NASA Just Shot A Laser At A Japanese Lunar Lander From Orbit

Navigating the Moon’s surface presents unique challenges, particularly because there is no GPS system to assist. To address this, NASA has developed an innovative solution: a small, power-free device that can be placed on lunar landers. This device enables the lander to be located by NASA’s Lunar Reconnaissance Orbiter (LRO), which shoots a laser at it. This technology, known as the Laser Retroreflector Array, has successfully been tested on both the Vikram rover from the Indian Space Research Organisation and the Smart Lander for Investigating Moon (SLIM) from the Japanese Aerospace Exploration Agency (JAXA).

The retroreflector on SLIM is compact, just 5 centimeters (2 inches) across, and consists of eight quartz corner-cube prisms set into a dome-shaped aluminum frame. These prisms allow it to reflect light from multiple directions, enabling the LRO’s laser altimeter to detect it. Despite the LRO’s altimeter not being specifically designed for this application, the team successfully used it to locate the retroreflector.

“LRO’s altimeter wasn’t built for this type of application, so the chances of pinpointing a tiny retroreflector on the Moon’s surface are already low,” explained Xiaoli Sun, who led the retroreflector development at NASA’s Goddard Space Flight Center in collaboration with JAXA.

SLIM’s landing posed an additional challenge: it landed on its side, making it difficult to receive a laser ping from the retroreflector. Initial attempts were unsuccessful, but on the ninth and tenth tries, the team managed to get a signal. This success, despite the lander’s unconventional position, highlights the resilience and effectiveness of the retroreflector system.

Future lunar navigation systems could benefit greatly from such technology, with an orbital partner specifically designed for this purpose. The fact that LRO’s altimeter, not originally intended for this use, could still achieve a successful signal is promising. As Sun noted, “For the LRO team to have reached a retroreflector that faces sideways, instead of the sky, shows that these little devices are incredibly resilient.”