Presolar grains are minerals that are older than anything else in our Solar System (Podcast). They formed before the birth of our Solar System and a small fraction survived in primitive asteroids and comets. We extract presolar grains from fragments of these objects: unaltered meteorites, interplanetary dust particles and comet dust. We study the elemental and isotopic compositions of presolar grains to understand the presolar history of meteoritic matter. The interdisciplinary field of presolar grain research informally also called Astrophysics in the Laboratory is delivering a wealth of information on stars and our Galaxy that are not accessible through astronomical observations. One of our main motivations to study presolar grains, a surviving fraction of the source materials of our Solar System, is to improve our understanding of the history of our Galaxy.
The delivery of extraterrestrial matter to Earth
We are also interested in the history of the delivery of extraterrestrial matter to Earth. We study the origins and delivery modes of meteorites and micrometeorites that are preserved in terrestrial archives such as sedimentary rocks. Such studies will help to better understand the collisional evolution of the solar system. Results from these studies also have the potential to investigate if accrection of extraterrestrial material affected the environment on Earth at different geological times.
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Surfaces of airless bodies like the Moon and asteroids are constantly bombarded by cosmic rays, energetic particles from the sun and other stars, and by micrometeorites. This bombardment changes the composition and appearance of the surface, and effect that is called space weathering. Space weathered surfaces can be observed with telescopes over hundreds of millions of miles from Earth but actually operate at the nanoscale. We are conducting research on the nanoscale with atom probe tomography to better characterize space weathering on the Moon and on asteroids.
Early solar System
We are interested in the earliest solar system processes that are recorded in components of meteorites. Minerals from refractory inclusions, like hibonite and spinel are among the first to have condensed in the cooling solar nebula. By studying their structure, chemical and isotopic composition we can gain a better understanding of the early solar system. Some of the key processes happened within the first 100,000 to millions of years in solar system evolution that defined the fate of the solar system.
Atom-Probe Tomography in Cosmochemistry
We have pioneered the application of atom-probe tomography (APT) in collaboration with colleagues from the Northwestern University Center for Atom Probe Tomography (NUCAPT). 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.
Chicago Center for Cosmochemistry
The Field Museum is part of the three-institution Chicago Center for Cosmochemistry (C^3) together with Argonne National Laboratory and the University of Chicago. C^3 is dedicated to promoting education and research in cosmochemistry. The center holds a weekly seminar during academic quarters. C^3 aims to take advantage of the strength of the cosmochemistry community in Chicago. The Field Museum's world-class meteorite collection, a superb array of cutting-edge analytical facilities and state-of-the-art sample preparation laboratories at Argonne and the U of C are core elements of C^3. It also serves as a magnet to attract cosmochemists from around the world to Chicago.
For our work we have the following tools and infrastructure available at the Field Museum: sample preparation laboratory incl. fine sectioning and polishing equipment, cosmochemistry laboratory with centrifuge, laminar flow benches, fumehoods and a cleanroom, a variety of optical microscopes, WITec 300R Raman spectroscopy system, Zeiss Evo 60 scanning electron microscope with Oxford Instruments XMax 50 SSD-EDS detector, Thermo Scientific iCAP LA-ICP-MS, XRF. Through collaboration we also have access to the Cameca LEAP 5000 Atom Probe at nearby Northwestern University, a Tescan Lyra FIB-SEM with EDS/WDS/EBSD at nearby University of Chicago. Our cosmochemists have also access to Northwestern's NUANCE instrument park. We are also performing important analyses for our projects at the noble gas spectrometry lab at ETH Zurich and the IMS-1280 at WiscSIMS through longstanding collaborations.