LLR measures the round-trip travel times of light pulses between stations on the Earth and four retroreflectors on the surface of the Moon.

In addition to its value for lunar sciences and the theory of gravitation, LLR is a key IERS technique for connecting reference frames. LLR is used to determine the obliquity of the ecliptic, the orientation of the dynamical frame of the Solar System in the extragalactic reference frame, and long-period nutation and precession.

The envisioned improvements in accuracy (a few millimeters in range) and network distribution (planned stations all around the world) could enhance the LLR contribution to IERS for the next decade.

Description of the french LLR station, located in Grasse (France), can be found here (CERGA) and that of the McDonald Observatory (USA) there (MLRS) .