Mars Keeps Spinning Faster, and Scientists Aren’t Sure Why

New recordings from Mars have delivered the most accurate measurement yet of how fast the red planet spins. The results have left scientists puzzled as mars keeps spinning faster.

Using data gathered by the now-retired InSight lander, researchers have discovered that Mars is spinning faster each year by about four milliarcseconds. This might not seem like much, as it only makes a Mars day a tiny bit shorter each Martian year, but we’re not sure why it’s happening.

This discovery, though confusing, could help us learn more about Mars and how it has changed over time. Scientists have two main ideas about what might be causing this speed-up. One is linked to long-term trends such as stuff building up at the icy caps, and the other is about movements inside the planet.

Bruce Banerdt, planetary geophysicist of NASA’s Jet Propulsion Laboratory, said, “It’s really cool to be able to get this latest measurement – and so precisely.”

“I’ve been involved in efforts to get a geophysical station like InSight onto Mars for a long time, and results like this make all those decades of work worth it,” Banerdt added.

InSight’s retirement and collection of information

In December 2022, InSight lost its power and was officially retired. Despite its relatively brief four-year mission, the data it collected during its active years has provided scientists with a wealth of information to think about.

In this short span, the rover’s observations of the insides of the red planet have completely changed the way we comprehend the planet.

By recording seismic vibrations, InSight not only unveiled the internal makeup of Mars but also disclosed details about its liquid core and the continuous movements happening within the planet.

Although the insights gathered from seismic readings have been enlightening, the latest study draws its data not from these vibrations but from radio communications. These transmissions occurred between InSight’s Rotation and Interior Structure Experiment (RISE) tools and NASA’s Deep Space Network on Earth.

As both Earth and Mars moved and turned, signals were exchanged between the two, enabling scientists to hunt for subtle changes in the radio wave frequency. These minute shifts allowed them to accurately measure Mars’ rotation.

Analyzing 900 Martian Days data

By analyzing around 900 Martian days’ worth of communications between InSight and Earth, the team uncovered a slight increase in speed. It seems to be linked to the way Mars’ mass is spread out, although the exact process remains unclear.

Interestingly, the opposite situation is occurring here on Earth. Our planet’s rotation is gradually slowing down over time. This deceleration happens because of the Moon’s gravitational influence, which affects Earth’s mass distribution by tugging on the oceans.

However, Mars doesn’t possess oceans, so a different mechanism must be at play. Scientists now face the task of conducting a more comprehensive investigation to pinpoint the most probable cause behind this acceleration.

The RISE data has brought an added benefit to the team by allowing them to fine-tune their measurements of the core of Mars. This was made possible by tracking a slight wobble, known as nutation, which is caused by the movement of fluids within the planet.

Measurements obtained from the data

The measurements obtained from seismic data had initially indicated that Mars’ core likely has a radius ranging from 1,780 to 1,830 kilometers (around 1,137 miles). To put it in perspective, this core size is quite substantial, being over half the radius of the entire planet, which is about 3,390 kilometers across.

Moreover, the analysis of seismic readings also suggested that the core’s density falls between 6.2 and 6.3 grams per cubic centimeter.

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The data from RISE has impressively aligned with these earlier measurements. It has provided a core radius estimation of 1,835 kilometers and a core density range of 5.9 to 6.3 grams per cubic centimeter.

However, what adds a twist to the tale is the nutation of the planet. This slight wobbling indicates that the density within the core is not consistent throughout. To get a clearer picture of this density variation, further analysis will be required in the future.

Astronomer Sebastien Le Maistre at the Royal Observatory of Belgium says, “It’s a historic experiment.”

He further said, “We have spent a lot of time and energy preparing for the experiment and anticipating these discoveries. But despite this, we were still surprised along the way – and it’s not over, since RISE still has a lot to reveal about Mars.”