A NASA satellite launched in 1976 carrying a Carl Sagan–designed plaque sealed inside its core 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 solid mass of brass and aluminium studded with 426 reflectors. The name stands for Laser Geodynamic Satellite. More

(Source: Space Daily - May 26)