Artist’s cutaway of theorized Martian interior
Using data from InSight’s seismometer, scientists have made their first approximation of the internal structure of Mars.
The first boundary Deng and Levander measured is the divide between Mars’ crust and mantle almost 22 miles (35 kilometers) beneath the lander.
The second is a transition zone within the mantle where magnesium iron silicates undergo a geochemical change. Above the zone, the elements form a mineral called olivine, and beneath it, heat and pressure compress them into a new mineral called wadsleyite. Known as the olivine-wadsleyite transition, this zone was found 690-727 miles (1,110-1,170 kilometers) beneath InSight. “The temperature at the olivine-wadsleyite transition is an important key to building thermal models of Mars,” Deng said. “From the depth of the transition, we can easily calculate the pressure, and with that, we can derive the temperature.”
The third boundary he and Levander measured is the border between Mars’ mantle and its iron-rich core, which they found about 945-994 miles (1,520-1,600 kilometers) beneath the lander. Better understanding this boundary “can provide information about the planet’s development from both a chemical and thermal point of view,” Deng said.
Because they only have one seismometer on the planet, this approximation has a great deal of uncertainty. Only when we have multiple such seismic instruments, scattered across the entire Martian globe, will scientists be able to hone their models more accurate of the planet’s interior.
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