An American, a Russian and a Chinese astronaut meet on the moon. The agreed time is 3 p.m. – and everyone is on time. But when the Russian woman arrives, the Chinese woman has already been standing in a crater angry for five hours, and the American woman hasn’t even put on her spacesuit yet. Because even though they are all standing on the moon, their clocks tick differently.
Since humans have explored space, astronauts have always followed the time of the country from which they started. But because things could get busy on the moon in the future, this becomes a problem. The USA, Europe, China, South Korea, India all want to go to the moon. From September 2026 onwards, the USA wants to send people to the moon via its Artemis program, China wants to send them to the moon by 2030, and even South Korea recently launched its own probe. According to current customs, everyone brings their own time to the moon. Misunderstandings or accidents would then be programmed. As early as November 2022, the European Space Agency Esa demanded: The moon needs its own time. Now the Americans are pushing forward.
But the matter is complicated. Because the moon not only needs its own time zone, but also its own clock. According to the theory of relativity, time is related to gravity, and the Moon’s gravitational pull is weaker than that of the Earth. This means that as seen from Earth, time passes faster on the Moon – according to the US Office of Science and Technology Regulation (OSTP), the difference is 58.7 microseconds per day. That doesn’t sound like much, but lunar missions are all about precision.
Now NASA should take care of it, and the OSTP believes a new time standard will “benefit all spacefaring nations.”. NASA wants to proceed like it does on Earth: Here time is defined by a network of atomic clocks. These record changes in the state of atoms and calculate an average. This creates an exact time.
An atomic clock would tick at its own speed on the moon
Following this example, atomic clocks could also be placed on the moon and calculate coordinated lunar time (LTC). The same model would also work on other celestial bodies. “It makes sense that every celestial body like the moon or Mars has its own heartbeat,” said Kevin Coggins, a communications and navigation expert at NASA Guardian. “Because an atomic clock on the moon will tick at a different speed than a clock on Earth.” For communication with Earth, this lunar time could then be coupled with Coordinated Universal Time (UTC).
In order to actually introduce the new LTC, international treaties on how people want to deal with space and the moon are still missing – agreements like the Artemis Agreement. The USA is one of 36 nations to sign this set of rules. China and Russia do not. Until an agreement is reached, the three astronauts on the moon would still have a problem. Will they ever meet?