NGLR: Next Generation Lunar Retroreflector

The project has been implemented at UMD under the direction of Dr. Douglas Currie, Professor Emeritus. In 1969 when he was a University of Maryland Professor of Physics, Dr. Currie helped to design the three still-in-use lunar instruments placed on the Moon by Apollo Missions 11, 14, and 15.

NASA Marshall Space Flight Center oversees implementation of the NGLR project at UMD and conducts regular meetings and receives monthly reports as well as other reports as needed.

• A description of the 19D mission may be found here
• A general description of the NGLR Project may be found here
• The Objectives and Status (03-12-2025) of our NGLR-1 Project may be found here
• NASA's Press Release describing the success of the Glue Ghost mission may be found here

Coverage of the landing and initial deployment may be viewed at https://plus.nasa.gov/ and https://fireflyspace.com/, and https://space.com.

The Firefly Blue Ghost Mission 1, named Ghost Riders in the Sky, launched on January 15 and completed its 45-day Earth to Moon transit before softly touching down on the Moon on March 2 at 3:34am EST at Mare Crisium near Mons Latreille.

Image taken from the Firefly lander showing the shadow of the Blue Ghose lander on the lunar surface. This was taken by a camera on the lander. The Earth appears in the sky.

Click here for a link to a Firefly Aerospace page with imagery.

• On the morning of 3 March, the French Lunar Laser Ranging Observatory (MeO) at Grasse, France received the first returns from NGLR-1.
• Using these returns the distance to the NGLR-1 on the Moon was determined to be 358727.670 km with an precision of a few parts per trillion (0.8 millimeters).
• On the morning of 4 March, MeO obtained additional range measurements. These were obtaining using both the IR laser (1064 nm) and the green laser (532 nm)
• Also, on the morning of 4 March the LLRO at Wettzell, Germany (WLRS) also obtained range measures using reflections from NGLR-1. These were conducted using their IR laser.
• The successful operation of NGLR-1 demonstrated by the LLROs in Grasse, France and Wettzell Germany illustrates that NGLR-1 has reached a Technical Readiness Level (TRL) of 9.

Starting in 2004 when NASA decided to return to the Moon, Professor Currie has been pursuing the design of a Cube Corner Retroreflector (CCR) of 10 cm aperture to provide the capability of a retroreflector that provides a much higher precision by eliminating the spread in ranges due to the effect of the librations on the array of smaller CCRs in the Apollo Retroreflector Arrays (ARAs). This results in photon returns with a very narrow spread in the timing of reflected photons, thereby providing returns with higher precision and realizable roundtrip travel time accuracy. It has taken many years of research to be able to manufacture reliably and accurately such a large retroreflector, which requires exceptionally high-purity fused silica in the manufacture of the retroreflector. The other critical challenge is to isolate the much colder CCR from the hot housing during the lunar daytime in order to preserve the optical perfection of the CCR.

A general description of the NGLR program

A simulation of the advances in the scientific results available with deployment of NGLRs

An earlier general description of the NGLR program and discussion of lack of change in Big G

Discovery of Liquid Core of the Moon and Rotational Energy Dissipation

Analysis of lack of change in the Weak Equivalence Principle (WEP) as a test of General Relativity

Another Analysis of lack of change in the Weak Equivalence Principle (WEP) as a test of General Relativity

Far Field Diffraction Patterns, Offset Angles for Correction of Velocity Aberration

Atmospheric Effects effects in the approaches toward sub-millimeter LLR Ranging Accuracy

Overview of NGLR Program for General Audience presented to the ILRS School

Cryogenic emissivity of LaserGold, SOOTO Thermal Simulation Program