(ORDO NEWS) — Mars is spinning faster than before. This is evidenced by data collected by NASA‘s InSight probe on the Red Planet. The now-defunct InSight craft was equipped with a range of instruments, including antennas and a transponder called RISE (Rotation and Interior Structure Experiment). These instruments were used to track the rate of rotation of Mars during the probe’s first 900 days on the planet.
Astronomers have found that the speed of the planet’s rotation around its axis increases by about four milliarseconds per year – that is, the length of the Martian day is reduced by a tiny fraction of a millisecond each year. A day on Mars lasts about 40 minutes longer than on Earth.
The acceleration of the rotation of the Red Planet seems extremely insignificant, but scientists still cannot answer the question of what causes it. They suggest that this may be due to the accumulation of ice at the poles or the rise of land masses after the ice has melted off them. This shift in land masses can cause the planet to spin faster.
The conclusions, which were based on an analysis of data taken from the InSight probe before its solar panels ran out and failed, were reported in the June issue of the journal Nature.
The InSight program, the first mission to study the seismic activity and interior of Mars, was originally supposed to last about two years after the probe landed in November 2018. But NASA extended the mission for another two years.
InSight continued to collect data on Mars until the very end. After the Martian dust completely covered the solar panels, the batteries were discharged and the probe fell silent.
InSight has benefited enormously from advances in radio technology, as its hardware has proven to be more advanced than the hardware found on the Viking modules in the 70s and Pathfinder in the 90s. Modernization of the equipment of NASA’s Deep Space Network – huge antennas that are located at three strategic points on the Earth and transmit information from space missions – also increased the accuracy of the data collected and sent by the probe to our planet.
Scientists used the Deep Space Network to transmit signals to the RISE instrument on the InSight probe, which reflected them and sent them back to Earth. These reflected signals helped scientists track the small changes in frequency caused by what is known as Doppler shift, a phenomenon in which a sound changes pitch depending on the distance from its source. Changes in frequency correlate with the rotation of the planet.
“We are looking for changes that are only a few tens of centimeters over an entire Martian year,” said Sebastien Le Maistre, lead author of the study, who is in charge of the RISE instrument at the Royal Observatory of Belgium. “It takes a lot of time and data for us to could see these changes.
Measurements of oscillations of the axis of rotation of Mars
Previous studies made possible by unique findings on the Red Planet have confirmed that it has a liquid metal core. The scientists used the RISE instrument to measure the wobble of Mars’ axis of rotation as a result of the molten core “splashing” inside it.
Tracking the oscillations—called nutations—allowed the team to determine the size of the planet’s core. RISE data showed that it has a radius of about 1835 kilometers.
They compared this figure with previous calculations, which were obtained by tracking seismic waves while passing through the interior of Mars.
Comparing these figures, scientists calculated that its core has a radius of approximately 1790-1850 kilometers.
Although the InSight probe stopped working, the extremely valuable data it collected during its four years of work on the surface of Mars changed the way scientists look at the Red Planet. This mission allowed for the first time to reveal some of the secrets of the Martian interior. Scientists will analyze the data for several more decades.
“It was really cool to get that last measurement – and with such accuracy,” said Bruce Banerdt, who ran InSight until his retirement on August 1st. He worked at NASA’s Jet Propulsion Laboratory in Pasadena, California for 46 years.
“I’ve been involved in trying to get a geophysical station like InSight to Mars for a long time, and the results justify all those decades of work,” he said.
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