Researchers use NASA's InSight lander to study Mars' interior; 3 key findings

Towards a step to better understand red planet's geology, seismologists at Texas' Rice University have me first direct measurements of three subsurface boundaries from crust to core of Mars using data from NASA’s InSight Lander.

While thickness of Mars’ crust and depth of its core have been calculated with a number of models, researchers said InSight data allowed for first direct measurements, which can be used to check models and ultimately to improve m. “Ultimately it may help us understand planetary formation,” said Alan Levander, co-author of a study available online this week in Geophysical Research Letters.

One researcher ted that in  absence of plate tectonics on Mars, its early history is mostly preserved compared with Earth. " depth estimates of Martian seismic boundaries can provide indications to better understand its past as well as formation and evolution of terrestrial planets in general," said study co-author Sizhuang Deng.

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Why seismology matters in study of Mars

Finding clues about Mars’ interior and processes that formed it are key goals for InSight (short for Interior Exploration using Seismic Investigations), a robotic lander that touched down in vember 2018. probe’s dome-shaped seismometer allows scientists to listen to faint rumblings inside planet, in much way that a doctor might listen to a patient’s heartbeat with a stethoscope.

Seismometers measure vibrations from seismic waves. Like circular ripples that mark spot where a pebble disturbed surface of a pond, seismic waves flow through planets, marking location and size of disturbances like meteor strikes or earthquakes, which are aptly called marsquakes on red planet. InSight’s seismometer recorded more than 170 of se from February to September 2019.

Seismic waves are also subtly altered as y pass through different kinds of rock. Seismologists have studied patterns in seismographic recordings on Earth for more than a century and can use m to map location of oil and gas deposits and much deeper strata.

Studying Mars' interior structure answers key questions about early formation of rocky planets in our inner solar system — Mercury, Venus, Earth, and Mars — more than 4 billion years ago, as well as rocky exoplanets. InSight also measures tectonic activity and meteorite impacts on Mars today.

“ tritional way to investigate structures beneath Earth is to analyze earthquake signals using dense networks of seismic stations,” said Deng. “Mars is much less tectonically active, which means it will have far fewer marsquake events compared with Earth. Moreover, with only one seismic station on Mars, we cant employ methods that rely on seismic networks,” he ds.

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Three interesting findings

Researchers analyzed InSight’s 2019 seismology data using a technique called ambient ise autocorrelation. technique uses continuous ise data recorded by single seismic station on Mars to extract prounced reflection signals from seismic boundaries.

first boundary researchers measured is divide between Mars’ crust and mantle almost 22 miles (35 kilometers) beneath lander.

second is a transition zone within mantle where magnesium iron silicates undergo a geochemical change. Above zone, elements form a mineral called olivine, and beneath it, heat and pressure compress m into a new mineral called wsleyite. Kwn as olivine-wsleyite transition, this zone was found 690-727 miles (1,110-1,170 kilometers) beneath InSight.

“ temperature at olivine-wsleyite transition is an important key to building rmal models of Mars,” Deng said. “From depth of transition, we can easily calculate pressure, and with that, we can derive temperature.”

third boundary  seismologists measured is border between Mars’ mantle and its iron-rich core, which y found about 945-994 miles (1,520-1,600 kilometers) beneath lander. Better understanding this boundary “can provide information about planet’s development from both a chemical and rmal point of view,” Deng said.

About Mars InSight lander: 

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