Coordinated Lunar Time (CLT) is a request from the Joe Biden administration to NASA due to the different intensity of the gravitational field on the Moon, which makes time pass faster in relation to Earth. It’s just 58.7 microseconds per day, which may not seem like much, but when it comes to spacecraft synchronization it can have a significant impact.
“The fundamental theory of gravity in our Universe results in the fact that time runs differently in different places in the Universe. Gravity on the Moon is slightly weaker and the clocks work differently,” Catherine Heymans, director of the Royal Observatory in Edinburgh, Scotland, told the BBC.
Time is measured on Earth by hundreds of atomic clocks placed around the planet, which measure the changing energetic state of atoms to record time to the nanosecond. If they were placed on the Moon, in 50 years they would be operating one second faster.
“An atomic clock on the Moon will have a different rhythm than a clock on Earth,” explains Kevin Coggins, NASA’s communications and navigation officer. “It makes sense that when you go to another body, like the Moon or Mars, each one would have its own heart rate,” he added.
But NASA isn’t the only one trying to create lunar time. The European Space Agency (ESA) is also developing a new time system for the Moon. A topic that will require an agreement between countries and a centralized coordination body – currently, this task falls to the International Space Agency. Weights and Measures (International Bureau of Weights and Measures), an intergovernmental body with 64 member countries (including Portugal), based outside Paris.
Currently, Coordinated Universal Time (UTC) is used on the International Space Station, since the orbit is low. UTC is the reference time zone from which all other time zones in the world are calculated and corresponds to winter time in mainland Portugal (that is, at the moment UTC is equivalent to one hour less than in mainland Portugal) .
The US wants Coordinated Lunar Time to be a reality in 2026, in time for its manned mission to the Moon. Artemis-3 will be the first North American mission to return to the surface of the Moon since Apollo 17 in 1972.
