(ORDO NEWS) — The days on Mars are getting shorter by three-quarters of a millisecond each year as the planet begins to spin faster. This is indicated by the data received by the Martian station InSight.
This is reported by Space.com.
The length of a standard sol or day on Mars is 24 hours and 37 minutes. But the measurement of the period of rotation of the planet to the millisecond made it possible to find that it is slightly shortened. Scientists are not completely sure why this happens.
Probably, the slowdown is related to the redistribution of the mass of the planet.
This redistribution may be caused by the accumulation of ice on the polar caps of Mars or by the fact that the surface itself is slowly recovering after being under the weight of huge glaciers that existed in equatorial latitudes during the last ice ages that ended about 400 thousand years ago.
Researchers were able to achieve incredible accuracy of measurements using radio waves. The researchers themselves call this experiment “historic”.
A powerful radio signal was sent toward the Red Planet by NASA‘s Deep Space Exploration Network, which consists of three radio antennas located around the world. The radio signal was then received by InSight’s RISE instrument and reflected back to Earth. The rotation of Mars adds a Doppler shift to these reflected radio waves.
Doppler shift is the same effect that causes an ambulance siren to increase in pitch as it approaches the listener and then decrease again as it moves away. When InSight is in the orbiting hemisphere of Mars in the field of view, the radio signal it emits is Doppler-shifted toward higher frequencies, and when InSight is in the orbiting hemisphere outside the field of view, the signal is Doppler-shifted toward lower frequencies.
In the course of the study, scientists used data obtained during the first 900 days of InSight’s stay on Mars. They found that the Red Planet accelerates its rotation by 0.76 milliseconds per year.
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