LAGEOS satellite with unidentified man during desgin phase.The aluminum sphere, retroreflector mounting hardware and handling fixture for the satellite were designed, developed and manufactured by Marshall Space Flight Center.

The design of LAGEOS evolved from several trade-offs which proved necessary for achievement of program objectives. For example, the satellite had to be as heavy as possible in order to offset the effects of drag and of variations in Earth's gravity, yet light enough to be placed in a high orbit by the Delta launch vehicle.

The satellite had to be big enough to accommodate a large number of retroreflectors, but small enough not to be affected by solar radiation drag. Aluminum would have been too light for the entire body of the sphere, while brass would have weighed too much. Design engineers finally decided on combining two aluminum hemispheres bolted together around a brass core to provide a large mass/surface ratio. Materials were selected to reduce magnetic effects between the satellite and the Earth's magnetic field.

Initial plans were to build both a full-scale prototype ground test satellite and a flight satellite. When the planned ground test model completed basic testing without adverse effects, a decision was made to use it as the flight unit and eliminate duplication.

LAGEOS assembly
retroreflector installation

The LAGEOS orbit was selected to reduce gravitational distortions and the satellite itself has been optimized to maintain a precise stable orbit that will last for millions of years. Because there are no active parts, LAGEOS will give geophysicists a stable reference system from which to accurately measure relative crustal motions of the Earth for many decades.

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