600km solid core inside Mars stuns scientists - Only the third after Earth and Moon

A team of scientists from the US and China has made a startling discovery about our red neighbour, Mars. They have found a solid core inside the planet, a finding that could reshape all understanding about the red planet. Mars should ideally not have this core, but astronomers are shocked to see that it is real. The finding was published in the journal Nature. Seismic data collected by NASA's InSight lander, which is no longer in use, was analysed by researchers from the University of Science and Technology of China and the University of Texas at Austin. They studied Marsquakes on the red planet and discovered that a 600km solid core sits inside Mars. The researchers say that this presents new clues to how Mars formed, and that Earth wasn't the only planet to have tectonic plates. Nicholas Schmerr, a planetary seismologist at the University of Maryland, College Park, wrote alongside the paper that this provides a new understanding of Mars’ deep interior. Also Read: Oldest black hole can fit 50 million suns and was born with the Big Bang — 'Lonely and naked'

What lies inside Mars?

The NASA InSight mission was launched in 2017 to specifically study the interior of Mars. A seismometer installed on it captured seismic activity, while a heat probe tracked internal heat flow. Mars’ crust, mantle and partially liquid metal core were earlier mapped using this data. The researchers used more data from the lander and found two distinctive types of seismic waves. The PKKP was one, which travelled through the planet’s core, while the PKiKP, bounced off the boundary of a solid inner core. The latter had proved that the Earth and Moon had solid cores. If Mars had a liquid core, then the PKKP waves should have been delayed by 50 to 200 seconds as compared to when they actually reached InSight. The speed of these waves helped calculate the radius of this solid inner core, which is measured at about 600km in radius. Also Read: 'We've never seen...' — Marsquakes reveal 4.5-billion-year-old structures embedded in the red planet

Tectonic plates on Mars

Meanwhile, Ross Mitchell, a geologist at the Institute of Geology and Geophysics in Beijing, told SCMP that high pressure and low temperature together force the liquid metal to "freeze" to form the core inside a planet. This is true for every cosmic body, be it a planet or a Moon; however, the time it takes to freeze the core differs. For most, this process doesn't happen fast enough. He says that if the revelation made in the paper holds true, "then it’s three of a kind: Earth, the moon and now Mars have inner cores." With Earth, the process was simple. The movement of surface plates helps carry heat from deep inside the planet to the surface. This was a major factor in the rapid cooling of the liquid metal.

For Mars, tectonic plates were not believed to exist. Besides, the cooling of the core was thought to have been impeded by the presence of a molten layer between its mantle and core. However, Mitchell argues, that this blanket's role could have been shoved aside if Mars had plate tectonics in the past, helping it "cool rapidly despite the insulation."