NASA Will Create a New Time Zone for the Moon, Called Coordinated Lunar Time

With dozens of lunar missions on the horizon, a standard time-keeping system for the moon will assist with precise navigation, docking and landing

View of Earth rising over Moon's horizon taken from Apollo 11 spacecraft
Earth rises over the moon's horizon, as seen from the Apollo 11 spacecraft in 1969. NASA

This week, the White House officially tasked NASA with establishing a time standard for the moon, called Coordinated Lunar Time (LTC) in the Office of the President’s memorandum, which international bodies can use to coordinate their activities on the lunar surface.

The move comes about a year after the European Space Agency (ESA) proposed the creation of a common time reference on the moon. Lunar missions from national agencies and private companies are expected to heavily ramp up in the coming years, with dozens already scheduled. Without a common reference frame, confusion can ensue—from small inconveniences to graver problems, such as mapping inconsistencies and navigation errors.

“Imagine if the world wasn’t syncing their clocks to the same time—how disruptive that might be and how challenging everyday things become,” an unnamed White House Office of Science and Technology Policy official tells Reuters’ Joey Roulette and Will Dunham.

“This is why we want to raise an alert now, saying let’s work together to take a common decision,” Patrizia Tavella, who leads the time department at the International Bureau of Weights and Measures in France, told Nature News’ Elizabeth Gibney in January 2023.

The White House is giving NASA until the end of 2026 to implement the final standardized time system, which it says must have four qualities: a logical traceability to Coordinated Universal Time (UTC), the global system that regulates all Earthly time zones; enough specificity and accuracy to time very short instants, which is important for precise scientific study and spacecraft landings; self-sufficiency in the event that connection with Earth is lost; and a scalability, so that other celestial objects or space environments could also reference this time standard.

Establishing a lunar time zone will better enable communications between spacecraft, data transfers, landing, docking and navigation. “Defining a suitable standard—one that achieves the accuracy and resilience required for operating in the challenging lunar environment—will benefit all spacefaring nations,” according to the memorandum.

A shadowy image of mountains and craters across the moon's surface
Lunar clocks move faster than those on Earth, gaining about 58.7 microseconds every 24 hours. NASA / JPL

Unlike on Earth, the moon will have just one time zone and no daylight saving time. But that doesn’t make the project any easier for NASA officials. Factors like mass and gravity can affect how time passes—here on Earth, even the gradual redistribution of mass due to sea ice melt is forcing scientists to reconsider our timekeeping.

On the moon, a smaller body where the gravitational pull is much weaker, time moves more quickly and unevenly: Lunar time gains about 58.7 microseconds per day compared to Earth’s time, though even this can vary, depending on the altitude and longitude where lunar clocks may be located.

NASA’s Artemis program is currently scheduled to send astronauts back to the moon no earlier than September 2026, a few months before the deadline to implement LTC. On later missions, the program will involve the establishment of a lunar base, which will help enable future flights to Mars. Other countries are also preparing to populate the moon, with China announcing a 2030 target for astronauts to arrive on the lunar surface and India’s arrival intended by 2040.

Meanwhile, neither China nor Russia have signed the Artemis Accords, which outline a framework for peace and responsible exploration of the moon. It remains to be seen if the countries’ non-participation in this agreement may affect their involvement in LTC.

Still, other officials see this step toward international lunar cooperation as necessary progress.

“An atomic clock on the moon will tick at a different rate than a clock on Earth,” Kevin Coggins, manager of NASA’s Space Communications and Navigation Program, tells the Guardian’s Diana Ramirez-Simon. “It makes sense that when you go to another body, like the moon or Mars, that each one gets its own heartbeat.”

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