Coordinated Lunar Time (LTC)

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Recently, 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.

About Coordinated Lunar Time (LTC)

  • It will provide a time-keeping benchmark for lunar spacecraft and satellites that require extreme precision for their missions.
  • It will also synchronise the communication between satellites, astronauts, bases and the Earth.
  • A unified time standard would be essential for coordinating operations, ensuring the reliability of transactions and managing the logistics of lunar commerce.
  • Why there is need of LTC?
    • As there is less gravity on the Moon, time ticks slightly faster there relative to the time 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.
    • It can create problems for situations such as a spacecraft seeking to dock on the Moon, data transferring at a specific time, communication, and navigation.

How does Earth’s time standard work?

  • Most of the clocks and time zones of the world are based on Coordinated Universal Time (UTC) which is essentially an internationally agreed upon standard for world time.
  • It 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, it has to add.

Q: What Is Greenwich meridian?

It is an imaginary line, last established in 1851, that was used to indicate 0° longitude. It passes through Greenwich, a borough of London, and terminates at the North and South poles. Because it indicated 0° longitude, it was also known as the prime meridian.

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