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The seismicity of Mars

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Mars is shaking. Credit: NASA/JPL – Caltech

On 26 November 2018, the NASA InSight lander successfully set down on Mars in the Elysium Planitia region. Seventy Martian days later, the mission’s seismometer SEIS began recording the planet’s vibrations. A team of researchers and engineers at ETH Zurich, led by ETH Professor Domenico Giardini, had delivered the SEIS control electronics and is responsible for the Marsquake Service. The latter is in charge of the daily interpretation of the data transmitted from Mars, in collaboration with the Swiss Seismological Service at ETH Zurich. Now, the journal Nature Geoscience published a series of articles on the results of the mission in the first months of operation on Mars.

As reported in these articles, InSight recorded 174 events until the end of September 2019. Since then, the measurements have continued leading to more than 450 observed marsquakes as of today, which have not yet been analysed in detail. This accounts for one event a day on average.

The data allows researchers observing how seismic waves travel through the planet and unveiling its internal characteristics—similar to how x-rays are used in medical tomography. Before InSight landed, researchers had developed a wide range of possible models to represent the internal structure of the red planet. The recorded marsquakes, already after few months, enable refining the understanding of the structure of the planet and to reduce the uncertainties.

Interpreting marsquake data is challenging  

Marsquakes are similar to the we see on Earth, although they are generally of smaller magnitude. The 174 registered marsquakes can be categorized in two families: One includes 24 low-frequency events with magnitudes between 3 and 4, as documented in the papers, with waves propagating through the Martian mantle. A second family of marsquakes comprises 150 events with smaller magnitudes, shallower hypocentral depth and high frequency waves trapped in the Martian crust.

“Marsquakes have characteristics already observed on the Moon during the Apollo era, with a long signal duration (10 to 20 minutes) due to the scattering properties of the Martian crust,” explains ETH Professor Giardini. In general, however, he says, interpreting data is very challenging and in most cases, it is only possible to identify the distance but not the direction from which the waves are arriving.

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InSight landed on a thin, sandy layer  

InSight opens a new era for planetary seismology. The SEIS performance exceeded so far expectations, considering the on Mars, characterized by temperatures ranging from minus 80 to 0 degrees Celsius every day and by strong wind oscillations. Indeed wind shakes the InSight lander and its instrumentation during the day leading to a high level of ambient noise. However, at sunset, the winds calm down allowing recording the quietest seismic data ever collected in the solar system. As a result, most seismic events detected on Mars by SEIS occurred in the quiet night hours. The challenging environment also requires to carefully distinguishing between seismic events and signals originating from movements of the lander, other instruments or atmospheric-induced perturbances.

The hammering by the HP3 instrument (another InSight experiment) and the close passage of whirlwinds (dust devils), recorded by SEIS, allow to map the physical properties of the shallow soil layers just below the station. We now know that SEIS landed on a thin, sandy layer reaching a few meters deep, in the middle of a 20 meter-wide ancient impact crater. At greater depths, the Martian crust has properties comparable to Earth’s crystalline massifs but appears to be more fractured. The propagation of the seismic waves suggest that the upper mantle has a stronger attenuation compared to the lower mantle.

The seismicity of Mars
Credit: ETH Zurich

Seismic activity also induced by tectonic stress

InSight landed in a rather quiet region of Mars, as no events near the station have been recorded up to now. The three biggest events were located in the Cerberus Fossae region about 1’500 km away. It is a tectonic graben system, caused by the weight of the Elysium Mons, the biggest volcano in the Elysium Planitia area. This provides strong evidence that seismic activity on Mars is not only a consequence of the cooling and therewith the shrinking of the planet but also induced by tectonic stress. The total seismic energy released on Mars lies between the one of Earth and of the Moon.

SEIS, complementary to other InSight measurements, also meaningfully contributed data to better understand the meteorological processes on Mars. The instrument’s sensitivity to both wind and atmospheric pressure allowed identifying meteorological phenomena characteristic of Mars, including the many dust devils that pass by the spacecraft every afternoon.


Explore further

First direct seismic measurements of Mars reveal a geologically active planet


More information:
W. Bruce Banerdt et al. Initial results from the InSight mission on Mars, Nature Geoscience (2020). DOI: 10.1038/s41561-020-0544-yD. Giardini et al. The seismicity of Mars, Nature Geoscience (2020). DOI: 10.1038/s41561-020-0539-8

P. Lognonné et al. Constraints on the shallow elastic and anelastic structure of Mars from InSight seismic data, Nature Geoscience (2020). DOI: 10.1038/s41561-020-0536-y

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The seismicity of Mars (2020, February 24)
retrieved 25 February 2020
from https://phys.org/news/2020-02-seismicity-mars.html

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Scientists observe total solar eclipse in Antarctica – Global Times

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Scientists from the Chilean Union Glacier Station observe a total solar eclipse in Antarctica, Dec. 4, 2021.Photo:Xinhua

 
Scientists from the Chilean Union Glacier Station observe a total solar eclipse in Antarctica, Dec. 4, 2021.Photo:Xinhua

Scientists from the Chilean Union Glacier Station observe a total solar eclipse in Antarctica, Dec. 4, 2021.Photo:Xinhua

 

Scientists from the Chilean Union Glacier Station observe a total solar eclipse in Antarctica, Dec. 4, 2021.Photo:Xinhua

Scientists from the Chilean Union Glacier Station observe a total solar eclipse in Antarctica, Dec. 4, 2021.Photo:Xinhua

 

Photo taken from Chilean Union Glacier Station in Antarctica on Dec. 4, 2021 shows a total solar eclipse.Photo:Xinhua

Photo taken from Chilean Union Glacier Station in Antarctica on Dec. 4, 2021 shows a total solar eclipse.Photo:Xinhua

 

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Dinosaur Tail Found In Chile Could Point To Discovery Of New Species – NDTV

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Paleontologists have discovered 80 percent of the dinosaur’s skeleton.

Santiago:

Chilean paleontologists on Wednesday presented their findings on a dinosaur discovered three years ago in Patagonia which they said had a highly unusual tail that has stumped researchers.

The remains of the Stegouros elengassen were discovered during excavations in 2018 at Cerro Guido, a site known to harbor numerous fossils, by a team who believed they were dealing with an already known species of dinosaur until they examined its tail.

“That was the main surprise,” said Alexander Vargas, one of the paleontologists. “This structure is absolutely amazing.”

“The tail was covered with seven pairs of osteoderms … producing a weapon absolutely different from anything we know in any dinosaur,” added the researcher during a presentation of the discovery at the University of Chile.

The osteoderms — structures of bony plaques located in the dermal layers of the skin – were aligned on either side of the tail, making it resemble a large fern.

Paleontologists have discovered 80 percent of the dinosaur’s skeleton and estimate that the animal lived in the area 71 to 74.9 million years ago. It was about two meters (almost seven feet) long, weighed 150 kilograms (330 pounds) and was a herbivore.

According to the scientists, who published their research in the journal Nature, the animal could represent a hitherto unknown lineage of armored dinosaur never seen in the southern hemisphere but already identified in the northern part of the continent.

“We don’t know why (the tail) evolved. We do know that within armored dinosaur groups there seems to be a tendency to independently develop different osteoderm-based defense mechanisms,” said Sergio Soto, another member of the team.

The Cerro Guido area, in the Las Chinas valley 3,000 km (1,800 miles) south of Santiago, stretches for 15 kilometers. Various rock outcrops contain numerous fossils.

The finds there allowed the scientists to surmise that present-day America and Antarctica were close to each other millions of years ago.

“There is strong evidence that there is a biogeographic link with other parts of the planet, in this case Antarctica and Australia, because we have two armored dinosaurs there closely related” to the Stegouros, said Soto.

(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)

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Chinese Rover Exploring What Appears to Be Cube-Shaped Object on Moon – Futurism

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There’s a Moon cube now! At least, it looks that way based on some intriguing photos from the Chinese lunar rover Yutu-2, released by the country’s space agency this week.

The photos show a distant object that looks like a perfect cube, and China say the rover is headed to check it out.

It’s worth worth noting a few caveats about the photo, spotted yesterday by space journalist Andrew Jones, who described the formation as a “cubic shape.” For one thing, the object is just a few pixels in the photo, meaning it could easily be some sort of optical illusion that’ll be a disappointment up close.

And China has struggled with lunar science communication in the past. In 2019, Yutu-2 “discovered” a “gel-like substance” on the lunar surface, but upon closer inspection it turned out to be, well, rocks. It also trumpeted the discover of a “shard” on the Moon earlier this year, but that turned out to just be another interesting rock. Did we mention that there’s not a lot other than rocks on the Moon?

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Jones, for his part, is managing expectations.

“So yeah, it’s not an obelisk or aliens, but certainly something to check out,” Jones tweeted in followup.

The idea of alien artifacts on the Moon runs deep in popular culture — remember that one scene in “2001: A Space Odyssey”? — but, needless to say, none have been found in reality.

The apparent cube sits in the Von Kármán crater, and China’s space program has been dubbed it, evocatively, the “mystery house.”

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Yutu-2 will spend two or three lunar days traveling to investigate the cube; lunar days are about 50 minutes longer than solar days on Earth.

Jones speculated that the object could be a boulder carved out by an asteroid impact, and posted a photo of a similarly sharply defined boulder found previously on the Moon’s surface.

CNET’s coverage of the most recent discovery agrees with Jones’ analysis, saying the most likely explanation is that the Moon cube is a boulder.

That’s not to say Yutu-2 hasn’t ever found anything cool. In 2019, CNET reported the rover discovered that the Moon’s surface was made of different materials than we previously thought, a discovery that could better predict how Earth’s internal layers might change over time.

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We’re not saying there isn’t weird stuff on the Moon. After all, we just recently found enough buried oxygen under its surface to sustain billions of people. But suffice it to say we aren’t holding our breath over Moon cube, and if it turns out to be anything other than a rock we’ll be really impressed.

More on space: Scientists Discover Enormous Black Hole Right Near Our Galaxy

Care about supporting clean energy adoption? Find out how much money (and planet!) you could save by switching to solar power at UnderstandSolar.com. By signing up through this link, Futurism.com may receive a small commission.

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