Researchers led by Jun Ye at JILA in Boulder, Colorado, suggest placing an ultrastable laser in one of the moon's permanently shadowed craters to enhance navigation for lunar landers and rovers. The frigid, vibration-free environment near the lunar poles could enable unprecedented precision in timing and positioning. This setup might support activities from lunar timekeeping to satellite coordination.
The proposal centers on exploiting the moon's polar regions, where hundreds of craters remain in perpetual shadow due to the moon's minimal tilt. These areas reach temperatures as low as -253°C (20 kelvin) during lunar winter, providing a stable thermal environment that varies only between 20 and 50 kelvin across seasons.
Jun Ye and his team at JILA argue that the absence of atmosphere, vibrations, and sunlight in these craters makes them ideal for an ultrastable laser. Such devices, which bounce light beams between mirrors in a silicon chamber, require isolation to maintain coherence. On Earth, the most advanced versions stay coherent for mere seconds, but a lunar installation could extend this to at least a minute.
"The whole environment is stable, that’s the key," Ye explains. "Even as you go through summers and winters on the moon, the temperature still varies between just 20 to 50 kelvin. That’s an incredibly stable environment."
The laser would function as a reference for various applications, including establishing a lunar time zone, synchronizing formation-flying satellites via laser distance measurements, and even transmitting signals to Earth, where a beam arrives in just over a second.
Simeon Barber at the Open University in the UK views the concept as promising despite implementation challenges. "We have seen various recent lunar polar landers have suboptimal landing events because of illumination conditions, which hinder the use of vision-based landing systems," Barber notes. "Using a stable laser to support positioning, navigation and timing could increase the reliability of successful high-latitude landings."
The idea draws from optical cavities already developed in JILA labs and is detailed in a preprint on arXiv.