Scientists have proposed placing an ultrastable laser system inside permanently shadowed craters near the Moon’s south pole, where extreme cold and near-perfect vacuum conditions could help create one of the most precise timing and navigation systems ever designed for space.

The concept focuses on using lunar craters that never receive sunlight. These regions remain in permanent darkness and experience temperatures close to 50 kelvins. According to researchers, such conditions reduce vibration, thermal noise, and surface instability that typically disrupt high-precision optical systems on Earth.

At the core of the proposal is an optical silicon cavity. This device allows only specific light frequencies to resonate between two mirrors, stabilizing the output of a laser locked to it. The goal is to produce a laser with an extremely stable frequency that does not drift over time.

Researchers say the Moon offers advantages beyond Earth-based laboratories. The absence of atmosphere, reduced seismic activity, and stable thermal environment make it a strong candidate for precision measurement systems that depend on extreme stability.

Cold lunar advantage

Physicist Jun Ye, affiliated with the National Institute of Standards and Technology and JILA, said the permanently shadowed craters provide unique conditions for such a system. He explained the advantages of the environment, saying it removes many sources of interference found on Earth.

“By radiating any residual heat from the cavity system into the much colder abyss of outer space, the optical cavity could be cooled further, without the need for a cryostat or other equipment, to a temperature of 16 K. At that temperature, silicon neither expands nor contracts when exposed to tiny changes in temperature, ensuring that light entering the cavity always traverses exactly the same distance between the two mirrors.”

The researchers say this stability is critical because even tiny physical changes can alter laser frequency. On the Moon, these fluctuations would be significantly reduced.

The system would work by locking a commercially available laser to the resonant frequency of the silicon cavity. Once stabilized, the laser could serve as a reference signal for navigation and timekeeping across the lunar surface.

Precision beyond earth

The proposed technology could enable a lunar-scale positioning system similar to GPS on Earth. It could also support spacecraft landings in low-visibility regions and provide a reference for optical atomic clocks operating beyond Earth.

“Multiple copies of these lunar lasers could precisely measure the distances between objects and potentially detect exotic physics phenomena such as ripples in space-time.”

Researchers also suggest that a network of such systems could support future experiments in gravitational wave detection by tracking minute changes in distance between lunar instruments.

Deployment would involve placing preassembled optical silicon cavities inside permanently shadowed craters using robotic systems or astronauts during future Artemis missions. A laser source would then be positioned nearby and locked to the cavity to maintain frequency stability.

If successful, the system could form the foundation of a lunar time standard and enable high-precision Earth-Moon optical communication networks. Researchers estimate that early demonstrations could begin in low Earth orbit within a few years, followed by lunar deployment later this decade.

The study appears in the journal Proceedings of the National Academy of Sciences.