Space

InSight finds molten core at red planet’s heart – Astronomy Now

A visualisation of the interior of Mars, based on seismic data from a French instrument carried to the red planet by NASA’s Insight lander, shows an oversize molten core with the seismic trace of a marsquake superimposed. Studying data from 35 marsquakes allowed researchers to determine the dimensions of the planet’s core, mantle and crust. Image: NASA/JPL-Caltech

Since landing on Mars in November 2018, NASA’s InSight lander has detected more than 730 marsquakes using an ultra-sensitive seismometer provided by the the French space agency. About 35 of the quakes detected to date were between magnitude 3.0 and 4.0, providing the data necessary to map out the deep interior of the red planet for the first time.

The martian crust turned out to be thinner than expected and may consist of two or possibly three sublayers, extending as much as 37 kilometres (23 miles) below the surface. The mantle is 1,560 kilometres (960 miles) thick, surrounding a large molten core with a radius of 1,830 kilometres (1,137 miles).

Three papers based on data from InSight’s Seismic Experiment for Interior Structure, or SEIS, instrument were published 22 July in the journal Science.

“When we first started putting together the concept of the mission more than a decade ago, the information in these papers is what we hoped to get at the end,” said InSight’s principal investigator Bruce Banerdt of NASA’s Jet Propulsion Laboratory. “This represents the culmination of all the work and worry over the past decade.”

Simon Stähler of the Swiss research university ETH Zurich, lead author of a paper about the core, called InSight’s mission a “once-in-a-lifetime chance.”

“It took scientists hundreds of years to measure Earth’s core; after the Apollo missions, it took them 40 years to measure the Moon’s core,” he said. “InSight took just two years to measure Mars’ core.”

One surprising finding is that all of the most powerful quakes detected by the SEIS instrument appear to have originated in one area – Cerberus Fossae – a region where lava may have flowed within the last few million years.

No quakes have been detected from more volcanic regions like Tharsis, where three of the biggest martian volcanoes are found. But NASA says it’s possible quakes are occurring that InSight can’t detect because of “shadow zones” where the core refracts seismic waves away from the lander’s location.

Researchers remain hopeful they will detect quakes stronger than 4.0, providing additional insight about the red planet’s interior.

“We’d still love to see the big one,” said Mark Panning of NASA’s Jet Propulsion Laboratory, co-lead author of a Science paper on the crust. “We have to do lots of careful processing to pull the things we want from this data. Having a bigger event would make all of this easier.”




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