Geodetic Missions

The geodetic satellites are so named for their contribution to geodesy. Geodesy is a branch of applied mathematics that determines by observations and measurements the exact positions of points on the earth's surface; the shape and size of the earth; and the variations of the terrestrial gravity and magnetic fields. Most of the geodetic satellites are inert massive spheres designed solely to reflect laser light back to its source, the laser ranging system.

Over the past three decades, global geodetic satellites have evolved into a powerful source of data for studies of the solid earth, its oceans, atmospheric systems, and their interactions. Satellite laser ranging accuracy and orbit determination techniques have improved over the last 30 years, to where today a 3-day arc of LAser GEOdynamics Satellite (LAGEOS) data can be routinely fit to a precision of 1-2 centimeters.

Reflectors have been placed on the moon by the Apollo astronauts and by unmanned Soviet probes. Lunar laser ranging data has also been used in earth geodynamics research.

Scientists now have a fairly good understanding how the tectonic plates move and how such movements relate to earthquake activity. (excerpt from United States Geodetic Survey (USGS) page, read on).

Responsible Government Official: Carey Noll
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