A NASA satellite launched in 1976 carries a Carl Sagan–designed plaque sealed inside its core, mapping Earth’s continents 268 million years ago, at launch, and 8.4 million years from now — and that last date is no accident, because it’s roughly when the satellite is expected to fall back to Earth and finally be opened.

On 4 May 1976, NASA launched a satellite called LAGEOS-1 from Vandenberg Air Force Base in California. It is one of the simplest objects ever put into orbit. It is a sphere about 60 centimetres across, weighing roughly 400 kilograms, with no electronics, no sensors, no power source, and no moving parts. It is a […]