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Varmuza, K., Filzmoser, P., Fray, N., Cottin, H., Merouane, S., Stenzel, O., . . . Hilchenbach, M. (2020). Composition of cometary particles collected during two periods of the Rosetta mission: multivariate evaluation of mass spectral data. Journal of Chemometrics, Article ID e3218.
Open this publication in new window or tab >>Composition of cometary particles collected during two periods of the Rosetta mission: multivariate evaluation of mass spectral data
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2020 (English)In: Journal of Chemometrics, ISSN 0886-9383, E-ISSN 1099-128X, article id e3218Article in journal (Refereed) Published
Abstract [en]

The instrument COSIMA (COmetary Secondary Ion Mass Analyzer) onboard of the European Space Agency mission Rosetta collected and analyzed dust particles in the neighborhood of comet 67P/Churyumov-Gerasimenko. The chemical composition of the particle surfaces was characterized by time-of-flight secondary ion mass spectrometry. A set of 2213 spectra has been selected, and relative abundances for CH-containing positive ions as well as positive elemental ions define a set of multivariate data with nine variables. Evaluation by complementary chemometric techniques shows different compositions of sample groups collected during two periods of the mission. The first period was August to November 2014 (far from the Sun); the second period was January 2015 to February 2016 (nearer to the Sun). The applied data evaluation methods consider the compositional nature of the mass spectral data and comprise robust principal component analysis as well as classification with discriminant partial least squares regression, k-nearest neighbor search, and random forest decision trees. The results indicate a high importance of the relative abundances of the secondary ions C+ and Fe+ for the group separation and demonstrate an enhanced content of carbon-containing substances in samples collected in the period with smaller distances to the Sun. © 2020 The Authors.

Place, publisher, year, edition, pages
John Wiley and Sons Ltd, 2020
Keywords
comet 67P/Churyumov-Gerasimenko, KNN classification, random forest classification, time-of-flight secondary ion mass spectrometry, variable importance
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-43958 (URN)10.1002/cem.3218 (DOI)2-s2.0-85078794585 (Scopus ID)
Available from: 2020-02-19 Created: 2020-02-19 Last updated: 2020-02-19Bibliographically approved
Hornung, K., Mellado, E. M., Paquette, J., Fray, N., Fischer, H., Stenzel, O., . . . Hilchenbach, M. (2019). Electrical properties of cometary dust particles derived from line shapes of TOF-SIMS spectra measured by the ROSETTA/COSIMA instrument. Planetary and Space Science, Article ID 104758.
Open this publication in new window or tab >>Electrical properties of cometary dust particles derived from line shapes of TOF-SIMS spectra measured by the ROSETTA/COSIMA instrument
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2019 (English)In: Planetary and Space Science, ISSN 0032-0633, E-ISSN 1873-5088, article id 104758Article in journal (Refereed) Epub ahead of print
Abstract [en]

Between Aug. 2014 and Sept. 2016, while ESA's cornerstone mission Rosetta was operating in the vicinity of the nucleus and in the coma of comet 67P/Churyumov-Gerasimenko, the COSIMA instrument collected a large number of dust particles with diameters up to a millimeter. Positive or negative ions were detected by a time-of-flight secondary ion mass spectrometer (TOF-SIMS) and the composition of selected particles was deduced. Many of the negative ion mass spectra show, besides mass peaks at the correct position, an additional, extended contribution at the lower mass side caused by partial charging of the dust. This effect, usually avoided in SIMS applications, can in our case be used to obtain information on the electrical properties of the collected cometary dust particles, such as the specific resistivity (ρr>1.2⋅1010Ωm) and the real part of the relative electrical permittivity (εr<1.2). From these values a lower limit for the porosity is derived (P>0.8).

Place, publisher, year, edition, pages
Elsevier Ltd, 2019
Keywords
Cometary dust, Electrical properties, Rosetta mission, Sample charging, Time-of-flight mass spectra, Dust, Electric properties, Mass spectrometers, Secondary ion mass spectrometry, 67p/churyumov-gerasimenko, Cometary dusts, Electrical permittivity, Secondary ion mass spectrometers, Specific resistivities, Time of flight, Negative ions
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-42491 (URN)10.1016/j.pss.2019.104758 (DOI)2-s2.0-85076613727 (Scopus ID)
Note

Funding details: Austrian Science Fund, FWF, P26871-N20; Funding details: Centre National d’Etudes Spatiales, CNES; Funding details: Deutsches Zentrum für Luft- und Raumfahrt, DLR, 50 QP 1801; Funding text 1: COSIMA was built by a consortium led by the Max-Planck-Institut für Extraterrestrische Physik, Garching, Germany in collaboration with Laboratoire de Physique et Chimie de l’Environnement et de l’Espace, Orléans, France, Institut d’Astrophysique Spatiale, CNRS/Université Paris Sud, Orsay, France, Finnish Meteorological Institute, Helsinki, Finland, Universität Wuppertal, Wuppertal, Germany, von Hoerner und Sulger GmbH, Schwetzingen, Germany, Universität der Bundeswehr München, Neubiberg, Germany, Institut für Physik, Forschungszentrum Seibersdorf, Seibersdorf, Austria, Institut für Weltraumforschung, Österreichische Akademie der Wissenschaften, Graz, Austria and is lead by the Max-Planck-Institut für Sonnensystemforschung, Göttingen, Germany. The support of the national funding agencies of Germany ( DLR , grant 50 QP 1801 ), France ( CNES ), Austria ( FWF , grant P26871-N20 ), Finland and the ESA Technical Directorate is gratefully acknowledged. We thank the Rosetta Science Ground Segment at ESAC, the Rosetta Mission Operations Centre at ESOC and the Rosetta Project at ESTEC for their outstanding work enabling the science return of the Rosetta Mission. Appendix A

Available from: 2020-01-10 Created: 2020-01-10 Last updated: 2020-01-10Bibliographically approved
Isnard, R., Bardyn, A., Fray, N., Briois, C., Cottin, H., Paquette, J., . . . Hilchenbach, M. (2019). H/C elemental ratio of the refractory organic matter in cometary particles of 67P/Churyumov-Gerasimenko. Astronomy and Astrophysics, 630, Article ID A27.
Open this publication in new window or tab >>H/C elemental ratio of the refractory organic matter in cometary particles of 67P/Churyumov-Gerasimenko
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2019 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 630, article id A27Article in journal (Refereed) Published
Abstract [en]

Context. Because comets are part of the most primitive bodies of our solar system, establishing their chemical composition and comparing them to other astrophysical bodies gives new constraints on the formation and evolution of organic matter throughout the solar system. For two years, the time-of-flight secondary ion mass spectrometer COmetary Secondary Ion Mass Analyzer (COSIMA) on board the Rosetta orbiter performed in situ analyses of the dust particles ejected from comet 67P/Churyumov-Gerasimenko (67P). Aims. The aim is to determine the H/C elemental ratio of the refractory organic component contained in cometary particles of 67P. Methods. We analyzed terrestrial and extraterrestrial calibration samples using the COSIMA ground-reference model. Exploiting these calibration samples, we provide calibration lines in both positive and negative ion registration modes. Thus, we are now able to measure the cometary H/C elemental ratio. Results. The mean H/C value is 1.04 +/- 0.16 based on 33 different cometary particles. Consequently, the H/C atomic ratio is on average higher in cometary particles of 67P than in even the most primitive insoluble organic matter extracted from meteorites. Conclusions. These results imply that the refractory organic matter detected in dust particles of 67P is less unsaturated than the material in meteorites.

Place, publisher, year, edition, pages
EDP SCIENCES S A, 2019
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-43292 (URN)10.1051/0004-6361/201834797 (DOI)
Available from: 2020-01-23 Created: 2020-01-23 Last updated: 2020-01-27Bibliographically approved
Siljeström, S., Thiel, V. & Steele, A. (2019). Preservation of heme derivatives in vertebrate fossils from the Messel Pit and Enspel, Germany. In: 29th International Meeting on Organic Geochemistry, IMOG 2019: . Paper presented at 29th International Meeting on Organic Geochemistry, IMOG 2019, 1 September 2019 through 6 September 2019. European Association of Geoscientists and Engineers, EAGE
Open this publication in new window or tab >>Preservation of heme derivatives in vertebrate fossils from the Messel Pit and Enspel, Germany
2019 (English)In: 29th International Meeting on Organic Geochemistry, IMOG 2019, European Association of Geoscientists and Engineers, EAGE , 2019Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
European Association of Geoscientists and Engineers, EAGE, 2019
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-40880 (URN)2-s2.0-85074252213 (Scopus ID)9789462823044 (ISBN)
Conference
29th International Meeting on Organic Geochemistry, IMOG 2019, 1 September 2019 through 6 September 2019
Available from: 2019-12-10 Created: 2019-12-10 Last updated: 2019-12-10Bibliographically approved
Drake, H., Roberts, N., Heim, C., Whitehouse, M., Siljeström, S., Kooijman, E., . . . Åström, M. (2019). Timing and origin of natural gas accumulation in the Siljan impact structure, Sweden. Nature Communications, 10(1), Article ID 4736.
Open this publication in new window or tab >>Timing and origin of natural gas accumulation in the Siljan impact structure, Sweden
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2019 (English)In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 10, no 1, article id 4736Article in journal (Refereed) Published
Abstract [en]

Fractured rocks of impact craters may be suitable hosts for deep microbial communities on Earth and potentially other terrestrial planets, yet direct evidence remains elusive. Here, we present a study of the largest crater of Europe, the Devonian Siljan structure, showing that impact structures can be important unexplored hosts for long-term deep microbial activity. Secondary carbonate minerals dated to 80 ± 5 to 22 ± 3 million years, and thus postdating the impact by more than 300 million years, have isotopic signatures revealing both microbial methanogenesis and anaerobic oxidation of methane in the bedrock. Hydrocarbons mobilized from matured shale source rocks were utilized by subsurface microorganisms, leading to accumulation of microbial methane mixed with a thermogenic and possibly a minor abiotic gas fraction beneath a sedimentary cap rock at the crater rim. These new insights into crater hosted gas accumulation and microbial activity have implications for understanding the astrobiological consequences of impacts. © 2019, The Author(s).

Place, publisher, year, edition, pages
Nature Publishing Group, 2019
Keywords
abiotic factor, anaerobic digestion, bedrock, cap rock, crater, Devonian, methane, methanogenesis, microbial activity, oxidation, shale, Dalarna, Siljan, Sweden
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-40597 (URN)10.1038/s41467-019-12728-y (DOI)2-s2.0-85073546979 (Scopus ID)
Note

Funding details: Vetenskapsrådet, VR, 04129, 2017–05186, 2017–00766; Funding text 1: Thanks to AB Igrene for access to drill cores, drilling logs and gas data. Swedish research council (contract 2017–05186 to H.D., 2015–04129 to S.S., 2017–04129 to M.I.) and Formas (contract 2017–00766 to H.D. and M.W.) are thanked for financial support. K. Lindén, M. Tillberg, and M. Schmitt are thanked for analytical or sample preparation assistance, and University of Gothenburg for access to SEM. This is NordSIM publication 617 and Vegacenter publication 20.

Available from: 2019-11-12 Created: 2019-11-12 Last updated: 2019-11-12Bibliographically approved
Ivarsson, M., Skogby, H., Phichaikamjornwut, B., Bengtson, S., Siljeström, S., Ounchanum, P., . . . Holmström, S. (2018). Intricate tunnels in garnets from soils and river sediments in Thailand - Possible endolithic microborings. PLoS ONE, 13(8), Article ID e0200351.
Open this publication in new window or tab >>Intricate tunnels in garnets from soils and river sediments in Thailand - Possible endolithic microborings
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2018 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 13, no 8, article id e0200351Article in journal (Refereed) Published
Abstract [en]

Garnets from disparate geographical environments and origins such as oxidized soils and river sediments in Thailand host intricate systems of microsized tunnels that significantly decrease the quality and value of the garnets as gems. The origin of such tunneling has previously been attributed to abiotic processes. Here we present physical and chemical remains of endolithic microorganisms within the tunnels and discuss a probable biological origin of the tunnels. Extensive investigations with synchrotron-radiation X-ray tomographic microscopy (SRXTM) reveal morphological indications of biogenicity that further support a euendolithic interpretation. We suggest that the production of the tunnels was initiated by a combination of abiotic and biological processes, and that at later stages biological processes came to dominate. In environments such as river sediments and oxidized soils garnets are among the few remaining sources of bio-available Fe2+, thus it is likely that microbially mediated boring of the garnets has trophic reasons. Whatever the reason for garnet boring, the tunnel system represents a new endolithic habitat in a hard silicate mineral otherwise known to be resistant to abrasion and chemical attack.

National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-35146 (URN)10.1371/journal.pone.0200351 (DOI)30089115 (PubMedID)2-s2.0-85051426408 (Scopus ID)
Note

 The authors acknowledge funding from the Swedish Research Council (Contracts No. 2007-4483 (SB), 2010-3929 (HS), 2012-4364 (MI), and 2013-4290 (SB), 2015-04129 (SS)), Danish National Research Foundation (DNRF53), and Paul Scherrer Institute (20130185) (MI) as well as Swedish National Space Board (Contract No. 83/10 (MI), 121/11 and 198/15 (SS)).

Available from: 2018-09-10 Created: 2018-09-10 Last updated: 2019-01-09Bibliographically approved
Steele, A., Benning, L. G., Wirth, R., Siljeström, S., Fries, M. D., Hauri, E., . . . Rodriguez Blanco, J. D. (2018). Organic synthesis on Mars by electrochemical reduction of CO<sub>2</sub>. Science Advances, 4(10), Article ID eaat5118.
Open this publication in new window or tab >>Organic synthesis on Mars by electrochemical reduction of CO<sub>2</sub>
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2018 (English)In: Science Advances, Vol. 4, no 10, article id eaat5118Article in journal (Refereed) Published
Abstract [en]

The sources and nature of organic carbon on Mars have been a subject of intense research. Steele et al. (2012) showed that 10 martian meteorites contain macromolecular carbon phases contained within pyroxene- and olivine-hosted melt inclusions. Here, we show that martian meteorites Tissint, Nakhla, and NWA 1950 have an inventory of organic carbon species associated with fluid-mineral reactions that are remarkably consistent with those detected by the Mars Science Laboratory (MSL) mission. We advance the hypothesis that interactions among spinel-group minerals, sulfides, and a brine enable the electrochemical reduction of aqueous CO2 to organic molecules. Although documented here in martian samples, a similar process likely occurs wherever igneous rocks containing spinel-group minerals and/or sulfides encounter brines.

National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-36375 (URN)10.1126/sciadv.aat5118 (DOI)2-s2.0-85055869978 (Scopus ID)
Available from: 2018-11-27 Created: 2018-11-27 Last updated: 2019-01-10Bibliographically approved
Varmuza, K., Filzmoser, P., Hoffmann, I., Walach, J., Cottin, H., Fray, N., . . . Hilchenbach, M. (2018). Significance of variables for discrimination: Applied to the search of organic ions in mass spectra measured on cometary particles. Journal of Chemometrics, 32(4), Article ID e3001.
Open this publication in new window or tab >>Significance of variables for discrimination: Applied to the search of organic ions in mass spectra measured on cometary particles
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2018 (English)In: Journal of Chemometrics, ISSN 0886-9383, E-ISSN 1099-128X, Vol. 32, no 4, article id e3001Article in journal (Refereed) Published
Abstract [en]

The instrument Cometary Secondary Ion Mass Analyzer (COSIMA) on board of the European Space Agency mission Rosetta to the comet 67P/Churyumov-Gerasimenko is a secondary ion mass spectrometer with a time-of-flight mass analyzer. It collected near the comet several thousand particles, imaged them, and analyzed the elemental and chemical compositions of their surfaces. In this study, variables have been generated from the spectral data covering the mass ranges of potential C-, H-, N-, and O-containing ions. The variable importance in binary discriminations between spectra measured on cometary particles and those measured on the target background has been estimated by the univariate t test and the multivariate methods discriminant partial least squares, random forest, and a robust method based on the log ratios of all variable pairs. The results confirm the presence of organic substances in cometary matter-probably a complex macromolecular mixture.

Keywords
Classification, Comet 67P/Churyumov-Gerasimenko, D-PLS, Pairwise log ratios, Random forest, Rosetta, Time-of-flight secondary ion mass spectrometry, Variable importance
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-33270 (URN)10.1002/cem.3001 (DOI)2-s2.0-85041032628 (Scopus ID)
Available from: 2018-02-12 Created: 2018-02-12 Last updated: 2018-12-20Bibliographically approved
Grady, M. M., Wright, I., Engrand, C. & Siljeström, S. (2018). The Rosetta mission and the chemistry of organic species in comet 67P/Churyumov-Gerasimenko. Elements, 14(2), 95-100
Open this publication in new window or tab >>The Rosetta mission and the chemistry of organic species in comet 67P/Churyumov-Gerasimenko
2018 (English)In: Elements, ISSN 1811-5209, E-ISSN 1811-5217, Vol. 14, no 2, p. 95-100Article in journal (Refereed) Published
Abstract [en]

Comets are regarded as probably the most primitive of solar system objects, preserving a record of the materials from which the solar system aggregated. Key amongst their components are organic compounds - molecules that may trace their heritage to the interstellar medium from which the protosolar nebula eventually emerged. The most recent cometary space mission, Rosetta, carried instruments designed to characterize, in unprecedented detail, the organic species in comet 67P/Churyumov-Gerasimenko (67P). Rosetta was the first mission to match orbits with a comet and follow its evolution over time, and also the first mission to land scientific instruments on a comet surface. Results from the mission revealed a greater variety of molecules than previously identified and indicated that 67P contained both primitive and processed organic entities. 

Keywords
Chemistry, Comet, Isotopes, Organics, Rosetta, Volatiles
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-33781 (URN)10.2138/gselements.14.2.95 (DOI)2-s2.0-85045679352 (Scopus ID)
Available from: 2018-05-02 Created: 2018-05-02 Last updated: 2018-08-21Bibliographically approved
Fornaro, T., Boosman, A., Brucato, J. R., ten Kate, I. L., Siljeström, S., Poggiali, G., . . . Hazen, R. M. (2018). UV irradiation of biomarkers adsorbed on minerals under Martian-like conditions: Hints for life detection on Mars. Icarus (New York, N.Y. 1962), 313, 38-60
Open this publication in new window or tab >>UV irradiation of biomarkers adsorbed on minerals under Martian-like conditions: Hints for life detection on Mars
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2018 (English)In: Icarus (New York, N.Y. 1962), ISSN 0019-1035, E-ISSN 1090-2643, Vol. 313, p. 38-60Article in journal (Refereed) Published
Abstract [en]

Laboratory simulations of Martian conditions are essential to develop quantitative models for the survival of organic biomarkers for future Mars exploration missions. In this work, we report the results of ultraviolet (UV) irradiation processing of biomarkers adsorbed on minerals under Martian-like conditions. Specifically, we prepared Mars soil analogues by doping forsterite, lizardite, antigorite, labradorite, natrolite, apatite and hematite minerals with organic compounds considered as potential biomarkers of extant terrestrial life such as the nucleotides adenosine monophosphate (AMP) and uridine monophosphate (UMP). We characterized such Mars soil analogues by means of Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) and Confocal Raman Imaging Spectroscopy (CRIS), in order to get insights into the specific molecule-mineral interactions and explore the capabilities of different techniques to reveal diagnostic features of these biomarkers. Then, we performed irradiation experiments in the mid-UV spectral region under simulated Martian conditions and under terrestrial ambient conditions for comparison, monitoring the degradation process through DRIFTS. We observed that degradation under Martian-like conditions occurs much slower than in terrestrial ambient conditions. The minerals labradorite and natrolite mainly promote photodegradation of nucleotides, hematite and forsterite exhibit an intermediate degrading effect, while apatite, lizardite and antigorite do not show any significant catalytic effect on the degradation of the target organic species.

Keywords
Biomarkers, Infrared spectroscopy, Laboratory simulations, Mars soil analogues, Raman spectroscopy, ToF-SIMS
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-34364 (URN)10.1016/j.icarus.2018.05.001 (DOI)2-s2.0-85047245545 (Scopus ID)
Note

 Funding details: TD1308-Origins; Funding details: NNX13AJ19G, NASA, National Aeronautics and Space Administration; Funding details: 198/15, SNSB, Swedish National Space Board; Funding details: ASI, Agenzia Spaziale Italiana; Funding details: UU, Universiteit Utrecht;

Available from: 2018-08-07 Created: 2018-08-07 Last updated: 2019-02-05Bibliographically approved
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-4975-6074

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