Greenwich lunar time?
As NASA works to return astronauts to the lunar surface for the first time since the early 1970s, astronomy experts say the moon rock needs its own local time zone.
Why?
The simple reason is that terrestrial clocks would not serve their purpose due to changes in gravity outside of Earth.
A new document from the National Institute of Standards and Technology (NIST) explains that even the most efficient Earth clocks, which keep time according to atomic principles, would tick slightly faster on the Moon, where gravity is weaker, at a rate of 56 microseconds per day.
That’s a significant number considering the scale of the upcoming manned Artemis lunar missions, which will “increase the number of resources on the lunar surface,” the authors add, publishing their results now in the Astronomical Journal.
“Communication and navigation systems are based on a network of clocks that are synchronized with each other within a few tens of nanoseconds.”
Similar to how car clocks lose their accurate time after a while, the same thing would happen to devices on the lunar surface.
The proposed alternative, still under development and recently supported by the International Astronomical Union, is the development of a lunar coordinate time. It would work similarly to the principle of terrestrial coordinated universal time (UTC).
Developed in 1960, this concept – accurate to one nanosecond – keeps a unique, ultra-specific time by averaging the measurements of atomic clocks worldwide. UTC is used by scientists and laboratories around the world.
Experts could optimize UTC for space research purposes.
“It’s as if the entire moon is synchronized to a ‘time zone’ that is adjusted to the moon’s gravity, rather than the clocks gradually becoming out of sync with Earth’s time,” said Bijunath Patla, a physicist at NIST.
It is not yet known whether there will be only one or several time zones on the moon.
Lunar coordinate time will also play a role in navigation in space and on the moon, added NIST physicist Neil Ashby. Specifically, it would form the basis for a “GPS-like system” on the moon, he said.
Palta is convinced that this approach could also be used beyond the surface of the moon.
“The proposed framework underlying lunar coordinate time could eventually enable exploration beyond the moon and even beyond our solar system,” the expert said.
In particular, Albert Einstein’s theory of relativity was the first to address the concept that time can pass more slowly under different gravitational conditions.
In this case, the changes are partly due to the moon’s orbit around the Earth and our planet’s rotation around the sun.
