Celestial Time Standardization
Given the current interest in expanding man's presence on the Moon by developing infrastructure on lunar soil, the White House issued a statement in April (2024) on the creation of a lunar time coordinate system (CLT). The aim of this project is to aid space navigation and allow structures on the ground and in lunar orbit to be synchronized with the Earth.
The creation of the CLT is a little more difficult than it might seem, because the passage of time on the Moon occurs at a different pace to that on Earth. This is because the passage of time is affected by the planet's force of gravity. As gravity on the Moon is lower than on Earth, time passes more quickly on the Moon. In fact, the length of a lunar day is around 58.7 microseconds shorter than the length of a day on Earth. Although this time difference seems negligible, it affects the synchronization between the satellites and space stations that orbit around the Moon.
To better understand this problem, you first need to know how the universal time coordinate system (UTC) used on Earth works. UTC is determined on the basis of 400 atomic clocks scattered around the Earth, under the care of the so-called National Time Laboratories. These clocks are extremely precise pieces of equipment that use the vibration of the atom to record the passage of time. To establish the CLT, Nasa will have to install clocks of this type on lunar soil and on spaceships. A clock of this type would move at a slightly faster pace on the Moon than it does here on Earth.
The use of atomic clocks in spacecraft serves to establish their position in outer space, working in a similar way to GPS, but being able to locate any point in three-dimensional space. This allows spacecraft to know their location and speed much more quickly than is possible with the positioning system in use. At the moment, Nasa has to send a signal to the spacecraft, the spacecraft has to receive the signal and send it again so that the position can then be calculated with extremely high precision on Earth and sent back to the spacecraft. This process takes around 40 minutes, and in the end provides outdated information. In fact, NASA has already tested the use of an atomic clock on board the spacecraft for positioning on a SpaceX mission. The experiment lasted a year (2019/2020) and was successful.
Nasa warns, however, that you shouldn't expect information on Google or any other application about the current time on the Moon any time soon. This should take at least a couple of years, as the Nasa project is due to be completed by the end of 2026.
Translated with DeepL.com (free version)
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