Before finishing his mission last December. Scientists analyzed the rotation of the red planet.
They looked more closely at the rotation of Mars and discovered that the planet wobbles due to the “sloshing” of its molten metal core. As a result, the planet’s rotation accelerates slightly, causing the day to shorten by a fraction of a millisecond per year.
Mars is spinning faster and faster
To track the planet’s spin rate, the study authors relied on one of InSight’s instruments: a radio transponder and antennas collectively called the Rotation and Interior Structure Experiment, or RISE.
They found that the planet’s rotation is accelerating by about 4 milliarcseconds per year, corresponding to a reduction in the length of the Martian day by a fraction of a millisecond per year.
The calculation was possible given that during the four years he studied the interior “pulse”, subsoil and the ‘temperature’ of Mars, they were obtained, thus it was easier to realize that each year the rotation of Mars accelerates by about 4 milliarcoseconds.
Although it is a subtle acceleration, scientists are not entirely sure of the cause, they have some ideas, such as the accumulation of ice on the polar caps or postglacial rebound, where land masses rise after being buried by the ice.
The change in a planet’s mass can cause it to speed up a little like an ice skater spinning with his arms outstretched and then retracting them.
Although, planets cannot modify the speed at which they rotate spontaneously. The rotation of a stellar body is determined by the angular momentuman intrinsic property related to mass, mass distribution, and initial acceleration that remains constant unless an external force is exerted.
Observation without explanation
A theory considered by experts is that the variation could be based on the redistribution of the mass of Mars, although it is not yet understood why. Scientists will have to conduct further analysis to determine the most likely cause of the acceleration.
InSight’s seismic records not only helped understand the interior structure of Mars, but also the composition of its liquid core and ongoing geodynamic activity. Seismic data measurements suggested that the core of Mars has a radius of between 1,780 and 1,830 kilometers, which is quite large – more than half the planetary radius of 3,390 kilometers, although there are density variations in the core that should also be probed in future analyses.