When Galileo observed Mars with a telescope more than 400 years ago, he recorded little more than an empty sphere, hanging in endless darkness. In the next four centuries, scholars tried to fill the void.
Not long after Galileo, the Dutch astronomer Christian Huygens arrived and made a profound discovery of Mars. Huygens observed the planet in 1659, had a large dark area on its face, shaded in the heart-shaped spot on the red planet image. This was the first time humans had observed the superficial features of another world.
About 359 years later, in November 2018, NASA Insight landed on Mars About 2,000 miles east of the site, this is the eighth time the space agency has placed an automated rover on the Red Planet. Its mission, which was recently extended to 2022, is to listen to the “swamps” and understand what is happening beneath the surface of our cosmic neighbour.
in a series from three Education Published in Science Thursday, the global research team described the interior of Mars using data obtained by the InSight seismometer, an instrument that responds to vibrations and sounds beneath the Martian surface. earthquake series analysis, I’ve been feeling it on InSight since 2019For the first time, researchers have been able to reveal the inner workings of other planets in our solar system – a breakthrough for planetary geoscience.
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ears on the ground
The first planetary crisis detected by InSight’s seismometers, known as SEIS, occurred in 2019 as early as Huygens imaged. This reveals that Mars is more seismically active than the Moon, but not as active as Earth, and gives researchers a tantalizing first look at what kind of data InSight can collect.
Clip from SEIS, a dome-shaped instrument mounted on the surface of Mars. The white outer layer protects sensitive devices from the environment, while the neatly arranged inner layer contains a pendulum that measures vibration and noise.
NASA / JPL-Caltech / CNES / IPGP
SEIS (pictured right) is a dome-shaped instrument used shortly after InSight’s arrival on Mars. It lies on the ground of Mars and, as NASA puts it, looks like a stethoscope, listening to the planet’s “pulse”. This is a very sensitive piece of technology, which records seismic waves vibrating and vibrating through the planet’s interior after an earthquake.
The outer dome is a shield against the Martian environment, and protects the SEIS from wind and dust that can affect internal vibration measurements. The seismometer itself is a fairly simple device: it has three weights, suspended like a pendulum, that can detect vibrations from different directions – such as when seismic waves from a swamp pass through it.
Previous research has shown that bogs are common, but not overpowering. Only a few records went up 3 Which, on the ground, might sound like a small roar from a few miles away, but it wasn’t strong enough to cause serious damage to structures and buildings. Most of it comes from the upper layers of the planet’s crust, but studies have investigated 10 from deep beneath the surface.
Hearing the waves from these earthquakes is how researchers understand Mars’ interior. Seismic waves traveling through a planet’s interior are altered by the material it comes in contact with – allowing InSight to paint a picture of what’s happening in a soil.
Ogre, onions, and other planets
The anatomy of a “different” planet like Mars, to quote from a 20-year-old film, is like an onion (…or a ghost). Layer. Although scientists have filled in the gaps regarding the nature of the surface and atmosphere and the chemical composition of the soil, what happens beneath the surface remains a mystery.
“For everything we know about Mars – most of it is confined to the top meter,” said Gretchen Benedix, an astronomer at Curtin University in Australia, who was not involved in the study. “It’s like looking at a gift and focusing on the packaging.”
In a new series of studies, researchers investigated this layer for the first time by studying the waves that shake environmental information systems with InSight. “This new information is like opening a bounty for peeping,” said Benedix.
One study, led by Brigitte Knappmayer-Endron, a geophysicist at the University of Cologne, used the data to study the planet’s top layer, known as the crust.
The top layer of the crust, consisting of basalt rock from ancient lava flows, appears to be at its thickest at about 10 kilometers (6.2 mi). But InSight data reveals that another layer, roughly twice that size, lies directly beneath it. Below that, Knapmeyer-Endrun said in a press release, is probably where the “mantle” begins — which makes Mars’ crust “very thin.”
A “selfie” of the InSight lander, taken on the surface of Mars.
NASA/JPL-Caltech
But the team also suggests that there may be a third layer in the Earth’s crust, extending to a depth of about 40 kilometers.
Then there’s the Martian core, which has created some surprises of its own.
As shown in the image above, swamps can send vibrations to the planet’s core, where they bounce off and rush back to SEIS. These signs, such as described in a study Led by Simon Stähler, a geophysicist at ETH Zurich in Switzerland, this is relatively weak but helps estimate the size of the planet’s core. And size matters here.
The boundary between the mantle and the core appears to be less than 1,000 miles below the surface, which is greater than some studies suggest. The suggestion, according to an accompanying article published in Science on Thursday, is that the iron-nickel core is less dense than previously thought, but is in a liquid state as other studies have suggested.
Why is the interior of Mars important?
University of Texas geophysicist Yosio Nakamura described the return of seismology to Mars as a “new dawn” in the Comments on Natural Geoscience in 2020. The ability to detect seismic waves helps place some fundamental constraints on how planets tend to evolve over time and, according to Benedix, “tells us a lot about planetary thermal evolution.”
Heat was emitted from the planet’s core during its early formation and evolution, and by understanding the composition of the core, researchers can hypothesize how Mars cooled over time. Combining this with other data, obtained by orbiting spacecraft, NASA and the Chinese spacecraft, not only helps us understand Mars – but also reveals how planets formed, changed and evolved in the Solar System and possibly beyond.
InSight is also trying to measure the temperature beneath the red planet’s surface directly using “hiding moles”. But early on, when the mole tried to dig into the crazy Martian soil, he stumbled. A heroic attempt by NASA engineers to free the mole proved unsuccessful, and in January, declared dead. However, the InSight mission is far from over – and will continue to listen to the marshes until 2022. Even though it only gives one “ear,” it’s as if repeated observations will allow scientists to improve their understanding of Mars’ interior. .
In less than four centuries, we have gone from Huygens sketching a heart-shaped smudge on the face of Mars to understanding the heart of Mars itself. Empty can be continuously filled.
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