Mars, our neighboring planet, is spinning faster on its axis and scientists aren’t sure what’s causing it.
The North American space agency NASA reported in August that experts have been analyzing data from the InSight module to track the planet’s rotation speed.
They found that the length of a day on the Red Planet has shortened by a fraction of a millisecond every year because it is spinning faster.
The team doesn’t know exactly what is causing this acceleration, but they have a theory.
They point out that it could be because Mars as a whole is changing slightly – for example, in the planet’s mass or what happens on its surface.
Researchers believe this may be due to the accumulation of ice in polar ice caps or in places where land masses rise after being buried by ice – also known as post-glacial rebound.
Until now, these changes in rotation had not been detected because there was no measurement as precise as that recorded by the InSight module, which stopped operating this year after completing its extended mission period.
“It’s really cool to be able to get this latest measurement, so precisely,” said InSight chief investigator Bruce Banerdt.
“I have been involved in efforts to bring a geophysical station like InSight to Mars for a long time, and results like this make all those decades of work worth it.”
How are measurements taken?
The InSight module was launched in May 2018 to help scientists understand more about the nature of the neighboring planet.
On board, InSight carried three main instruments that took measurements: a seismograph, a heat probe, and a radio wave measuring instrument. Together, they were called the Rotation and Interior Structure Experiment, or RISE.
The seismograph’s job was to wait patiently on the surface to detect pulses called seismic waves from earthquakes and shocks from meteorite impacts.
The heat probe measured temperatures below the surface. To do this, he dug to a depth of about 5 m, deeper than any previous drilling or rig.
In turn, the radio instrument tracked InSight’s exact location to determine the way Mars moves around the Sun.
All this information was used by scientists who discovered the acceleration of the planet’s rotation. And now they are trying to find out the possible reasons for this.
“What we are looking for are variations of just a few tens of centimeters over the course of a Martian year,” said the paper’s lead author and RISE principal investigator Sebastien Le Maistre of the Royal Observatory of Belgium.
“It takes a lot of time and a lot of accumulated data before we can see these variations,” he added.
The study examined data from the first 900 Martian days recorded by InSight, a time considered sufficient to look for such variations.