Scientists aim to establish a groundbreaking laser system in one of the moon’s coldest craters to significantly enhance the navigation capabilities of lunar landers and rovers.

Ultra-stable lasers are vital for highly precise timing and navigation systems. These lasers operate by reflecting a beam between two mirrors within a cavity, maintaining a consistent beam speed. This precision is largely due to the chamber’s size stability, which neither expands nor contracts. To achieve this, mirrors are typically maintained in a cryogenic vacuum, insulated from external vibrations.

The moon hosts numerous craters at its poles, which lack direct sunlight due to minimal axial tilt. Consequently, these permanently shadowed areas are extremely cold, with some craters projected to reach temperatures around -253°C (20 Kelvin) during the lunar winter.

Junye from JILA, along with a research team in Boulder, Colorado, has proposed that these icy conditions, combined with the moon’s absence of natural vibrations and an almost non-existent atmosphere, make these craters ideal for ultra-stable lasers. The potential stability of these lunar lasers could surpass that of any terrestrial counterparts.

“The entire environment is incredibly stable,” Ye emphasizes. “Despite variations between summer and winter on the Moon, temperature fluctuations range only from 20 to 50 Kelvin, contributing to a remarkably consistent environment.”

Ye and his research team envision a lunar laser device akin to an optical cavity already developed in JILA’s lab, featuring a silicon chamber equipped with dual mirrors.

Current optical cavity lasers on Earth can maintain coherence for just a few seconds, meaning their light waves can synchronize briefly. However, the moon-based laser is projected to sustain coherence for at least a minute, which will facilitate its role as a reference laser for a variety of lunar missions. This includes maintaining the lunar time zone and coordinating satellite formations using lasers for distance measurement. Given that light from the moon takes just over a second to reach Earth, it could also serve as a reliable reference for Earth-based activities, as highlighted by Ye.

Although implementing this idea poses challenges, the rationale is sound and could greatly benefit future lunar missions. According to Simeon Barber from the Open University, UK, “Recent lunar landers have experienced suboptimal landings due to varying lighting conditions, complicating vision-based systems. Leveraging stable lasers for positioning, navigation, and timing could enhance the reliability of landings in high-latitude areas.”