Coordinated Lunar Time or LTC is a proposed primary
lunar time standard for the
Moon.[1] 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.[2] 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.[1][3]
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.[4] For example, the
Apollo missions utilized the
Central Time Zone (CDT) as the missions were controlled from Houston, Texas.[5]
History
As part of an ongoing global
billionaire space race[6][7] and a wider international
space race between the United States and China,[8][9] 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.[10] Due to differences in
gravitational force and other factors, time passes fractionally faster on the Moon when observed from Earth.[11][12]
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.[13] The proposed standard would therefore solve a current timekeeping issue.[14] 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".[15]
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:[16]
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.[17]