The spacecraft are aluminum-covered brass spheres with diameters of 60 centimetres (24 in) and masses of 400 and 411 kilograms (882 and 906 pounds), covered with 426 cube-corner retroreflectors, giving them the appearance of disco balls.

The LAGEOS satellites make it possible to determine positions of points on the Earth with extremely high accuracy due to the stability of their orbits.

The LAGEOS mission consists of the following key goals: Ground tracking stations located in many countries (including the US, Mexico, France, Germany, Poland, Australia, Egypt, China, Peru, Italy, and Japan) have ranged to the satellites and data from these stations are available worldwide to investigators studying crustal dynamics.

[8] LAGEOS-1 (which is predicted to re-enter the atmosphere in 8.4 million years[6]) also contains a 4 in × 7 in plaque designed by Carl Sagan[9] to indicate to future humanity when LAGEOS-1 was launched.

It then shows 268,435,456 years in the past (binary: 228), indicated by a left arrow and the arrangement of the Earth's continents at that time (during the Permian period).