How to tell time on Mars

Tracking the visits of the first astronauts Mars it won't be as easy as I look at my watch or mark weekends on the calendar. Thanks to the theory of relativityIn fact, time moves faster on the Red Planet than here on Earth. For years, scientists have wondered about the exact time difference between the planets, but physicists National Institute of Standards and Technology (NIST) has finally found the answer. Their calculations were published on December 1 in Astronomical Journal will not only answer a long-standing question, but will also help advance the future of humanity beyond Earth, as well as improve our understanding of physics itself.

It's all relative

In fact, people on Earth perceive time in the same way. One hour in Omaha, Nebraska is essentially the same as an hour in Shanghai, China. But how Einstein famously demonstrated in his theory of relativity, linear time is directly related to the force of gravity. This is why travelers making the theoretical round trip to black hole When they returned home, they found themselves much younger than their children.

Earth's gravity is significantly weaker than that of a black hole, but physicists now have instruments sensitive enough to detect minute differences around the planet. Someone who lives at the top of Everest will end up aging faster than someone who lives at sea level, even if it's just a matter of microseconds. But these effects are not purely hypothetical. At an altitude of approximately 12,544 miles above Earth GPS satellites are 45.7 microseconds faster than terrestrial clocks – an important lag that must be taken into account when maintaining telecommunications systems.

Four body problem

Although gravity on Mars is about five times weaker than on Earth, it is not the only factor contributing to the passage of time on our cosmic neighbor. It is also necessary to take into account its speed and the masses of nearby planets. And although a Martian day is 40 minutes longer than Earth's, its 687-day eccentric orbit around the Sun is especially difficult to calculate. This is particularly challenging compared to measuring the largely stable orbital velocity relationships between the Earth, Moon and Sun – an example of what is known as three body problem.

“The three-body problem is extremely difficult. Now we're dealing with four: the Sun, Earth, Moon and Mars. Lifting weights is proving to be more challenging than I originally thought,” NIST physicist and study co-author Bijunath Patla. admitted in a statement.

To find a solution, Patla and NIST physicist Neil Ashby began by choosing a control point on the surface of Mars, similar to sea level at Earth's equator. They then took into account all the cosmic influences on Mars in their calculations and ultimately came up with the exact answer: time on the Red Planet moves 477 microseconds faster than on Earth. This is about a thousandth of the time it takes to blink.

Small numbers, big consequences

While these delays are extremely small by most standards, they can add up. For example, for 5G networks to function properly, they must be accurate to one-tenth of a microsecond. Today, it often takes more than 24 minutes to send or receive a message from a Martian visitor such as NASA's Curiosity rover. In the future, installed network repeaters could significantly reduce this gap between the millions of miles separating astronauts and mission control.

“If you get synchronization, it's almost like real-time communication without losing information. You don't have to wait to see what happens,” Patla said.

Patla admits it will likely be decades before humans visit Mars regularly, but that won't delay other advances thanks to their work.NIST even published a lunar timing plan. just last year. These new Mars calculations could help improve the nascent system, as well as develop similar methods for other planets or moons.

“The passage of time is fundamental to relativity: how you perceive it, how you calculate it, and what influences it,” Patla said. “This is the closest we've come to realizing the science fiction vision of an expanding solar system.”