NASA Insight data show that Mars rotation is accelerating.
CTOnews.com, August 8 (Xinhua)-- NASA's InSight Mars lander lost power due to ash from solar panels in December 2022, but data from its four years on Mars continue to provide scientists with new discoveries. A recent study published in the journal Nature used data from the InSight lander to make the most accurate measurement of the rotation speed of Mars and to detect for the first time the planetary wobble caused by the "wobble" of its molten metal core.
The InSight lander carries a variety of instruments, one of which is the RISE, which is used to measure the rotation speed of Mars, which consists of a radio transceiver and antenna that can receive and reflect radio signals from the NASA Deep Space Network (DSN) on Earth. By analyzing the Doppler effect of the signal (that is, the signal frequency varies with distance), scientists can determine the speed and direction of the planet's rotation.
The researchers found that the rotation rate of Mars accelerates by about 4 milliseconds a year, which is equivalent to a fraction of a millisecond shorter than the Mars day (the time of a day on Mars) each year. This is a small acceleration, and scientists are not entirely sure why, but they speculate that it may have something to do with the accumulation of the polar ice sheet, and changes in the mass of the planet will cause it to spin like an ice skater.
RISE data are also used to measure the wobble (called nutation) caused by the liquefaction of the Martian core, allowing scientists to determine the size of the Martian core: according to RISE, the Martian core has a radius of about 1140 miles (CTOnews.com Note: about 1835 km). The researchers also compared this number with two previous measurements from the InSight lander seismograph, and taking these three measurements together, they estimated the radius of the Martian core at between 1112 and 1150 miles (1790 to 1850 kilometers). Mars itself has a radius of 2106 miles (3390 kilometers), about half the radius of Earth.
