In early April 2024, the White House asked NASA to develop a plan to implement a single standard for calculating time on the Moon. It should become the standard for international lunar space missions, where extreme accuracy is important when performing complex tasks in the development of a satellite. To implement the plan, scientists need to know the exact time difference between the Earth and the Moon, because it moves faster on Selene. This difference was calculated by American astrophysicists.

All probes and other spacecraft for the study of the Moon have been and are being sent into space by scientists according to the time of the country responsible for the mission. Therefore, the so-called cyclogram of the task is calculated based on the station’s schedule divided into time slots. Most often, the control of these machines originates from a specific point on Earth, so there have been no problems among the countries participating in such projects about the need to introduce an interim standard to the Moon.

Recently, researchers have been talking about creating large and complex international lunar programs, including sending a person to the surface of our satellite (Artemis III is planned for 2026). In this case, it will be quite difficult to manage these missions, focusing only on the Earth’s time, which depends on a certain time zone. Due to the time difference, a number of technical errors may occur both on the way to the Moon and during the landing of the apparatus (affecting navigation).

In this regard, the White House instructed NASA to develop a single standard for calculating time on the Moon – Coordinated Lunar Time (LTC) – by the end of 2026. This will not be a system of time zones, as on our planet, but rather its own time reference system for the Earth’s satellite. American officials are confident that without this system, joint missions to the Moon with other countries will be much more difficult.

The clock on the moon runs faster than on Earth. This happens due to gravity: it is about six times weaker there than on our planet. It is known that the stronger the gravity at a particular point, the slower time flows relative to an outside observer. In order for LTC to be put into service, the difference between the Earth and the Moon must be determined exactly.

American astrophysicists led by Vyacheslav Turyshev from NASA’s Jet Propulsion Laboratory made calculations and revealed the meaning of this difference. The team published the results of the research on the electronic preprint archive’s website. arXiv.

To calculate the exact time difference, astrophysicists studied the motion of the Moon and Earth around the center of mass of the entire solar system, or the center of gravity, which moves depending on the planets’ position relative to the Sun. Scientists then used mathematical formulas and calculated that time on the lunar surface is 57.5 microseconds (0.0000575 seconds) faster per Earth day than on the Earth’s surface. This means that a one-second difference accumulates over almost 50 years.

“Our method can be used to synchronize the communication and operation of any lunar apparatus. Theoretically, the lunar time problem is solved,” Turyshev explained.

Scientists have repeatedly tried to calculate the time difference between the Moon and the Earth, and often obtained different values ​​- 58.7 microseconds or 56 microseconds. Such calculations were made taking into account the method of studying the orbits of these two bodies, which sometimes causes controversy, and without taking into account the motion of the Moon and the Earth around the center of gravity of the Solar System.

Although at first glance the difference in microseconds may seem small, this assumption is fundamentally wrong. Such temporal differences can cause errors in data transmission between space probes, as well as disrupt the synchronization of communication between the Earth, bases, astronauts and lunar satellites. In addition, they can lead to errors (including software bugs) in working with mapping and geolocation, both on the satellite itself and in lunar orbit.

In August 2024, a meeting of some expert organizations from different countries will be held, including the International Bureau of Weights and Measures, the International Astronomical Union. Scientists will probably try to agree on a plan to solve the problem of a single standard for calculating time on the moon.

Before LTC can begin studying, researchers need to decide what counts as a “zero day” on the Moon. In other words, from which moment the new calculation time should be entered and how far into the lunar region it extends. One solution to the problem of a single standard for calculating time on the Moon is an atomic clock placed on the surface of the satellite and monitoring the effect of time slowing down relative to the Earth, starting from the “zero day” of the moon.