NASA researchers have long considered a network of corner reflectors on the Moon to assist future spacecraft landings. The project, known as the Lunar Retroreflector Array (LRA) or Lunar Retroreflector Network, aims to place tiny, passive devices on the lunar surface to improve precision during descent.
These reflectors are compact, dome-shaped units housing eight glass prisms. Each hemisphere tips the scales at about 20 grams and does not require any power source to operate.
Once deployed, the reflectors would bounce back laser and optical signals sent from Earth, enabling lunar landers to determine their position with higher accuracy and select safer, more optimal landing sites. This concept builds on decades of lunar laser ranging ideas and seeks to provide a practical navigation aid for robotic and, potentially, crewed missions.
The initial element of the LRA was delivered to the Moon aboard India’s Chandrayaan-3 mission, marking a significant milestone for international collaboration in lunar science.
NASA has also sent an LRA component to the Moon on a Peregrine lander from Astrobotic, though that particular mission encountered a launch issue that limited the fuel available for the ascent and subsequent operations. The setback underscores the challenges of early hardware deployment on the Moon but has not halted the broader plan to expand the reflector network.
Future deliveries are expected to continue with additional missions, including one from the Japanese SLIM lander. If everything proceeds as planned, SLIM aims to touch down on the lunar surface in early 2025, bringing another set of reflectors to support navigation and site selection.
While some lunar missions have faced delays due to technical hurdles, the LRA program remains a central part of efforts to improve autonomous landing accuracy and mission reliability for both Canada and the United States, as researchers explore how passive optical systems can complement active sensors. [NASA attribution]