We are excited to announce that our latest research on the activity of the young Sun has just been published in The Astrophysical Journal. The study is led by Field Museum and UChicago resident graduate student Xin Yang, as part of his PhD thesis under the supervision of Philipp Heck in collaboration with Fred Ciesla, a professor and expert in modeling at UChicago. 

Building on previous work that a record of an active young Sun in the first minerals formed in the Solar System, this new study tackles a critical unknown: how long these minerals were exposed to solar energetic particles. By combining two state-of-the-art physical models, we were able to estimate this exposure time and provide new insights into the Sun's early activity.

Our findings reveal that the young Sun may have been up to 10 million times more active than the Sun today. This exciting discovery aligns with observations of the most active young solar-like stars in our galaxy, offering a deeper understanding of our Sun's early history.

This research was made possible through funding from NASA Emerging Worlds and NASA FINESST, and support to the Robert A. Pritzker Center from the TAWANI Foundation.

Philipp Heck was elected as Fellow of the Meteoritical Society. Philipp was honored for his significant contributions to the study of presolar grains and fossil meteorites, development of atom probe tomography techniques for cosmochemistry, and his service to the community through his curation work at the Field. Nominations are submitted by members, and the Leonard Medal Committee reviews those nominations and makes a recommendation to Council. Fellows are elected in even-numbered years, and no more than 1% of the membership can be elected for each class. Along with the other fellows Philipp was honored at the Annual Meeting of the Meteoritical Society in Brussels on July 31st, 2024 in the Palace of the Academies.

Field Museum resident graduate student Debarun Mukherjee (UChicago) got awarded the prestigious 2024 Quad Fellowship. He's one of only two UChicago students to receive the honor this year.

Now in its second year, the Quad Fellowship supports exceptional master's and doctoral students pursuing studies in science, technology, engineering, and mathematics (STEM) in the United States. Debarun will join a cohort of 50 Fellows out of nearly 3,000 applicants, from across the Quad and Southeast Asian countries dedicated to developing a network for science and technology experts that will advance innovation and collaboration in your own countries and among the Quad countries and Indo-Pacific. By bringing together students from different parts of the world, the fellowship creates a network of innovators who can address global challenges and drive technological advancements. The fellowship is administered by the Institute of International Education (IIE), a global not-for-profit organization that manages many of the world’s most prestigious scholarship and fellowship programs.

Resident Graduate student Xin Yang has been awarded the prestigious 2023 National Outstanding Self-Funded Student Scholarship. This award, established in 2003 by the China Scholarship Council of the Ministry of Education of China, is the highest government honor granted to Chinese students overseas. It recognizes doctoral students with exceptional academic achievements or significant research potential. Out of more than half a million Chinese students studying abroad annually, only 650 young talents from various disciplines are selected globally each year, making this award highly competitive. Recipients of this award include Chinese students in the United States, EU countries, Canada, Singapore, Switzerland, Norway, Japan, Australia, and more. The award ceremony is traditionally held at the local Chinese Embassy or Consulate. The award specifically honors “self-financed students abroad,” meaning those who are not funded directly by the Chinese government but often hold full scholarships from overseas universities. 

Xin Yang has been also awarded the Stephen E. Dwornik Planetary Geoscience Best Graduate Poster Presentation Award at the Lunar and Planetary Science Conference 2024 in the Woodlands, Texas. Congratulations!

Xin’s main research focus involves the first minerals that formed in the Solar System.

What can be said about Antarctica beyond the obvious? 

Which is that it is the fifth largest continent, 1.5 times the size of the continental United States, a desert covered with a layer of ice that averages a mile thick and is up to 3 miles thick. This is 70% of the earth’s freshwater, and it is enough to raise the global sea levels by 200 feet / 61 meters and drastically change ocean temperature if the sheet melts completely.

Antarctica is governed, if you want to call it that, by the Antarctic Treaty, which stipulates Antarctica can be used only for peaceful purposes, to ensure scientists can freely research and co-operate, so their observations and results can be exchanged and made available to the larger world.

Continue reading the fascinating personal account of Erin Solaro who participated in an expedition to Antarctica in the 2023/24 field season. 

The Robert A. Pritzker Center at the Field Museum has recently classified a new iron meteorite, discovered in Vienna, Wisconsin as a rare IVA iron meteorite. This is the second meteorite classified by the Pritzker Center from the US Midwest that was found near a small town sharing its name with a major European city, following the Hamburg meteorite.

IVA iron meteorites are exceptionally rare, representing only about 1 permill of all known meteorites and about 7% of all known iron meteorites.

This discovery adds to the world-class meteorite collection at Field Museum’s Robert A. Pritzker Center which has a particular strength in iron meteorites.

The classification was performed by Philipp Heck with help from Jim Holstein, Noriko Kita, Carrie Eaton, and Richard Slaughter. Philipp Heck acknowledges help from Laure Dussubieux for providing access to and help with the Field Museum’s Elemental Analysis Facility.

Learn more about the discovery and classification. 

Our group has published a paper in Meteoritics & Planetary Science introducing a Raman-spectroscopy method to identify extraterrestrial material in sedimentary rock. We identified extraterrestrial chrome-spinel minerals in 467-million-year-old sedimentary rock, unveiling a very different mix of micrometeorites during that period. While at the Center postdocs Xenia Ritter and Surya Rout, along with former interns Katarina Keating and Kevin Eisenstein, contributed to the study, along with Birger Schmitz, Fredrik Terfelt, Noriko Kita and Céline Defouilloy. This research sheds light on the diversity of known sources including S-type asteroids, Vesta, and vestoids and currently unknown parent bodies in deep time. The calibrated Raman method opens doors to identifying extraterrestrial minerals in sediments across different ages. Read the paper at: https://doi.org/10.1111/maps.14133

Xin Yang, Field Museum Resident Graduate Student (University of Chicago) received the Hadean Award. The award is provided by the Museum's Earth Science Section and recognizes graduate student excellence, and is named for the first and oldest of the four known geologic eons of Earth's history (derives from Hades, the Greek god of the underworld). Xin came to Chicago in 2019 with a B.A. in Geochemistry from the University of Science and Technology of China. During his time in Chicago, where he collaborates with Robert A. Pritzker Curator of Meteoritics and Polar Studies Philipp Heck, he has made commendable progress in isotope geochemistry and cosmochemistry thanks to his analytical skills, collaborative spirit and strong work ethic. Notably, his efforts led to a first author publication in Nature Astronomy  on his discovery of the first record of a new geological process that rejuvenates surfaces of asteroids. Xin’s main research focus involves the first minerals that formed in the Solar System that were the building blocks of the planets. He uses Scanning Electron Microscopy, Raman, XCT scanning, mass spectrometry, and combines these techniques with dynamical modeling to provide new insights into the activity and evolution of the young Sun and early Solar System. He is a great Field Museum citizen and always there to support colleagues by providing help with analytical tools like Raman, SEM, and modeling.

Kate Golembiewski/FMNH: More than 4 billion years ago, when the Solar System was still young and the Earth was still growing, a giant object the size of Mars crashed into the Earth. The ejecta from that impact formed our Moon. But precisely when this happened has remained a mystery. In a new study in the journal Geochemical Perspectives Letters, researchers used crystals brought back from the Moon by Apollo astronauts in 1972 to help pinpoint the time of the Moon’s formation. Their discovery pushes back the age of the Moon by 40 million years, to at least 4.46 billion years old.

“These crystals are the oldest known solids that formed after the giant impact. And because we know how old these crystals are, they serve as an anchor for the lunar chronology,” says Philipp Heck, the Field Museum’s Robert A. Pritzker Curator for Meteoritics and Polar Studies and the Senior Director of the Negaunee Interactive Research Center, a professor at the University of Chicago, and the study’s senior author. The discovery was born of Heck’s work with the study’s lead author, Jennika Greer, when she was a doctoral candidate at the Field Museum and the University of Chicago. “We were approached by our coauthors, Bidong Zhang and Audrey Bouvier, who needed a nanoscale look at these samples in order to understand them fully,” says Greer, who is now a research associate at the University of Glasgow.

Read the full press release, paper and more covered in the media: Fox32 Chicago, Reuters, Washington Post, National Geographic, CBC, Newsweek. 

A perfect day and a historic landing on September 24, 2023 of the first US-spacecraft with a precious sample from an asteroid. Launched from Cape Canaveral in 2016, the spacecraft travelled to asteroid Bennu, where it orbited and mapped the asteroid and then grabbed a subsurface sample in 2020. Because asteroid Bennu is a carbon-rich asteroid that hasn't changed much since it formed about 4.6 billion years ago in the early Solar System it promises to have preserved the ingredients from which the planets, including Earth and its life later developed. On Earth scientists will use the latest, cutting-edge technology to analyze samples of asteroid Bennu and even set aside material for future generations of scientists who will have instruments that we cannot even imagine today. This is the power of sample return to Earth. Scientists Philipp Heck and Yuke Zheng at the Field Museum are part of the sample analysis team and will work on a sample after return. Philipp was recently interviewed on this topic by The Economist and Vox. Read updates and watch the live broadcast from NASA.

Philipp Heck had the honor of presenting the Barringer award citation to fossil meteorite pioneer Birger Schmitz at the Annual Meeting of the Meteoritical Society in Los Angeles in August. Birger received the prestigious Barringer Medal in recognition of his groundbreaking utilization of micrometeorites within the sedimentary record. This innovative approach has provided valuable insights into the history of impact processes and our comprehension of the effects of impact events on Earth's systems.

The Barringer Medal is a distinguished accolade bestowed upon individuals who have demonstrated exceptional contributions in the realm of impact cratering or those whose work has contributed significantly to our enhanced understanding of impact-related phenomena. Birger's journey began during his postdoctoral phase, mentored by the renowned Luis Alvarez at Lawrence Berkeley National Laboratory. Notably, Luis' son, Walter Alvarez, was also in attendance at the award ceremony, as depicted in the photograph.

Another Field Museum-related medalist was Andy Davis (Research Associate Earth Science) who received the Society’s Leonard Medal for his profound contributions to deciphering early solar system processes by improving the chronology, constraining the differentiation of planetesimals, exploring diffusion and condensation/evaporation processes, and revealing stellar nucleosynthetic pathways; and for advancing the chemical and isotopic microanalysis of meteoritic materials. The Leonard Medal is given to individuals who have made outstanding original contributions to the science of meteoritics or closely allied fields.

An international team of researchers who just got back from Antarctica can attest to the continent’s meteorite-hunter-friendliness: they returned with five new meteorites, including one that weighs 16.7 pounds (7.6 kg), and micrometeorites-containing sediment.

Maria Valdes, a research scientist at the Field Museum's Robert A. Pritzker Center for Meteoritics and Polar Studies and the University of Chicago, estimates that of the roughly 45,000 meteorites retrieved from Antarctica over the past century, only about a hundred or so are this size or larger. “Size doesn’t necessarily matter when it comes to meteorites, and even tiny micrometeorites can be incredibly scientifically valuable,” says Valdes, “but of course, finding a big meteorite like this one is rare, and really exciting.”

Valdes was one of four scientists on the mission, led by Vinciane Debaille of the Université Libre de Bruxelles (FNRS-ULB); the research team was rounded out by Maria Schönbächler (ETH-Zurich) and Ryoga Maeda (VUB-ULB). The researchers were the first to explore potential new meteorite sites mapped using satellite imagery by Veronica Tollenaar, a thesis student in glaciology at the ULB.

The meteorites recovered by the team will be analyzed at the Royal Belgian Institute of Natural Sciences; meanwhile, sediment potentially containing tiny micrometeorites was divided among the researchers for study at their institutions.

The team was guided by Manu Poudelet of the International Polar Guide Association and assisted by Alain Hubert. They were supported in part by the Belgian Science Policy. Valdes’s work is supported by the Field Museum’s Robert A. Pritzker Center for Meteoritics and Polar Studies, the TAWANI Foundation, and the Meeker family.

Media coverage on the expedition includes reports on Science Magazine, CNN, NPR, Space.com, Forbes, and several international media outlets including Swissinfo, Tagesspiegel, VRT, Gizmodo Japan – and Saturday Night Live!

The coming decade is expected to bring a veritable bonanza for the science of planets: space missions are scheduled to bring back samples of rock from the moon, Mars, the Martian moon of Phobos, and a primitive asteroid. And scientists say there is a new technique for determining the age of rocks, meteorites, and even artifacts, that could help open up a new era of discovery.

A group with the University of Chicago and the Field Museum of Natural History tested an instrument made by Thermo Fisher Scientific on a piece of a Martian meteorite nicknamed ‘Black Beauty’ and were able to quickly and precisely date it by probing it with a tiny laser beam—a significant improvement over past techniques, which involved far more work and destroyed parts of the sample. The meteorite was donated to the Field Museum's Robert A. Pritzker Center by private meteorite collector Jay Piatek.

“We are very excited by this demonstration study, as we think that we will be able to employ the same approach to date rocks that will be returned by multiple space missions in the future,” said Nicolas Dauphas, the Louis Block Professor of Geophysical Sciences at the University of Chicago, Honorary Research Associate at the Field Museum, and first author on a study laying out the results. “The next decade is going to be mind-blowing in terms of planetary exploration.”

Read the press release and paper in the Journal of Analytical Atomic Spectrometry. 

Jennika Greer, UChicago resident graduate student at the  Field Museum’s Robert A. Pritzker Center and Negaunee Integrative Research Center successfully defended her PhD. Her dissertation is titled “Atom Probe Tomography of Lunar Materials,” and her committee includes Philipp Heck (primary advisor), Nicolas Dauphas, Andy Davis, and Edwin Kite.

Lunar materials preserve records of the conditions and processes of the time when the Moon was first formed in the giant impact event, but also show evidence of more recent activity that involves the processes of impact cratering and space weathering that are active on the lunar surface today. Alteration due to space weathering can drastically change the reflectance spectra of these bodies as viewed with remote sensing through ground-based telescopes and spacecraft compared to laboratory analysis of the same material that was not space weathered. My work uses atom probe tomography (APT) to investigate the nanoscale characteristics of lunar materials and show how such analyses can be used to better understand the large-scale processes on the Moon. This includes the analysis of space weathered soils brought back by astronauts and the distribution of Pb in the oldest lunar zircon to date.

Kate Golembiewski/FMNH: In 2019, NASA’s OSIRIS-REx spacecraft sent back images of a geological phenomenon no one had ever seen before: pebbles were flying off the surface of the asteroid Bennu. The asteroid appeared to be shooting off swarms of marble-sized rocks. Scientists had never seen this behavior from an asteroid before, and it’s a mystery exactly why it happens. But in a new paper in Nature Astronomy, researchers show the first evidence of this process in a meteorite.

”It’s fascinating to see something that was just discovered by a space mission on an asteroid millions of miles away from Earth, and find a record from the same geological process in the museum’s meteorite collection,” says Philipp Heck, the Robert A. Pritzker Curator of Meteoritics at Chicago’s Field Museum and the senior author of the Nature Astronomy study.

Meteorites are pieces of rock that fall to Earth from outer space; they can be made of pieces of moons and planets, but most often, they're broken-off bits of asteroids. The Aguas Zarcas meteorite is named after the Costa Rican town where it fell in 2019; it came to the Field Museum  as a donation from Terry and Gail Boudreaux. Heck and his student, Xin Yang, were preparing the meteorite for another study when they noticed something strange.

“We were trying to isolate very tiny minerals from the meteorite by freezing it with liquid nitrogen and thawing it with warm water, to break it up,” says Yang, a graduate student at the Field Museum and the University of Chicago and the paper’s first author. “That works for most meteorites, but this one was kind of weird-- we found some compact fragments that wouldn’t break apart.”

Heck says that finding bits of meteorite that won’t disintegrate isn’t unheard of, but scientists usually just shrug and break out the mortar and pestle. “Xin had a very open mind, he said, ‘I’m not going to crush these pebbles to sand, this is interesting,’” says Heck. Instead, the researchers devised a plan to figure out what these pebbles were and why they were so resistant to breaking apart.

“We did CT scans to see how the pebbles compared to the other rocks making up the meteorite,” says Heck. “What was striking is that these components were all squished-- normally, they’d be spherical-- and they all had the same orientation. They were all deformed in the same direction, by one process.” Something had happened to the pebbles that didn’t happen to the rest of the rock around them. 

“This was exciting, we were very curious about what it meant,” says Yang.

The scientists had a clue, though, from the 2019 OSIRIS-REx findings. From there, they put together a hypothesis, which they supported with physical models. The asteroid underwent a high-speed collision, and the area of impact got deformed. That deformed rock eventually broke apart due to the huge temperature differences the asteroid experiences when it rotates, since the side facing the sun is more than 300° F warmer than the side facing away. “This constant thermal cycling makes the rock brittle, and it breaks apart into gravel,” says Heck. 

These pebbles are then ejected from the asteroid’s surface. “We don’t yet know what the process is that ejects the pebbles,” says Heck-- they might be dislodged by smaller impacts other space collisions, or they might just get released by the thermal stress the asteroid undergoes. But once the pebbles are disturbed, Heck says, “you don’t need much to eject something-- the escape velocity is very low.” A recent study of Bennu revealed that its surface is loosely bound and behaves like popcorn in a bucket.

The pebbles then entered a very slow orbit around the asteroid, and eventually, they fell back down to its surface further away where there was no deformation. Then, Heck and Yang say, the asteroid underwent another collision, the loose mixed pebbles on the surface got  transformed into a solid rock. “It basically packed everything together, and this loose gravel became a cohesive rock,” says Heck. The same impact may have dislodged the new rock, sending it careening into space. Eventually, that chunk fell to Earth as the Aguas Zarcas meteorite, carrying evidence of the pebble mixing.

This could explain the pebbles present in Aguas Zarcas, making the meteorite the first physical evidence of the geological process observed by OSIRIS-REx on Bennu. “It provides a new way of explaining the way that minerals on the surfaces of asteroids get mixed,” says Yang.

That’s a big deal, Heck says, because for a long time, scientists assumed that the main way that the minerals on the surfaces of asteroids get rearranged is through big crashes, which don’t happen very often. “From OSIRIS-REx we know that these particle ejection events are much more frequent than these high-velocity impacts,” says Heck, “so they probably play a more important role in determining the makeup of asteroids and meteorites.”

Aguas Zarcas is the first meteorite to show signs of this behavior, but it’s probably not the only one. “We would expect this in other meteorites,” says Heck. “People just haven't looked for it yet.” 

Philipp Heck, Robert A. Pritzker Curator of Meteoritics and Polar Studies, was recently selected as a Participating Scientist Collaborator on NASA’s OSIRIS-REx mission. Philipp will collaborate with Yongsong Huang from Brown University to study samples from the asteroid Bennu that were collected as part of the mission and are scheduled to be brought to Earth in September 2023. (Read more on the mission on Eos.) The team will analyze the samples to determine how the asteroid and its organic compounds formed, and will compare them to other meteorite samples in the Field Museum’s collection. The proposal was made possible thanks to preliminary work supported by the Museum’s Science Innovation Award.

The Field Museum's Robert A. Pritzker Center received the world’s largest collection of fossil meteorites, which fell to Earth hundreds of millions of years before the time of the dinosaurs. Members of the media were invited on Monday to see the meteorites getting unpacked from giant shipping crates and added to the museum’s research collection. 

Fox 32 Chicago, ABC 7 News, Chicago Sun Times, WBBM Radio, WTTW, WGN-TV,  all covered the event.

In the 1980s, workers in a limestone quarry in Sweden noticed some of these fossil meteorites in slabs of limestone. Since then, more than 100 fossil meteorites have been identified, making them some of the rarest geological specimens in the world.

The Field Museum has received 115 fossil meteorites as a donation from the Boudreaux family. Terry and Gail Boudreaux were present to help unpack the meteorites, along with Field Museum scientists, interns, and volunteers. The meteorites are preserved in large limestone slabs from the Swedish quarry, sometimes alongside fossilized marine life.

“Fossil meteorites are really important because they can tell us about the evolution of the Solar System,” says Philipp Heck, “These fossil meteorites are remnants of a massive collision and provide insight into catastrophic events in our Solar System.”

Resident UChicago graduate student Jennika Greer and collaborating Purdue  graduate student Alexander Kling presented latest results from our NASA-funded project on lunar soil at LPSC 2022. We use TEM and atom probe tomography on the same lunar soil grains to study space weathering products, including water. Read our abstracts at "Nanoscale Analyses of Vesicles in Space-Weathered Lunar Soil Silicates and Ilmenite" and "Identification of Solar Wind-Sourced Water in the Space Weathered Rims of Lunar Soils". Direct evidence / That lunar space weathering / Forms water on Moon.

The Consulate General of Switzerland in Chicago started their inaugural Skyline Chat with a discussion on presolar grains with Philipp Heck, Robert A. Pritzker Curator of Meteoritics and Polar Studies. We thank Consul General Bruno Ryff, Joerg Oberschmied, Deputy Consul General & Senior Public Diplomacy Officer, and Roberta Neuhäusler, Executive Assistant & Project Manager, for inviting us and for their interest in presolar stardust!

Our long-term collaboration with Northwestern University's Materials Science and Engineering Department was featured in the Northwestern Engineering Magazine. One of our current projects is in collaboratorion with Purdue University and Northwestern and looks at space-weathering products in lunar soil from the Apollo 17 mission and is funded by NASA. Learn More.

You are cordially invited to Chicago to attend the 84th Annual Meeting of the Meteoritical Society on August 14–21, 2021. We are planning for an in-person meeting and are excited to host those willing to travel. Travel awards will be available. Online attendance will be possible for those who cannot travel to Chicago. The meeting will be an excellent opportunity to present and discuss your research and learn about the state-of-the-art advancements in our fields. 

The scientific program is now posted online. Register now. A full refund will be provided until July 30, 2021 if you cannot travel.

More information.

June 30 was Asteroid Day, and members of the press were invited to meet with Field Museum postdoctoral scientist Dr. Maria C. Valdes (John Caldwell Meeker Postdoctoral Fellow) who described and classified a new brecciated eucrite NWA 13993. Maria performed X-ray microtomography, SEM/EDS and Raman spectroscopy on the rock. The specimen was collected in northwest Africa, purchased by Terry Boudreaux in 2020 and subsequently acquired by the Field Museum. Several Chicago media reported on this including the Chicago Sun Times, NBC Chicago, FOX32 Chicago.

An atom probe is on exhibit in the Searle Gallery on the 2nd floor of the Field Museum until March 2022. The instrument on display is an atom probe field ion microscope (VG FIM100) and is a precursor of the atom probe tomograph that we use today. The atom probe is a device that has been specifically designed to analyze tiny samples on an atomic scale. The atom probe provides us with a chemical map of the sample, atom by atom in three dimensions. Currently, our team uses the CAMECA LEAP 5000X at Northwestern University to study lunar soil, nanodiamonds, presolar stardust, and other meteoritic samples. 

Together with our colleagues from the Northwestern University Center for Atom Probe Tomography (NUCAPT) we have pioneered the application of atom probe tomography (APT) in cosmochemistry. APT is particularly useful for studying samples that are too small for conventional techniques like NanoSIMS and where chemical and in some cases isotopic compositions in 3D needs to be analyzed. So far, we have successfully analyzed meteoritic nanodiamonds, silicon carbide, olivine, ilmenite, kamacite and taenite. We are continuing to expand applications of APT in cosmochemistry. 

We thank the Museum of Science and Industry for the loan of the instrument and Northwestern University for their initiative for this exhibit. The Field Museum's research with the atom probe is funded by NASA and the TAWANI Foundation.

The Robert A. Pritzker Center's 2020 presolar stardust study published in PNAS made headlines again. The study was featured by National Geographic as the top story in "the top 10 awesome science discoveries you may have missed in 2020", by Yahoo! News as the top story in "The biggest and most important scientific breakthroughs of 2020", by Live Science among the "10 science records broken in 2020", by CNN among "Science's most fascinating and awe-inspiring discoveries in 2020", and by BBC Science Focus among the "20 moments in science to make you feel better about 2020". In our study we present cosmic-ray exposure ages of presolar stardust, the oldest dated solid samples available to science. We are honored by having been featured on these lists!

The Hamburg meteorite that fell in January 16, 2018 was recovered quickly thanks to a map of the strewnfield that made possible by weather radar data. Because the meteorite landed on frozen lakes in winter it did not get exposed to liquid water, did not get weathered, and also did not have time to get contaminated much. This is what makes this meteorite special compared to others that were not recovered as quickly and compared to those that got rained on. Thanks to meteorite hunters and collectors this meteorite was quickly made available to science. Read our international consortium study featuring work from 29 scientists at 24 institutions that appeared on October 27, 2020 in Meteoritics & Planetary Science. The study is featured on the journal cover and was covered by news media including CNN, The Guardian, Gizmodo, Courthouse News Service.

On October 7th, 2019 Terry and Evan Boudreaux visited the Pritzker Center to donate the main mass of the Aguas Zarcas meteorite that fell April 23, 2019 in Costa Rica. The Boudreaux family has supported the Pritzker Center over the last decade with many generous donations of scientifically important meteorites. Terry Boudreaux is one of the world's top meteorite collectors and loves to support scientific research with meteorites. Aguas Zarcas is an unusual carbonaceous chondrite, which at first resembles Murchison, but at a closer look reveals a more diverse collection of different lithologies that also include parts that were not aqueously altered. This makes it particular interesting to search for the earliest solar system condensates and presolar materials. The Field Museum is extremely grateful to the Boudreaux family for this scientifically highly valuable donation. 

The donation was covered by local news outlets, including Chicago Tonight WTTW, the Chicago Sun Times, NBC5 Chicago, FOX32 Chicago, ABC7 Chicago, and WBBM Newsradio.

About 466 million years ago, long before the age of the dinosaurs, the Earth froze. The seas began to ice over at the Earth's poles, and the new range of temperatures around the planet set the stage for a boom of new species evolving. The cause of this ice age was a mystery, until now: a new study in Science Advances lead by Birger Schmitz, a Professor at Lund University and an international team of colleagues incl. Philipp Heck, Pritzker Associate Curator and University of Chicago Associate Professor (part time), argues that the ice age was caused by global cooling, triggered by extra dust in the atmosphere from a giant asteroid collision in outer space.

There's always a lot of dust from outer space floating down to Earth, little bits of asteroids and comets, but this dust is normally only a tiny fraction of the other dust in our atmosphere such as volcanic ash, dust from deserts and sea salt. But when a 93-mile-wide asteroid between Mars and Jupiter broke apart 466 million years ago, it created way more dust than usual. "Normally, Earth gains about 40,000 tons of extraterrestrial material every year," says Philipp Heck. "Imagine multiplying that by a factor of a thousand or ten thousand." To contextualize that, in a typical year, one thousand semi trucks' worth of interplanetary dust fall to Earth. In the couple million years following the collision, it'd be more like ten million semis a year. 

"Our hypothesis is that the large amounts of extraterrestrial dust over a timeframe of at least two million years played an important role in changing the climate on Earth, contributing to cooling," says Heck.

The story generated a lot of media interest and was featured in New York Times, CBC, Reuters, Cosmos Magazine among others.

Read more.

This September we are celebrating the 50thanniversary of the fall of the Murchison meteorite, one of the most important meteorites to science. Since its fall near Murchison, Victoria in September 1969, the Murchison meteorite has been the source of numerous spectacular discoveries. Thanks to the large amount recovered, about 100 kg comprising of a large number of specimens, and its availability to the scientific community, the Murchison meteorite is one of the most studied meteorites of the type carbonaceous chondrite. The scientific community is grateful to the meteorite finders in Murchison to have made available the vast majority of the mass to science. The main fraction of Murchison was acquired by the Field Museum of Natural History in Chicago and since has been curated there another large fraction is at the Smithsonian Institution in Washington DC. 

Some of the most important discoveries made by studying Murchison in the last 50 years  includes the discovery of presolar stardust grains, solid samples of our parent stars more than 4.6 billion years old, which gave rise to presolar grains research, a new interdisciplinary subdiscipline within cosmochemistry and astrophysics. Other remarkable findings include the detection of a large variety of extraterrestrial organic matter incl. sugars, amino acids and urea, and the results obtained from studying refractory inclusions, which are among the first solids that formed in the solar system and are essentially time capsules from that time period. Murchison also served as an analog sample for the carbonaceous asteroid Bennu to test instruments of the OSIRIS-REx spacecraft. OSIRIS-Rex is scheduled to return to Earth with a sample of Bennu in 2023. The knowledge gained by studying Murchison significantly advanced our scientific understanding of the formation of our solar system 4.6 billion years ago.

The town of Murchison will hold an Anniversary Symposium on the anniversary weekend. Robert A. Pritzker Associate Curator Philipp R. Heck will speak there and will also give a public talk about the Murchison meteorite at the University of Melbourne. See this short video about Murchison.

Philipp Heck (Robert A. Pritzker Associate Curator) is the lead author, with a large group of meteorite and astromaterial curators, of an article about best practices for the use of meteorite names in publications. The article appears in the early view section of the journal Meteoritics & Planetary Science. When meteorite specimens are loaned for research, recipients are not only expected to acknowledge the loaning institution, but also to refer to the loaned specimen in an unambiguous way to avoid confusion and enable reproducibility of the research. That means not only the meteorite name should be reported but also the specimen’s full catalog number (example at left). Knowing which specimen was studied can help resolve the rare cases of mislabeling, but is also very important when referring to meteorites with varied composition—for example, breccias can contain clasts of different meteorite types. In many cases, pieces of the same meteorites were recovered at different times and thus experienced varying degrees of alteration from terrestrial weathering (e.g., rain!). There are also cases in which specimens from the same meteorite have several different unofficial names because they were found by different people at different places at different times. The iron meteorite North Chile shown in the photo, for example, has accrued some 16 names! Many of the recommendations by Heck et al. may be transferrable to other collections. You can read the paper in Meteoritics & Planetary Science at https://onlinelibrary.wiley.com/doi/10.1111/maps.13291

Philipp Heck (Robert A. Pritzker Associate Curator for Meteoritics and Polar Studies) has received a grant from NASA’s Emerging Worlds program. Together with Resident Grad Student Jennika Greer (University of Chicago) and collaborators from Northwestern University and ETH Zurich, Switzerland, the research will focus on “Underexplored aspects of the history of our solar system’s presolar starting material.” The knowledge of the origin of the starting material of our Solar System is an issue of fundamental interest in planetary science. After the discovery of presolar grains in 1987 (by Edward Anders, Roy S. Lewis and their colleagues at the University of Chicago), it was possible to study solid samples of stars in the laboratory for the first time, providing a unique perspective on the origin and composition of the material from which the Solar System formed. However, most studies have focused on the larger size fraction of grains, which are rarer and therefore less representative. Philipp and colleagues will focus on presolar nanograins that are too small to study with conventional analytical techniques. Philipp’s group has pioneered the use of atom-probe tomography to study the composition of extraterrestrial samples with a goal of better understanding the origins of these understudied samples, and hence our origins, information not obtainable otherwise. The team will also significantly extend the known ages of presolar grains, information that is currently very limited. The team will apply a unique analytical method developed by Philipp and collaborators, and improved physics, to determine the presolar chronology of the Solar System’s starting material. The Murchison meteorite from the Field Museum’s collection will serve as the main source for presolar grains.

Our Sun's beginnings are a mystery. It burst into being 4.6 billion years ago, about 50 million years before the Earth formed. Since the Sun is older than the Earth, it's hard to find physical objects that were around in the Sun's earliest days--materials that bear chemical records of the early Sun. But in a new study in Nature Astronomy, ancient blue crystals trapped in meteorites reveal what the early Sun was like. And apparently, it had a pretty rowdy start.

"The Sun was very active in its early life--it had more eruptions and gave off a more intense stream of charged particles. I think of my son, he's three, he's very active too," says Philipp Heck, a curator at the Field Museum, professor at the University of Chicago, and co-author of the study. "Almost nothing in the Solar System is old enough to really confirm the early Sun's activity, but these minerals from meteorites in the Field Museum's collections are old enough. They're probably the first minerals that formed in the Solar System."

The minerals the team looked at are microscopic ice-blue crystals called hibonite, and their composition bears earmarks of chemical reactions that only would have occurred if the early Sun was spitting lots of energetic particles. "These crystals formed over 4.5 billion years ago and preserve a record of some of the first events that took place in our Solar System. And even though they are so small--many are less than 100 microns across--they were still able to retain these highly volatile nobles gases that were produced through irradiation from the young Sun such a long time ago," says lead author Levke Kööp, a post-doc from the University of Chicago and an affiliate of the Field Museum. In its early days, before the planets formed, the Solar System was made up of the Sun with a massive disk of gas and dust spiraling around it. The region by the sun was hot. Really hot-- more than 1,500 C, or 2,700 F. For comparison, Venus, the hottest planet in the Solar System, with surface temperatures high enough to melt lead, is a measly 872 F. As the disk cooled down, the earliest minerals began to form--blue hibonite crystals."

The larger mineral grains from ancient meteorites are only a few times the diameter of a human hair. When we look at a pile of these grains under a microscope, the hibonite grains stand out as little light blue crystals--they're quite beautiful," says Andy Davis, another co- author also affiliated with the Field Museum and the University of Chicago. These crystals contain elements like calcium and aluminum. When the crystals were newly formed, the young Sun continued to flare, shooting protons and other subatomic particles out into space. Some of these particles hit the blue hibonite crystals. When the protons struck the calcium and aluminum atoms in the crystals, the atoms split apart into smaller atoms--neon and helium. And the neon and helium remained trapped inside the crystals for billions of years. These crystals got incorporated into space rocks that eventually fell to Earth as meteorites for scientists like Heck, Kööp, and Davis to study. Researchers have looked at meteorites for evidence of an early active Sun before. But the findings could be explained by other mechanisms than direct particle irradiation of minerals by the early Sun. For the new study the team examined the crystals with a unique state-of-the-art mass spectrometer at ETH Zurich in Switzerland--a garage-sized machine that can determine objects' chemical make-up. Attached to the mass spectrometer, a laser melted a tiny grain of hibonite crystal from a meteorite, releasing the helium and neon trapped inside so they could be detected. "We got a surprisingly large signal, clearly showing the presence of helium and neon--it was amazing," says Kööp.The bits of helium and neon provide the first concrete evidence of the Sun's long-suspected early activity. "It'd be like if you only knew someone as a calm adult--you'd have reason to believe they were once an active child, but no proof. But if you could go up into their attic andfind their old broken toys and books with the pages torn out, it'd be evidence that the person was once a high-energy toddler," says Heck.Unlike other hints that the early Sun was more active than it is today, there's no other good explanation for the crystals' make-up. "It's always good to see a result that can be clearly interpreted," says Heck. "The simpler an explanation is, the more confidence we have in it." "In addition to finally finding clear evidence in meteorites that disk materials were directly irradiated, our new results indicate that the Solar System's oldest materials experienced a phase of irradiation that younger materials avoided. We think that this means that a major change occurred in the nascent Solar System after the hibonites had formed--perhaps the Sun's activity decreased, or maybe later-formed materials were unable to travel to the disk regions in which irradiation was possible," says Kööp.

Read original article Kööp L. et al. (2018) Nature Astronomy 2:709–713.

Scientists reconstruct distribution of space rocks predating giant collision

By Kate Golembiewski – January 26, 2017 

About 466 million years ago, there was a giant collision in outer space. Something hit an asteroid and broke it apart, sending chunks of rock falling to Earth as meteorites. But what kinds of meteorites were making their way to Earth before that collision?

In a study published in Nature Astronomy, scientists tackled that question by creating the first reconstruction of the distribution of meteorite types before the collision. They discovered that most of the meteorites falling to Earth today are rare, while many meteorites that are rare today were common before the collision.

“We found that the meteorite flux—the variety of meteorites falling to Earth—was very, very different from what we see today,” said Philipp Heck, associate professor of geophysical sciences at the University of Chicago, the paper’s lead author. “Looking at the kinds of meteorites that have fallen to Earth in the last hundred million years doesn’t give you a full picture. It would be like looking outside on a snowy day and concluding that every day is snowy, even though it’s not snowy in the summer.”

Meteorites are pieces of rock that have fallen to Earth from outer space. They’re formed from the debris of collisions between bodies like asteroids, moons and even planets. There are many different types of meteorites, which reflect the different compositions of their parent bodies. By studying the different meteorites that have made their way to Earth, scientists can develop a better understanding of how the basic building blocks of the solar system formed and evolved.

“Before this study, we knew almost nothing about the meteorite flux to Earth in geological deep time,” said co-author Birger Schmitz, professor of nuclear physics at Lund University. “The conventional view is that the solar system has been very stable over the past 500 million years. So it is quite surprising that the meteorite flux at 467 million years ago was so different from (that of) the present.”

To learn what the meteorite flux was like before the big collision event, Heck and his colleagues analyzed meteorites that fell more than 466 million years ago. Such finds are rare, but the team was able to look at micrometeorites—tiny specks of space-rock less than 2 millimeters in diameter that fell to Earth. They are less rare. Heck’s Swedish and Russian colleagues retrieved samples of rock from an ancient seafloor exposed in a Russian river valley that contained micrometeorites. They then dissolved almost 600 pounds of the rocks in acid so that only microscopic chromite crystals remained.

Not having changed during hundreds of millions of years, the crystals revealed the nature of meteorites over time. Analysis of their chemical makeup showed that the meteorites and micrometeorites that fell earlier than 466 million years ago are different from the ones that have fallen since. A full 34 percent of the pre-collision meteorites belong to a meteorite type called primitive achondrites; today, only 0.45 percent of the meteorites that land on Earth are this type.

Other micrometeorites sampled turned out to be relics from Vesta—the brightest asteroid visible from Earth, which underwent its own collision event over a billion years ago.

Meteorite delivery from the asteroid belt to the Earth is a little like observing landslides started at different times on a mountainside, said co-author William Bottke, senior research scientist at the Southwest Research Institute. “Today, the rocks reaching the bottom of the mountain might be dominated by a few recent landslides. Going back in time, however, older landslides should be more important. The same is true for asteroid breakup events; some younger ones dominate the current meteorite flux, while in the past older ones dominated.”

“Knowing more about the different kinds of meteorites that have fallen over time gives us a better understanding of how the asteroid belt evolved and how different collisions happened,” said Heck, an associate curator of meteoritics and polar studies at the Field Museum of Natural History. “Ultimately, we want to study more windows in time, not just the area before and after this collision. That will deepen our knowledge of how different bodies in our solar system formed and interact with each other.”

—Adapted from a story first published by the Field Museum of Natural History.

Read the article at: “Rare meteorites common in the Ordovician period,” Nature Astronomy, Jan. 23, 2017. DOI: 10.1038/s41550-016-0035.

Read the associated News & Views piece: DeMeo 2017, "Meteorites: A shift in shooting stars", Nature Astronomy, DOI: http://dx.doi.org/10.1038/s41550-017-0041

Funding: European Research Council and Tawani Foundation

Former Field Museum postdoc Surya Rout together with Robert A. Pritzker Associate Curator Philipp Heck published an atom-probe tomography (APT) study in Meteoritics & Planetary Science on the Bristol iron meteorite together with collaborators at Northwestern University, Argonne National Laboratory and the University of Chicago. The study demonstrates that APT in conjunction with transmission electron microscopy (TEM) is a useful approach to study the major, minor, and trace elemental composition of nanoscale features within iron meteorites. This combined approached proved particularly fruitful for fast-cooled irons, as many of their features are on the nanoscale, and are well resolved with the near atomic spatial resolution of APT. The study measured composition of different phases in the specimen generated new knowledge about phase compositional changes during the fast cooling. The study also shows that the Bristol meteorite did not experience high shock pressures and temperatures due to impacts on its parent asteroid. The article can be read in full at Meteoritics & Planetary Science. 

The team also present a new method using SEMGlu adhesive to speed up sample preparation for APT. Their method appeared in March 2018 issue of Microscopy Today.