Mars' timepiece tinkered: NASA discovers faster spin, shorter days on red planet

Scientists have achieved the most precise measurement of Mars' rotation to date, unravelling the planet's enigmatic "wobble" caused by its molten core's dynamic movements.

This remarkable insight also revealed an unexpected acceleration in Mars' rotation, presenting a complex situation for researchers trying to find out the underlying causes behind it.

The catalyst for this groundbreaking discovery was NASA's InSight lander, which spent a four-year tenure on the Martian surface before its power reserves depleted in December 2022.

During its mission, the lander collected invaluable data that has offered a deeper understanding of Mars' intricate internal dynamics.

Rotation and interior structure experiment (RISE)

Published in the journal Nature, a study led by researchers harnessed data from the InSight lander's Rotation and Interior Structure Experiment (RISE).

This analytical approach unveiled a startling revelation that Mars' rotation is undergoing an acceleration of approximately 4 milliarcseconds per year.

Despite its subtlety, this acceleration perplexes scientists, leaving them to grapple with the mechanisms behind this phenomenon.

In the quest to figure out the cause behind Mars' acceleration, researchers have put forth several hypotheses.

But, why is Mars spinning faster?

Among these, the accumulation of ice on the polar caps and the concept of post-glacial rebound, wherein previously ice-covered landmasses rise due to released pressure, have been suggested.

This alteration in the planet's mass distribution could potentially trigger the acceleration, akin to an ice skater varying their spin speed by altering their arm position.

The Doppler effect, the phenomenon that causes an ambulance's siren pitch to change as it approaches or moves away, underpins a crucial aspect of this research.

Astronomers ingeniously employed this principle to gauge Mars' rotation speed. Using the Deep Space Network, scientists sent a radio signal to the InSight lander.

The signal was reflected back by the RISE instrument's radio transponder and antennae. By scrutinising minute alterations in frequency, known as Doppler shift, caused by the lander's motion, scientists could accurately deduce the planet's rotational velocity.