The Experts below are selected from a list of 1656 Experts worldwide ranked by ideXlab platform
Anton T. Kearsley - One of the best experts on this subject based on the ideXlab platform.
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SARIM PLUS—sample return of comet 67P/CG and of interstellar matter
Experimental Astronomy, 2012Co-Authors: Ralf Srama, V. Sterken, F. Postberg, Scott Kempf, Meghan Burchell, H. Krüger, Anton T. Kearsley, T. Stephan, T. Yamaguchi, Eberhard GrünAbstract:The Stardust Mission returned cometary, interplanetary and (probably) interstellar dust in 2006 to Earth that have been analysed in Earth laboratories worldwide. Results of this Mission have changed our view and knowledge on the early solar nebula. The Rosetta Mission is on its way to land on comet 67P/Churyumov-Gerasimenko and will investigate for the first time in great detail the comet nucleus and its environment starting in 2014. Additional astronomy and planetary space Missions will further contribute to our understanding of dust generation, evolution and destruction in interstellar and interplanetary space and provide constraints on solar system formation and processes that led to the origin of life on Earth. One of these Missions, SARIM-PLUS, will provide a unique perspective by measuring interplanetary and interstellar dust with high accuracy and sensitivity in our inner solar system between 1 and 2 AU. SARIM-PLUS employs latest in-situ techniques for a full characterisation of individual micrometeoroids (flux, mass, charge, trajectory, composition) and collects and returns these samples to Earth for a detailed analysis. The opportunity to visit again the target comet of the Rosetta Mission 67P/Churyumov-Gerasimeenternko, and to investigate its dusty environment six years after Rosetta with complementary methods is unique and strongly enhances and supports the scientific exploration of this target and the entire Rosetta Mission. Launch opportunities are in 2020 with a backup window starting early 2026. The comet encounter occurs in September 2021 and the reentry takes place in early 2024. An encounter speed of 6 km/s ensures comparable results to the Stardust Mission.
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sarim plus sample return of comet 67p cg and of interstellar matter
Experimental Astronomy, 2012Co-Authors: V. Sterken, F. Postberg, H. Krüger, Anton T. Kearsley, T. Stephan, Ralf Srama, T. Yamaguchi, Mark J. BurchellAbstract:The Stardust Mission returned cometary, interplanetary and (probably) interstellar dust in 2006 to Earth that have been analysed in Earth laboratories worldwide. Results of this Mission have changed our view and knowledge on the early solar nebula. The Rosetta Mission is on its way to land on comet 67P/Churyumov-Gerasimenko and will investigate for the first time in great detail the comet nucleus and its environment starting in 2014. Additional astronomy and planetary space Missions will further contribute to our understanding of dust generation, evolution and destruction in interstellar and interplanetary space and provide constraints on solar system formation and processes that led to the origin of life on Earth. One of these Missions, SARIM-PLUS, will provide a unique perspective by measuring interplanetary and interstellar dust with high accuracy and sensitivity in our inner solar system between 1 and 2 AU. SARIM-PLUS employs latest in-situ techniques for a full characterisation of individual micrometeoroids (flux, mass, charge, trajectory, composition) and collects and returns these samples to Earth for a detailed analysis. The opportunity to visit again the target comet of the Rosetta Mission 67P/Churyumov-Gerasimeenternko, and to investigate its dusty environment six years after Rosetta with complementary methods is unique and strongly enhances and supports the scientific exploration of this target and the entire Rosetta Mission. Launch opportunities are in 2020 with a backup window starting early 2026. The comet encounter occurs in September 2021 and the reentry takes place in early 2024. An encounter speed of 6 km/s ensures comparable results to the Stardust Mission.
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SARIM PLUS--sample return of comet 67P/CG and of interstellar matter
Experimental Astronomy, 2012Co-Authors: Ralf Srama, V. Sterken, F. Postberg, Scott Kempf, Meghan Burchell, H. Krüger, Anton T. Kearsley, T. Stephan, T. Yamaguchi, Eberhard GrünAbstract:The Stardust Mission returned cometary, interplanetary and (probably) interstellar dust in 2006 to Earth that have been analysed in Earth laboratories worldwide. Results of this Mission have changed our view and knowledge on the early solar nebula. The Rosetta Mission is on its way to land on comet 67P/Churyumov-Gerasimenko and will investigate for the first time in great detail the comet nucleus and its environment starting in 2014. Additional astronomy and planetary space Missions will further contribute to our understanding of dust generation, evolution and destruction in interstellar and interplanetary space and provide constraints on solar system formation and processes that led to the origin of life on Earth. One of these Missions, SARIM-PLUS, will provide a unique perspective by measuring interplanetary and interstellar dust with high accuracy and sensitivity in our inner solar system between 1 and 2 AU. SARIM-PLUS employs latest in-situ techniques for a full characterisation of individual micrometeoroids (flux, mass, charge, trajectory, composition) and collects and returns these samples to Earth for a detailed analysis. The opportunity to visit again the target comet of the Rosetta Mission 67P/Churyumov-Gerasimeenternko, and to investigate its dusty environment six years after Rosetta with complementary methods is unique and strongly enhances and supports the scientific exploration of this target and the entire Rosetta Mission. Launch opportunities are in 2020 with a backup window starting early 2026. The comet encounter occurs in September 2021 and the reentry takes place in early 2024. An encounter speed of 6 km/s ensures comparable results to the Stardust Mission.
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Experimental investigation of impacts by solar cell secondary ejecta on silica aerogel and aluminum foil: Implications for the Stardust Interstellar Dust Collector
Meteoritics & Planetary Science, 2011Co-Authors: Mark J. Burchell, Mark C. Price, Mike J. Cole, Anton T. KearsleyAbstract:– We have shown in laboratory experiment that hypervelocity impacts on a solar cell produce ejecta that can be captured on aluminum (Al 1100) foil or in low density (33 kg m−3) aerogel. The origin of the secondary impacts can be determined by either analysis of the residue in the craters in the foils (which preserve an elemental signature of the solar cell components) or by their pointing direction for tracks in the aerogel (which we show align with the impact direction to ± 0.4°). This experimental evidence explains the observations of the NASA Stardust Mission which has reported that the majority of tracks in the aerogel collector used to collect interstellar dust actually point at the spacecraft’s solar panels. From our results, we suggest that it should also be possible to recognize secondary ejecta craters in the Stardust Mission aluminum foils, also used as dust sampling devices during the Mission.
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Aerogel tracks made by impacts of glycine: Implications for formation of bulbous tracks in aerogel and the Stardust Mission
Meteoritics & Planetary Science, 2011Co-Authors: Adam Nixon, Anton T. Kearsley, Mark J. Burchell, Mark C. Price, Steven JonesAbstract:Abstract– Impacts of small particles of soda-lime glass and glycine onto low density aerogel are reported. The aerogel had a quality similar to the flight aerogels carried by the NASA Stardust Mission that collected cometary dust during a flyby of comet 81P/Wild 2 in 2004. The types of track formed in the aerogel by the impacts of the soda-lime glass and glycine are shown to be different, both qualitatively and quantitatively. For example, the soda-lime glass tracks have a carrot-like appearance and are relatively long and slender (width to length ratio 0.26). In consequence, the glycine particles would be underestimated in diameter by a factor of 1.7–3.2, if the glycine tracks were analyzed using the soda-lime glass calibration and density. This implies that a single calibration for impacting particle size based on track properties, as previously used by Stardust to obtain cometary dust particle size, is inappropriate.
Michael E. Zolensky - One of the best experts on this subject based on the ideXlab platform.
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Using the Fe/Mn Ratio of FeO-Rich Olivine In WILD 2, Chondrite Matrix, and Type IIA Chondrules to Disentangle Their Histories
2012Co-Authors: David R. Frank, Michael E. ZolenskyAbstract:The Stardust Mission returned a large abundance of impactors from Comet 81P/Wild2 in the 5-30 m range. The preliminary examination of just a limited number of these particles showed that the collection captured abundant crystalline grains with a diverse mineralogy [1,2]. Many of these grains resemble those found in chondrite matrix and even contain fragments of chondrules and CAIs [1-3]. In particular, the olivine found in Wild 2 exhibits a wide compositional range (Fa0-97) with minor element abundances similar to the matrix olivine found in many carbonaceous chondrites (CCs) and unequilibrated ordinary chondrites (UOCs). Despite the wide distribution of Fa content, the olivine found in the matrices of CCs, UOCs, and Wild 2 can be roughly lumped into two types based solely on fayalite content. In fact, in some cases, a distinct bi-modal distribution is observed.
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Olivine and Pyroxene Compositions in Fine-Grained Chondritic Materials
2011Co-Authors: Michael E. Zolensky, David R. FrankAbstract:Our analyses of the Wild-2 samples returned by the Stardust Mission have illuminated critical gaps in our understanding of related astromaterials. There is a very large database of olivine and low-calcium pyroxene compositions for coarse-grained components of chondrites, but a sparse database for anhydrous silicate matrix phases. In an accompanying figure, we present comparisons of Wild-2 olivine with the available chondrite matrix olivine major element data. We thus have begun a long-term project measuring minor as well as major element compositions for chondrite matrix and chondritic IDPs, and Wild 2 grains. Finally, we wish to re-investigate the changes to fine-grained olivine and low-Ca pyroxene composition with progressive thermal metamorphism. We have examined the LL3-4 chondrites which because of the Hayabusa Mission have become very interesting.
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Lessons Learned from Three Recent Sample Return Missions
2011Co-Authors: Michael E. Zolensky, Scott A. SandfordAbstract:We share lessons learned from participation on the Science Teams and Recovery/Preliminary Examination/Curation teams for three recent sample return Missions: (1) the Long Duration Exposure Facility (LDEF), which returned to Earth with interplanetary dust and spacecraft debris particles in 1990, (2) the Stardust Mission, which returned grains from comet Wild-2 and fresh interstellar dust to Earth in 2006, and (3) the Hayabusa Mission, which returned regolith grains from asteroid Itokawa in 2010.
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TOF-SIMS analysis of cometary particles extracted from Stardust aerogel
Meteoritics & Planetary Science, 2008Co-Authors: Thomas Stephan, Scott A. Sandford, George J. Flynn, Michael E. ZolenskyAbstract:Sections of seven cometary fragments extracted from the aerogel collector flown on the Stardust Mission to comet 81P/Wild 2 were investigated with TOF-SIMS. These grains showed a rather heterogeneous chemical and mineralogical composition on a submicrometer scale. However, their average chemical composition is close to bulk CI chondritic values, which is consistent with analyses of numerous Stardust samples using various techniques. As a result, the TOF-SIMS analyses support the conclusion that Wild 2 has a CI-like bulk composition. The cometary particles resemble anhydrous chondritic porous interplanetary dust particles, which have previously been suggested to originate from comets. For one of the fragments, polycyclic aromatic hydrocarbons that could possibly be attributed to the comet were observed.
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TOF-SIMS analysis of cometary matter in Stardust aerogel tracks
Meteoritics & Planetary Science, 2008Co-Authors: Thomas Stephan, Scott A. Sandford, Andrew J. Westphal, George J. Flynn, Detlef Rost, Edward P. Vicenzi, Emma S. Bullock, Glenn J. Macpherson, Christopher J. Snead, Michael E. ZolenskyAbstract:Cometary matter in aerogel samples from the Stardust Mission was investigated with TOF- SIMS for its elemental and organic composition. While single grains >1 μm are highly variable in their chemical composition, nanometer-scale material found in the wall of one track has within a factor of 1.22 bulk CI chondritic element ratios relative to Fe for Na, Mg, Al, Ti, Cr, Mn, and Co. Compared to CI, a depletion in Ca by a factor of four and an enrichment in Ni by a factor of two was observed. These results seem to confirm recent reports of a CI-like bulk composition of Wild 2. The analysis of organic compounds in aerogel samples is complicated by the presence of contaminants in the capture medium. However, polycyclic aromatic hydrocarbons that could possibly be attributed to the comet were observed.
Andrew J. Westphal - One of the best experts on this subject based on the ideXlab platform.
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Helium and neon in comet 81P/Wild 2 samples from the NASA Stardust Mission
Meteoritics & Planetary Science, 2018Co-Authors: R. L. Palma, Zack Gainsforth, Andrew J. Westphal, Robert O. Pepin, Evelyn Füri, D. J. Schlutter, D. R. FrankAbstract:International audienc
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More than 30 000 volunteers involved in identification of tiny rare interstellar dust particle candidates collected by the Stardust Mission
2017Co-Authors: Andrew J. Westphal, Mario TrieloffAbstract:The NASA Stardust Mission returned the first tiny samples of interstellar dust from beyond the borders of our solar system. This region is almost devoid of matter and the interstellar dust particles floating through our solar system are extremely rare and small. Finding a few micrometer sized particles in an aerogel collector required the assistance of >30,000 volunteers over a search period of about 6 years, before individual particles could be analysed. This citizen science effort provided the first direct and astonishing look at particle candidates that reached us from our cosmic neighborhood.
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Coordinated Microanalyses of Seven Particles of Probable Interstellar Origin from the Stardust Mission
Microscopy and Microanalysis, 2014Co-Authors: Andrew J. Westphal, Zack Gainsforth, Frank E. Brenker, Anna L. Butterworth, Hans A. Bechtel, George J. Flynn, Rhonda M. Stroud, David R. Frank, Jon K. Hillier, Frank PostbergAbstract:Stardust, a NASA Discovery-class Mission, was the first sample-return Mission to return solid samples from beyond the Moon. Stardust was effectively two Missions in one spacecraft: it returned the first materials from a known primitive solar system body, the Jupiter-family comet Wild 2; Stardust also returned a collector that was exposed to the contemporary interstellar dust stream for 200 days during the interplanetary cruise. Both collections present severe technical challenges in sample preparation and in analysis. By far the largest collection is the cometary one: approximately 300 micro g of material was returned from Wild 2, mostly consisting of approx. 1 ng particles embedded in aerogel or captured as residues in craters on aluminum foils. Because of their relatively large size, identification of the impacts of cometary particles in the collection media is straightforward. Reliable techniques have been developed for the extraction of these particles from aerogel. Coordinated analyses are also relatively straightforward, often beginning with synchrotron-based x-ray fluorescence (S-XRF), X-ray Absorption Near-Edge Spectoscopy (XANES) and x-ray diffraction (S-XRD) analyses of particles while still embedded in small extracted wedges of aerogel called ``keystones'', followed by ultramicrotomy and TEM, Scanning TransMission X-ray Microscopy (STXM) and ion microprobe analyses (e.g., Ogliore et al., 2010). Impacts in foils can be readily analyzed by SEM-EDX, and TEM analysis after FIB liftout sample preparation. In contrast, the interstellar dust collection is vastly more challenging. The sample size is approximately six orders of magnitude smaller in total mass. The largest particles are only a few pg in mass, of which there may be only approx.10 in the entire collection. The technical challenges, however, are matched by the scientific importance of the collection. We formed a consortium carry out the Stardust Interstellar Preliminary Examination (ISPE) to carry out an assessment of this collection, partly in order to characterize the collection in sufficient detail so that future investigators could make well-informed sample requests. The ISPE is the sixth PE on extraterrestrial collections carried out with NASA support. Some of the basic questions that we asked were: how many impacts are there in the collector, and what fraction of them have characteristics consistent with extraterrestrial materials? What is the elemental composition of the rock-forming elements? Is there crystalline material? Are there organics? Here we present coordinated microanalyses of particles captured in aerogel, using S-FTIR, S-XRF, STXM, S-XRD; and coordinated microanalyses of residues in aluminum foil, using SEMEDX, Auger spectroscopy, STEM, and ion microprobe. We discuss a novel approach that we employed for identification of tracks in aerogel, and new sample preparation techniques developed during the ISPE. We have identified seven particles - three in aerogel and four in foils - that are most consistent with an interstellar origin. The seven particles exhibit a large diversity in elemental composition. Dynamical evidence, supported supported by laboratory simulations of interstellar dust impacts in aerogel and foils, and numerical modeling of interstellar dust propagation in the heliosphere, suggests that at least some of the particles have high optical cross-section, perhaps due to an aggregate structure. However, the observations are most consistent with a variety of morphologies
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Characterization of preserved primitive fine-grained material from the Jupiter family comet 81P/Wild 2 – A new link between comets and CP-IDPs
Earth and Planetary Science Letters, 2014Co-Authors: Julien Stodolna, Zack Gainsforth, Anna L. Butterworth, Andrew J. WestphalAbstract:Abstract We report the presence of preserved primitive fine-grained material containing an enstatite whisker with the crystallographic characteristics of a primary condensate in a sample of the Jupiter-family comet Wild 2, returned to earth by NASAʼs Stardust Mission. The preserved primitive material is composed of silica-rich amorphous material embedded with iron sulfides and silicates. It is in close association with a type II chondrule-like object in the track C2052,2,74 ( Ogliore et al., 2012 ). The close association of a chondrule and a primary condensate shows they must have formed in different environments and probably met in the comet-forming region. The first observation of an enstatite whisker with properties indicating primary condensation in a comet is a new link between comets and Chondritic Porous IDPs (CP-IDPs).
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Nebular mixing constrained by the Stardust samples
Meteoritics & Planetary Science, 2010Co-Authors: Ryan C. Ogliore, Zack Gainsforth, Andrew J. Westphal, Anna L. Butterworth, Sirine C. Fakra, Matthew A. MarcusAbstract:Using X-ray microprobe analysis of samples from comet Wild 2 returned by the Stardust Mission, we determine that the crystalline Fe-bearing silicate fraction in this Jupiter-family comet is greater than 0.5. Assuming this mixture is a composite of crystalline inner solar system material and amorphous cold molecular cloud material, we deduce that more than half of Wild 2 has been processed in the inner solar system. Several models exist that explain the presence of crystalline materials in comets. We explore some of these models in light of our results.
Mark J. Burchell - One of the best experts on this subject based on the ideXlab platform.
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Raman identification of olivine grains in fine grained mineral assemblages fired into aerogel
Procedia Engineering, 2017Co-Authors: Jamie E. Wickham-eade, Mark J. Burchell, Mark C. Price, L. J. Hicks, J. L. Macarthur, John BridgesAbstract:Abstract NASA’s Stardust Mission returned from the comet 81P/Wild2 in 2006 and has yielded a plethora of research looking into the composition and attributes of the comet. The Mission itself collected thousands of cometary dust particles as it flew through the coma of the comet at a relative speed of 6.1 km s -1 . This work focuses on one of the most abundant minerals in the solar system – olivine. Previous work has shown capture affects on this mineral in similar impacts to that experienced during the Stardust Mission. However, the past work looked into effects on isolated mineral grains which would be a rare occurrence in the Solar System. A more accurate representation of this would be to investigate the capture effects on olivine as a constituent of an assemblage of minerals. Accordingly, here we used samples from the NWA 10256 CR2 carbonaceous chondrite meteorite. This natural sample contains fine grains of olivine, and brings additional issues when analysing the olivine due to limited homogeneity. Shifts in the Raman spectra for olivine, enstatite and hematite were observed after capture due to shock effects. However, this work suggests that olivine may well experience a different shock effect during capture when part of a mineral assemblage as distinct from that experienced by single grains.
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sarim plus sample return of comet 67p cg and of interstellar matter
Experimental Astronomy, 2012Co-Authors: V. Sterken, F. Postberg, H. Krüger, Anton T. Kearsley, T. Stephan, Ralf Srama, T. Yamaguchi, Mark J. BurchellAbstract:The Stardust Mission returned cometary, interplanetary and (probably) interstellar dust in 2006 to Earth that have been analysed in Earth laboratories worldwide. Results of this Mission have changed our view and knowledge on the early solar nebula. The Rosetta Mission is on its way to land on comet 67P/Churyumov-Gerasimenko and will investigate for the first time in great detail the comet nucleus and its environment starting in 2014. Additional astronomy and planetary space Missions will further contribute to our understanding of dust generation, evolution and destruction in interstellar and interplanetary space and provide constraints on solar system formation and processes that led to the origin of life on Earth. One of these Missions, SARIM-PLUS, will provide a unique perspective by measuring interplanetary and interstellar dust with high accuracy and sensitivity in our inner solar system between 1 and 2 AU. SARIM-PLUS employs latest in-situ techniques for a full characterisation of individual micrometeoroids (flux, mass, charge, trajectory, composition) and collects and returns these samples to Earth for a detailed analysis. The opportunity to visit again the target comet of the Rosetta Mission 67P/Churyumov-Gerasimeenternko, and to investigate its dusty environment six years after Rosetta with complementary methods is unique and strongly enhances and supports the scientific exploration of this target and the entire Rosetta Mission. Launch opportunities are in 2020 with a backup window starting early 2026. The comet encounter occurs in September 2021 and the reentry takes place in early 2024. An encounter speed of 6 km/s ensures comparable results to the Stardust Mission.
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Experimental investigation of impacts by solar cell secondary ejecta on silica aerogel and aluminum foil: Implications for the Stardust Interstellar Dust Collector
Meteoritics & Planetary Science, 2011Co-Authors: Mark J. Burchell, Mark C. Price, Mike J. Cole, Anton T. KearsleyAbstract:– We have shown in laboratory experiment that hypervelocity impacts on a solar cell produce ejecta that can be captured on aluminum (Al 1100) foil or in low density (33 kg m−3) aerogel. The origin of the secondary impacts can be determined by either analysis of the residue in the craters in the foils (which preserve an elemental signature of the solar cell components) or by their pointing direction for tracks in the aerogel (which we show align with the impact direction to ± 0.4°). This experimental evidence explains the observations of the NASA Stardust Mission which has reported that the majority of tracks in the aerogel collector used to collect interstellar dust actually point at the spacecraft’s solar panels. From our results, we suggest that it should also be possible to recognize secondary ejecta craters in the Stardust Mission aluminum foils, also used as dust sampling devices during the Mission.
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Aerogel tracks made by impacts of glycine: Implications for formation of bulbous tracks in aerogel and the Stardust Mission
Meteoritics & Planetary Science, 2011Co-Authors: Adam Nixon, Anton T. Kearsley, Mark J. Burchell, Mark C. Price, Steven JonesAbstract:Abstract– Impacts of small particles of soda-lime glass and glycine onto low density aerogel are reported. The aerogel had a quality similar to the flight aerogels carried by the NASA Stardust Mission that collected cometary dust during a flyby of comet 81P/Wild 2 in 2004. The types of track formed in the aerogel by the impacts of the soda-lime glass and glycine are shown to be different, both qualitatively and quantitatively. For example, the soda-lime glass tracks have a carrot-like appearance and are relatively long and slender (width to length ratio 0.26). In consequence, the glycine particles would be underestimated in diameter by a factor of 1.7–3.2, if the glycine tracks were analyzed using the soda-lime glass calibration and density. This implies that a single calibration for impacting particle size based on track properties, as previously used by Stardust to obtain cometary dust particle size, is inappropriate.
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Investigation of iron sulfide impact crater residues: a combined analysis by scanning and transMission electron microscopy
Meteoritics & Planetary Science, 2011Co-Authors: Penelope J. Wozniakiewicz, Anton T. Kearsley, John P. Bradley, Hope A. Ishii, Zu Rong Dai, Mark J. Burchell, Philip A. Bland, Nick Teslich, Gareth S. Collins, Mike J. ColeAbstract:Abstract–Samples returned from comet 81P⁄Wild 2 by the Stardust Mission provided anunequaled opportunity to compare previously available extraterrestrial samples against thosefrom a known comet. Iron sulfides are a major constituent of cometary grains commonlyidentified within cometary interplanetary dust particles (IDPs) and Wild 2 samples. Chemicalanalyses indicate Wild 2 sulfides are fundamentally different from those in IDPs. However, asWild 2 dust was collected via impact into capture media at approximately 6.1 km s )1 ,itisunclear whether this is due to variation in preaccretional⁄parent body processes experiencedby these materials or due to heating and alteration during collection. We investigatedalteration in pyrrhotite and pentlandite impacted into Stardust flight spare Al foils underencounter conditions by comparing scanning and transMission electron microscope (SEM,TEM) analyses of preimpact and postimpact samples and calculating estimates of variousimpact parameters. SEM is the primary method of analysis during initial in situ examinationof Stardust foils, and therefore, we also sought to evaluate the data obtained by SEM usinginsights provided by TEM. We find iron sulfides experience heating, melting, separation, andloss of S, and mixing with molten Al. These results are consistent with estimated peakpressures and temperatures experienced (approximately 85 GPa, approximately 2600 K) andrelative melting temperatures. Unambiguous identification of preserved iron sulfides may bepossible by TEM through the location of Al-free regions. In most cases, the Ni:Fe ratio ispreserved in both SEM and TEM analyses and may therefore also be used to predict originalchemistry and estimate mineralogy.INTRODUCTIONIron sulfides are one of the major mineral typesfound in cometary dust. They are common inchondritic porous (CP) interplanetary dust particles(IDPs) (Bradley 2003) and have been identified as amajor constituent of the comet 81P⁄Wild 2 samplescollected by NASA’s Stardust Mission (Zolensky et al.2006). Iron sulfides in CP IDPs are predominantlypyrrhotite with up to 20 atom% Ni althoughoccasionally other iron sulfides such as pentlandite,troilite, and sphalerite are found (e.g., Fraundorf 1981;1007
Scott A. Sandford - One of the best experts on this subject based on the ideXlab platform.
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Lessons Learned from Three Recent Sample Return Missions
2011Co-Authors: Michael E. Zolensky, Scott A. SandfordAbstract:We share lessons learned from participation on the Science Teams and Recovery/Preliminary Examination/Curation teams for three recent sample return Missions: (1) the Long Duration Exposure Facility (LDEF), which returned to Earth with interplanetary dust and spacecraft debris particles in 1990, (2) the Stardust Mission, which returned grains from comet Wild-2 and fresh interstellar dust to Earth in 2006, and (3) the Hayabusa Mission, which returned regolith grains from asteroid Itokawa in 2010.
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Comparison of the Organic Composition of Cometary Samples with Residues Formed from the UV Irradiation of Astrophysical Ice Analogs
2010Co-Authors: Stefanie N. Milam, Scott A. Sandford, Michel Nuevo, G. D. Cody, A. L. D. Kilcoyne, R. M. Stroud, B. T. DegregorioAbstract:The NASA Stardust Mission successfully collected material from Comet 81P/Wild 2 [1], including authentic cometary grains [2]. X-ray absorption near-edge structure (XANES) spectroscopy analysis of these samples indicates the presence of oxygen-rich and nitrogen-rich organic materials, which contain a broad variety of functional groups (carbonyls, C=C bonds, aliphatic chains, amines, arnides, etc.) [3]. One component of these organics appears to contain very little aromatic carbon and bears some similarity to the organic residues produced by the irradiation of ices of interstellar/cometary composition, Stardust samples were also recently shown to contain glycine, the smallest biological amino acid [4]. Organic residues produced froth the UV irradiation of astrophysical ice analogs are already known to contain a large suite of organic molecules including amino acids [5-7], amphiphilic compounds (fatty acids) [8], and other complex species. This work presents a comparison between XANES spectra measured from organic residues formed in the laboratory with similar data of cometary samples collected by the Stardust Mission
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TOF-SIMS analysis of cometary particles extracted from Stardust aerogel
Meteoritics & Planetary Science, 2008Co-Authors: Thomas Stephan, Scott A. Sandford, George J. Flynn, Michael E. ZolenskyAbstract:Sections of seven cometary fragments extracted from the aerogel collector flown on the Stardust Mission to comet 81P/Wild 2 were investigated with TOF-SIMS. These grains showed a rather heterogeneous chemical and mineralogical composition on a submicrometer scale. However, their average chemical composition is close to bulk CI chondritic values, which is consistent with analyses of numerous Stardust samples using various techniques. As a result, the TOF-SIMS analyses support the conclusion that Wild 2 has a CI-like bulk composition. The cometary particles resemble anhydrous chondritic porous interplanetary dust particles, which have previously been suggested to originate from comets. For one of the fragments, polycyclic aromatic hydrocarbons that could possibly be attributed to the comet were observed.
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TOF-SIMS analysis of crater residues from Wild 2 cometary particles on Stardust aluminum foil
Meteoritics & Planetary Science, 2008Co-Authors: Jan Leitner, Anton T. Kearsley, Friedrich Hörz, Thomas Stephan, George J. Flynn, Scott A. SandfordAbstract:Impact residues of cometary particles on aluminum foils from the Stardust Mission were investigated with TOF-SIMS for their elemental and organic composition. The residual matter from comet 81P/Wild 2 shows a wide compositional range, from nearly monomineralic grains to polymict aggregates. Despite the comparably small analyzed sample volume, the average element composition of the investigated residues is similar to bulk CI chondritic values. Analysis of organic components in impact residues is complicated, due to fragmentation and alteration of the compounds during the impact process and by the presence of contaminants on the aluminum foils. Nevertheless, polycyclic aromatic hydrocarbons (PAHs) that are unambiguously associated with the impact residues were observed, and thus are most likely of cometary origin.
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TOF-SIMS analysis of cometary matter in Stardust aerogel tracks
Meteoritics & Planetary Science, 2008Co-Authors: Thomas Stephan, Scott A. Sandford, Andrew J. Westphal, George J. Flynn, Detlef Rost, Edward P. Vicenzi, Emma S. Bullock, Glenn J. Macpherson, Christopher J. Snead, Michael E. ZolenskyAbstract:Cometary matter in aerogel samples from the Stardust Mission was investigated with TOF- SIMS for its elemental and organic composition. While single grains >1 μm are highly variable in their chemical composition, nanometer-scale material found in the wall of one track has within a factor of 1.22 bulk CI chondritic element ratios relative to Fe for Na, Mg, Al, Ti, Cr, Mn, and Co. Compared to CI, a depletion in Ca by a factor of four and an enrichment in Ni by a factor of two was observed. These results seem to confirm recent reports of a CI-like bulk composition of Wild 2. The analysis of organic compounds in aerogel samples is complicated by the presence of contaminants in the capture medium. However, polycyclic aromatic hydrocarbons that could possibly be attributed to the comet were observed.