ERS-1's Laser Retro Reflector

The ERS satellites Laser Retro-Reflector (LRR)

The Laser Retro Reflector (LRR), mounted on the `lower' side of the payload module, reflects the laser beams directed to the satellite back to the tracking station. The two-way travel time is a measure for the distance between the satellite and the tracking station. Tracking information from various sites throughout the world provides the essential information for computing the ERS orbits.