  The Lunar Laser Ranging (LLR) experiment has accumulated 50 years of range
data of improving accuracy from ground stations to the laser retroreflector
arrays (LRAs) on the lunar surface. The upcoming decade offers several
opportunities to break new ground in data precision through the deployment of
the next generation of single corner-cube lunar retroreflectors and active
laser transponders. This is likely to expand the LLR station network. Lunar
dynamical models and analysis tools have the potential to improve and fully
exploit the long temporal baseline and precision allowed by millimetric LLR
data. Some of the model limitations are outlined for future efforts.
Differential observation techniques will help mitigate some of the primary
limiting factors and reach unprecedented accuracy. Such observations and
techniques may enable the detection of several subtle signatures required to
understand the dynamics of the Earth-Moon system and the deep lunar interior.
LLR model improvements would impact multi-disciplinary fields that include
lunar and planetary science, Earth science, fundamental physics, celestial
mechanics and ephemerides.
