NASA launched the two interstellar space probes Voyager 1 and 2 in 1977, data records containing visual and audio information were brought on board. Led by Carl Sagan, a research team put together a set of messages which, with the help of instructions engraved on gold-plated copper records, should still be playable in 500 million years. The messages are for extra-terrestrials.