In September 2024, NASA officially announced that it will coordinate with stakeholders in the US government, international partners, and global standards organizations to establish a time system called "Lunar Coordinated Time" (LTC).
The biggest difference between time on the Moon and on Earth comes from Einstein's theory of relativity, which states that time changes depending on speed and gravity. Because the Moon has a weaker gravitational pull than Earth, time passes faster there: An Earth clock on the Moon would be about 56 microseconds faster per day than it would be on Earth.
Although this number is small, in space missions that require high precision, this deviation can have major consequences.
"If something were to travel at the speed of light, just 56 microseconds would be enough to travel about 168 football fields," Cheryl Gramling, NASA's program manager for standards and timing, stressed in a press release.
At the direction of the White House, NASA will work with agencies such as the Department of Commerce, the Ministry of National Defense, the Ministry of Foreign Affairs, and the Ministry of Transportation to develop a roadmap for introducing LTC by the end of 2026.
In addition, global stakeholders, especially signatory countries of the Artemis Agreement, will also contribute to this process.
The Artemis Accord, established in 2020, brings together 43 countries to commit to norms in space. Notably, China and Russia have refused to participate in the agreement.
NASA's Space Communications and Navigation (SCaN) program will lead the initiative to develop a lunar time zone. One of the key goals of LTC is to be able to expand it to other celestial bodies in the future, including Mars.
This time system will be determined by a weighted average of atomic clocks placed on the Moon. The exact locations of these clocks are still under discussion. This weighted average method is similar to how scientists calculate Coordinated Universal Time (UTC) on Earth.
Returning astronauts to the Moon through the Artemis program is a key part of NASA’s roadmap. Artemis 2, scheduled for September 2025, will send four people on a trip around the Moon. Then, in 2026, the Artemis 3 mission will follow with the goal of landing astronauts near the Moon’s south pole.
Developing a separate time zone for the Moon is not only necessary to ensure accuracy for space missions, but also opens up potential future applications on other planets. This represents an important step forward in expanding human understanding and exploration of the universe.
