Sweet surprise: NASA’s first look at Land Insight inside Mars reveals that the crust of the red planet looks like a three-layer cake
- The lander’s seismometer has recorded more than 480 earthquakes since April 2019
- Differences in the movement of seismic waves allow scientists to evaluate the size and composition of the crust
- They believe that the crust of Mars is about 23 kilometers thick, much thicker than that of Earth
- Seismic activity has virtually stopped, with only four earthquakes since June
Data sent back to Earth from NASA’s InSight landing suggests that the crust of Mars is made up of three layers similar to those of cakes.
Anchored near the equator of Mars, the super-sensitive seismometer of the Earth’s robot, known as SIX, has recorded hundreds of “earthquakes” in the past two years.
Each earthquake emits two sets of seismic waves and analyzing the differences in how these waves move has allowed researchers to begin calculating 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 lab scientist Bruce Banerdt told Nature.
Launched in 2018, the InSight mission is the first time scientists have looked at a different planet from Earth.
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Analysis of primary and secondary waves caused by hundreds of earthquakes suggests that the crust of the red planet is made up of three “cake-like” layers.
The Earth’s crust is divided into three sublayers of rock: metamorphic, igneous, and sedimentary.
Scientists had theorized that the crust of Mars was similarly structured, but so far had no data to work with.
According to the Nature report, Mars may have only two layers, but a three-layer crust aligns with the analysis of Martian meteorites.
Comparing the primary and secondary waves of marsquakes, they have deduced that the crust is about 23 miles thick, and about 42, as thicker.
NASA’s InSight landing came to Mars in 2018, but the “Mole” spacecraft has had difficulty drilling beneath the surface
InSight’s super-sensitive seismometer, known as SEIS, has recorded more than 480 earthquakes. Analyzing the primary and secondary waves of these earthquakes, the researchers believe that the crust of Mars is about 23 kilometers thick.
It is much thicker than Earth, which has a crust that ranges from about 3 kilometers under the oceans to 18 kilometers under the continents.
InSight (short for Indoor Exploration through Seismic Research, Geodesy, and Heat Transport) arrived on Mars in November 2018.
Its probe, called the “Mole,” was designed to dig beneath the surface and catch the planet’s temperature, but unexpected properties on Martian soil made progress difficult.
Other lander equipment is fully functional, fortunately, including the seismometer, provided by the French space agency, Center National d’Études Spatiales.
Since April 2019, SEIS has recorded more than 480 earthquakes. The tremors are relatively mild, with no magnitude greater than magnitude 3.7.
“It’s a little surprising that we haven’t seen any major events,” said seismologist Mark Panning of NASA’s Jet Propulsion Laboratory.
Panning says it’s still unclear if Mars is more static than Earth or if InSight landed during a quiet interval.
The earthquakes had been daily for some time, but stopped abruptly in late June, just as the planet entered its windiest season of the year.
The seismometer has protection, but it is possible that the wind is so strong that it shakes the ground and masks legitimate tremors.
Researchers hope that more major earthquakes will occur, which will allow us to better understand the inner layers of the planet.
“Sometimes you get great flashes of amazing information, but most of the time you’re trying what nature has to tell you,” Banerdt said.
“It’s more like trying to follow a trail of complicated clues than presenting us with the answers in a very well-wrapped package.”
WHAT ARE THE THREE KEY INSIGHT INSTRUMENTS?
The lander that could reveal how the Earth formed: the InSight lander headed for the landing 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, listening to the pulse of Mars.
The seismometer records the waves that travel through the inner 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 earthquakes or meteorites hitting the surface.
Heat probe: InSight’s heat flux probe, HP3, is interrupted more than any other lever, drill, or probe on Mars before it.
It will investigate how much heat still springs from Mars.
Radio antennas: Like Earth, Mars oscillates slightly as it revolves around its axis.
To study this, two radio antennas, which are part of the RISE instrument, track the location of the lander very accurately.
This helps scientists test the planet’s reflections and tells them how the deep inner structure affects the planet’s motion around the Sun.