NASA is gearing up to return astronauts to the lunar surface for the first time since the early 1970s. Meanwhile, experts are advocating for a special time zone tailored specifically for the moon as earth-based clocks might not be precise enough due to the moon’s weaker gravity.
A recent study published in The Astronomical Journal by the National Institute of Standards and Technology (NIST) highlights that even the most accurate terrestrial clocks, which rely on atomic principles, would run slightly faster on the moon—by about 56 microseconds per day. This discrepancy, while seemingly minor, could accumulate significantly given the scale of upcoming Artemis missions and the growing number of assets on the lunar surface.
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“Communication and navigation systems depend on a network of clocks that are synchronized to each other within a few tens of nanoseconds,” the study notes. Just as car clocks gradually drift from accuracy, lunar equipment would face similar challenges if Earth-based time standards were used.
To address this issue, experts are proposing the development of a new time standard known as Lunar Coordinate Time. This system would function similarly to Coordinated Universal Time (UTC) on Earth, which averages atomic clock measurements globally to maintain a single, precise time standard.
Lunar Coordinate Time would be adjusted for the moon’s unique gravitational conditions, aiming to prevent clocks from drifting out of sync with Earth’s time. “It’s like having the entire moon synchronized to one ‘time zone’ adjusted for the moon’s gravity, rather than having clocks gradually drift out of sync with Earth’s time,” explained NIST physicist Bijunath Patla.
The concept of Lunar Coordinate Time has garnered support from the International Astronomical Union. It could also play a critical role in lunar navigation and operations, laying the groundwork for a system akin to GPS but designed for the moon, according to NIST physicist Neil Ashby.
The proposal could have broader implications beyond lunar exploration. “The framework underpinning Lunar Coordinate Time could eventually enable exploration beyond the moon and even beyond our solar system,” Patla added.
The study taps into principles from Albert Einstein’s theory of relativity, which suggests that time can move differently under varying gravitational conditions. This theoretical foundation explains the need for a distinct lunar timekeeping system, considering both the moon's orbit around Earth and Earth’s revolution around the sun.
