The US government has instructed the space agency NASA to develop a uniform time for the moon and other celestial bodies. NASA should present a strategy for the introduction of so-called lunar time (LTC; Coordinated Lunar Time) by the end of 2026, the White House Science Office said.

Time seems to pass at different speeds in different parts of space, depending on gravity and one’s own relative speed, it said, citing the theory of relativity. For an observer on the moon, an Earth-based clock appears to run an average of 58.7 microseconds – or 58.7 millionths of a second – slower per Earth day. This tiny shift can be important for things like location determination and communication.

So far, lunar missions have been based on the coordinated universal time UTC (Coordinated Universal Time), but have not synchronized with each other. Given the manageable number of such projects so far, this wasn’t a major problem. However, NASA, governments of other countries and private companies are planning to send people to the moon for the first time since 1972 in the coming years and to establish a permanent human presence there. A uniform definition of time is “fundamental” for the safe operation of spaceships and satellites on and around the moon.

According to the Science Office, the world time UTC is based on the timekeeping of several atomic clocks on Earth. Similarly, lunar time could also be set using atomic clocks on the Earth’s satellite. NASA was instructed to coordinate with various US ministries and international partners when developing the lunar time, it said.