Sweet surprise: a look inside Mars reveals that the red planet’s crust resembles a three-layer cake

Data transmitted to Earth from NASA’s InSight lander suggests that the crust of Mars is made up of three cake-shaped layers.

Anchored near the equator of Mars, the robotic lander’s super-sensitive seismometer, known as SEIS, has recorded hundreds of ‘marsquakes’ in the past two years.

Each earthquake emits two sets of seismic waves, and analyzing the differences in how those waves move has allowed researchers to begin to calculate the size and composition of the planet’s crust, mantle and core.

“We have enough data to start answering some of these big questions,” Jet Propulsion Laboratory scientist Bruce Banerdt told Nature.

Launched in 2018, the InSight mission marks the first time scientists have looked inside a planet other than Earth.

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Analysis of the primary and secondary waves caused by hundreds of earthquakes suggests that the red planet’s crust is made up of three ‘pastel-like’ layers

The earth’s crust is divided into three rock sublayers: metamorphic, igneous, and sedimentary.

Scientists had theorized that the crust of Mars was similarly structured but, until now, they had no data to work with.

According to the Nature report, Mars may only have two layers, but a three-layer crust lines up with the analysis of Martian meteorites.

By comparing the primary and secondary waves of the marsquakes, they have deduced that the crust is about 37 kilometers thick on average and about 42 kilometers at its thickest point.

NASA’s InSight lander reached Mars in 2018, but its ‘Mole’ probe has struggled to drill below the surface.

InSight’s super-sensitive seismometer, known as SEIS, has recorded more than 480 marsquakes. By analyzing the primary and secondary waves from these earthquakes, the researchers believe that the crust of Mars is approximately 37 kilometers thick.

That’s considerably thicker than Earth, which has a crust that ranges from about 3 miles below the oceans to 18 miles below the continents.

InSight (short for interior exploration using seismic, geodesy, and heat transport investigations) arrived on Mars in November 2018.

Its probe, dubbed the ‘Mole’, was designed to dig below the surface and take the planet’s temperature, but unexpected properties in the Martian soil hampered progress.

Fortunately, other equipment on the lander is fully functional, including the seismometer, provided by the French space agency, Center National d’Études Spatiales.

Since April 2019, SIX has recorded more than 480 earthquakes. The tremors are relatively mild, none greater than a magnitude of 3.7.

“It’s a bit surprising that we haven’t seen a larger event,” said seismologist Mark Panning of NASA’s Jet Propulsion Laboratory.

Panning says it is not yet clear if Mars is more static than Earth or if InSight landed during a silent interlude.

Earthquakes had been daily for some time, but stopped abruptly in late June, just as the planet entered the windiest season of the year.

The seismometer is protected, but the wind may be so strong that it shakes the ground and masks legitimate tremors.

The researchers hope that more major earthquakes will occur, which will provide a greater understanding of the inner layers of the planet.

“Sometimes you get big flashes of amazing information, but most of the time you are unraveling what nature has to tell you,” Banerdt said.

“It is more like trying to follow a trail of complicated clues than having the answers presented in a tightly wrapped package.”

WHAT ARE THE THREE KEY INSTRUMENTS OF INSIGHT?

The lander that could reveal how the Earth was formed: InSight lander ready to land on Mars on November 26

Three key instruments will allow the InSight lander to ‘take the pulse’ of the red planet:

Seismometer: The InSight lander carries a seismometer, SIX, who listens to the pulse of Mars.

The seismometer records the waves that travel through the interior structure of a planet.

The study of seismic waves tells us what might be creating the waves.

On Mars, scientists suspect that the culprits may be tidal waves or meteorites hitting the surface.

Heat probe: InSight’s heat flux probe, HP3, digs deeper than any shovel, drill, or probe on Mars before it.

It will investigate how much heat continues to flow from Mars.

Radio antennas: Like Earth, Mars wobbles a bit as it rotates around its axis.

To study this, two radio antennas, part of the RISE instrument, track the location of the lander very precisely.

This helps scientists test the reflections of the planet and tells them how the deep interior structure affects the movement of the planet around the Sun.