Why scientists say we need to send clocks to the moon soon
NASA and Partners Working to Establish a New Time Scale for the Moon
On the day of May 24 2024. On the lunar surface, a single Earth day would be roughly 56 microseconds shorter than on our home planet a tiny number that can lead to significant inconsistencies over time. NASA and its international partners are currently grappling with this conundrum. Scientists aren’t just looking to create a new “time zone” on the moon, as some headlines have suggested, said Cheryl Gramling, the lunar position, navigation, and timing and standards lead at NASA’s Goddard Space Flight Center in Maryland. Rather, the space agency and its partners are looking to create an entirely new “time scale” or system of measurement that accounts for that fact that seconds tick by faster on the moon.
Lunar Time Scale Crucial for Future Moon Missions
The agency’s goal is to work with international partners to set up a new method of tracking time, specifically for the moon, that space faring nations agree to observe. A recent memo from the White House also directed NASA to map out its plans for this new time scale by December 31, calling it “foundational” to renewed US efforts to explore the lunar surface. The memo also asks that NASA implement such a system by the end of 2026, the same year the space agency is aiming to return astronauts to the moon for the first time in five decades. Such a framework will be crucial for humans visiting our closest celestial neighbor, Gramling told CNN. Astronauts on the moon, for example, are going to leave their habitats to explore the surface and carry out science investigations, she said. They’re also going to be communicating with one another or driving their moon buggies while on the lunar surface. “When they’re navigating relative to the moon,” Gramling said, “time needs to be relative to the moon.”
Time Dilation in Space: Lessons from Earth Orbit and Deep Space
If time moves differently on the peaks of mountains than the shores of the ocean, you can imagine that things get even more bizarre the farther away from Earth you travel. To add more complication time also passes slower the faster a person or spacecraft is moving, according to Einstein’s theory of special relativity. Astronauts on the International Space Station, for example, are lucky, said Dr. Bijunath Patla, a theoretical physicist with the US National Institute of Standards and Technology, in a phone interview. Though the space station orbits about 200 miles (322 kilometers) above Earth’s surface, it also travels at high speeds looping the planet 16 times per day so the effects of relativity somewhat cancel each other out, Patla said. For that reason, astronauts on the orbiting laboratory can easily use Earth time to stay on schedule. For other missions it’s not so simple. Fortunately, scientists already have decades of experience contending with the complexities. Spacecraft, for example, are equipped with their own clocks called oscillators, Gramling said. “They maintain their own time,” Gramling said. “And most of our operations for spacecraft even spacecraft that are all the way out at Pluto, or the Kuiper Belt, like New Horizons rely on ground stations that are back on Earth. So everything they’re doing has to correlate with UTC. But those spacecraft also rely on their own kept time, Gramling said. Vehicles exploring deep into the solar system, for example, have to know based on their own time scale when they are approaching a planet in case the spacecraft needs to use that planetary body for navigational purposes, she added.
Measuring Lunar Time and Its Relation to Earth Time
For 50 years, scientists have also been able to observe atomic clocks that are tucked aboard GPS satellites, which orbit Earth about 12,550 miles (20,200 kilometers) away or about one nineteenth the distance between our planet and the moon. Studying those clocks has given scientists a great starting point to begin extrapolating further as they set out to establish a new time scale for the moon, Patla said. “We can easily compare (GPS) clocks to clocks on the ground,” Patla said, adding that scientists have found a way to gently slow GPS clocks down, making them tick more in line with Earth bound clocks. “Obviously, it’s not as easy as it sounds, but it’s easier than making a mess.” For the moon, however, scientists likely won’t seek to slow clocks down. They hope to accurately measure lunar time as it is while also ensuring it can be related back to Earth time, according to Patla, who recently co authored a paper detailing a framework for lunar time. The study, for the record, also attempted to pinpoint exactly how far apart moon and Earth time are, as estimates have wavered between 56 and 59 microseconds per day. Clocks on the moon’s equator would tick 56.02 microseconds faster per day than clocks at the Earth’s equator, according to the paper.