First Use of Laser Ranging to Surface Retroreflectors for Orbit Determination: LRO-LOLA at the Moon

Abstract

We document the first operational demonstration of two-way spacecraft-to-surface laser ranging using Laser Retroreflector Arrays (LRAs) for orbit determination (OD) of the Lunar Reconnaissance Orbiter (LRO). We detail how the Lunar Orbiter Laser Altimeter (LOLA) was operationally adapted to target and successfully range to several LRAs on the lunar surface. Although LOLA was not designed for this purpose, and despite many spacecraft constraints that limited the number of measurements we could collect, we demonstrate that incorporating these ranging observations into OD procedures yields tangible improvements in LRO’s orbital solution. Our analysis yields two key findings: (1) systematic ranging to different types of surface LRAs from orbit is operationally feasible, and (2) such measurements provide valuable geodetic data for spacecraft navigation. This first demonstration is particularly timely as more LRAs are being deployed across the lunar surface through various international and commercial missions, while LiDAR technology continues to advance. Combined with the growing number of missions requiring Position, Navigation, and Timing services in lunar orbit, our findings indicate that spacecraft-to-LRA ranging could become an essential technique for navigation in the near future, complementing traditional Earth-based tracking methods.