LAGEOS satellites were first launched in 1976 and they have served as super-accurate references for position measurement on Earth. They have been used for measuring the motions of tectonic plates, plotting tiny variations in the Earth's gravity, measuring tiny shifts in the Earth's rate of rotation, and other measurements requiring extreme precision across long distances.

Perhaps the most interesting thing about LAGEOS, however, is the extreme simplicity of these satellites: A LAGEOS satellite is nothing more than a simple metal ball -- no electronics, transmitters, or even batteries of any kind. They look like 2-foot (0.6m) golf balls, the surface studded with hundreds of glass reflectors, very much like the "cat's eye" reflectors used on bicycles and signposts to reflect headlights. They are placed in very precise orbits and serve as reflective targets for laser beams fired from the ground.