Volatile components are abundant in carbonaceous asteroids and can be important tracers for the evolution of asteroid surfaces interacting with the space environment, but their behavior on airless surfaces is poorly understood. Samples... more
Volatile components are abundant in carbonaceous asteroids and can be important tracers for the evolution of asteroid surfaces interacting with the space environment, but their behavior on airless surfaces is poorly understood. Samples from the C-type carbonaceous asteroid Ryugu show dehydration of phyllosilicate, indicating ongoing surface modifications on the aqueously-altered asteroid. Here we report the analysis of Ryugu samples showing selective liberation of carbon, oxygen, and sulfur from iron-rich oxide, sulfide, and carbonate, which are major products of aqueous alteration. These mineral surfaces are decomposed to metallic iron, iron nitride, and magnesium-iron oxide. The modifications are most likely caused by solar wind implantation and micrometeorite impacts and are distinct indicators of surface space exposure over 103 years. Nitridation of metallic iron may require micrometeorites rich in solid nitrogen compounds, which implies that the amount of nitrogen available for...
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We measured the elemental compositions of material from 23 particles in aerogel and from residue in seven craters in aluminum foil that was collected during passage of the Stardust spacecraft through the coma of comet 81P/Wild 2. These... more
We measured the elemental compositions of material from 23 particles in aerogel and from residue in seven craters in aluminum foil that was collected during passage of the Stardust spacecraft through the coma of comet 81P/Wild 2. These particles are chemically heterogeneous at the largest size scale analyzed (â¼180 ng). The mean elemental composition of this Wild 2 material is consistent with the CI meteorite composition, which is thought to represent the bulk composition of the solar system, for the elements Mg, Si, Mn, Fe, and Ni to 35%, and for Ca and Ti to 60%. The elements Cu, Zn, and Ga appear enriched in this Wild 2 material, which suggests that the CI meteorites may not represent the solar system composition for these moderately volatile minor elements.
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Particles emanating from comet 81P/Wild 2 collided with the Stardust spacecraft at 6.1 kilometers per second, producing hypervelocity impact features on the collector surfaces that were returned to Earth. The morphologies of these... more
Particles emanating from comet 81P/Wild 2 collided with the Stardust spacecraft at 6.1 kilometers per second, producing hypervelocity impact features on the collector surfaces that were returned to Earth. The morphologies of these surprisingly diverse features were created by particles varying from dense mineral grains to loosely bound, polymineralic aggregates ranging from tens of nanometers to hundreds of micrometers in size. The cumulative size distribution of Wild 2 dust is shallower than that of comet Halley, yet steeper than that of comet Grigg-Skjellerup.
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The Stardust spacecraft collected thousands of particles from comet 81P/Wild 2 and returned them to Earth for laboratory study. The preliminary examination of these samples shows that the nonvolatile portion of the comet is an... more
The Stardust spacecraft collected thousands of particles from comet 81P/Wild 2 and returned them to Earth for laboratory study. The preliminary examination of these samples shows that the nonvolatile portion of the comet is an unequilibrated assortment of materials that have both presolar and solar system origin. The comet contains an abundance of silicate grains that are much larger than predictions of interstellar grain models, and many of these are high-temperature minerals that appear to have formed in the inner regions of the solar nebula. Their presence in a comet proves that the formation of the solar system included mixing on the grandest scales.
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Hydrogen, carbon, nitrogen, and oxygen isotopic compositions are heterogeneous among comet 81P/Wild 2 particle fragments; however, extreme isotopic anomalies are rare, indicating that the comet is not a pristine aggregate of presolar... more
Hydrogen, carbon, nitrogen, and oxygen isotopic compositions are heterogeneous among comet 81P/Wild 2 particle fragments; however, extreme isotopic anomalies are rare, indicating that the comet is not a pristine aggregate of presolar materials. Nonterrestrial nitrogen and neon isotope ratios suggest that indigenous organic matter and highly volatile materials were successfully collected. Except for a single 17 O-enriched circumstellar stardust grain, silicate and oxide minerals have oxygen isotopic compositions consistent with solar system origin. One refractory grain is 16 O-enriched, like refractory inclusions in meteorites, suggesting that Wild 2 contains material formed at high temperature in the inner solar system and transported to the Kuiper belt before comet accretion.
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Table of data of carbon, nitrogen and oxygen elemental compositions prior to corrections. Supporting data for journal article published in Proceedings of the National Academy of Sciences in June 2018, titled "Multiple generations of... more
Table of data of carbon, nitrogen and oxygen elemental compositions prior to corrections. Supporting data for journal article published in Proceedings of the National Academy of Sciences in June 2018, titled "Multiple generations of grain aggregation in different environments preceded solar system body formation".Table of data of carbon, nitrogen and oxygen elemental compositions prior to corrections. Supporting data for journal article published in Proceedings of the National Academy of Sciences in June 2018, titled "Multiple generations of grain aggregation in different environments preceded solar system body formation"
The bulk of the comet 81P/Wild 2 (hereafter Wild 2) samples returned to Earth by the Stardust spacecraft appear to be weakly constructed mixtures of nanometer-scale grains, with occasional much larger (over 1 micrometer) ferromagnesian... more
The bulk of the comet 81P/Wild 2 (hereafter Wild 2) samples returned to Earth by the Stardust spacecraft appear to be weakly constructed mixtures of nanometer-scale grains, with occasional much larger (over 1 micrometer) ferromagnesian silicates, Fe-Ni sulfides, Fe-Ni metal, and accessory phases. The very wide range of olivine and low-Ca pyroxene compositions in comet Wild 2 requires a wide range of formation conditions, probably reflecting very different formation locations in the protoplanetary disk. The restricted compositional ranges of Fe-Ni sulfides, the wide range for silicates, and the absence of hydrous phases indicate that comet Wild 2 experienced little or no aqueous alteration. Less abundant Wild 2 materials include a refractory particle, whose presence appears to require radial transport in the early protoplanetary disk.
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Abstract. X-ray fluorescence microCT (computed tomography) is a novel technique that allows non-destructive determination of the 3D distribution of chemical elements inside a sample. This is especially important in samples for which... more
Abstract. X-ray fluorescence microCT (computed tomography) is a novel technique that allows non-destructive determination of the 3D distribution of chemical elements inside a sample. This is especially important in samples for which sectioning is undesirable either due to the risk of contamination or the requirement for further analysis by different characterization techniques. Developments made by third generation synchrotron facilities and laboratory X-ray focusing systems have made these kinds of measurements more attractive by significantly reducing scan times and beam size. First results from the x-ray fluorescence microCT experiments performed at SSRL beamline 6-2 are reported here. Beamline 6-2 is a 54 pole wiggler that uses a two mirror optical system for focusing the x-rays onto a virtual source slit which is then reimaged with a set of KB mirrors to a (2 x 4) µm 2 beam spot. An energy dispersive fluorescence detector is located in plane at 90 degrees to the incident beam t...
IMPLICATIONS FOR THE NATURE OF COMETS. P. J. Wozniakiewicz, H. A. Ishii, A. T. Kearsley, M. J. Burchell, J. P. Bradley, N. Teslich and M. J. Cole. Institute of Geophysics and Planetary Physics, Lawrence Livermore National Laboratory... more
IMPLICATIONS FOR THE NATURE OF COMETS. P. J. Wozniakiewicz, H. A. Ishii, A. T. Kearsley, M. J. Burchell, J. P. Bradley, N. Teslich and M. J. Cole. Institute of Geophysics and Planetary Physics, Lawrence Livermore National Laboratory (LLNL), 7000 East Avenue, Livermore, CA 94550, USA (wozniakiewic1@llnl.gov). Impacts & Astromaterials Research Centre (IARC), Department of Mineralogy, Natural History Museum (NHM), London SW7 5BD, UK. Centre for Astrophysics and Planetary Science, School of Physical Sciences, University of Kent, Canterbury, Kent CT2 7NH, UK.
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1 , S. Brennan 2 , J. P. Bradley 1 , P. Pianetta 2 , A. T. Kearsley 3 and M. J. Burchell 4 , 1 Institute of Geophysics & Planetary Physics, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA (hope.ishii@llnl.gov), 2 Stanford... more
1 , S. Brennan 2 , J. P. Bradley 1 , P. Pianetta 2 , A. T. Kearsley 3 and M. J. Burchell 4 , 1 Institute of Geophysics & Planetary Physics, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA (hope.ishii@llnl.gov), 2 Stanford Synchrotron Radiation Laboratory, Stanford Linear Accelerator Center, Menlo Park, CA 94025, USA, 3 Department of Mineralogy, Natural History Museum, London, SW7 5BD UK, 4 School of Physical Sciences, University of Kent, Canterbury, Kent CT2 7NH UK.
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Introduction: Historically, comet dust composition measurements have been made remotely or with poor resolution and detection limits due to spaceflight limitations on instrumentation. Comet 81P/Wild 2’s serendipitous orbit change to the... more
Introduction: Historically, comet dust composition measurements have been made remotely or with poor resolution and detection limits due to spaceflight limitations on instrumentation. Comet 81P/Wild 2’s serendipitous orbit change to the inner solar system provided the chance for NASA’s Stardust mission to collect a sample from an object originally from the cold and distant Kuiper belt and return it to Earth for in-depth analysis. Kuiper belt objects have been expected to contain primitive materials preserved since the solar system formed ~4.6 Gyr ago. The Stardust samples were subjected to intense study in the year since its January 2006 return [1], and synchrotron xray microprobe x-ray fluorescence (micro-SXRF) measurements have provided much information on their (non-volatile) composition and heterogeneity [2]. Measurement of bulk chemistry is of prime interest for comparison with other classes of extraterrestrial materials to understand Wild 2’s place in the continuum of solar sy...
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Introduction: NASA’s Stardust mission returned the first samples of a known comet, 81P/Wild 2 [1], permitting comparison with chondritic porous interplanetary dust particles (CP IDPs) also believed to originate from comets [c.f. 2].... more
Introduction: NASA’s Stardust mission returned the first samples of a known comet, 81P/Wild 2 [1], permitting comparison with chondritic porous interplanetary dust particles (CP IDPs) also believed to originate from comets [c.f. 2]. Unfortunately, hypervelocity capture of Wild 2 dust in silica aerogel severely altered the fine-grained fraction; however, large (few to 10s of microns) refractory Wild 2 grains survived capture relatively intact, and surviving CAIs and chondrule fragments [3-7] provide a compelling link to carbonaceous chondrites (CCs) and unprecedented insight into grain transport in the solar nebula [1]. Linking Wild 2 to specific classes of CCs, IDPs or micrometeorites (MMs) has proven significantly more challenging. Comparisons with fine-grained materials, like CP IDPs, are particularly difficult because the loss and damage to the fine-grained fraction was so severe – although some authors argue CP IDP-like material must have been present [8,9]. GEMS and enstatite (...
Bleuet, F. Brenker, S. Brennan, C. Daghlian, Z. Djouadi, T. Ferroir, J.-P. Gallien, Ph. Gillet, P. G. Grant, F. Grossemy, G. F. Herzog, H. A. Ishii, H. Khodja, A. Lanzirotti, J. Leitner, L. Lemelle, K. Luening, G. MacPherson, M. Marcus,... more
Bleuet, F. Brenker, S. Brennan, C. Daghlian, Z. Djouadi, T. Ferroir, J.-P. Gallien, Ph. Gillet, P. G. Grant, F. Grossemy, G. F. Herzog, H. A. Ishii, H. Khodja, A. Lanzirotti, J. Leitner, L. Lemelle, K. Luening, G. MacPherson, M. Marcus, G. Matrajt, T. Nakamura, T. Nakano, M. Newville, P. Pianetta, W. Rao, D. Rost, J. Sheffield-Parker, A. Simionovici, T. Stephan, S. R. Sutton, S. Taylor, A. Tsuchiyama, K. Uesugi, A. Westphal, E. Vicenzi, L. Vincze, SUNY, Plattsburgh NY 12901 (george.flynn@plattsburgh.edu), Institut d'Astrophysique Spatiale, Orsay, France, ESRF, Grenoble, France, JWG-University Frankfurt, Germany, Stanford Linear Accelerator Center, Menlo Park CA, Dartmouth College, Hanover NH, Lab. Pierre Süe, CEA/CNRS, Saclay, France. École Normale Supérieure de Lyon, Lyon, France, Lawrence Livermore National Laboratory, Livermore CA, Rutgers Univ., Piscataway NJ, University of Chicago, Chicago IL, Institut für Planetologie, Universität Münster, Germany, Smithsonian Institution,...
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AN EDX AND EELS COMPARISON H. A. Ishii, K. K. Ohtaki, J. P. Bradley, K. C. Bustillo, K. L. Villalon, A. M. Davis, T. Stephan, and P. Longo, Hawai‘i Institute of Geophysics and Planetology, University of Hawai‘i at Mānoa, Honolulu, HI,... more
AN EDX AND EELS COMPARISON H. A. Ishii, K. K. Ohtaki, J. P. Bradley, K. C. Bustillo, K. L. Villalon, A. M. Davis, T. Stephan, and P. Longo, Hawai‘i Institute of Geophysics and Planetology, University of Hawai‘i at Mānoa, Honolulu, HI, USA, National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA, Department of Geophysical Sciences, The University of Chicago, Chicago, IL, USA, Gatan Inc., Pleasanton, CA, USA. Email: hope.ishii@hawaii.edu or kohtaki@hawaii.edu.
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M. Kaluna , G. J. Taylor and M. S. Nii, Hawai‘i Institute of Geophysics and Planetology, University of Hawai‘i at Mānoa, 1680 East West Road, POST 602, Honolulu, HI 96822, USA (hope.ishii@hawaii.edu), Department of Physics and Astronomy,... more
M. Kaluna , G. J. Taylor and M. S. Nii, Hawai‘i Institute of Geophysics and Planetology, University of Hawai‘i at Mānoa, 1680 East West Road, POST 602, Honolulu, HI 96822, USA (hope.ishii@hawaii.edu), Department of Physics and Astronomy, University of Hawai‘i at Hilo, 200 W. Kawili St., Hilo, HI 96720, USA, Hawai‘i Space Grant Consortium, University of Hawai‘i at Mānoa, 1680 East West Road, POST 501, Honolulu, HI 96822, USA.
Ishii, P. J. Wozniakiewicz, J. P. Bradley, K. Farley and M. Martinsen, Hawai‘i Institute of Geophysics and Planetology, University of Hawai‘i at Mānoa, 1680 East West Road, POST 602, Honolulu, HI 96822, USA (hope.ishii@hawaii.edu), School... more
Ishii, P. J. Wozniakiewicz, J. P. Bradley, K. Farley and M. Martinsen, Hawai‘i Institute of Geophysics and Planetology, University of Hawai‘i at Mānoa, 1680 East West Road, POST 602, Honolulu, HI 96822, USA (hope.ishii@hawaii.edu), School for Physical Sciences, Ingram Building, University of Kent, Canterbury, Kent CT2 7NH, UK, Division of Geological and Planetary Sciences, California Institute of Technology, MC 170-25, Pasadena, CA 91125, USA, National Oceanic and Atmospheric Administration, Earth System Research Laboratory, Global Monitoring Division, Mauna Loa Observatory, 1437 Kilauea Avenue, Suite 102, Hilo, HI 96720, USA.
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SIS. H.A. Ishii, S. Brennan, K. Luening, P. Pianetta, J.P. Bradley, C.J. Snead and A.J. Westphal, Bay Area Particle Analysis Consortium, Institute for Geophysics and Planetary Physics, Lawrence Livermore National Laboratory, Livermore, CA... more
SIS. H.A. Ishii, S. Brennan, K. Luening, P. Pianetta, J.P. Bradley, C.J. Snead and A.J. Westphal, Bay Area Particle Analysis Consortium, Institute for Geophysics and Planetary Physics, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA (hope.ishii@llnl.gov), Stanford Synchrotron Radiation Laboratory, Stanford Linear Accelerator Center, Stanford, CA 94025, USA (brennan@stanford.edu), Space Science Laboratory, University of California at Berkeley, Berkeley, CA 94720, USA.
SAMPLES. S. Brennan 1 , H.A. Ishii 2 , K. Luening 1 , P. Pianetta 1 , and D.S. Burnett 3 , 1 Stanford Synchrotron Radiation Laboratory, Stanford Linear Accelerator Center, Stanford, CA 94025, USA (sean.brennan@stanford.edu), 2 Institute... more
SAMPLES. S. Brennan 1 , H.A. Ishii 2 , K. Luening 1 , P. Pianetta 1 , and D.S. Burnett 3 , 1 Stanford Synchrotron Radiation Laboratory, Stanford Linear Accelerator Center, Stanford, CA 94025, USA (sean.brennan@stanford.edu), 2 Institute for Geophysics and Planetary Physics, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA (hope.ishii@llnl.gov), 3 California Institute of Technology, MS 100-23, Pasadena, CA 91125 USA.
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CONSIDERATIONS FOR TRACE ELEMENT ANALYSIS. H. A. Ishii, K. Luening, S. Brennan, P. Pianetta, K. Ignatyev, G. Matrajt and J. P. Bradley, Institute for Geophysics and Planetary Physics, Lawrence Livermore National Laboratory, Livermore, CA... more
CONSIDERATIONS FOR TRACE ELEMENT ANALYSIS. H. A. Ishii, K. Luening, S. Brennan, P. Pianetta, K. Ignatyev, G. Matrajt and J. P. Bradley, Institute for Geophysics and Planetary Physics, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA (hope.ishii@llnl.gov), Stanford Synchrotron Radiation Laboratory, Stanford Linear Accelerator Center, Stanford, CA 94025, USA (sean.brennan@stanford.edu), Department of Astronomy, University of Washington, Seattle, WA 98195, USA.
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The 2175 angstrom extinction feature is the strongest (visible-ultraviolet) spectral signature of dust in the interstellar medium. Forty years after its discovery, the origin of the feature and the nature of the carrier(s) remain... more
The 2175 angstrom extinction feature is the strongest (visible-ultraviolet) spectral signature of dust in the interstellar medium. Forty years after its discovery, the origin of the feature and the nature of the carrier(s) remain controversial. Using a transmission electron microscope, we detected a 5.7-electron volt (2175 angstrom) feature in interstellar grains embedded within interplanetary dust particles (IDPs). The carriers are organic carbon and amorphous silicates that are abundant in IDPs and in the interstellar medium. These multiple carriers may explain the enigmatic invariant central wavelength and variable bandwidth of the astronomical 2175 angstrom feature.
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Introduction: Isheyevo, a metal-rich CH/CB-like meteorite, shows whole-rock δ 15 N enrichment up to ~+1500‰ [1]. Bonal et al. discovered rare chondritic clasts in Isheyevo containing mafic silicates, large bulk 15 N enrichments (δ 15 N... more
Introduction: Isheyevo, a metal-rich CH/CB-like meteorite, shows whole-rock δ 15 N enrichment up to ~+1500‰ [1]. Bonal et al. discovered rare chondritic clasts in Isheyevo containing mafic silicates, large bulk 15 N enrichments (δ 15 N from +1000 to 1300‰) and µm-sized " hotspots " with δ 15 N approaching +5000‰ [2,3]. The source of these high 15 N enrichments, whether due to molecular cloud, nebular and/or parent body processing, is presently unknown. Because the clast matrix material is fine-grained, we are carrying out FIB/TEM petrographic studies to be coordinated with NanoSIMS mapping to identify in situ the carrier(s) of their bulk and hotspot 15 N enrichments and to establish the possible origin(s) of these clasts. Methods: Regions of lithic clasts with anhydrous silicates were isotope-mapped (Cameca ims1280 ion microprobe) [2]. Sample outgassing of the polished section prevented direct NanoSIMS isotope imaging at higher spatial resolution. Cameca ims1280 mapped are...
Introduction: The benefits of integrating instruments to enhance science yield were demonstrated during the Stardust preliminary examination [1-3]. We are implementing this approach at the University of Hawai‘i (UH). Existing electron... more
Introduction: The benefits of integrating instruments to enhance science yield were demonstrated during the Stardust preliminary examination [1-3]. We are implementing this approach at the University of Hawai‘i (UH). Existing electron microprobe capabilities in the Dept. of Geology and Geophysics and ion microprobe, SEM and Raman capabilities in the W. M. Keck Cosmochemistry Lab are now augmented with the new Advanced Electron Microscopy Center (AMEC), which hosts a 60-300 keV monochromated and dual spherical (Cs) aberration-corrected Titan TEM/STEM and our newest addition, a Helios NanoLab 660 dual-beam focused ion beam (FIB) instrument. The Titan has a high-angle annular dark field (HAADF) detector, Tridium Gatan imaging filter (GIF) for imaging and spectroscopy, and an EDAX Genesis 4000 Si(Li) energy dispersive x-ray spectrometer. The FIB is equipped with an Oxford Instruments Xmax N80 SD detector for x-ray spectroscopy and mapping, retractable back-scatter and STEM detectors, Ea...
Introduction: Amorphous silicates are arguably the least-understood solids in extraterrestrial materials, despite comprising the majority of rock-forming material in the interstellar (IS) medium from which our Solar System formed. Their... more
Introduction: Amorphous silicates are arguably the least-understood solids in extraterrestrial materials, despite comprising the majority of rock-forming material in the interstellar (IS) medium from which our Solar System formed. Their significance arises from astronomical observations that IS silicates are >99% amorphous, while protoplanetary disks contain crystalline silicate fractions varying by heliocentric distance (and from disk to disk) [e.g. 1,2]. Thus, amorphous (a-) silicates in comets and primitive meteorites are potential survivors from the original interstellar a-silicate population that dominated the presolar dust from which the Sun and Solar System formed. Some asilicates retain unambiguous evidence of a pre-solar origin demonstrated by non-solar isotopic compositions [3], but it remains an open and debated question how much of the IS presolar a-silicates survive in recognizable form in primitive bodies [e.g. 4]. Since asilicates are, by nature, metastable, they a...
1 , D. Joswiak 2 , J. P. Bradley 1 , N. Teslich 1 , J. Matzel 1 , I. D. Hutcheon 1 , D. Brownlee 2 , G. Matrajt 2 , G. MacPherson 3 and K. D. McKeegan 4 , 1 Institute of Geophysics & Planetary Physics, LLNL, 7000 East Avenue, Livermore,... more
1 , D. Joswiak 2 , J. P. Bradley 1 , N. Teslich 1 , J. Matzel 1 , I. D. Hutcheon 1 , D. Brownlee 2 , G. Matrajt 2 , G. MacPherson 3 and K. D. McKeegan 4 , 1 Institute of Geophysics & Planetary Physics, LLNL, 7000 East Avenue, Livermore, CA 94550; hope.ishii@llnl.gov, 2 Dept. of Astronomy, Box 351580, University of Washington, Seattle, WA 98195, 3 US National Museum of Natural History, Smithsonian Institution, Washington DC 20560, 4 Dept. Earth and Space Sci., University of California, Los Angeles, CA 90095.
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Among solar system objects visible to the unaided eye, only one has not yet been explored by a dedicated space mission: our zodiacal cloud. The cloud is made up of specks of dust, each a tiny time capsule from one of the solar system’s... more
Among solar system objects visible to the unaided eye, only one has not yet been explored by a dedicated space mission: our zodiacal cloud. The cloud is made up of specks of dust, each a tiny time capsule from one of the solar system’s most primitive bodies or our interstellar neighborhood. The dust provides a unique opportunity to learn about hundreds of comets and asteroids, which remains an impossible task for targeted missions with a small number of destinations. Sampling thousands of dust particles from our solar system’s building blocks and interstellar space is the purpose of the FOSSIL mission (Fragments from the Origins of the Solar System and our Interstellar Locale) and the key to revealing our cosmic roots. The FOSSIL Mission Concept FOSSIL would be placed in an Earth-trailing orbit, carrying four state-of-the-art Dust Telescopes (DT) pointed anti-sunward to measure impacting dust particles’ mass, composition, charge, and velocity vector. This approach connects decades o...
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clicking here. colleagues, clients, or customers by , you can order high-quality copies for your If you wish to distribute this article to others here. following the guidelines can be obtained by Permission to republish or repurpose... more
clicking here. colleagues, clients, or customers by , you can order high-quality copies for your If you wish to distribute this article to others here. following the guidelines can be obtained by Permission to republish or repurpose articles or portions of articles ): March 6, 2013 www.sciencemag.org (this information is current as of The following resources related to this article are available online at http://www.sciencemag.org/content/316/5824/543.full.html A correction has been published for this article at: http://www.sciencemag.org/content/314/5806/1735.full.html version of this article at: including high-resolution figures, can be found in the online Updated information and services, http://www.sciencemag.org/content/suppl/2006/12/11/314.5806.1735.DC1.html can be found at: Supporting Online Material http://www.sciencemag.org/content/314/5806/1735.full.html#related found at: can be related to this article A list of selected additional articles on the Science Web sites http://...
H.A. Ishii2, P. Pianetta1, J.P. Bradley2, 1Stanford Synchrotron Radiation Laboratory, Stanford Linear Accelerator Center, Menlo Park, CA 94025, USA, 2Institute of Geophysics & Planetary Physics, Lawrence Livermore National Laboratory,... more
H.A. Ishii2, P. Pianetta1, J.P. Bradley2, 1Stanford Synchrotron Radiation Laboratory, Stanford Linear Accelerator Center, Menlo Park, CA 94025, USA, 2Institute of Geophysics & Planetary Physics, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA (sean.brennan@stanford.edu). Introduction: The NASA Stardust mission returned the first solid cometary samples to Earth in 2006 from Comet 81P/Wild 2. The results of the Preliminary Examination [1,2] provided an overview of the captured material. Cometary material was collected in silica aerogel to provide more gradual deceleration. Although studies of analogue samples using light gasgun shots have been performed [3], there seem to be significant differences in mechanical properties between the pyrrhotite samples used in the terrestrial experiments and the actual 81P/Wild 2 material. Thus, 2-D and especially 3-D images of the impact tracks and associated impact debris in aerogel may help elucidate the deceleration process. We h...
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Introduction: The origin, abundance, chemical state, and distribution of volatiles, including water and organic compounds, are a primary focus of lunar exploration. Water is of particular significance to exploration as a resource for... more
Introduction: The origin, abundance, chemical state, and distribution of volatiles, including water and organic compounds, are a primary focus of lunar exploration. Water is of particular significance to exploration as a resource for astronauts, future robotic missions, and fuel to explore the Solar System [1]. The presence of water ice at the lunar poles is wellestablished but whether its origin is primordial and a product of lunar volcanism or due to (an) ongoing, perhaps steady-state, process(es) is uncertain [2-5]. Volatile-rich micrometeorite impacts that produce lunar agglutinates are a likely volatile source [6]. Bradley et al [7] established that solar wind produces water by insitu radiolysis of minerals. They discovered radiolytic water in solar wind amorphized rims on the surfaces of interplanetary dust particles (IDPs), confirmed by laboratory H+ (and He+) irradiation of crystalline silicates. We focus on detection of volatiles in space weathered lunar, asteroidal and com...
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Correction for ‘Performance and limits of 2.0 eV bandgap CuInGaS2 solar absorber integrated with CdS buffer on F:SnO2 substrate for multijunction photovoltaic and photoelectrochemical water splitting devices’ by Nicolas Gaillard et al.,... more
Correction for ‘Performance and limits of 2.0 eV bandgap CuInGaS2 solar absorber integrated with CdS buffer on F:SnO2 substrate for multijunction photovoltaic and photoelectrochemical water splitting devices’ by Nicolas Gaillard et al., Mater. Adv., 2021, DOI: 10.1039/D1MA00570G.
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In situ incorporation of nanosized amorphous Al2O3 for defect passivation in solution-processed CuIn(S,Se)2 solar cells was demonstrated with significant efficiency enhancement.
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A new transmission electron microscopy (TEM) specimen preparation method that utilizes a combination of focused ion beam (FIB) methods and ultramicrotomy is demonstrated. This combined method retains the benefit of site-specific sampling... more
A new transmission electron microscopy (TEM) specimen preparation method that utilizes a combination of focused ion beam (FIB) methods and ultramicrotomy is demonstrated. This combined method retains the benefit of site-specific sampling by FIB but eliminates ion beam-induced damage except at specimen edges and allows recovery of many consecutive sections. It is best applied to porous and/or fine-grained materials that are amenable to ultramicrotomy but are located in bulk samples that are not. The method is ideal for unique samples from which every specimen is precious, and we demonstrate its utility on fine-grained material from the one-of-a-kind Paris meteorite. Compared with a specimen prepared by conventional FIB methods, the final sections are uniformly thin and free from re-deposition and curtaining artifacts common in FIB specimens prepared from porous, heterogeneous samples.
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Just as geological samples from Earth record the natural history of our planet, astromaterials hold the natural history of our solar system and beyond. Astromaterials acquisition and curation practices have direct consequences on the... more
Just as geological samples from Earth record the natural history of our planet, astromaterials hold the natural history of our solar system and beyond. Astromaterials acquisition and curation practices have direct consequences on the contamination levels of astromaterials and hence the types of questions that can be answered about our solar system and the degree of precision that can be expected of those answers. Advanced curation was developed as a cross-disciplinary field to improve curation and acquisition practices in existing astromaterials collections and for future sample return activities, including meteorite and cosmic dust samples that are collected on Earth. These goals are accomplished through research and development of new innovative technologies and techniques for sample collection, handling, characterization, analysis, and curation of astromaterials. In this contribution, we discuss five broad topics in advanced curation that are critical to improving sample acquisit...
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Comet 81P/Wild 2 dust, the first comet sample of known provenance, was widely expected to resemble anhydrous chondritic porous (CP) interplanetary dust particles (IDPs). GEMS, distinctly characteristic of CP IDPs, have yet to be... more
Comet 81P/Wild 2 dust, the first comet sample of known provenance, was widely expected to resemble anhydrous chondritic porous (CP) interplanetary dust particles (IDPs). GEMS, distinctly characteristic of CP IDPs, have yet to be unambiguously identified in the Stardust mission samples despite claims of likely candidates. One such candidate is Stardust impact track 57 "Febo" in aerogel, which contains fine-grained objects texturally and compositionally similar to GEMS. Their position adjacent the terminal particle suggests that they may be indigenous, fine-grained, cometary material, like that in CP IDPs, shielded by the terminal particle from damage during deceleration from hypervelocity. Darkfield imaging and multi-detector energy-dispersive x-ray mapping were used to compare GEMS-like-objects in the Febo terminal particle with GEMS in an anhydrous, chondritic IDP. GEMS in the IDP are within 3× CI (solar) abundances for major and minor elements. In the Febo GEMS-like objects, Mg and Ca are systematically and strongly depleted relative to CI; S and Fe are somewhat enriched; and Au, a known aerogel contaminant is present, consistent with ablation, melting, abrasion and mixing of the SiOx aerogel with crystalline Fe-sulfide and minor enstatite, high-Ni sulfide and augite identified by elemental mapping in the terminal particle. Thus, GEMS-like objects in "caches" of fine-grained debris abutting terminal particles are most likely deceleration debris packed in place during particle transit through the aerogel.