A NASA series of passive satellites whose data are used to measure the motion of the Earth's tectonic plates, its gravitational field, and the wobble in its rotation. They can also provide a more accurate measurement of the length of an Earth day. The satellites have aluminium shells covered with retroreflectors, which reflect laser beams transmitted from ground stations around the world.
LAGEOS-1 was launched in May 1976 into a circular orbit 5 800 km above the Earth. LAGEOS-2 was built by the Agenzia Spaziale Italiana (Italian Space Agency), as a joint project with NASA. It was launched in October 1992 into an orbit 5 900 km above the Earth. A third multinational satellite is planned. Both satellites should remain in orbit for 8.4 million years, and LAGEOS-1 contains a plaque for future generations. It depicts three maps of the Earth and its continents: as they looked 268 million years ago, as they appear today, and as they will appear at the end of the spacecraft's life.
Subjects: Astronomy and Astrophysics.