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Laser Retro-Reflector

How it Works

Each GRACE-FO satellite is equipped with a Laser Retro-Reflector consisting of four corner cubes mounted in a small pyramid on the underside of the spacecraft. They provide a means of tracking the GRACE-FO satellites from the ground for backup and orbit verification. They will be tracked by the Satellite Laser Ranging (SLR) global ground station network of the International Laser Ranging Service (ILRS). Ground controllers can verify the satellites’ orbits by firing lasers up toward the satellites, where the laser beam bounces off the reflector. By measuring how long it takes for the outgoing laser light to return to the ground station, we can measure the distance (very precisely).

The data will be valuable in evaluating and strengthening orbit and gravity field solutions. They are manufactured by GFZ.

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