||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
pulse time-of-flight to the satellite.
||SLR systems are equpped with short-pulse laser
transmitters that can range to orbiting satellites. Lunar Laser
Ranging (LLR) systems can range to retroreflectors located on
||The current global SLR network consists of over
forty systems, several of which are managed by NASA. During the
past three decades, this network has evolved into a powerful
source of data for studies of the solid Earth and its ocean and
atmospheric systems. This map of
SLR sites is also available
in PDF form.
The International Laser Ranging Service (ILRS)
was formed to provide a service to support, through Satellite and
Lunar Laser Ranging data and related products, geodetic and geophysical
research activities as well as IERS products important to the maintenance
of an accurate International Terrestrial Reference Frame (ITRF).
The service also develops the necessary standards/specifications
and encourages international adherence to its conventions. The ILRS
collects, merges, archives and distributes Satellite Laser Ranging
(SLR) and Lunar Laser Ranging (LLR) observation datasets of sufficient
accuracy to satisfy the objectives of a wide range of scientific,
engineering, and operational applications and experimentation.
An excellent discussion on the history, science, and future of SLR
can be found in the SLR
Some of the scientific results derived from SLR include:
- Detection and monitoring of tectonic plate motion, crustal deformation,
Earth rotation, and polar motion
- Modeling of the spatial and temporal variations of the Earth's
- Determination of basin-scale ocean tides
- Monitoring of millimeter-level variations in the location of
the center of mass of the total Earth system (solid Earth-atmosphere-oceans)
- Establishment and maintenance of the International Terrestrial
Reference System (ITRS)
- Detection and monitoring of post-glacial rebound and subsidence
In addition, SLR provides precise orbit determination for spaceborne
radar altimeter missions mapping the ocean surface (which are used
to model global ocean circulation), for mapping volumetric changes
in continental ice masses, and for land topography. It provides a
means for subnanosecond global time transfer, and a basis for special
tests of the Theory of General Relativity.
Related SLR information and data links:
A description of CDDIS SLR data
sets is available.