How and why US wants to establish a time standard for the Moon

Contact Counsellor

Last Updated11/04/2024

Last week, the US White House officially directed the National Aeronautics and Space Administration (NASA) to create a time standard for the Moon, which different international bodies and private companies can use to coordinate their activities on the lunar surface.

Most of the clocks and time zones — a geographical region which uses the same standard time — of the world are based on Coordinated Universal Time (UTC)
- which is set by the International Bureau of Weights and Measures in Paris, France.
It is tracked by a weighted average of more than 400 atomic clocks placed in different parts of the globe.
Atomic clocks measure time in terms of the resonant frequencies — the natural frequency of an object where it tends to vibrate at a higher amplitude — of atoms such as cesium-133.
In atomic time, a second is defined as the period in which a caesium atom vibrates 9,192,631,770 times.
As the vibration rates at which atoms absorb energy are highly stable and ultra-accurate, atomic clocks make for an excellent device for gauging the passage of time.
To obtain their local time, countries need to subtract or add a certain number of hours from UTC depending on how many time zones they are away from 0 degree longitude meridian, also known as the Greenwich meridian.
If a country lies on the west of the Greenwich meridian, it has to subtract from the UTC, and if a country is located on the east of the meridian

UTC, however, cannot be used to determine time on the Moon.
That is because time on the Moon flows differently than it does on the Earth.
In other words, for someone on the Moon, an Earth-based clock will appear to lose on average 58.7 microseconds per Earth day with “additional periodic variations”, according to the OSTP memo.
Several countries, including India, are looking to populate the Moon in the following years.
While NASA’s Artemis program aims to send astronauts back to the lunar surface no earlier than September 2026
China has announced plans to land its astronauts by 2030, and India intends to arrive by 2040.
There are also proposals to build a long-term human outpost on the Moon. Therefore, there is a need for a unified lunar time standard.