Satellite Laser Ranging (SLR) targets are satellites equipped with corner cubes or retroreflectors. Currently, the global SLR network tracks over forty such satellites. The observable is the round-trip laser pulse time-of-flight to the satellite.

SLR and Lunar Laser Ranging (LLR) use short-pulse lasers and state-of-the-art optical receivers and timing electronics to measure the two-way time of flight (and hence distance) from ground stations to retroreflector arrays on Earth orbiting satellites and the Moon.

SLR and Lunar Laser Ranging (LLR) use short-pulse lasers and state-of-the-art optical receivers and timing electronics to measure the two-way time of flight (and hence distance) from ground stations to retroreflector arrays on Earth orbiting satellites and the moon. The laser stations are also used to measure one-way distance from the ground stations to remote optical receivers on space and for very accurate time-transfer. Laser ranging activities are organized under the ILRS.

SLR is an accurate technique for determining the geocentric position of an Earth satellite, allowing for the precise calibration of radar altimeters and separation of long-term instrumentation drift from secular changes in ocean topography. SLR’s ability to measure the temporal variations in the Earth’s gravity field and to monitor motion of a global network of stations with respect to the geocenter, together with the capability to monitor vertical motion in an absolute system, makes it unique for modeling and evaluating long-term climate change.