Researchers at the Purple Mountain Observatory in China have developed new software, called LTE440which has the task of precisely determining the discrepancy between the lunar coordinated time (lunar coordinates time) and the terrestrial coordinated universal time (universal coordinated time). Synchronizing the lunar clocks with the terrestrial ones is essential to be able to establish some sort of “lunar time zone” on which future lunar missions, such as those planned for the plan Artemis of NASA, they will be able to rely on to synchronize their operations.
But why should the weather on the Moon be “different” from that on Earth? The reason is Albert Einstein’s general relativity. According to this theory, gravity influences the passage of time for observers in different reference systems. For this reason, on the Moon, which has a lower gravity than the Earth, Time measured on the Moon flows slightly differently than on Earththus creating a small difference between times measured for the same event on the two celestial bodies. According to the researchers, the software is capable of ensuring a precision less than 0.15 billionths of a second between now and 2050.
How the software works and why it matters
The LTE 440 software was presented in an article published in the scientific journal Astronomy & Astrophysics and it was released publicly on the Github platform, so as to make it available to every space agency (and everyone in general). It is a software, written in the Python programming language, which allows you to coordinate two time measurements carried out in different reference systemsin this case the Moon and the Earth, passing through the time measured in a reference system stationary in the center of gravity of the Solar System (barycentric coordinate time). All this using the effect of time dilation in the vicinity of bodies with a strong gravitational field predicted by Einstein’s general relativity.
This transformation is essential for coordinating clocks on the Moon, which measure lunar coordinated time, with those on Earth that measure universal coordinated time, so that scientific measurements and human missions can measure events on a synchronized time system. According to researchers, the software is so accurate that “losing” only 0.15 billionths of a second by 2050.
The importance of this result is not only scientific, but also geopolitics. The Moon is at the center of a new space race which this time sees each other facing each other China and USA/Europewith NASA preparing to launch its mission Artemis II in the next few weeks. There is therefore great interest in developing a time measurement system that allows the coordination of space missionsso much so that already in 2024 the United States government, under the leadership of former president Joe Biden, tasked NASA with developing a coordinated lunar timeattributable to coordinated universal time. China has certainly not remained idle, on the contrary managed to develop this system before NASA and ESAmaking the race for our natural satellite even more heated.
Because time flows differently on the Moon
Remember the movie Interstellar? In director Nolan’s masterpiece, the two astronauts Cooper and Brand, played by Matthew McConaughey and Anne Hathaway, after spending about 7 hours on Miller’s planet, once they return to the orbiting module realize that 23 years have actually passed for astronaut Romilly. That’s because Miller’s planet is so close to the black hole Gargantua that his immense gravitational field significantly alters the passage of timeto the point that, for every hour spent on the planet, approximately seven years are spent in orbit. In fact, the theory of general relativity predicts that, for the same event, the duration time measured is shorter for an observer who is inside an intense gravitational field than that measured by one who is outside. In practice, the more intense the gravity, the slower time passes compared to an observer who is in a weaker gravitational field.
For this reason On the Moon, time passes more quickly than on Earth. How much? About 57 millionths of a second per day. In practice it means that, if we stayed on the Moon for 50 years, we would have aged about 1 second more than those who remained on Earth.
The same effect is also the basis of the functioning of GPS: the satellites and the receiver in fact experience two gravitational fields of very slightly different intensity, so the time marked by a clock on Earth and one on the satellite flows differently due to time dilation. The clocks on the GPS satellites run faster than those on Earth, by about 38 microseconds per day, which, if not corrected, would lead to positioning errors of 10 km per day.
