Why is it in the News?

Recently, the US White House has officially instructed NASA to create a lunar time standard for international and private sector coordination on the Moon.

What is Coordinated Lunar Time (LTC)?

• Coordinated Lunar Time (LTC) is a lunar-based time system being developed by NASA in collaboration with other government agencies to establish a standardized time zone for the Moon.
• LTC aims to provide a precise timekeeping benchmark for lunar spacecraft and satellites, synchronizing communication between astronauts, bases, and Earth.

Importance of LTC:

• As lunar exploration and commerce expand, a unified time standard becomes essential for managing operations, ensuring transaction reliability, and coordinating logistics.
• Furthermore, LTC addresses the discrepancy in timekeeping between Earth and the Moon due to differences in gravity, as time ticks faster on the Moon, causing Earth-based clocks to lose an average of 58.7 microseconds per day.
• Establishing LTC will prevent potential problems in spacecraft docking, data transfer, communication, and navigation.

How Will a Lunar Time Standard Be Established?

• Like on Earth, atomic clocks can be deployed on the lunar surface to set a time standard.
• These clocks have to be placed on the Moon at different locations since the Moon’s rotation and even local lumps of mass, called mascons, beneath the crust of the Moon affect the flow of time ever so slightly.
  • Mascons or mass concentrations are so dense that they alter the Moon’s local gravity field.
• These effects are minor but the output from these clocks can be synthesized to give the Moon its own independent time, which can be tied back to UTC for seamless operations from Earth as well.

How Does Earth’s Time Standard Work?

• Most of the clocks and time zones of the world are based on Coordinated Universal Time (UTC), set by the International Bureau of Weights and Measures in Paris, France.
• UTC is essentially an internationally agreed-upon standard for world time.
• 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 cesium 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 must 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, it has to add.