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.
