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  • richardmitnick 9:59 am on July 18, 2019 Permalink | Reply
    Tags: , , Chondrules, , H5 ordinary chondrite, In some meteorites there is 'stardust' even older than our Solar System which shows us how stars form and evolve to create elements of the periodic table., Maryborough meteorite, Meteorites, Meteorites provide the cheapest form of space exploration, Other rare meteorites contain organic molecules such as amino acids; the building blocks of life.,   

    From Science Alert: “Man Keeps Rock For Years Thinking It’s Gold. Turns Out It’s a Super Rare Meteorite” 

    ScienceAlert

    From Science Alert

    18 JUL 2019
    JACINTA BOWLER

    1
    (Museums Victoria)

    In 2015, David Hole was prospecting in Maryborough Regional Park near Melbourne, Australia.

    Armed with a metal detector, he discovered something out of the ordinary – a very heavy, reddish rock resting in some yellow clay.

    He took it home and tried everything to open it, sure that there was a gold nugget inside the rock – after all, Maryborough is in the Goldfields region, where the Australian gold rush peaked in the 19th century.

    To crack open his find, Hole tried a rock saw, an angle grinder, a drill, even putting the thing in acid, but not even a sledgehammer could make a crack. That’s because what he was trying so hard to open was no gold nugget. As he found out years later, it was a rare meteorite.

    “It had this sculpted, dimpled look to it,” Melbourne museum geologist Dermot Henry told The Sydney Morning Herald.

    “That’s formed when they come through the atmosphere, they are melting on the outside, and the atmosphere sculpts them.”

    Unable to open the ‘rock’, but still intrigued, Hole took the meteorite into the Melbourne Museum to be identified.

    “I’ve looked at a lot of rocks that people think are meteorites,” Henry told 10 daily.

    In fact, after 37 years of working at the museum and examining thousands of rocks, Henry explains only two of the offerings have ever turned out to be real meteorites.

    This was one of the two.

    2
    (Melbourne Museum)

    “If you saw a rock on Earth like this, and you picked it up, it shouldn’t be that heavy,” another Melbourne Museum geologist, Bill Birch, told The Sydney Morning Herald.

    The researchers have recently published a scientific paper [below] describing the 4.6 billion-year-old meteorite, which they’ve called Maryborough after the town near where it was found.

    It’s a huge 17 kilograms (37.5 pounds), and after using a diamond saw to cut off a small slice, they discovered its composition has a high percentage of iron, making it a H5 ordinary chondrite.

    Once open, you can also see the tiny crystallised droplets of metallic minerals throughout it, called chondrules.

    “Meteorites provide the cheapest form of space exploration. They transport us back in time, providing clues to the age, formation and chemistry of our Solar System (including Earth),” explains Henry.

    “Some provide a glimpse at the deep interior of our planet. In some meteorites, there is ‘stardust’ even older than our Solar System, which shows us how stars form and evolve to create elements of the periodic table.

    “Other rare meteorites contain organic molecules such as amino acids; the building blocks of life.”

    3
    (Birch et al., PRSV, 2019)

    Although the researchers don’t yet know where the meteorite came from and how long it may have been on Earth, they do have some guesses.

    Our Solar System was once a spinning pile of dust and chondrite rocks. Eventually gravity pulled a lot of this material together into planets, but the leftovers mostly ended up in a huge asteroid belt.

    “This particular meteorite most probably comes out of the asteroid belt between Mars and Jupiter, and it’s been nudged out of there by some asteroids smashing into each other, then one day it smashes into Earth,” Henry explained 10 daily.

    Carbon dating suggests the meteorite has been on Earth between 100 and 1,000 years, and there’s been a number of meteor sightings between 1889 and 1951 that could correspond to its arrival on our planet.

    The researchers argue that the Maryborough meteorite is much rarer than gold. It’s one of only 17 meteorites ever recorded in the Australian state of Victoria, and it’s the second largest chondritic mass, after a huge 55-kilogram specimen identified in 2003.

    “This is only the 17th meteorite found in Victoria, whereas there’s been thousands of gold nuggets found,” Henry told 10 daily.

    “Looking at the chain of events, it’s quite, you might say, astronomical it being discovered at all.”

    It’s not even the first meteorite to take a few years to make it to a museum. In a particularly amazing story we covered last year, one space rock took 80 years, two owners, and a stint as a doorstop before making it to a museum.

    Now is probably as good a time as any to check your backyard for particularly heavy and hard-to-break rocks – you might be sitting on a metaphorical gold mine.

    The research has been published in Proceedings of the Royal Society of Victoria, and if you’re in Victoria, you can find out how to see the meteorite in person here.

    See the full article here .


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  • richardmitnick 12:07 pm on June 5, 2019 Permalink | Reply
    Tags: , , Meteorites,   

    From Schmidt Ocean Institute: “The Hunt for the Quinault Meteorite Begins” 

    From Schmidt Ocean Institute

    June 4, 2019
    Linda Welzenbach

    The sea is pitching 8 foot swells at the R/V Falkor as the “Seeking Space Rocks” team transits to the first dive site in Olympic Coast National Marine Sanctuary. We have three days to look for meteorites on the seafloor, the second time this has ever been attempted.

    Schmidt Ocean Institute RV Falkor

    1
    The science team heads to R/V Falkor via “Water Taxi” to board at sea.

    As with most science operations, plans and their contingencies are adjusted as the situation demands. The crew are making last minute adjustments to the vacuum pump system that will operate in concert with the “cosmic dust pan,” a special seafloor scoop that was designed and fabricated by Jason Williams (Lead Mechanical Engineer of the R/V Falkor) and his team.

    2
    Jason Williams (Lead Mechanical Engineer shows the research team ROV SuBastian’s “cosmic dust pan” – a special seafloor scoop that was designed and fabricated for this mission. Linda Welzenbach Fries

    The Seeking Space Rocks science team, which includes PI Dr. Marc Fries, with Dr. Betsy Pugel, Dr. Ralph Harvey, and Dr. Ryan Ziegler, have to quickly decide on the first dive site. They pick a location that will allow testing of the meteorite acquisition equipment, provide information about the seafloor environment, and possibly net a few of the largest samples that fell from the sky following a dramatic fireball in March 2018. (For more information about the fireball go here.)

    Cosmic adventure: Seeking space rocks in Olympic Coast National Marine Sanctuary

    Two expeditions to the deep

    In summer of 2018, researchers from Olympic Coast National Marine Sanctuary, NASA, and the University of Washington joined Ocean Exploration Trust on the E/V Nautilus to attempt to locate and recover meteorite fragments from the seafloor. Once at the location of the fall, they mapped the area of the debris field and conducted a remotely operated vehicle (ROV) dive.

    Researchers located and recovered fragments with a variety of tools, including a specially-designed magnetic rake. One small melted fragment, called “fusion crust,” was confirmed to be from the meteorite exterior.

    3
    Overnight shift in the ROV control room, lit up by many monitors from various cameras on ROV SuBastian. Linda Welzenbach Fries

    Starting Things Off

    Dr. Marc Fries and Dr. Betsy Pugel take the first watch of ROV operations, which began at 1 a.m. Large screens in the science control room reveal a seafloor surface that is very flat, nearly featureless except for holes created from worms and other benthic infauna, and blanketed with mud and silt (very fine sand). Just before lunch Dr. Fries, the ROV Lead, Russell Coffield, and pilot, Cody Peyres, pick up a promising sample- a plumose anemone (unofficially named ‘Side-show Bob’) clasping what is obviously the only rock sample around. SuBastian picks it up and places it in the sample crate for return to the surface.

    4

    Needle In a Haystack

    Meteorites exhibit several unique characteristics that are not found in earth rocks, but finding and identifying them still requires experience. Today that experience, or “Ralphtroscopy,” is provided by team member Dr. Ralph Harvey. Dr. Harvey, who has extensive experience identifying meteorites in unusual field sites, can very quickly identify and classify the native seafloor materials in order to spot that which is different. Once he is calibrated for that which is different, he can then more easily “see” the meteorites.

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    Dr. Ralph Harvey sorting through mud looking for meteorite fragments. Linda Welzenbach Fries

    _________________________________________________________
    Cosmic adventure: Seeking space rocks in Olympic Coast National Marine Sanctuary

    May 2019

    On March 7, 2018, a large meteorite broke up and fell into the ocean about 15 miles off the coast of Washington into NOAA’s Olympic Coast National Marine Sanctuary. Eyewitnesses from nearby areas including Quinault Indian Nation and Grays Harbor County reported a bright flash in the sky and sonic booms loud enough to shake homes and cars. The event was so strong it was recorded by seismometers located deep on the seafloor. This summer, researchers will be searching for fragments of the meteorite within sanctuary waters.

    Meteorites include samples of the earliest stages in the formation of our solar system. Earth and other planets formed from smaller material, and meteorites are leftover remnants of that smaller material. They are pieces of the ancient solar system that you can hold in your hand or take to a laboratory to study. While meteorites fall harmlessly to Earth on a daily basis, occasionally a meteorite large enough to cause damage will fall.

    By studying the composition and mechanical properties of meteorites, we can better understand the potential danger from meteorite falls. One way to do this is by using weather radar imagery produced by NOAA, using software developed by NASA.

    7
    NASA scientist Dr. Marc Fries examines early sample returns attached to a magnetic board in 2018. Photo: Susan Poulton/OET

    Two expeditions to the deep

    In summer of 2018, researchers from Olympic Coast National Marine Sanctuary, NASA, and the University of Washington joined Ocean Exploration Trust on the E/V Nautilus to attempt to locate and recover meteorite fragments from the seafloor.

    7

    Once at the location of the fall, they mapped the area of the debris field and conducted a remotely operated vehicle (ROV) dive.

    Researchers located and recovered fragments with a variety of tools, including a specially-designed magnetic rake. One small melted fragment, called “fusion crust,” was confirmed to be from the meteorite exterior.

    7
    The fusion crust piece is shown here under a scanning electon micrscope. It is made of a silicate glass. Magnetic dendrites – the small feathery texture – indicate rapid cooling that occurred as the molten droplet flew through the upper atmosphere at several hundred miles per hour. Image courtesy of Marc Fries.

    In early June, NASA’s Dr. Marc Fries and international researchers will join the crew of Schmidt Ocean Institute’s R/V Falkor to return to the area, working 24 hours a day for five days. Jenny Waddell, research coordinator for Olympic Coast National Marine Sanctuary, will be on the team. During the Seeking Space Rocks expedition, researchers will use the ROV SuBastian to search for meteorite material and explore the seafloor.

    Schmidt Oceam Institute ROV Subastian

    Working in a previously explored range, they will use new sampling tools designed and fabricated by scientists at Schmidt Ocean Institute to retrieve rocks from the seafloor while leaving sediments and organisms in place.

    As the community closest to the debris field, the Quinault Indian Nation will have the opportunity to suggest a name for the meteorite in the event sufficient material is recovered during the expedition to warrant a record in the official database. In addition, the team plans to hold a ship-to-shore event with students from the Quinault Indian Nation during the expedition to give tribal youth an opportunity to speak to NASA scientists and ROV pilots directly. The event will be facilitated by Olympic Coast National Marine Sanctuary’s education and outreach specialist, Nicole Harris, in cooperation with teachers from Taholah School on the Quinault Indian Reservation.

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    Located on the outer shores of Washington state, Olympic Coast National Marine Sanctuary protects one of the last relatively undeveloped coastlines in the United States. Photo: NOAA

    Why seek meteorites?

    Meteorites are small pieces of the very complicated process that formed the solar system, each with its own formation and alteration history. Together the meteorites in the world’s collections make up a vast set of puzzle pieces, each with a contribution to make toward understanding the early days of our solar system. The more puzzle pieces we have, the more complete our picture of the puzzle becomes.

    Last year’s expedition with the E/V Nautilus produced a tiny melted fragment of meteorite, which is helpful but doesn’t provide enough information to clearly identify the meteorite. The follow-on expedition with the R/V Falkor is intended to learn from the Nautilus mission and attempt to recover at least one unmelted meteorite fragment. That will be enough to identify the meteorite, and to enter it into the Meteoritical Society database as another piece of the puzzle.

    The meteorite that caused the Olympic Coast fall behaved in an unusual fashion when it fell to Earth. Data from NOAA weather radar imagery shows that it was especially resistant to fragmentation, causing a surprising number of larger meteorites to survive the fall. If we can find out what kind of meteorite did this, we can use data on the abundance of different meteorite types to refine our expectations on how often a damaging meteorite fall might occur. If the Olympic Coast meteorite is a very rare type, then meteorite falls with its fragmentation behavior will be equally rare. If it is a more common type of meteorite, we may need to re-think the likelihood of meteorite falls that are capable of causing damage on the ground.

    Artist-At-Sea

    Scientists aren’t the only seekers on this mission. Schmidt Ocean Institute offers an Artist-At-Sea program, where artists work together with scientists and crew to take inspiration from research aboard Falkor.

    During the Seeking Space Rocks expedition, artist Abrian Cruington will be on board to illustrate the journey and mission. Her goal is to create a large map, incorporating scientific data and creating graphic stories. University of Washington graduate Elisa Aitoro will also join the expedition as a Schmidt Student Opportunities participant to assist the science party in their work.

    For media inquiries and other questions, contact Sarah Marquis, (949) 222-2212, sarah.marquis@noaa.gov.

    _________________________________________________________

    See the full article here .

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    Our Vision
    The world’s oceans understood through technological advancement, intelligent observation, and open sharing of information.

    Schmidt Ocean Institute RV Falkor

    Schmidt Ocean Institute ROV Subastian

    Schmidt Ocean Institute is a 501(c)(3) private non-profit operating foundation established in March 2009 to advance oceanographic research, discovery, and knowledge, and catalyze sharing of information about the oceans.

    Since the Earth’s oceans are a critically endangered and least understood part of the environment, the Institute dedicates its efforts to their comprehensive understanding across intentionally broad scope of research objectives.

    Eric and Wendy Schmidt established Schmidt Ocean Institute in 2009 as a seagoing research facility operator, to support oceanographic research and technology development focusing on accelerating the pace in ocean sciences with operational, technological, and informational innovations. The Institute is devoted to the inspirational vision of our Founders that the advancement of technology and open sharing of information will remain crucial to expanding the understanding of the world’s oceans.

     
  • richardmitnick 8:32 am on April 30, 2019 Permalink | Reply
    Tags: "Ashes of a Dying Star Hold Clues about Solar System's Birth", , , , By taking a sample of Bennu and bringing it back to Earth the OSIRIS-REx mission team hopes to provide scientists with material that has seen little if any alteration since the formation of our solar , Classified as a carbonaceous chondrite it is believed to be analogous to the material on Bennu the target asteroid of the UA-led OSIRIS-REx mission., , Dust grain LAP-149, Its companion is either a low-mass main sequence star or a red giant., LAP-149 is the first known grain consisting of graphite that contains an oxygen-rich silicate inclusion., Meteorites, Novae are binary star systems in which a core remnant of a star called a white dwarf is on its way to fading out of the universe, Stellar explosions have contributed to the chemical enrichment of the cosmos resulting in the plethora of elements we see today, The white dwarf then begins syphoning material off its bloated companion., Traced to a specific type of stellar explosion called a nova, Tucked inside a chondritic meteorite collected in Antarctica the tiny speck represents actual stardust, , UA's Kuiper Materials Imaging and Characterization Facility   

    From University of Arizona: “Ashes of a Dying Star Hold Clues about Solar System’s Birth” 

    U Arizona bloc

    From University of Arizona

    4.29.19
    Daniel Stolte

    A dust grain forged in a stellar explosion predating our solar system reveals new insights about how stars end their lives and seed the universe with the building blocks of new stars and planets.

    1
    Pierre Haenecour, the study’s lead author, is pictured with one of the ultra-high-resolution electron microscopes used to obtain chemical and microstructural information about the stardust grain. (Photo: Maria Schuchardt/University of Arizona)

    A grain of dust forged in the death throes of a long-gone star was discovered by a team of researchers led by the University of Arizona.

    2
    A team of researchers found a grain (inset image) encased in a meteorite that survived the formation of our solar system and analyzed it with instruments sensitive enough to identify single atoms in a sample. Measuring 1/25,000th of an inch, the carbon-rich graphite grain (red) revealed an embedded speck of oxygen-rich material (blue), two types of stardust that were thought could not form in the same nova eruption. (Image: Heather Roper/University of Arizona)

    The discovery challenges some of the current theories about how dying stars seed the universe with raw materials for the formation of planets and, ultimately, the precursor molecules of life.

    Tucked inside a chondritic meteorite collected in Antarctica, the tiny speck represents actual stardust, most likely hurled into space by an exploding star before our own sun existed. Although such grains are believed to provide important raw materials contributing to the mix from which the sun and our planets formed, they rarely survive the turmoil that goes with the birth of a solar system.

    “As actual dust from stars, such presolar grains give us insight into the building blocks from which our solar system formed,” said Pierre Haenecour, lead author of the paper that was published in Nature Astronomy. “They also provide us with a direct snapshot of the conditions in a star at the time when this grain was formed.”

    Dubbed LAP-149, the dust grain represents the only known assemblage of graphite and silicate grains that can be traced to a specific type of stellar explosion called a nova. Remarkably, it survived the journey through interstellar space and traveled to the region that would become our solar system some 4.5 billion years ago, perhaps earlier, where it became embedded in a primitive meteorite.

    Novae are binary star systems in which a core remnant of a star, called a white dwarf, is on its way to fading out of the universe, while its companion is either a low-mass main sequence star or a red giant. The white dwarf then begins syphoning material off its bloated companion. Once it accretes enough new stellar material, the white dwarf re-ignites in periodic outbursts violent enough to forge new chemical elements from the stellar fuel and spew them deep into space, where they can travel to new stellar systems and become incorporated in their raw materials.

    Since shortly after the Big Bang, when the universe consisted of only hydrogen, helium and traces of lithium, stellar explosions have contributed to the chemical enrichment of the cosmos, resulting in the plethora of elements we see today.

    Taking advantage of sophisticated ion and electron microscopy facilities at the UA’s Lunar and Planetary Laboratory, a research team led by Haenecour analyzed the microbe-sized dust grain down to the atomic level. The tiny messenger from outer space turned out to be truly alien – highly enriched in a carbon isotope called 13C.

    “The carbon isotopic compositions in anything we have ever sampled that came from any planet or body in our solar system varies typically by a factor on the order of 50,” said Haenecour, who will join the Lunar and Planetary Laboratory as an assistant professor in the fall. “The 13C we found in LAP-149 is enriched more than 50,000-fold. These results provide further laboratory evidence that both carbon- and oxygen-rich grains from novae contributed to the building blocks of our solar system.”

    Although their parent stars no longer exist, the isotopic and chemical compositions and microstructure of individual stardust grains identified in meteorites provide unique constraints on dust formation and thermodynamic conditions in stellar outflows, the authors wrote.

    Detailed analysis revealed even more unexpected secrets: Unlike similar dust grains thought to have been forged in dying stars, LAP-149 is the first known grain consisting of graphite that contains an oxygen-rich silicate inclusion.

    “Our find provides us with a glimpse into a process we could never witness on Earth,” Haenecour added. “It tells us about how dust grains form and move around inside as they are expelled by the nova. We now know that carbonaceous and silicate dust grains can form in the same nova ejecta, and they get transported across chemically distinct clumps of dust within the ejecta, something that was predicted by models of novae but never found in a specimen.”

    Unfortunately, LAP-149 does not contain enough atoms to determine its exact age, so researchers hope to find similar, larger specimens in the future.

    “If we could date these objects someday, we could get a better idea of what our galaxy looked like in our region and what triggered the formation of the solar system,” said Tom Zega, scientific director of the UA’s Kuiper Materials Imaging and Characterization Facility and associate professor in the Lunar and Planetary Laboratory and UA Department of Materials Science and Engineering. “Perhaps we owe our existence to a nearby supernova explosion, compressing clouds of gas and dust with its shockwave, igniting stars and creating stellar nurseries, similar to what we see in Hubble’s famous ‘Pillars of Creation’ picture.”

    The meteorite containing the speck of stardust is one of the most pristine meteorites in the Lunar and Planetary Laboratory’s collection. Classified as a carbonaceous chondrite, it is believed to be analogous to the material on Bennu, the target asteroid of the UA-led OSIRIS-REx mission. By taking a sample of Bennu and bringing it back to Earth, the OSIRIS-REx mission team hopes to provide scientists with material that has seen little, if any, alteration since the formation of our solar system.

    NASA OSIRIS-REx Spacecraft

    Until then, researchers depend on rare finds like LAP-149, which survived being blasted from an exploding star, caught in a collapsing cloud of gas and dust that would become our solar system and baked into an asteroid before falling to the earth.

    “It’s remarkable when you think about all the ways along the way that should have killed this grain,” Zega said.

    For a complete list of authors who contributed to this study and their affiliations, please see the paper, “Laboratory evidence for co-condensed oxygen- and carbon-rich meteoritic stardust from nova outbursts,” Nature Astronomy, DOI: 10.1038/s41550-019-0757-4. Support for this study was provided by organizations including NASA and the National Science Foundation, which also supports the UA Kuiper Material Imaging and Characterization Facility, which made the detailed analysis of the LAP-149 sample possible.

    See the full article here .


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    U Arizona campus

    The University of Arizona (UA) is a place without limits-where teaching, research, service and innovation merge to improve lives in Arizona and beyond. We aren’t afraid to ask big questions, and find even better answers.

    In 1885, establishing Arizona’s first university in the middle of the Sonoran Desert was a bold move. But our founders were fearless, and we have never lost that spirit. To this day, we’re revolutionizing the fields of space sciences, optics, biosciences, medicine, arts and humanities, business, technology transfer and many others. Since it was founded, the UA has grown to cover more than 380 acres in central Tucson, a rich breeding ground for discovery.

    Where else in the world can you find an astronomical observatory mirror lab under a football stadium?

    U Arizona mirror lab


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  • richardmitnick 3:36 pm on April 15, 2019 Permalink | Reply
    Tags: , , , , , Meteorites, The cometary building block material was swallowed by an asteroid and preserved inside this meteorite, The LaPaz meteorite, This research used resources of the Advanced Light Source at LBNL   

    From Carnegie Institution for Science: “Cometary surprise found inside meteorite” 

    Carnegie Institution for Science
    From Carnegie Institution for Science

    April 15, 2019

    An ancient sliver of the building blocks from which comets formed was discovered encased inside a meteorite like an insect in amber by a Carnegie-led research team. The finding, published by Nature Astronomy, could offer clues to the formation and evolution of our Solar System.

    Meteorites were once part of larger bodies, asteroids, which broke up due to collisions in space and survived the trip through the Earth’s atmosphere. Their makeup can vary substantially from meteorite to meteorite, reflecting their varying origin stories in different parent bodies that formed in different parts of the Solar System. Asteroids and comets both formed from the disk of gas and dust that once rotated around our young Sun, but they aggregated at different distances from the Sun, affecting their chemical makeup. Compared to asteroids, comets contain larger fractions of water ice and far more carbon.

    By studying a meteorite’s chemistry and mineralogy, researchers like the paper’s lead author, Carnegie’s Larry Nittler, can reveal details about its formation and how much heating and other chemical processing it experienced during the Solar System’s formative years.

    A particularly primitive class of meteorites called carbonaceous chondrites are thought to have formed beyond Jupiter. One such meteorite, discovered in Antarctica’s LaPaz Icefield, is a particularly pristine example with minimal weathering since its landing on Earth’s surface.

    2
    An illustration showing how a sliver of cometary building block material was swallowed by an asteroid and preserved inside a meteorite, where it was discovered by a Carnegie-led team of scientists. Image is courtesy of Larry Nittler and NASA.

    Inside the LaPaz meteorite, Nittler’s team found a very carbon-rich slice of primitive material that bears some striking similarities to extraterrestrial dust particles that are thought to have originated in comets that formed near the Solar System’s outer edges. Approximately 3-3.5 million years after the Solar System formed, but still long before Earth finished growing, this object—about one tenth of a millimeter across—was captured by the growing asteroid from which the meteorite originated.

    By undertaking sophisticated chemical and isotopic analysis of the material, Nittler and his colleagues—Carnegie’s Conel Alexander and Jemma Davidson (who is now at Arizona State University), as well as Rhonda Stroud and Bradley De Gregorio of the U.S. Naval Research Laboratory, and Josep Trigo-Rodríguez, Carles Moyano-Cambero, and Safoura Tanbakouei of the Institute of Space Sciences in Barcelona, Catalonia—were able to show that the encased material likely originated in the icy outer Solar System along with objects from the Kuiper Belt, where many comets originate.

    Kuiper Belt. Minor Planet Center

    “Because this sample of cometary building block material was swallowed by an asteroid and preserved inside this meteorite, it was protected from the ravages of entering Earth’s atmosphere,” Nittler explained. “It gave us a peek at material that would not have survived to reach our planet’s surface on its own, helping us to understand the early Solar System’s chemistry.”

    The existence of this primitive material inside the meteorite indicates that due to the drag caused by the surrounding gas, particles like it migrated from the outer edges of the Solar System, where comets and Kuiper Belt objects formed, to the closer-in area beyond Jupiter, where the carbonaceous chondrites formed, revealing details about how our Solar System’s architecture was shaped during the early stages of planet formation.

    3
    LaPaz Icefield 02342, named for where it was found in Antarctica, is a primitive meteorite of a type that formed at the dawn of our Solar System’s history. However, the LaPaz meteorite, which is seen here in thin section under polarized light, contains a scientific surprise—a carbon-rich fragment of the building blocks from which comets formed. An arrow points to the cometary fragment. to Image is courtesy of Carles Moyano-Cambero.

    This work was supported by Spanish grants AYA 2011-26522 and AYA 2015-67175-P. and NASA grants NNX10AI63G and NNH16AC42I.

    This research used resources of the Advanced Light Source, which is a DOE Office of Science user Facility at LBNL under contract no. DE-AC02-05CH11231.

    LBNL ALS

    See the full article here .


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    Carnegie Institution of Washington Bldg

    Carnegie Institution for Science

    Andrew Carnegie established a unique organization dedicated to scientific discovery “to encourage, in the broadest and most liberal manner, investigation, research, and discovery and the application of knowledge to the improvement of mankind…” The philosophy was and is to devote the institution’s resources to “exceptional” individuals so that they can explore the most intriguing scientific questions in an atmosphere of complete freedom. Carnegie and his trustees realized that flexibility and freedom were essential to the institution’s success and that tradition is the foundation of the institution today as it supports research in the Earth, space, and life sciences.

    6.5 meter Magellan Telescopes located at Carnegie’s Las Campanas Observatory, Chile.
    6.5 meter Magellan Telescopes located at Carnegie’s Las Campanas Observatory, Chile


    Carnegie Las Campanas 2.5 meter Irénée Dupont telescope, Atacama Desert, over 2,500 m (8,200 ft) high approximately 100 kilometres (62 mi) northeast of the city of La Serena,Chile


    Carnegie Institution Swope telescope at Las Campanas, Chile, 100 kilometres (62 mi) northeast of the city of La Serena. near the north end of a 7 km (4.3 mi) long mountain ridge. Cerro Las Campanas, near the southern end and over 2,500 m (8,200 ft) high, at Las Campanas, Chile

    [/caption]

     
  • richardmitnick 1:11 pm on August 6, 2018 Permalink | Reply
    Tags: (NWA) 11119, , , , , , Meteorites, UNM-University of New Mexico   

    From University of New Mexico: “Researchers at The University of New Mexico uncover remnants of early solar system” 

    From University of New Mexico

    August 02, 2018

    Steve Carr
    Supervisor, Communications
    University of New Mexico
    505-277-1821
    scarr@unm.edu

    1
    Srinivasan studies NWA 11119
    Lead author Poorna Srinivasan studies the mineralogy of the rock, Northwest Africa (NWA) 11119.

    2
    NWA 11119

    3
    An artist’s rendition of Northwest Africa (NWA) 11119 (far right bottom corner of illustration) is the oldest igneous meteorite recorded.Credit: University of New Mexico

    Oldest-ever igneous meteorite contains clues to planet building blocks.

    Scientists believe the solar system was formed some 4.6 billion years ago when a cloud of gas and dust collapsed under gravity possibly triggered by a cataclysmic explosion from a nearby massive star or supernova. As this cloud collapsed, it formed a spinning disk with the sun in the center.

    Since then scientists have been able to establish the formation of the solar system piece by piece. Now, new research has enabled scientists from The University of New Mexico, Arizona State University and NASA’s Johnson Space Center to add another piece to that puzzle with the discovery of the oldest-ever dated igneous meteorite.

    The research titled, Silica-rich volcanism in the Early Solar System Dated at 4.565 Ga (billion years), was published today in Nature Communications. This research provides direct evidence that chemically evolved silica-rich crustal rocks were forming on planetsimals within the first 10 million years prior to the assembly of the terrestrial planets and helps scientists further understand the complexities of planet formation.

    “The age of this meteorite is the oldest, igneous meteorite ever recorded,” said Professor and Director of the UNM Institute of Meteoritics Carl Agee. “Not only is this just an extremely unusual rock type, it’s telling us that not all asteroids look the same. Some of them look almost like the crust of the Earth because they’re so light colored and full of SiO2. These not only exist, but it occurred during one of the very first volcanic events to take place in the solar system.”

    The research started to unfold at UNM when graduate student and lead author Poorna Srinivasan, asked Agee for ideas on her Ph.D. thesis. Agee had a yet-to-be studied crustal rock that was found in a sand dune in Mauritania by a nomad that he received from a meteorite dealer. The rock was lighter in color than most meteorites and was laced with green crystals, cavities and surrounded by quench melt. He gave the sample to Srinivasan who began to study the mineralogy of the rock, Northwest Africa (NWA) 11119.

    Using an electron microprobe and a CT (computed tomography) scan at UNM and NASA’s Johnson Space Center facilities, Srinivasan started to examine the composition and mineralogy of the rock. Srinivasan started to note the intricacies of NWA 11119 and noted the unusual light-green fusion crust, silica mineral-rich achondrite meteorite containing information substantially widening scientific knowledge involving the range of volcanic rock compositions within the first 3.5 million years of solar system creation.

    “The mineralogy of this rock is a very, very different from anything that we’ve worked on before,” said Srinivasan. “I examined the mineralogy to understand all of the phases that comprise the meteorite. One of the main things we saw first were the large silica crystals of tridymite which is a similar to the mineral quartz. When we conducted further image analyses to quantify the tridymite, we found that the amount present was a staggering 30 percent of the total meteorite – this amount is unheard of in meteorites and is only found at these levels in certain volcanic rocks from the Earth.”

    Part of Srinivasan’s research also involved trying to figure out through chemical and isotopic analyses what body the meteorite could be from. Utilizing oxygen isotopes done in collaboration with Dr. Karen Ziegler in UNM’s Center for Stable Isotope (CSI) lab, she was able to determine that it was definitely extraterrestrial.

    “Based on oxygen isotopes, we know it’s from an extraterrestrial source somewhere in the solar system, but we can’t actually pinpoint it to a known body that has been viewed with a telescope,” said Srinivasan. “However, through the measured isotopic values, we were able to possibly link it to two other unusual meteorites (Northwest Africa 7235 and Almahata Sitta) suggesting that they all are from the same parent body – perhaps a large, geologically complex body that formed in the early solar system.”

    3
    The sample size of NWA 11119 was similar to that of a baseball.

    One possibility is that this parent body was disrupted through a collision with another asteroid or planetesimal and some of its ejected fragments eventually reached the Earth’s orbit, falling through the atmosphere and ending up as meteorites on the ground – in the case of NWA 11119, falling in Mauritania at a yet unknown time in the past.

    “The oxygen isotopes of NWA11119, NWA 7235, and Almahata Sitta are all identical, but this rock – NWA 11119 – stands out as something completely different from any of the over 40,000 meteorites that have been found on Earth,” said Srinivasan.

    Further, research using an inductively coupled plasma mass spectrometry was performed in the Isotope Cosmochemistry and Geochronology Laboratory (ICGL) at the Center for Meteorite Studies at Arizona State University to determine the precise formation age of the meteorite. The research confirmed that NWA 11119 is the oldest-ever igneous meteorite recorded at 4.565 billion years.

    “The purpose of this research was to understand the origin and formation time of an unusually silica-rich igneous meteorite,” says co-author and ASU’s Center for Meteorite Studies director, Meenakshi Wadhwa. “Most other known igneous asteroidal meteorites have ‘basaltic’ compositions that have much lower abundances of silica – so we wanted to understand how and when this unique silica-rich meteorite formed in the crust of an asteroidal body in the early Solar System.”

    Most meteorites are formed through the collision of asteroids orbiting the sun in a region called the asteroid belt. Asteroids are the remains from the formation of the solar system formation some 4.6 billion years ago. The chemical composition ranges of ancient igneous meteorites, or achondrites, are key to understanding the diversity and geochemical evolution of planetary building blocks. Achondrite meteorites record the first episodes of volcanism and crust formation, the majority of which are basaltic.

    “The meteorite studied is unlike any other known meteorite,” says co-author and ASU School of Earth and Space Exploration graduate student Daniel Dunlap. “It has the highest abundance of silica and the most ancient age (4.565 billion years old) of any known igneous meteorite. Meteorites like this were the precursors to planet formation and represent a critical step in the evolution of rocky bodies in our solar system.”

    “This research is key to how the building blocks of planets formed early in the solar system,” said Agee. “When we look out of the solar system today, we see fully formed bodies, planets, asteroids, comets and so forth. Then, our curiosity always pushes us to, to ask the question – How did they form? How did the Earth form? This is basically a missing part of the puzzle that we’ve now found that tells us these igneous processes act like little blast furnaces that are melting rock and processing all of the solar system solids. Ultimately, this is how planets are forged.”

    See the full article here .

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  • richardmitnick 8:30 am on April 18, 2018 Permalink | Reply
    Tags: A meteorite called Almahata Sitta, , Diamonds from the heart of a lost planet, , Meteorites, Ureilites   

    From EPFL via COSMOS: “Diamonds from the heart of a lost planet” 

    EPFL bloc

    École Polytechnique Fédérale de Lausanne

    COSMOS

    18 April 2018
    Richard A Lovett

    1
    Audrey Hepburn was a diamond-studded star, but scientists now think they’ve found evidence of a diamond studded planet. Wikipedia.

    Diamonds in a meteorite recovered from Sudan’s Nubian Desert have revealed traces of a lost planet, possibly as large as Mars, smashed to rubble early in the solar system’s history.

    Planetary scientists have long believed the solar system once teemed with such bodies, which, during its chaotic infancy, either merged into larger planets, fell into the sun, were flung into interstellar space, or were dashed to bits by catastrophic collisions. But this is the first direct evidence that any such lost world truly existed.

    The diamonds come from a meteorite called Almahata Sitta, which made headlines in 2008 when astronomers tracked a 4.1-metre asteroid into the Earth’s atmosphere and watched it explode in the skies above Sudan.

    3
    Almahata Sitta. https://www.meteorite-times.com/micro-visions/almahata-sitta/.

    Fragments collectively weighing about 10.5 kilograms were subsequently recovered and named for a railroad station between Khartoum and Wadi Halfa.

    Almahata Sitta proved to be part of a family of meteorites called ureilites [Space Science Reviews], of which several hundred are known.

    “They are interesting meteorites, with strange properties,” says Farhang Nabiei, a materials scientist at École Polytechnique Fédérale de Lausanne, Switzerland.

    Among other things, they include diamonds — enough to pose challenges to researchers.

    “Ureilites are hard to cut and grind for thin sections because of the diamonds,” says Melinda Hutson, curator of the Cascadia Meteorite Laboratory at Portland State University in the US.

    Nabiei and his team are the first to study these diamonds in detail.

    Diamonds can be produced in space by a number of processes, but the ones in Almahata Sitta are too large to have been formed by most of them, Nabiei says.

    They are not so large that thieves will be plundering them for gemstones. They are only 100 microns (0.1 millimetre) in size — barely large enough to be seen without a magnifying glass — and are badly cracked by subsequent events, such as impact shocks.

    But they are large enough, Nabiei says, that they must originally have formed deep inside a protoplanet, just as Earth’s diamonds formed far below its the surface.

    How deep can be determined by studying materials trapped within them.

    To jewellers, such materials, dubbed “inclusions”, would be considered defects, but to planetary scientists they are the true gems. Nabiei calls them “direct samples” of the places where the diamonds formed.

    Based on measurements of about 30 inclusions, he says, it appears that they could only have formed at pressures above 20 gigapascals (roughly 200,000 atmospheres).

    “So the body should have been large enough to have had 20 gigapascals pressure inside its mantle,” Nabiei explains.

    That means it must have been at least as large as Mercury, he says, which has a diameter of 4,900-kilometres, and possibly as big as Mars, with a 6,800 kilometre diameter. The difference depends on whether the Almahata Sitta diamonds formed all the way at the planet’s centre, or not quite as far down.

    Hutson, who was not part of the study team, notes that Nabiei’s lost planet isn’t the only protoplanet that may have been destroyed in collisions.

    Studies of a different class of meteorites, known as iron meteorites, she says, indicate that they may have been formed in protoplanets hundreds to thousands of kilometres across, “implying [other] large objects that have broken apart”. These, however, would not have been as large as the source of Nabiei’s diamonds.

    Fragments of such bodies, she says, could have helped produce the large impact basins we see today on the moon, Mercury, Mars, and Jupiter’s moon Callisto. They may also have crashed into the Earth or Venus, where we can no longer see their imprint. And, she adds, “A lot of material could have been ground down to small pieces in [subsequent] collisions [and] ejected from the solar system by a number of processes that remove sand and dust-sized particles.”

    The next step for Nabiei, whose work is published in the journal Nature Communications, is to look at more ureilites, seeking additional information about how their minerals formed — and from that, additional information about the lost world from which they originated.

    For example, he says, these meteorites have some characteristics of materials that formed in the inner solar system, but they also contain large amounts of carbon, similar to things that formed in its outer regions.

    “There are things we don’t understand,” he says, “and that’s where we learn.”

    See the full article here .

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  • richardmitnick 6:28 am on March 29, 2018 Permalink | Reply
    Tags: , , , , Meteorites, , Surprising meteorite discovery points to early solar system chaos   

    From Science: “Surprising meteorite discovery points to early solar system chaos” 

    AAAS
    Science Magazine

    Mar. 28, 2018
    Paul Voosen

    1
    Meteorites suggest that a proto-Jupiter separated two sets of asteroids in the solar system’s disk of dust. ESO/L. CALÇADA.

    The stately solar system of today was in turmoil in its first several million years, theorists believe, with giant planets sowing chaos as they strayed far from their current orbits. But corroborating evidence has been thin—until now.

    Scientists have found a new window into the early dynamics: a curious chemical divide in the dozens of species of meteorites. The picture has emerged over several years, but in work presented last week at the Lunar and Planetary Science Conference here, a group of German geochemists reported clinching evidence. They tested 32 meteorites representing nearly all known types and found that “any meteorite you take, it belongs to either one of these groups,” says Thorsten Kleine, a geochemist at the University of Münster in Germany who led the work.

    Those divergent chemistries imply distinct origin stories for asteroids, the parent bodies of most meteorites. One group formed from grist that began near the current location of the asteroid belt. The others coalesced much farther out, beyond a proto-Jupiter, near where Saturn orbits today. Only later, pushed and pulled by the wandering giant planets, did these immigrant asteroids find their home in today’s asteroid belt. Bill Bottke, a planetary dynamicist at the Southwest Research Institute (SwRI) in Boulder, Colorado, thinks the chemical divide holds other clues to the timing and formation of the planets. “It really seems to be a powerful mechanism for understanding our solar system.”

    Paul Warren, a meteoriticist at the University of California, Los Angeles, was the first to notice what has come to be called the Warren gap. He gathered measurements of chromium and titanium isotopes for two meteorite types. Those metals, forged by the explosions of dying stars, were mixed throughout the disk of gas and dust from which planets and asteroids took shape. Warren expected his meteorites to display a continuum of isotopic abundances, because he assumed they had formed across the one broad region of the asteroid belt. Instead, he found that, in one meteorite type, called carbonaceous chondrites, the isotope levels were starkly different from other types. “I knew a good thing when I saw it,” he says.

    In a 2011 study, Warren argued that such a dichotomy could exist only if the two groups were separated for millions of years at formation. The most plausible source of that split was a void created by the gravity of a proto-Jupiter. But carbonaceous chondrites are known to have formed later than other meteorites—so it was possible that their peculiar isotopic chemistry reflected changes over time in the disk, rather than a distinct place of origin.

    A few years ago, Kleine’s group began looking at isotopes of molybdenum, another metal, and found a Warren gap there, too. It also found that iron meteorites fell into two populations even though they must all have formed at about the same time. That meant a physical barrier. “And the most obvious one would be Jupiter,” Kleine says.

    Kleine’s team began spelling out the implications: By 1 million years after the solar system’s start, Jupiter’s core had grown large enough to sweep up dust in its path, creating a barrier. A new influx of metalrich dust to the solar system, perhaps from a nearby supernova, would have augmented isotopes in the outer asteroids but not the inner ones. Then, 3 million to 4 million years later, Jupiter migrated inward, mixing the two reservoirs. The Warren gap is both a validation of dynamic solar system models that predict a similar scenario, and a constraint they must reckon with, says Kevin Walsh, a SwRI dynamicist.

    Now, scientists are gleaning other clues about the early solar system from the meteorites. One group is studying rare meteorites that mix up carbonaceous and noncarbonaceous components, a hint that they formed just after Jupiter’s migration, in an effort to date when the two reservoirs combined. And by comparing molybdenum isotopes in rocks from Earth’s mantle with those in meteorites, Kleine’s team has found preliminary signs that Earth’s water was partially delivered by a shower of impactors from the more distant asteroid population.

    The meteorite studies could even set back the clock on the age of the 4.6-billion-year-old solar system itself. That date comes from the decay of uranium in calcium-aluminum–rich inclusions in meteorites. These little metal snowflakes, created by the sun’s heat, are thought to have arisen in the earliest years of the solar system. But scientists have long wondered why carbonaceous meteorites are richer in these snowflakes. It appears that the inclusions are also isotopically similar to the outer solar system meteorites. Researchers now speculate that they formed far from the sun, driven by heat from a proto-Jupiter. If so, some inclusions must have formed after Jupiter took shape, meaning they are at least 1 million years younger than the solar system. “A huge advance,” Bottke said. “My jaw was on the floor about that.”

    Meanwhile, the hunt is on to interpret other meteorites in this new light. It’s amazing to think that samples on Earth originated near Saturn, Bottke says. “A few years ago if you had said that you would have had people laugh at you.”

    See the full article here .

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  • richardmitnick 10:00 am on February 8, 2018 Permalink | Reply
    Tags: , , Meteorites, Rapid Detection and Recovery: The Science of Hunting Meteorites,   

    From University of Arizona: “Rapid Detection and Recovery: The Science of Hunting Meteorites” 

    U Arizona bloc

    University of Arizona

    Feb. 6, 2018
    Emily Walla

    Science contact
    Vishnu Reddy
    UA Lunar and Planetary Laboratory
    520-621-6963
    vishnureddy@email.arizona.edu

    1
    A sample of the Michigan meteorite recovered by citizen scientists using maps produced by UA assistant professor Vishnu Reddy’s Doppler radar technique (Photo: Vishnu Reddy)

    UA professor Vishnu Reddy is leading a NASA-funded project to find freshly fallen meteorites like the one in Michigan last month.

    2
    Composite image of weather radar signatures of the falling meteorite (Image: Marc Fries)

    At 8:10 p.m. on Jan. 16, hundreds of people in Michigan reported the bright glow of a meteor streaking through the sky, rattling windows as it broke the sound barrier. The meteor then broke apart in the Earth’s atmosphere, and its pieces rained quietly to the ground.

    Using predictions by the Rapid Detection and Recovery of Meteorites, or RADARMET, project, scientists and meteorite hunters were able to recover more than half a dozen fragments of the rock within two days of the fall.

    RADARMET is led by Vishnu Reddy, assistant professor in the University of Arizona’s Lunar and Planetary Laboratory. He procured funding from NASA to operate RADARMET, which uses National Weather Service Doppler radar data and computer models to locate meteorites within hours of their fall.

    “Historically, people would see a meteor in the sky and they would say, ‘I saw it go that way behind the tree,'” Reddy said. “Even if someone takes a picture of the meteor, using the image to trace a trajectory for the meteorite is difficult and can be quite time-consuming.”

    3
    Computed strewn field of the meteorite. The dark orange shows where the largest, heaviest pieces of the meteorite fell, and the yellow shows where the lightest and smallest pieces fell. (Image: Marc Fries)

    Upper-atmosphere winds make extrapolation challenging, Reddy said. For a meteor to survive the trip through the atmosphere and fall onto the ground as a meteorite, it has to slow from its cosmic velocity. The friction from the atmosphere makes the meteor glow visibly between 30 and 65 miles above ground.

    “Typically, meteorite-dropping meteors need to slow down to around 6,700 mph, the speed when they no longer glow brightly while descending into the atmosphere,” Reddy said.

    Falling at Terminal Velocity

    The meteor then enters a period known as “dark flight,” during which it falls at terminal velocity. During this dark flight, winds in the upper atmosphere can buffet the meteorite miles away from where its glowing bright flight ends.

    Marc Fries, Reddy’s co-investigator for RADARMET and a scientist at NASA’s Johnson Space Center, developed a method that can predict how a meteorite would travel during its dark flight. He also has developed software tools to calculate where meteorites land under the influence of winds, and to estimate the total mass that reaches the ground.

    Tanner Campbell, a UA graduate student in aerospace and mechanical engineering, adapted Fries’ dark flight model into a computer program that quickly and accurately determines where a meteorite will fall.

    “We can accomplish this because the kinetics of an object in near freefall are known quite well,” Campbell said. “Since these meteorites are typically fairly small, we can make some assumptions about how they travel through the atmosphere. We can then take whatever data can be gathered on the meteorite while it is glowing in the sky, and measured atmospheric data from near the event, and use it to predict the path to the ground.”

    Atmospheric data include wind speeds and information collected by weather radar stations, which detect anything falling through the air, whether it is rain, birds, airplanes or meteorites. Although the radar cannot distinguish between a sparrow and a space rock, the RADARMET team has a method to do just that.

    “The first trigger is eyewitness reports from the public,” Reddy said.

    Using an online tool on the American Meteor Society website, members of the public can log their location, which direction they were facing and how long the meteor was visible in the sky. When an event has corroborating videos and other evidence such as sonic booms, Reddy and his co-investigators download radar data from the nearest weather station and power up the dark flight model.

    Accuracy of Location Is Vital

    Within hours of the event, the RADARMET team can locate the exact area where meteorite fragments have fallen. The information is quickly shared with the public, including scientists and meteorite hunters. RADARMET’s method is so accurate that hunters have been able to travel to a location, park their cars and find meteorites within that parking lot.

    When hunting meteorites, time is of the essence. The sooner a sample is found, the more scientists can learn from it.

    “The longer a meteorite sits on the Earth, the less scientifically useful it becomes, because the weathering process degrades the minerals and destroys it,” Reddy said.

    Rain can dissolve and wash away minerals, microbes can contaminate any evidence of the building blocks of life, and oxygen can rust the iron in the meteorite within a day.

    Although recovering pieces of the Michigan meteorite took slightly more than a day, some samples were found in nearly pristine condition. One piece was found in ice, protected from exposure to liquid water. Pristine samples such as this one enable scientists to study materials that are easily destroyed or of astrobiological significance.

    Reddy and students in the UA Department of Planetary Sciences plan to be involved in the study of the meteorite.

    “While we’re not out there hunting the meteorites, we’re doing the science,” Reddy said.

    See the full article here .

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  • richardmitnick 5:36 pm on January 10, 2018 Permalink | Reply
    Tags: , , , , , , , Meteorites, , , STXM-scanning transmission X-ray microscope, We’re looking at the organic ingredients that can lead to the origin of life” including the amino acids needed to form proteins,   

    From LBNL: “Ingredients for Life Revealed in Meteorites That Fell to Earth” 

    Berkeley Logo

    Berkeley Lab

    January 10, 2018
    Glenn Roberts Jr.
    geroberts@lbl.gov
    (510) 486-5582

    1
    A blue crystal recovered from a meteorite that fell near Morocco in 1998. The scale bar represents 200 microns (millionths of a meter). (Credit: Queenie Chan/The Open University, U.K.)

    Two wayward space rocks, which separately crashed to Earth in 1998 after circulating in our solar system’s asteroid belt for billions of years, share something else in common: the ingredients for life. They are the first meteorites found to contain both liquid water and a mix of complex organic compounds such as hydrocarbons and amino acids.

    A detailed study of the chemical makeup within tiny blue and purple salt crystals sampled from these meteorites, which included results from X-ray experiments at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), also found evidence for the pair’s past intermingling and likely parents. These include Ceres, a brown dwarf planet that is the largest object in the asteroid belt, and the asteroid Hebe, a major source of meteorites that fall on Earth.

    The study, published Jan. 10 in the journal Science Advances, provides the first comprehensive chemical exploration of organic matter and liquid water in salt crystals found in Earth-impacting meteorites. The study treads new ground in the narrative of our solar system’s early history and asteroid geology while surfacing exciting possibilities for the existence of life elsewhere in Earth’s neighborhood.

    “It’s like a fly in amber,” said David Kilcoyne, a scientist at Berkeley Lab’s Advanced Light Source (ALS), which provided X-rays that were used to scan the samples’ organic chemical components, including carbon, oxygen, and nitrogen.

    LBNL/ALS

    Kilcoyne was part of the international research team that prepared the study.

    While the rich deposits of organic remnants recovered from the meteorites don’t provide any proof of life outside of Earth, Kilcoyne said the meteorites’ encapsulation of rich chemistry is analogous to the preservation of prehistoric insects in solidified sap droplets.

    Queenie Chan, a planetary scientist and postdoctoral research associate at The Open University in the U.K. who was the study’s lead author, said, “This is really the first time we have found abundant organic matter also associated with liquid water that is really crucial to the origin of life and the origin of complex organic compounds in space.”

    She added, “We’re looking at the organic ingredients that can lead to the origin of life,” including the amino acids needed to form proteins.

    If life did exist in some form in the early solar system, the study notes that these salt crystal-containing meteorites raise the “possibility of trapping life and/or biomolecules” within their salt crystals. The crystals carried microscopic traces of water that is believed to date back to the infancy of our solar system – about 4.5 billion years ago.

    Chan said the similarity of the crystals found in the meteorites – one of which smashed into the ground near a children’s basketball game in Texas in March 1998 and the other which hit near Morocco in August 1998 – suggest that their asteroid hosts may have crossed paths and mixed materials.

    There are also structural clues of an impact – perhaps by a small asteroid fragment impacting a larger asteroid, Chan said.

    This opens up many possibilities for how organic matter may be passed from one host to another in space, and scientists may need to rethink the processes that led to the complex suite of organic compounds on these meteorites.

    “Things are not as simple as we thought they were,” Chan said.

    There are also clues, based on the organic chemistry and space observations, that the crystals may have originally been seeded by ice- or water-spewing volcanic activity on Ceres, she said.

    “Everything leads to the conclusion that the origin of life is really possible elsewhere,” Chan said. “There is a great range of organic compounds within these meteorites, including a very primitive type of organics that likely represent the early solar system’s organic composition.”

    Chan said the two meteorites that yielded the 2-millimeter-sized salt crystals were carefully preserved at NASA’s Johnson Space Center in Texas, and the tiny crystals containing organic solids and water traces measure just a fraction of the width of a human hair. Chan meticulously collected these crystals in a dust-controlled room, splitting off tiny sample fragments with metal instruments resembling dental picks.

    2
    These ALS X-ray images show organic matter (magenta, bottom) sampled from a meteorite, and carbon (top). (Credit: Berkeley Lab)

    “What makes our analysis so special is that we combined a lot of different state-of-the-art techniques to comprehensively study the organic components of these tiny salt crystals,” Chan said.

    Yoko Kebukawa, an associate professor of engineering at Yokohama National University in Japan, carried out experiments for the study at Berkeley Lab’s ALS in May 2016 with Aiko Nakato, a postdoctoral researcher at Kyoto University in Japan. Kilcoyne helped to train the researchers to use the ALS X-ray beamline and microscope.

    The beamline equipped with this X-ray microscope (a scanning transmission X-ray microscope, or STXM) is used in combination with a technique known as XANES (X-ray absorption near edge structure spectroscopy) to measure the presence of specific elements with a precision of tens of nanometers (tens of billionths of a meter).

    “We revealed that the organic matter was somewhat similar to that found in primitive meteorites, but contained more oxygen-bearing chemistry,” Kebukawa said. “Combined with other evidence, the results support the idea that the organic matter originated from a water-rich, or previously water-rich parent body – an ocean world in the early solar system, possibly Ceres.”

    Kebukawa also used the same STXM technique to study samples at the Photon Factory, a research site in Japan. And the research team enlisted a variety of other chemical experimental techniques to explore the samples’ makeup in different ways and at different scales.

    Chan noted that there are some other well-preserved crystals from the meteorites that haven’t yet been studied, and there are plans for follow-up studies to identify if any of those crystals may also contain water and complex organic molecules.

    3
    Ceres, a dwarf planet in the asteroid belt pictured here in this false-color image, may be the source of organic matter found in two meteorites that crashed to Earth in 1998. (Credit: NASA)

    Kebukawa said she looks forward to continuing studies of these samples at the ALS and other sites: “We may find more variations in organic chemistry.”

    The Advanced Light Source is a DOE Office of Science User Facility.

    Scientists at NASA Johnson Space Center, Kochi Institute for Core Sample Research in Japan, Carnegie Institution of Washington, Hiroshima University, The University of Tokyo, the High-Energy Accelerator Research Organization (KEK) in Japan, and The Graduate University for Advanced Studies (SOKENDAI) in Japan also participated in the study. The work was supported by the U.S. DOE Office of Science, the Universities Space Research Association, NASA, the National Institutes of Natural Sciences in Japan, Japan Society for the Promotion of Science, and The Mitsubishi Foundation.

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  • richardmitnick 2:00 pm on December 1, 2017 Permalink | Reply
    Tags: Astonomy Magazine, , Meteorites   

    From Astronomy: “The story of the fossil meteorites” 

    Astronomy magazine

    astronomy.com

    November 29, 2017
    David Boehnlein

    What four small pieces of rock can teach us about the history of the solar system.

    1
    An ancient meteorite sits embedded in a piece of limestone near the fossilized shell of a cephalopod. Courtesy Steve Zitowsky

    Visitors

    Imagine a traveler from outer space, hurtling through the atmosphere of a bright, blue planet to land upon a world populated by strange, multi-tentacled creatures. It sounds like something from the pages of a science fiction novel, but it’s a true story and it’s written in stone. The stone is at Chicago’s Field Museum of Natural History, one of four unusual slabs in a recently opened display of meteorites.

    At the time of the World’s Columbian Exposition in 1893, the collection of curiosities that would become the Field Museum included 170 meteorites. The museum now houses the Robert A. Pritzker Center for Meteoritics and Polar Studies, with a collection that includes more than 15,000 meteorites from over 1500 falls. “A fall,” explains Philipp Heck, associate curator of the Pritzker Center, “is an event in which the arrival of a meteorite is observed and recorded.” This allows fragments to be identified with that event. Meteorites not identified with a fall are known in the field of meteoritics as “finds.”

    The museum has pieces of many famous meteorites.There’s a thousand-pound remnant of the Canyon Diablo meteorite that gouged the great meteor crater in the Arizona desert.

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    Canyon Diablo iron meteorite (IIIAB) 2,641 grams. Note colorful natural patina. Image is missing a needed scale.
    Geoffrey Notkin, Aerolite Meteorites of Tucson Original uploader was Geoking42 at en.wikipedia

    There are fragments of the Chelyabinsk meteor, which made a fiery descent over Russia in 2014. There is even a meteorite that fell on a garage in Illinois in 1938, displayed alongside the holed seat and dented muffler of the car it struck. In a photograph taken shortly after the fall, the vehicle’s owner looks rather dismayed.

    But possibly the most intriguing meteorites in the collection are four that are embedded in slabs of limestone. They are surrounded by a whitish discoloration of the rock, evidence of something leaching from them. These are fossil meteorites. One of them, our aforementioned celestial visitor, rests only inches away from the mineralized shell of a cephalopod, an extinct mollusk related to the modern nautilus. Fossils of prehistoric sea creatures are common in rocks dating from the Ordovician Period, which lasted from 500 to 435 million years ago. But fossil meteorites are rare. In fact, they were unknown until 1952, when the first find was made in Sweden. To date, only 115 have been found, almost all of them at a single quarry.

    The Thorsberg Quarry

    Among the wooded hills along the southeast shore of Lake Vänern in southern Sweden, a line of rust-colored bluffs overlooks a smaller lake where limestone has been quarried for many years. This is the Thorsberg quarry, near the town of Kinnekulle. Striations in the stone there represent layers of sediment laid down over millions of years, when this place was at the bottom of an ancient sea. In that age there were no land animals or even true vertebrates; the first dinosaurs were still 230 million years in the future. Life was in the ocean, teeming with creatures now long gone. Trilobites scuttled along the sea floor and crinoids waved lazily with the movement of the water. Among them swam cephalopods of the genus Orthoceras, the apex predator, residing within a long, conical shell, tentacles groping for whatever luckless creature would become its next meal.

    This was the pattern of life in the Ordovician ocean; preserved by the long, slow process of fossilization to record a chapter in the history of life on Earth. But something extraordinary happened in the middle of the Ordovician Period. Meteorites began to fall among the future fossils, lots of them. As the meteorites settled into the sea floor, they were buried along with the remains of the sea creatures to become fossils themselves. And just as the fossilized animals tell a story about the history of life on Earth, the fossil meteorites relate a chapter in the history of the solar system.

    The L Chondrite Parent Body

    That story begins in the asteroid belt. The vast majority of meteorites that fall to Earth come from this ring of irregular, rocky bodies that never managed to form a planet. The asteroids occasionally jostle each other and when they do, the bits and pieces broken from them are sometimes sent Earthward. But 470 million years ago, there was a titanic collision among the asteroids. It shattered one of them completely in the biggest breakup the solar system has seen in the last 3 billion years. Immense amounts of debris from this collision were flung toward the inner solar system, where it quickly subjected Planet Earth to an intense bombardment. On a cosmic time scale, the number of meteorites falling to Earth jumped overnight. Scientists now refer to this doomed asteroid as the L Chondrite Parent Body (LCPB).

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    L Chondrite from Wikipdia

    That’s quite a story, but how can we know it’s true? After all, the trilobites didn’t leave us any observation logbooks. Nature, however, has left us a number of clues in the limestone beds of the Thorsberg quarry and in the meteorites themselves. Cosmochemistry is the study of the composition of materials in the universe and the processes that produced them. Like detectives tracking down a mystery, Heck and his colleagues have been using a combination of geology and cosmochemistry to piece together the story of the LCPB.

    The first step in proving the story is to verify that the objects found in the Thorsberg quarry are meteorites. “It’s not easy to identify a meteorite by just looking at it,” says Steve Zitowsky, who works in the Field Museum’s Pritzker Center. “People send us lots of items that they’ve found, thinking they might be a meteorite. Usually they’re not.” Zitowsky keeps the museum’s meteorite database up to date, weighing, measuring and photographing each new specimen. “I also found the critters,” he says with evident satisfaction, on examining the slabs with the fossil meteorites.

    Identifying fossils as meteorites also poses a special challenge. They’ve been buried and embedded in stone for hundreds of millions of years. Just as the seashells underwent a mineralogical change, turning to stone over the eons, so did the meteorites. The meteorites, of course, were already stone, but they underwent a process called diagenesis, which changes their mineral content. That’s what caused the whitish discoloration in the stone surrounding them. Researchers have to study their microscopic structure, along with their chemical composition, to be sure of their identity.

    The presence of the mineral chromite (FeCr2O4) in the fossils was one thing that identified them as meteorites. “Chromite is very resistant to diagenesis,” says Heck. Another important giveaway is the presence of chondrules: small, round particles found embedded inside the meteorite.

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    An ordinary chondrite meteorite displays the unique round “chondrules” that give this type of meteorite its name. James St. John.

    Types of Meteorites

    Although meteorites come in many varieties, there are three basic types: iron, stony iron, and stony. Stony meteorites are by far the most common, making up about 96 percent of those that fall to Earth. They are composed largely of silicate minerals, such as olivine and pyroxene. Iron meteorites, as the name suggests, are mostly iron, although they often contain other elements, such as nickel and cobalt. Stony irons, the most rare of the three types, combine the characteristics of the other two.

    The type of meteorite depends on where it came from in the parent body that broke apart to produce it. Some asteroids are differentiated — that is, they have an iron core surrounded by a rocky mantle and crust, just as Earth does. Differentiation occurs when a body is heated by collisions or radioactivity to the point where its materials can flow. The iron meteorites come from the core of such a body, stony irons from a narrow region between the core and mantle, and stony meteorites from the mantle and crust.

    Stony meteorites also come from asteroids that are not differentiated. Some asteroids were never hot enough to form an iron core, but did generate enough heat to melt bits of material embedded in them. These melted mineral grains are called chondrules and meteorites that contain them are called chondrites. Microscopic examination of the fossil meteorites shows that they are all chondrites.

    Having established that the embedded stones in the quarry are meteorites, and specifically that they are chondrites, can scientists go a step further in demonstrating that they all came from the same parent body? As a matter of fact, they can, because chondrites come in several varieties. The family of ordinary chondrites (there are also some not-so-ordinary ones that won’t be discussed here) includes three basic types: These are the H, L and LL chondrites. The H chondrites have a relatively high metal content; the L chondrites have a low metal content; and the LL chondrites have both a low metal content overall and a low iron content relative to other stony meteorites. Of the meteorites that fall to Earth today, 38 percent are L chondrites. In contrast, all of the fossil meteorites found to date are all L chondrites. They were the predominant type of meteorite in the Ordovician and moreover, they all came from the same asteroid, the L Chondrite Parent Body.

    The Million-Year Meteor Shower

    What happened after the LCPB disintegrated? The distribution of the meteorites in the quarry provides a clue. The limestone in which they are embedded was laid down as layers sediment over millions of years. The bottom layers are the oldest and the upper layers are the youngest. Geologists determine the ages of the layers by several methods. By applying sedimentation rates measured in modern environments, they can estimate how long it took to build up a layer. Index fossils, which are fossils of species known to have lived at a particular point in time, can pinpoint the age of a specific layer. There were many species of the mollusk Orthoceras and they are so common at Kinnekulle that the limestone is called orthoceratite. Finally, the decay products from natural radioactivity can date the rocks.

    A combination of these methods shows that the L chondrites began to arrive here just under 470 million years ago. And when they arrived, they came en masse. Birger Schmitz of the University of Lund in Sweden has been searching the Thorsberg quarry for fossil meteorites since 1993. The search has covered all of the old sea floor that has been quarried since then. “There is a clear and confirmed two-orders-of-magnitude increase in the flux of small meteorites to Earth,” says Schmitz. “The abundance of meteorites on the mid-Ordovician sea floor is far too high to be explained by a meteorite flux similar to that of today.” When the debris of the LCPB breakup began to reach this planet, meteorites fell with a frequency 100 times the modern rate for a million years. Furthermore, data from preserved craters indicates an order-of-magnitude increase in the flux of small asteroids as well. There must have been some spectacular meteor showers, but unfortunately nobody was there to see them.

    The L Chondrite Express

    Not only did the L chondrites bombard Earth in huge numbers, they did it very quickly. The typical travel time for a meteorite is millions to tens of millions of years. This is the time from when its parent body breaks apart to when a piece of it lands on Earth as a meteorite. The fossil meteorites, however, began to arrive mere tens of thousands of years after the breakup of the LCPB. “They came to us by express delivery,” says Heck.

    How is it possible to know how long a meteorite travelled through interplanetary space? There would have to be some kind of clock built into it. There is such a clock and the cosmochemists are able to read it by measuring the amount of certain rare isotopes of elements that are in the meteorite.

    The clock works like this: Every atom of every element has a mass number equal to the combined number of protons and neutrons in its nucleus. For example, helium with two protons and two neutrons has a mass number of 4 and is written as 4He. Likewise, an atom of neon normally has 10 protons and 10 neutrons and is denoted as 20Ne. In rare cases, a nuclear reaction can produce a nucleus with fewer or more neutrons than normal, resulting in isotopes like 3He (2 protons, 1 neutron) or 21Ne (10 protons, 11 neutrons). On Earth, naturally occurring neon has only about a quarter of a percent 21Ne; naturally occurring helium has a mere ten-thousandth of a percent 3He. These rare nuclei are produced by cosmic rays, the high-energy radiation that permeates outer space, and are called cosmogenic isotopes.

    While an asteroid is intact, the rock in its interior is shielded from the cosmic rays and cosmogenic isotopes are not produced. When the asteroid breaks apart, the fragments are exposed to cosmic rays and production of cosmogenic isotopes begins. When the fragment falls to Earth as a meteorite, it is shielded once again by Earth’s atmosphere and production of the cosmogenic isotopes stops. Thus, the quantity of cosmogenic isotopes in the meteorite provides a measure of how long it was travelling in space.

    Heck and his colleagues studied the fossil meteorites for cosmogenic isotopes of 3He and 21Ne, cross-checking the results against the layers of rock where they were found. Their remarkable result was that the older the rock layer, the less time the meteorites in it had spent in transit. This is basically the result you’d expect if all of the meteorites came from a single parent body, with the ones making the shortest trip sitting here longest. What is surprising, though, is just how little time it took them to get here. That celestial traveler mentioned at the beginning of the article spent a mere 50,000 years on its journey here, only 1 percent of the travel time of a typical meteorite. As if being embedded next to a cephalopod didn’t make it rare enough. The probable explanation for this rapid transit, says Heck, is that the breakup occurred near an orbital resonance, a spot where the gravity of Jupiter pulled them out of the asteroid belt and onto an Earthbound expressway.

    Meteorites Before the Breakup

    That’s a good deal of evidence to support the story of a cataclysmic collision of asteroids followed by a rain of L chondrites on Earth, yet there is still another way to check it. What about L chondrites before the breakup of the LCPB? We know that L chondrites dominated the meteorite flux in the mid-Ordovician, but today, they’re just over a third of the meteorites landing here. So another way to verify the story of a big burst of meteorites from the LCPB is to look at how common or rare L chondrites were in the early Ordovician Period. The problem is how to check for L chondrites when there are so few meteorites to be found. The answer is micrometeorites.

    Meteoritic material is constantly falling to Earth. The planet typically gains about five tons per year from meteorites, much of it in the form of tiny grains or microscopic fragments coming off of larger bodies. With the proper chemical methods, these micrometeorites can be recovered from the limestone. In a recent international study, scientists recovered micrometeorites from a Russian quarry and studied their isotopes to determine their type. They found that prior to 470 million years ago, most of the meteorites falling to Earth were achondrites; that is, stony meteorites with no chondrules. L chondrites were very rare. Once again, the LCPB story is verified.

    This sort of cosmochemical research, however, might go well beyond verifying the hypothesis of a single asteroid breakup. Schmitz has suggested that, just as geologists use strata of rocks and biologists use strata of fossils to describe the progression of Earth’s history, so might astronomers use meteoritic material to develop an astrostratigraphy that could add to our understanding of this history. Over the years, some scientists have conjectured that meteorites have been at least partially responsible for mass extinctions and subsequent evolutionary events. So far, only the Chicxulub Meteor, which struck at the end of the age of dinosaurs, is known to be associated with such an event.

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    This shaded relief image of Mexico’s Yucatan Peninsula show a subtle, but unmistakable, indication of the Chicxulub impact crater. Most scientists now agree that this impact was the cause of the Cretatious-Tertiary Extinction, the event 65 million years ago that marked the sudden extinction of the dinosaurs as well as the majority of life then on Earth.
    NASA/JPL-Caltech, modified by David Fuchs at en.wikipedia

    A more thorough understanding of fossilized meteorites and micrometeorites could further test such hypotheses.

    The Chicago L Chondrites

    The Field Museum has displayed its four fossil meteorites in a section that was added to the meteorite exhibit in early 2017. These are the only fossil meteorites in the western hemisphere, so they have a prominent place in the display. Even so, they’re not alone, because the LCPB isn’t quite finished with us yet.

    Just before midnight on March 26, 2003, residents of Park Forest, Illinois, were startled by what many thought was a bomb. Bright flashes in the sky, resounding booms and falling debris were reported throughout this Chicago suburb. It was, of course, a meteorite. Several homes were hit and one strike left the occupants looking up at a softball-sized hole in their ceiling. Fortunately, nobody was hurt. For the Chicago Center for Cosmochemistry at the nearby University of Chicago and for the Field Museum, the fall was a bonanza. When the fragments were collected and studied they were found to be L chondrites from the same source as the fossils in the Thorsberg quarry. Pieces of the Park Forest meteorite now reside in a display case alongside the fossil meteorites from Sweden. After 470 million years, they are reunited at last.

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    A piece of the Park Forest meteorite, also believed to have originated from the LCPB. James St. John

    See the full article here .

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