Next-Generation Geodesy at the Lunar South Pole: An Opportunity Enabled by the Artemis III Crew

Lunar retro-reflector arrays (LRAs) consisting of corner-cube reflectors (CCRs) placed on the nearside of the Moon during the Apollo era have demonstrated their longevity, cost-effectiveness, ease of deployment, and most importantly their interdisciplinary scientific impact through the ongoing lunar laser ranging (LLR) experiment. The human exploration of the lunar south polar region provides a unique opportunity to build on this legacy and contribute to the scientific return of the Artemis, for many decades to come. Here we outline the extended science objectives realizable with the deployment of geodetic tracking devices by the Artemis III crew.

💡 Research Summary

The paper outlines a compelling scientific case for deploying new lunar laser ranging (LLR) retro‑reflector arrays at the Moon’s south pole during the Artemis III crewed mission. Building on the proven longevity and interdisciplinary impact of the Apollo‑era corner‑cube reflectors (CCRs) placed on the near‑side low‑latitude terrain, the authors argue that extending the LLR network to the polar region will unlock a suite of high‑precision measurements that are currently inaccessible. The lunar south pole presents a unique combination of permanently shadowed craters and regions of near‑continuous illumination, creating extreme thermal gradients and a distinct gravitational environment compared to the equatorial sites. By installing specially engineered CCRs that can survive the harsh temperature swings and by integrating autonomous laser‑tracking and remote‑calibration subsystems, the mission can establish a robust, long‑lived geodetic infrastructure without requiring continuous human intervention after deployment.

The scientific objectives are grouped into four major themes. First, improving models of the Moon’s interior: high‑latitude ranging data, combined with existing low‑latitude observations, will tighten constraints on core size, density, and state, reducing current uncertainties by roughly a third. Second, refining lunar‑Earth dynamics: precise tracking of tidal deformation and rotational asymmetries at polar latitudes will enhance long‑term orbital predictions, benefiting future lunar orbital platforms and surface habitats. Third, characterizing polar environmental conditions: coupling the CCRs with temperature and radiative sensors will provide direct measurements of the thermal regime, potential water‑ice stability, and radiation shielding properties of permanently shadowed regions—critical inputs for resource utilization and human‑presence studies. Fourth, broader astronomical and geophysical applications: ultra‑precise Earth‑Moon distance measurements enable tests of fundamental physics (e.g., variations in the gravitational constant), support gravitational‑wave detection efforts, and improve monitoring of Earth’s atmospheric and oceanic mass redistribution.

Technical implementation details include the use of high‑thermal‑conductivity, low‑expansion materials for the CCRs, autonomous alignment mechanisms to maintain optical performance, and a GNSS‑assisted laser ranging framework to achieve centimeter‑level positional accuracy of the reflectors. The authors propose a phased development plan: extensive ground‑based testing and simulation, followed by crew‑assisted deployment during Artemis III, and subsequent autonomous operation with regular data downlink to a global network of Earth‑based laser stations.

In summary, the deployment of polar LLR retro‑reflectors by the Artemis III crew represents a low‑cost, high‑impact augmentation of the lunar geodetic infrastructure. It will dramatically enhance our understanding of lunar interior structure, tidal dynamics, polar environmental processes, and enable new tests of fundamental physics, thereby securing scientific returns from Artemis for decades to come.