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ATLANTA — Mars is spinning faster than it ever was, according to data collected by NASA’s InSight lander on the red planet.
The now-retired InSight was armed with a suite of instruments, including antennas and a radio transceiver called the RISE, or Internal Structure and Rotation Experiment. The instruments were used to track the rotation of Mars during the mission’s first 900 days on the planet.
Astronomers have determined that the planet’s rotation is increasing by about 4 milliseconds per year², or shortening the length of a day on Mars by a fraction of a millisecond per year. A Martian day lasts about 40 minutes longer than a day on Earth.
The increased acceleration appears to be minuscule, and researchers aren’t entirely sure why that is. However, they suggest that it may be due to the accumulation of ice at the poles of Mars or the appearance of landmasses after being covered with ice. When a planet’s mass changes in this way, it can cause the planet’s rotation to speed up.
The findings, which are based on an analysis of InSight data shared before the mission was depleted and retired, are reported in a report The June study was published in the journal Nature.
Initially, InSight, the first mission to study the interior of Mars, was supposed to continue about two years after landing in November 2018. But NASA extended the mission for another two years.
The InSight mission continued to collect data on Mars until the end, Silence in December 2022 After dust prevented the solar panels from receiving sunlight.
Scientists used the Deep Space Network to transmit signals to RISE on InSight, which then reflected the signal back to Earth. These transmitted signals helped the researchers track small frequency changes caused by the Doppler shift, which is what causes sirens to change pitch depending on their distance. The frequency changes due to the rotation of the planet.
“What we’re looking for are differences of only a few tens of centimeters over the course of a Martian year,” study senior author Sebastien Le Maistre, RISE principal investigator at the Royal Observatory of Belgium, said in a statement. “It takes a very long time and a lot of data to accumulate before we can even see these differences.”
Mars oscillation measurement
Previous research made possible by the mission’s unique findings of the planet’s interior confirmed that Mars has a molten metallic core. The researchers then used RISE to measure Mars’ wobble as its core flows.
Tracking the Mars wobble, or morphing, enabled the team to measure the core’s size.
RISE data indicates that the core’s radius is about 1,140 miles.
This new figure was compared with previous estimates of the radius of the core that was Collected by tracking seismic waves as they travel through inner Mars. By combining these measurements, the researchers estimate that the radius of Mars’ core is between 1,112 and 1,150 miles.
Although InSight is no longer operational, its treasure trove of data collected during its four years on Mars has changed the way scientists understand the Red Planet. The mission was the first to reveal some of the secrets of Mars’ interior, and scientists will analyze its data for decades to come.
“It’s really cool to be able to get this latest measurement — and that’s just that,” Bruce Banerdt, who served as principal investigator for InSight before retiring on Aug. 1, said in a statement. He worked at NASA’s Jet Propulsion Laboratory in Pasadena, California, for 46 years.
“I’ve been involved in efforts to bring a geophysical station like InSight to Mars for a long time, and results like this make all those decades of work worth it.”
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