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    A moon-forming cataclysm could have also triggered Earth’s plate tectonics

    THE WOODLANDS, TEXAS — Vestiges of a moon-forming cataclysm could have kick-started plate tectonics on Earth.

    The leading explanation for the origin of the moon proposes that a Mars-sized planet, dubbed Theia, struck the nascent Earth, ejecting a cloud of debris into space that later coalesced into a satellite (SN: 3/2/18). New computer simulations suggest that purported remains of Theia deep inside the planet could have also triggered the onset of subduction, a hallmark of modern plate tectonics, geodynamicist Qian Yuan of Caltech reported March 13 at the Lunar and Planetary Science Conference.

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    The story offers a cohesive explanation for how Earth gained both its moon and its moving tectonic plates, and it could aid in the search for other Earthlike worlds. But others caution that it’s much too early to say that this is, in fact, what happened.

    Of all the worlds yet discovered, ours is the only one confirmed to have plate tectonics (SN: 1/13/21). For billions of years, Earth’s creeping plates have spread, collided and plunged beneath one another, birthing and splitting continents, uplifting mountain ranges and widening oceans (SN: 4/22/20, SN: 1/11/17). But all this reshaping has also erased most of the clues to the planet’s early history, including how and when plate tectonics first began.

    Many hypotheses have been proposed to explain the initiation of subduction, a tectonic process in which one plate slides under another (SN: 5/2/22; SN: 6/5/19; SN: 1/2/18). Yuan and his colleagues chose to focus on two continent-sized blobs of material in Earth’s lower mantle known as large low-shear velocity provinces (SN: 5/12/16). These are regions through which seismic waves are known to move anomalously slow. Researchers had previously proposed these regions could have formed from old, subducted plates. But in 2021, Yuan and colleagues alternatively proposed that the mysterious masses could be the dense, sunken remnants of Theia.

    Building off that previous work, the researchers used computers to simulate how Theia’s impact, and its lingering remains, would impact the flow of rock inside the Earth.

    They found that once these hot alien blobs had sunk to the bottom of the mantle, they could have compelled large plumes of warm rock to upwell and wedge into Earth’s rigid outer layer. As upwelling continued to feed into the risen plumes, they would have ballooned and pushed slabs of Earth’s surface beneath them, triggering subduction about 200 million years after the moon formed.

    While the simulations suggest the large low-shear velocity provinces could have had a hand in starting subduction, it’s not yet clear whether these masses came from Theia. “The features … are a fairly recent discovery,” says geodynamicist Laurent Montési of the University of Maryland in College Park. “They’re very fascinating structures, with a very unknown origin.” As such, he says, it’s too early to say that Theia triggered plate tectonics.

    “It’s provoking. This material down there is something special,” Montési says of the large low-shear velocity provinces. “But whether it has to be originally extraterrestrial, I don’t think the case is made.”

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    However, if confirmed, the explanation could have implications that reach beyond our solar system. “If you have a large moon, you likely have a large impactor,” Yuan said. Scientists have yet to confirm the discovery of such an exomoon (SN: 4/30/19). But keeping an eye out, Yuan said, could help us uncover another world as tectonically active as our own. More

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    What has Perseverance found in two years on Mars?

    In August 2021 on a lonely crater floor, the newest Mars rover dug into one of its first rocks.

    The percussive drill attached to the arm of the Perseverance rover scraped the dust and top several millimeters off a rocky outcrop in a 5-centimeter-wide circle. From just above, one of the rover’s cameras captured what looked like broken shards wedged against one another. The presence of interlocking crystal textures became obvious. Those textures were not what most of the scientists who had spent years preparing for the mission expected.

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    Then the scientists watched on a video conference as the rover’s two spectrometers revealed the chemistry of those meshed textures. The visible shapes along with the chemical compositions showed that this rock, dubbed Rochette, was volcanic in origin. It was not made up of the layers of clay and silt that would be found at a former lake bed.

    Nicknamed Percy, the rover arrived at the Jezero crater two years ago, on February 18, 2021, with its sidekick helicopter, Ingenuity. The most complex spacecraft to explore the Martian surface, Percy builds on the work of the Curiosity rover, which has been on Mars since 2012, the twin Spirit and Opportunity rovers, the Sojourner rover and other landers.

    But Perseverance’s main purpose is different. While the earlier rovers focused on Martian geology and understanding the planet’s environment, Percy is looking for signs of past life. Jezero was picked for the Mars 2020 mission because it appears from orbit to be a former lake environment where microbes could have thrived, and its large delta would likely preserve any signs of them. Drilling, scraping and collecting pieces of the Red Planet, the rover is using its seven science instruments to analyze the bits for any hint of ancient life. It’s also collecting samples to return to Earth.

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    Since landing, “we’ve been able to start putting together the story of what has happened in Jezero, and it’s pretty complex,” says Briony Horgan, a planetary scientist at Purdue University in West Lafayette, Ind., who helps plan Percy’s day-to-day and long-term operations.

    Volcanic rock is just one of the surprises the rover has uncovered. Hundreds of researchers scouring the data Perseverance has sent back so far now have some clues to how the crater has evolved over time. This basin has witnessed flowing lava, at least one lake that lasted perhaps tens of thousands of years, running rivers that created a mud-and-sand delta and heavy flooding that brought rocks from faraway locales.

    Jezero has a more dynamic past than scientists had anticipated. That volatility has slowed the search for sedimentary rocks, but it has also pointed to new alcoves where ancient life could have taken hold.

    Perseverance has turned up carbon-bearing materials — the basis of life on Earth — in every sample it has abraded, Horgan says. “We’re seeing that everywhere.” And the rover still has much more to explore.

    On the floor of the Jezero crater (shown on July 28, 2021), Perseverance found rocks that were volcanic in nature, not the sedimentary rocks that scientists expected from a dry lake bed.JPL-CALTECH/NASA, ASU, MSSS

    Perseverance finds unexpected rocks

    Jezero is a shallow impact crater about 45 kilo­meters in diameter just north of the planet’s equator. The crater formed sometime between 3.7 billion and 4.1 billion years ago, in the solar system’s first billion years. It sits in an older and much larger impact basin known as Isidis. At Jezero’s western curve, an etched ancient riverbed gives way to a dried-out, fan-shaped delta on the crater floor.

    That delta “is like this flashing signpost beautifully visible from orbit that tells us there was a standing body of water here,” says astrobiologist Ken Williford of Blue Marble Space Institute of Science in Seattle.

    Perseverance landed on the crater floor about two kilometers from the front of the delta. Scientists thought they’d find compacted layers of soil and sand there, at the base of what they dubbed Lake Jezero. But the landscape immediately looked different than expected, says planetary geologist Kathryn Stack Morgan of NASA’s Jet Propulsion Laboratory in Pasadena, Calif. Stack Morgan is deputy project scientist for Perseverance.

    Closeup images of an abraded rock from the floor of the Jezero crater show a distinct crystalline structure.JPL-CALTECH/NASA, MSSS

    For the first several months after the landing, the Mars 2020 mission team tested the rover’s movements and instruments, slowly, carefully. But from the first real science drilling near the landing location, researchers back on Earth realized what they had found. The texture of the rock, Stack Morgan says, was “a textbook igneous volcanic rock texture.” It looked like volcanic lava flows.

    Over the next six months, several more rocks on the crater floor revealed igneous texture. Some of the most exciting rocks, including Rochette, showed olivine crystals throughout. “The crystal fabric was obviously cooled from a melt, not transported grains,” as would be the case if it were a sedimentary sample, says Abigail Allwood of the Jet Propulsion Lab. She leads the rover’s PIXL instrument, which uses an X-ray beam to identify each sample’s composition.

    Mission scientists now think the crater floor is filled with igneous rocks from two separate events — both after the crater was created, so more recently than the 3.7 billion to 4.1 billion years ago time frame. In one, magma from deep within the planet pushed toward the surface, cooled and solidified, and was later exposed by erosion. In the other, smaller lava flows streamed at the surface.

    Sometime after these events, water flowed from the nearby highlands into the crater to form a lake tens of meters deep and lasting tens of thousands of years at least, according to some team members. Percy’s instruments have revealed the ways that water altered the igneous rocks: For example, scientists have found sulfates and other minerals that require water to form, and they’ve seen empty pits within the rocks’ cracks, where water would have washed away material. As that water flowed down the rivers into the lake, it deposited silt and mud, forming the delta. Flooding delivered 1.5-meter-wide boulders from that distant terrain. All of these events preceded the drying of the lake, which might have happened about 3 billion years ago.

    Core samples, which Perseverance is collecting and storing on board for eventual return to Earth, could provide dates for when the igneous rocks formed, as well as when the Martian surface became parched. During the time between, Lake Jezero and other wet environments may have been stable enough for microbial life to start and survive.

    “Nailing down the geologic time scale is of critical importance for us understanding Mars as a habitable world,” Stack Morgan says. “And we can’t do that without samples to date.”

    About a year after landing on Mars, Perseverance rolled several kilometers across the crater floor to the delta front — where it encountered a very different geology.

    The delta might hold signs of ancient life

    Deltas mark standing, lasting bodies of water — stable locales that could support life. Plus, as a delta grows over time, it traps and preserves organic matter.

    Sand and silt deposited where a river hits a lake get layered into sedimentary material, building up a fan-shaped delta. “If you have any biological material that is trapped between that sediment, it gets buried very quickly,” says Mars geologist Eva Scheller of MIT, a researcher with the Percy team. “It creates this environment that is very, very good for preserving the organic matter.”

    While exploring the delta front between April 2022 and December 2022, Perseverance found some of the sedimentary rocks it was after.

    Sedimentary rocks made of layers of sand and silt turned up in the delta front region (shown on April 16, 2022), which Perseverance has been exploring since April of last year.JPL-CALTECH/NASA, ASU

    Several of the rover’s instruments zoomed in on the textures and shapes of the rocks, while other instruments collected detailed spectral information, revealing the elements present in those rocks. By combining the data, researchers can piece together what the rocks are made of and what processes might have changed them over the eons. It’s this chemistry that could reveal signs of ancient Martian life — biosignatures. Scientists are still in the early stages of these analyses.

    There won’t be one clear-cut sign of life, Allwood says. Instead, the rover would more likely reveal “an assemblage of characteristics,” with evidence slowly building that life once existed there.

    Chemical characteristics suggestive of life are most likely to hide in sedimentary rocks, like those Perseverance has studied at the delta front. Especially interesting are rocks with extremely fine-grained mud. Such mud sediments, Horgan says, are where — in deltas on Earth, at least — organic matter is concentrated. So far, though, the rover hasn’t found those muddy materials.

    But the sedimentary rocks studied have revealed carbonates, sulfates and unexpected salts — all materials indicating interaction with water and important for life as we know it. Percy has found carbon-based matter in every rock it has abraded, Horgan says.

    “We’ve had some really interesting results that we’re pretty excited to share with the community,” Horgan says about the exploration of the delta front. Some of those details may be revealed in March at the Lunar and Planetary Science Conference.

    Perseverance leaves samples for a future mission

    As of early February, Perseverance has collected 18 samples, including bits of Mars debris and cores from rocks, and stored them on board in sealed capsules for eventual return to Earth. The samples come from the crater floor, delta front rocks and even the thin Martian atmosphere.

    In the final weeks of 2022 and the first weeks of 2023, the rover dropped — or rather, carefully set down — half of the collected samples, as well as a tube that would reveal whether samples contained any earthly contaminants. These captured pieces of Mars are now sitting at the front of the delta, at a predetermined spot called the Three Forks region.

    Perseverance deposited a cache of samples in the Three Forks region in December and January. If the rover isn’t operable when a future mission arrives at Mars, the samples can still be collected and returned to Earth.JPL-CALTECH/NASA, MSSS

    If Perseverance isn’t functioning well enough to hand over its onboard samples when a future sample-return spacecraft arrives, that mission will collect these samples from the drop site to bring back to Earth.

    Researchers are currently working on designs for a joint Mars mission between NASA and the European Space Agency that could retrieve the samples. Launching in the late 2020s, it would land near the Perseverance rover. Percy would transfer the samples to a small rocket to be launched from Mars and returned to Earth in the 2030s. Lab tests could then confirm what Perseverance is already uncovering and discover much more.

    Meanwhile, Percy is climbing up the delta to explore its top, where muddy sedimentary rocks may still be found. The next target is the edge of the once-lake, where shallow water long ago stood. This is the site Williford is most excited about. Much of what we know about the history of how life has evolved on Earth comes from environments with shallow water, he says. “That’s where really rich, underwater ecosystems start to form,” he says. “There’s so much going on there chemically.”

    Perseverance landed on Mars in February 2021. As of early February of this year, the rover had gathered 18 samples — and deposited half for a future potential return to Earth.JPL-CALTECH/NASA More

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    Enceladus is blanketed in a thick layer of snow

    Saturn’s moon Enceladus is shrouded in a thick layer of snow. In some places, the downy stuff is 700 meters deep, new research suggests.

    “It’s like Buffalo, but worse,” says planetary scientist Emily Martin, referring to the famously snowy city in New York. The snow depth suggests that Enceladus’ dramatic plume may have been more active in the past, Martin and colleagues report in the Mar. 1 Icarus.

    Planetary scientists have been fascinated by Enceladus’ geysers, made up of water vapor and other ingredients, since the Cassini spacecraft spotted them in 2005 (SN: 12/16/22). The spray probably comes from a salty ocean beneath an icy shell.

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    Some of that water goes to form one of Saturn’s rings (SN: 5/2/06). But most of it falls back onto the moon’s surface as snow, Martin says. Understanding the properties of that snow — its thickness and how dense and compact it is — could help reveal Enceladus’ history, and lay groundwork for future missions to this moon.

    “If you’re going to land a robot there, you need to understand what it’s going to be landing into,” says Martin, of the National Air and Space Museum in Washington, D.C.

    To figure out how thick Enceladus’ snow is, Martin and colleagues looked to Earth — specifically, Iceland. The island country hosts geological features called pit chains, which are lines of pockmarks in the ground formed when loose rubble such as rocks, ice or snow drains into a crack underneath (SN: 10/23/18). Similar features show up all over the solar system, including Enceladus.

    Pit chain craters in Iceland, like those shown here, helped planetary scientist Emily Martin and colleagues verify that they could measure the depth of craters on Enceladus. Martin took this image during a field excursion.E. Martin

    Previous work suggested a way to use geometry and the angle at which sunlight hits the surface to measure the depth of the pits. That measurement can then reveal the depth of the material the pits sit in. A few weeks of fieldwork in Iceland in 2017 and 2018 convinced Martin and her colleagues that the same technique would work on Enceladus.

    Using images from Cassini, Martin and colleagues found that the snow’s thickness varies across Enceladus’ surface. It is hundreds of meters deep in most places and 700 meters deep at its thickest.

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    It’s hard to imagine how all that snow got there, though, Martin says. If the plume’s spray was always what it is today, it would take 4.5 billion years — the entire age of the solar system — to deposit that much snow on the surface. Even then, the snow would have to be especially fluffy.

    It seems unlikely that the plume switched on the moment the moon formed and never changed, Martin says. And even if it did, later layers of snow would have compressed the earlier ones, compacting the whole layer and making it much less deep than it is today.

    “It makes me think we don’t have 4.5 billion years to do this,” Martin says. Instead, the plume might have been much more active in the past. “We need to do it in a much shorter timeframe. You need to crank up the volume on the plume.”

    The technique was clever, says planetary scientist Shannon MacKenzie of the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. Without rovers or astronauts on the ground, there’s no way to scoop up the snow and see how far down it goes. “Instead, the authors are very cleverly using geology to be their rovers, to be their shovels.”

    MacKenzie was not involved in the new work, but she led a mission concept study for an orbiter and lander that could one day visit Enceladus. One of the major questions in that study was where a lander could safely touch down. “Key to those discussions was, what do we expect the surface to be?” she says. The new paper could help “identify the places that are too fluffy to land in.” More

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    Io may have an underworld magma ocean or a hot metal heart

    CHICAGO — An entire ocean of liquid magma, or maybe a hot heart of solid metal, may lurk in Io’s underworld.

    The surface of Jupiter’s innermost moon is covered in scorching lava lakes and gored by hundreds of active volcanoes, some spitting molten rock dozens of kilometers high (SN: 8/6/14). Over the years, the moon’s restless, mesmerizing hellscape has attracted the attention of many planetary scientists (SN: 5/3/22).

    Now, researchers are digging into the nature of Io’s infernal interior to explain what is driving the spectacular volcanism on the moon’s fiery surface. “It’s the most volcanically active place in the solar system,” says planetary scientist Samuel Howell of NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “But it’s not really clear where that energy comes from.”

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    Researchers generally agree that Io gets most of its energy from a gravitational tug-of-war between its parent planet Jupiter and its sibling moon Europa. Those grand forces pull on Io’s rocky body, generating tremendous frictional heat in its interior. But how that heat is stored and moved around remains a mystery.

    One explanation is that Io’s netherworld may house an enormous ocean of liquid magma, planetary scientist David Stevenson of Caltech said December 15 at the American Geophysical Union’s fall meeting. Though the exact size of the proposed molten sea remains uncertain, it would need to be relatively large, he said. “The magma ocean could be, say, 100 kilometers thick.”

    In 2011, researchers reported that Io’s mantle couldn’t be completely solid. Magnetic measurements of Io from the Galileo spacecraft indicated there must be an electrically conductive layer inside the moon. A global underground layer containing molten rock, the scientists wrote, would fit the bill.  

    Hot spots speckle the surface of the volcanic moon Io in this infrared image captured by NASA’s Juno spacecraft on July 5, 2022, when the spacecraft was about 80,000 kilometers from the moon.JPL-Caltech/NASA, SwRI, ASI, INAF, JIRAM

    But the researchers couldn’t tell whether that layer would consist of a continuous sea of magma or many little pockets of molten rock dispersed throughout solid rock, resembling a soggy sponge.

    Building off that previous work, Stevenson and Caltech geophysicist Yoshinori Miyazaki calculated that a mixed layer of magma and solid rock beneath Io’s crust would be fundamentally unstable under the amount of heating they predict occurs inside the moon. The molten rock and solid rock would split into distinct layers, with the molten rock coalescing into a subsurface sea, Stevenson said. “The final conclusion is [that] Io has a magma ocean.”

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    But there are other possibilities. “A lot of information is consistent with a large, global conductive layer that could be a magma ocean,” Howell says. “But I wouldn’t say there’s consensus on how to interpret that data.”

    Instead, the truth may lie within Io’s heart, where a core made of solid metal may lurk, Howell reported December 15 at the meeting. Previous research has suggested that Io has a core rich in metals. Howell and colleagues calculate that a metal core that’s about as rigid as solid ice and a rocky mantle as viscous as Earth’s could fully dispense the immense quantities of heat that Io is estimated to emit. That would fulfill the energy-shedding role of a magma ocean.

    Future measurements collected by NASA’s ongoing Juno mission as well two future spacecraft — NASA’s Europa Clipper and the European Space Agency’s JUICE — may provide the data needed to determine whether either, or some combination, of the hypotheses is correct, Stevenson and Howell said (SN: 12/15/22). Until then, the mystery of what dwells in Io’s dark depths may have to remain in purgatory. More

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    The last vital ingredient for life has been discovered on Enceladus

    CHICAGO — The last key ingredient for life has been discovered on Saturn’s icy moon Enceladus.

    Phosphorus is a vital building block of life, used to construct DNA and RNA. Now, an analysis of data from NASA’s Cassini spacecraft reveals that Enceladus’ underground ocean contains the crucial nutrient. Not only that, its concentrations there may be thousands of times greater than in Earth’s ocean, planetary scientist Yasuhito Sekine reported December 14 at the American Geophysical Union’s fall meeting.

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    The essential element may abound on many other icy worlds too, holding promise for the search for alien life, said Sekine, of the Tokyo Institute of Technology.

    “We knew that Enceladus had most of the elements that are essential for life as we know it — carbon, hydrogen, nitrogen, oxygen and sulfur,” says Morgan Cable, an astrobiologist at the Jet Propulsion Laboratory in Pasadena, Calif., who was not involved in the research. “Now that [phosphorus] has been confirmed … Enceladus now appears to meet all of the criteria for a habitable ocean.”

    Many researchers consider Enceladus to be among the most likely places to house extraterrestrial life. It’s a world encased in ice, with an ocean of salty water hidden beneath (SN: 11/6/17). What’s more, in 2005 the Cassini spacecraft observed geysers blasting vapor and ice grains out of Enceladus’ icy shell (SN: 8/23/05). And in that space-faring spray, scientists have detected organic molecules.

    But until now, researchers weren’t sure if phosphorus also existed on Enceladus. On Earth’s surface, the element is relatively scarce. Much of the phosphorus is locked away in minerals, and its availability often controls the pace at which life can proliferate.

    So Sekine and colleagues analyzed chemical data, collected by the now-defunct Cassini, of particles in Saturn’s E ring, a halo of material ejected from Enceladus’ jets that wraps around Saturn.

    Some ice grains in the E ring are enriched in a phosphorus compound called sodium phosphate, the researchers found. They estimate that a kilogram of water from Enceladus’ ocean contains roughly 1 to 20 millimoles of phosphate, a concentration thousands of times greater than in Earth’s big blue ocean.

    At the floor of Enceladus’ subsurface ocean, phosphate may arise from reactions between seawater and a phosphate-bearing mineral called apatite, Sekine said, before being ejected through geysers into space. Apatite is often found in carbonaceous chondrites, a primitive, planet-building material (SN: 7/14/17).

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    But that’s not all. Many other icy ocean worlds may contain apatite as well, Sekine said. Similarly, they too could also carry high levels of phosphate in their oceans. That richness could be a boon for any potential alien organisms.

    Though the findings are promising, they give rise to a glaring conundrum, Sekine said. “If life exists [on] Enceladus, why [does] such [an] abundance of chemical energy and nutrients remain?” After all, here on Earth, any available phosphorus is rapidly scavenged by life.

    It’s possible that the moon is simply barren of life, Sekine said. But there’s another more hopeful explanation too. Life on frigid Enceladus, he said, may simply consume the nutrient at a sluggish pace. More

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    NASA’s Perseverance rover captured the sound of a dust devil on Mars

    Thanks to a bit of good luck, the Mars rover Perseverance has captured the first-ever sound of a Martian dust devil.

    The NASA rover has witnessed dusty whirlwinds before. But when this one swept right over Perseverance, the rover’s microphone happened to be turned on. So the first-of-its-kind data include the sounds of dust grains either pinging off the microphone or being transmitted to the mic through the rover’s structure, researchers report December 13 in Nature Communications.

    Because the rover’s microphone is turned on only occasionally, the team estimates that such events, when they occur, might be recorded just around 0.5 percent of the time.

    [embedded content]
    On September 27, 2021, Perseverance’s navigation camera spotted a dust devil (purplish cloud in the images at top, which were processed to reveal the dust) whirling toward it from 50 to 60 meters away. As the whirlwind swept across the rover, Perseverance’s microphone recorded the sound it made, capturing the first-ever audio of a Martian dust devil (middle), and the rover’s instruments detected a slight drop in atmospheric pressure (bottom). These data may someday help researchers better understand dust dynamics on Mars.

    Wind speeds in the walls of the dust devil reached nearly 40 kilometers per hour, planetary scientist Naomi Murdoch of the Institut Supérieur de l’Aéronautique et de l’Espace in Toulouse, France, and colleagues report. As with previous whirlwinds detected by other instruments, this late-morning dust devil caused a slight drop in atmospheric pressure and rise in temperature as it swept over the rover on September 27, 2021. It was 25 meters in diameter, at least 118 meters tall and ambled by at about 20 kilometers per hour.

    One big surprise, Murdoch says, is that a prodigious amount of dust was airborne in the calm center of the whirlwind as well as in the brisk winds that formed its walls. Data from this event, as well as from other whirlwinds measured by the rover’s instruments, will help researchers better understand how dust gets lifted off the Martian surface (SN: 10/24/06). As of yet, Murdoch says, that remains a mystery to planetary scientists (SN: 7/14/20). More

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    The pristine Winchcombe meteorite suggests that Earth’s water came from asteroids

    Late in the evening of February 28, 2021, a coal-dark space rock about the size of a soccer ball fell through the sky over northern England. The rock blazed in a dazzling, eight-second-long streak of light, split into fragments and sped toward the Earth. The largest piece went splat in the driveway of Rob and Cathryn Wilcock in the small, historic town of Winchcombe.

    An analysis of those fragments now shows that the meteorite came from the outer solar system, and contains water that is chemically similar to Earth’s, scientists report November 16 in Science Advances. How Earth got its water remains one of science’s enduring mysteries. The new results support the idea that asteroids brought water to the young planet (SN: 5/6/15).

    The Wilcocks were not the only ones who found pieces of the rock that fell that night. But they were the first. Bits of the Winchcombe meteorite were collected within 12 hours after they hit the ground, meaning they are relatively uncontaminated with earthly stuff, says planetary scientist Ashley King of London’s Natural History Museum.

    The first bits of the Winchcombe meteorite to be recovered were from Rob and Cathryn Wilcock’s driveway in England. The meteorite was so brittle it shattered on impact and made only a small dent in the driveway.R. Wilcock

    Other meteorites have been recovered after being tracked from space to the ground, but never so quickly (SN: 12/20/12).

    “It’s as pristine as we’re going to get from a meteorite,” King says. “Other than it landing in the museum on my desk, or other than sending a spacecraft up there, we can’t really get them any quicker or more pristine.”

    After collecting about 530 grams of meteorite from Winchcombe and other sites, including a sheep field in Scotland, King and colleagues threw a kitchen sink of lab techniques at the samples. The researchers polished the material, heated it and bombarded it with electrons, X-rays and lasers to figure out what elements and minerals it contained.

    The team also analyzed video of the fireball from the UK Fireball Alliance, a collaboration of 16 meteor-watching cameras around the world, plus many more videos from doorbell and dashboard cameras. The films helped to determine the meteorite’s trajectory and where it originated.

    The meteorite is a type of rare, carbon-rich rock called a carbonaceous chondrite, the team found. It came from an asteroid near the orbit of Jupiter, and got its start toward Earth around 300,000 years ago, a relatively short time for a trip through space, the researchers calculate.

    Chemical analyses also revealed that the meteorite is about 11 percent water by weight, with the water locked in hydrated minerals. Some of the hydrogen in that water is actually deuterium, a heavy form of hydrogen, and the ratio of hydrogen to deuterium in the meteorite is similar to that of the Earth’s atmosphere. “It’s a good indication that water [on Earth] was coming from water-rich asteroids,” King says.

    Researchers also found amino acids and other organic material in the meteorite pieces. “These are the building blocks for things like DNA,” King says. The pieces “don’t contain life, but they have the starting point for life locked up in them.” Further studies can help determine how those molecules formed in the asteroid that the meteorite came from, and how similar organic material could have been delivered to the early Earth.

    “It’s always exciting to have access to material that can provide a new window into an early time and place in our solar system,” says planetary scientist Meenakshi Wadhwa of Arizona State University in Tempe, who was not involved in the study.

    She hopes future studies will compare the samples of the Winchcombe meteorite to samples of asteroids Ryugu and Bennu, which were collected by spacecraft and sent back to Earth (SN: 1/15/19). Those asteroids are both closer to Earth than the main asteroid belt, where the Winchcombe meteorite came from. Comparing and contrasting all three samples will build a more complete picture of the early solar system’s makeup, and how it evolved into what we see today. More

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    in Space & Astronomy

    Marsquakes hint that the planet might be volcanically active after all

    Mars might be, geologically speaking, not quite dead.

    Researchers have analyzed a slew of recent temblors on the Red Planet and shown that these Marsquakes are probably caused by magma moving deep under the Martian surface. That’s evidence that Mars is still volcanically active, the researchers report October 27 in Nature Astronomy.

    Since touching down on Mars four years ago, NASA’s InSight lander has detected more than 1,000 Marsquakes (SN: 11/26/18). Its seismometer records seismic waves, which reveal information about a temblor’s size and location.

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    Previous studies have determined that several Marsquakes originated from a swath of Martian terrain known as Cerberus Fossae (SN: 5/13/22). This region, which is particularly riddled with faults, is more than 1,000 kilometers from the InSight lander.

    But most of the Marsquakes linked to Cerberus Fossae so far have been pretty familiar, scientifically speaking, says Anna Mittelholz, a planetary scientist at Harvard University. Their seismic waves, which are low frequency, “are ones that look much more like what we see for an earthquake,” she says.

    Mittelholz and her colleagues have now analyzed a large sample of Marsquakes, including more than 1,000 high-frequency temblors, which look nothing like their earthly brethren. To better understand the origin of the high-frequency quakes, the researchers added together their relatively weak signals. In that stack of seismic waves, the researchers saw a peak in the amount of seismic energy coming from the direction of Cerberus Fossae. That was an impressive undertaking, says Hrvoje Tkalčić, a geophysicist at the Australian National University in Canberra who was not involved with the research. “No study before this one attempted to locate the high-frequency quakes.”

    The fact that different types of Marsquakes are all concentrated in one region is a surprise. Previous research has suggested that Marsquakes might be due to Mars’ surface cooling and shrinking over time. That process, which occurs on the moon, would produce temblors evenly spread over the planet, Mittelholz says (SN: 5/13/19). “The expectation was that Marsquakes would originate from all over the place.”

    And by comparing the seismic waves that InSight measured with the seismic waves produced in different regions on our own planet, the researchers further showed that the low-frequency Marsquakes are probably produced by magma moving several tens of kilometers below Mars’ surface. “Our results are much more consistent with data from volcanic regions on Earth,” Mittelholz says.

    Rather than being a geologically dead planet, as some have suggested, Mars might be a surprisingly dynamic place, the researchers conclude. This finding rewrites our understanding of Mars, Mittelholz says, and there’s still so much more to learn about our celestial neighbor. “We’re only scratching the surface.”   More