Coordinated Lunar Time

Coordinated Lunar Time or LTC is a proposed primary lunar time standard for the Moon. In early April 2024, NASA was asked by the White House to work alongside domestic and international agencies for the purpose of establishing a unified standard time for the Moon and other celestial bodies by 2026. The White House's request, led by the Office of Science and Technology Policy, called for a "Coordinated Lunar Time", which was first proposed by the European Space Agency in early 2023.

Currently, the time on the Moon is different for each country involved. As a result, activities on the Moon are coordinated using the time zone of where a mission's headquarters is based. For example, the Apollo missions utilized the Central Time Zone (CDT) as the missions were controlled from Houston, Texas.

History
As part of an ongoing global billionaire space race and a wider international space race between the United States and China,  a need exists for a universal time-keeping benchmark so that lunar spacecraft and satellites are able to fulfill their respective missions with precision and accuracy. Due to differences in gravitational force and other factors, time passes fractionally faster on the Moon when observed from Earth.

Under the Artemis program, and supported by the Commercial Lunar Payload Services missions, astronauts and a proposed scientific "Moonbase" are envisioned to take place on and around the lunar surface from the 2020s onwards. The proposed standard would therefore solve a current timekeeping issue. According to OSTP Chief Arati Prabhakar, currently, time would "appear to lose on average 58.7 microseconds per Earth-day and come with other periodic variations that would further drift moon time from Earth time".

The development of the standard is set to be a collaborative effort, initially amongst members of the Artemis Accords, but will be meant to apply globally. The initial proposal of the standard calls for four key features:


 * traceability back to Coordinated Universal Time,
 * accuracy sufficient for navigation and science,
 * resilience to disruptions, and
 * scalability to potential environments beyond cislunar space.

LunaNet, an upcoming lunar communications and navigation service under development with the European Space Agency, calls for a Lunar Time System Standard which the LTC is meant to address.