Mars News and Discussions

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caltrek
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Largest Recent Impact Craters on Mars: Orbital Imaging and Surface Seismic Co-investigation
October 27, 2022

Introduction:
(Science)
An insightful impact

On 24 December 2021, the seismometer for the InSight mission on Mars detected a large seismic event with a distinct signature. Posiolova et al. discovered that the event was caused by a meteor impact on the surface of Mars, which was confirmed by satellite observations of a newly formed 150-kilometer crater. The surface nature and size of the impact allowed Kim et al. to detect surface waves from the event, which have yet to be observed on Mars. These surface waves help to untangle the structure of the Martian crust, which has various amounts of volcanic and sedimentary rock, along with subsurface ice, in different regions of the planet (see the Perspective by Yang and Chen). The characteristics of the impact itself are important because they provide a seismic fingerprint of an impact event that is different from the marsquakes observed so far. —BG

Abstract

Two >130-meter-diameter impact craters formed on Mars during the later half of 2021. These are the two largest fresh impact craters discovered by the Mars Reconnaissance Orbiter since operations started 16 years ago. The impacts created two of the largest seismic events (magnitudes greater than 4) recorded by InSight during its 3-year mission. The combination of orbital imagery and seismic ground motion enables the investigation of subsurface and atmospheric energy partitioning of the impact process on a planet with a thin atmosphere and the first direct test of martian deep-interior seismic models with known event distances. The impact at 35°N excavated blocks of water ice, which is the lowest latitude at which ice has been directly observed on Mars.
Read more here: https://www.science.org/doi/10.1126/science.abq7704
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Scientists unveil further proof of salty water on Mars
https://phys.org/news/2022-11-scientist ... -mars.html
by University of Southern Queensland
It may be known as a rocky, red planet but evidence is mounting that salty water exists at the base of polar deposits on Mars.

University of Southern Queensland's Professor Graziella Caprarelli is part of an international team investigating bright reflection signals below the Martian surface, first spotted in data acquired between 2010 and 2019 by the radar sounder MARSIS on board Mars Express.

The primarily Italian team proposed that the reflections pointed to a patchwork of salty lakes, publishing their research in Science in 2018 and in Nature Astronomy in 2021. Recently a new collaboration between the Italian team and U.S.-based researchers provided new evidence further corroborating this interpretation.

The results of these studies have been recently published in the journals Nature Communications and the Journal of Geophysical Research: Planets.

Professor Caprarelli said new laboratory experiments and simulations have ruled out alternative interpretations.

"We've explored questions such as 'is it possible that the strong radar signals could be produced by other types of materials like clays or saline ice, or by constructive interference,'" she said.

"The latest papers address the long standing question related to the temperatures at the base of the south polar cap: thus far, these were considered to be too low even for brines to be liquid."
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New Research Shows Mars's Crust is More Complex and Evolved Than Previously Thought
November 4, 2022

Introduction:
(EurekAlert) Early crust on Mars may be more complex than previously thought—and it may even be similar to our own planet’s original crust.

The Martian surface is uniformly basaltic, a product of billions of years of volcanism and flowing lava on the surface that eventually cooled. Because Mars did not undergo full-scale surface remodeling like the shifting of continents on Earth, scientists had thought Mars’ crustal history was a relatively simple tale.

But in a new study, researchers found locations in the Red Planet’s southern hemisphere with greater concentrations of silicon, a chemical element, than what would be expected in a purely basaltic setting. The silica concentration had been exposed by space rocks that slammed into Mars, excavating material that was embedded miles below the surface, and revealing a hidden past.

“There is more silica in the composition that makes the rocks not basalt, but what we call more evolved in composition,” says Valerie Payré, assistant professor in the Department of Earth and Environmental Sciences at the University of Iowa and the study’s corresponding author. “That tells us how the crust formed on Mars is definitely more complex than what we knew. So, it’s more about understanding that process, and especially what it means for how Earth’s crust first formed.”

Scientists believe Mars formed about 4.5 billion years ago. Exactly how the Red Planet came into being is a mystery, but there are theories. One idea is that Mars formed via a titanic collision of rocks in space that, with its intense heat, spawned an entirely liquefied state, also known as a magma ocean. The magma ocean gradually cooled, the theory goes, yielding a crust, like a layer of skin, that would be singularly basaltic.
Read more here: https://www.eurekalert.org/news-releases/969797
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Mars's crust is more complex and evolved than previously thought
https://phys.org/news/2022-11-mars-crus ... ously.html
by University of Iowa
Early crust on Mars may be more complex than previously thought—and it may even be similar to our own planet's original crust.

The Martian surface is uniformly basaltic, a product of billions of years of volcanism and flowing lava on the surface that eventually cooled. Because Mars did not undergo full-scale surface remodeling like the shifting of continents on Earth, scientists had thought Mars's crustal history was a relatively simple tale.

But in a new study, researchers found locations in the Red Planet's southern hemisphere with greater concentrations of silicon, a chemical element, than what would be expected in a purely basaltic setting. The silica concentration had been exposed by space rocks that slammed into Mars, excavating material that was embedded miles below the surface, and revealing a hidden past. The study, "An evolved early crust exposed on Mars revealed through spectroscopy," was published online Nov. 4 in the journal Geophysical Research Letters.

"There is more silica in the composition that makes the rocks not basalt, but what we call more evolved in composition," says Valerie Payré, assistant professor in the Department of Earth and Environmental Sciences at the University of Iowa and the study's corresponding author. "That tells us how the crust formed on Mars is definitely more complex than what we knew. So, it's more about understanding that process, and especially what it means for how Earth's crust first formed."

Scientists believe Mars formed about 4.5 billion years ago. Exactly how the Red Planet came into being is a mystery, but there are theories. One idea is that Mars formed via a titanic collision of rocks in space, that with intense heat spawned an entirely liquefied state, also known as a magma ocean. The magma ocean gradually cooled, the theory goes, yielding a crust, like a layer of skin, that would be singularly basaltic.
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NASA’s Perseverance Rover Discovers Possible Organic Compounds in Mars Crater Rocks
TOPICS:AstrobiologyImperial College LondonMarsMars 2020 Perseverance Rover
https://scitechdaily.com/nasas-persever ... ter-rocks/
November 25, 2022
Kodiak Butte Jezero Crater
Rock samples from the Jezero crater analyzed by NASA’s Perseverance Mars rover show evidence of liquid water and signatures that could be organic compounds.

Analyses of multiple rocks found at the bottom of Jezero Crater on Mars, where the Perseverance rover landed in 2020, has revealed significant interaction between the rocks and liquid water. Evidence consistent with the presence of organic compounds has also been discoved in those rocks.

“I hope that one day these samples could be returned to Earth so that we can explore whether conditions were right for life in the early history of Mars.” — Professor Mark Sephton

Organic compounds (chemical compounds with carbon–hydrogen bonds) can be created through nonbiological processes, so the mere existence of these compounds is not direct evidence of life. To determine this conclusively, a future mission returning the samples to Earth would be needed.

Led by researchers at Caltech and carried out by an international team including Imperial College London researchers, the study was published on November 23 in the journal Science.

Professor Mark Sephton, from the Imperial College London Department of Earth Science & Engineering, is a member of the science team who took part in rover operations on Mars and considered the implications of the results. He said: “I hope that one day these samples could be returned to Earth so that we can look at the evidence of water and possible organic matter, and explore whether conditions were right for life in the early history of Mars.”
Moving water

Perseverance previously found organic compounds at Jezero’s delta. Deltas are fan-shaped geologic formations created at the intersection of a river and a lake at the edge of the crater.

Mission scientists had been particularly interested in the Jezero delta because such formations can preserve microorganisms. Deltas are created when a river transporting fine-grained sediments enters a deeper, slower-moving body of water. As the river water spreads out, it abruptly slows down, depositing the sediments it is carrying and trapping and preserving any microorganisms that may exist in the water.

However, the crater floor, where the rover landed for safety reasons before traveling to the delta, was more of a mystery. In lake beds, the researchers expected to find sedimentary rocks, because the water deposits layer after layer of sediment. However, when the rover touched down there, some researchers were surprised to find igneous rocks (cooled magma) on the crater floor with minerals in them that recorded not just igneous processes but significant contact with water.

These minerals, such as carbonates and salts, require water to circulate in the igneous rocks, carving out niches and depositing dissolved minerals in different areas like voids and cracks. In some places, the data show evidence for organics within these potentially habitable niches.
Discovered by SHERLOC

The minerals and co-located possible organic compounds were discovered using SHERLOC, or the Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals instrument.

Mounted on the rover’s robotic arm, SHERLOC is equipped with a number of tools, including a Raman spectrometer that uses a specific type of fluorescence to search for organic compounds and also see how they are distributed in a material, providing insight into how they were preserved in that location.
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Mars megatsunami may have been caused by Chicxulub-like asteroid impact
https://phys.org/news/2022-12-mars-mega ... mpact.html
by Nature Publishing Group
A Martian megatsunami may have been caused by an asteroid collision similar to the Chicxulub impact—which contributed to the mass extinction of all non-avian dinosaurs on Earth 66 million years ago—in a shallow ocean region, according to a study published in Scientific Reports.

Previous research has proposed that an asteroid or comet impact within an ocean in the Martian northern lowlands may have caused a megatsunami approximately 3.4 billion years ago. However, prior to this study the location of the resulting impact crater was unclear.

Alexis Rodriguez and colleagues analyzed maps of Mars' surface, created by combining images from previous missions to the planet, and identified an impact crater that could have caused the megatsunami. The crater—which they have named Pohl—has a diameter of 110 kilometers and is located within an area of the northern lowlands that previous studies have suggested may have been covered by an ocean, in a region around 120 meters below its proposed sea level. The authors suggest that Pohl may have formed around 3.4 billion years ago based on its position above and below rocks previously dated to this time.
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Giant mantle plume reveals Mars is more active than previously thought
https://phys.org/news/2022-12-giant-man ... -mars.html
by University of Arizona
On Earth, shifting tectonic plates reshuffle the planet's surface and make for a dynamic interior, so the absence of such processes on Mars led many to think of it as a dead planet, where not much happened in the past 3 billion years.

In the current issue of Nature Astronomy, scientists from the University of Arizona challenge current views of Martian geodynamic evolution with a report on the discovery of an active mantle plume pushing the surface upward and causing earthquakes and volcanic eruptions. The finding suggests that the planet's deceptively quiet surface may hide a more tumultuous interior than previously thought.

"Our study presents multiple lines of evidence that reveal the presence of a giant active mantle plume on present-day Mars," said Adrien Broquet, a postdoctoral research associate in the UArizona Lunar and Planetary Laboratory and co-author of the study with Jeff Andrews-Hanna, an associate professor of planetary science at the LPL.

Mantle plumes are large blobs of warm and buoyant rock that rise from deep inside a planet and push through its intermediate layer—the mantle—to reach the base of its crust, causing earthquakes, faulting and volcanic eruptions. The island chain of Hawaii, for example, formed as the Pacific plate slowly drifted over a mantle plume.
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Long-lived lakes reveal a history of water on Mars
https://phys.org/news/2022-12-long-live ... -mars.html
by Sarah Derouin, Eos

The northern hemisphere of Mars is divided into two broadly distinctive areas: the smooth northern lowlands and the pockmarked southern highlands. The region of Arabia Terra sits along the transition between these two regions and is thought to contain some of the planet's oldest rocks, at more than 3.7 billion years old.

Among the craters in the southern highlands, valleys and paleolakes abound, exposing sedimentary and geomorphologic evidence of liquid water. However, relatively few paleolakes have been identified in Arabia Terra.

Z. I. Dickeson and colleagues used imagery and data from NASA's Context Camera (CTX), High Resolution Imaging Science Experiment (HiRISE), and Thermal Emission Imaging System (THEMIS) to study a roughly 22,000-square-kilometer area of Arabia Terra in detail.

From this imagery, the team created high-resolution maps and digital elevation models to study the area's geomorphology, which allowed them to identify and describe seven new paleolakes in the region. The work is published in the Journal of Geophysical Research: Planets.

The researchers focused on paleolake features including lake levels, drainage catchments, fans, and lake outlets. They found that the shapes of the lakes were irregular in comparison with the circular-shaped lakes found in craters in the southern highlands. There was evidence of surface water inflows that filled the lakes as well as outlet streams that drained them, forming a cascading chain of lakes.

The team also observed multiple past water levels within each of the paleolakes, indicating that the lakes persisted over long periods of time during the Noachian, rather than forming and disappearing quickly.
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