No doubt you’ve heard about the gold records on the Voyager probes, which are one of the few human artifacts that’ll escape our solar system. I thought all similar objects were permanently resting on another rock, like the Apollo plaques, or permanently floating through space, like the Rosetta disc. Thanks to VSauce, though, I’ve learned there’s a third type out there.
Dr. Carl Sagan designed a plaque that was installed in LAGEOS-1. The plaque is 4 inches by 7 inches (10 cm by 18 cm) stainless steel plate. The spacecraft carries two identical copies included in its interior. In its upper center it displays the simplest counting scheme, binary arithmetic. The numbers one to ten in binary notation are shown. At upper right is a schematic drawing of the Earth in orbit around the Sun, and an arrow indicating direction of motion. The arrowhead points to the right, the convention adopted for indicating the future. All arrows accompanying numbers are “arrows of time”. Under the Earth’s orbit is the binary number one, denoting the period of time used on the plaque — one revolution of the Earth, or one year. The remainder of the LAGEOS plaque consists of three maps of the Earth’s surface. The first map denotes the Earth 268 million years in the past. All the continents are shown together in one mass. The close fit of South America into West Africa was one of the first hints that continental drift actually occurs. The middle map represents the zero point in time for the other two maps. It displays the present configuration of the planet. The final map shows the Earth’s surface 8.4 million years from now — very roughly the estimated lifetime of the LAGEOS.
Yes, that’s effectively a time capsule slowly drifting back to earth, with an arrival time 8.4 million years in the future.
Let that sink in for a bit.