The impact of a meteorite on Mars has provided scientists in Zurich with the key to solving a mystery: based on the seismic waves caused by the meteorite, they have been able to determine more precisely the size and composition of the Red Planet’s core.
The results, published on Wednesday in the journal Nature, show that a layer of liquid silicates around 150 km thick lies between the liquid iron-alloy core and the mantle of solid silicate rocks.
The core of Mars is therefore smaller than previously thought. “This helps to explain the density of the Martian core,” said study author Amir Khan, a professor at the Swiss Federal Institute of Technology in Zurich.
Two years ago, the research team published for the first time a calculation of the size of the Red Planet’s core. “We were surprised by the results: if the core of Mars were really that big, the average density would have to be very low,” noted Prof Khan.
This meant that there should be more light elements such as sulphur, carbon, oxygen and hydrogen in the core than is possible according to estimates of the abundance of these elements at the beginning of the history of the formation of Mars.
The scientists based their calculations on earthquakes recorded by NASA’s InSight lander. But for the first calculations, they only had data from earthquakes that had taken place fairly close to the probe.
In August and September 2021, the seismometer recorded two earthquakes that occurred on the other side of Mars. One was triggered by the impact of a meteorite. The InSight probe was thus able to record seismic waves that passed through the core.
