| 1. |
- Hilchenbach, M., et al.
(författare)
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COMET 67P/CHURYUMOV-GERASIMENKO : CLOSE-UP on DUST PARTICLE FRAGMENTS
- 2016
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Ingår i: Astrophysical Journal Letters. - : Institute of Physics Publishing (IOPP). - 2041-8205 .- 2041-8213. ; 816:2
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Tidskriftsartikel (refereegranskat)abstract
- The COmetary Secondary Ion Mass Analyser instrument on board ESA's Rosetta mission has collected dust particles in the coma of comet 67P/Churyumov-Gerasimenko. During the early-orbit phase of the Rosetta mission, particles and particle agglomerates have been imaged and analyzed in the inner coma at distances between 100 km and 10 km off the cometary nucleus and at more than 3 AU from the Sun. We identified 585 particles of more than 14 μm in size. The particles are collected at low impact speeds and constitute a sample of the dust particles in the inner coma impacting and fragmenting on the targets. The sizes of the particles range from 14 μm up to sub-millimeter sizes and the differential dust flux size distribution is fitted with a power law exponent of -3.1. After impact, the larger particles tend to stick together, spread out or consist of single or a group of clumps, and the flocculent morphology of the fragmented particles is revealed. The elemental composition of the dust particles is heterogeneous and the particles could contain typical silicates like olivine and pyroxenes, as well as iron sulfides. The sodium to iron elemental ratio is enriched with regard to abundances in CI carbonaceous chondrites by a factor from ∼1.5 to ∼15. No clear evidence for organic matter has been identified. The composition and morphology of the collected dust particles appear to be similar to that of interplanetary dust particles.
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| 2. |
- Hornung, K., et al.
(författare)
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Electrical properties of cometary dust particles derived from line shapes of TOF-SIMS spectra measured by the ROSETTA/COSIMA instrument
- 2019
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Ingår i: Planetary and Space Science. - : Elsevier Ltd. - 0032-0633 .- 1873-5088. ; 182
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Tidskriftsartikel (refereegranskat)abstract
- 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).
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| 3. |
- Bienert, K., et al.
(författare)
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Technologies for biomethane production in small and medium scale applications – Assessment within the European project record biomap
- 2018
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Ingår i: European Biomass Conf. Exhib. Proc.. ; , s. 586-591
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Konferensbidrag (refereegranskat)abstract
- The European Horizon 2020 project “Research Coordination for a Low-Cost Biomethane Production at Small and Medium Scale Applications”, short Record Biomap aims to foster technology solutions for a cost efficient biomethane production at small to medium scale. This includes substrate pre-treatment, digestion systems and gas upgrading processes. The project collected technology descriptions of 46 technologies which are still in their development phase and presented them on the biomethane map (https://biomethane-map.eu). All technologies with a Technology Readiness Level between 3 and 7, which are in the focus of this project, were also evaluated through an impact assessment. The presentation gives an overview of the project´s results, concentrating on the first results of the assessment for innovative technology solutions along the biomethane supply chain and especially upgrading of biogas to biomethane. The assessment includes aspects such as energy efficiency, specific technical characteristics of the systems as well as economic parameters. Results are expected to characterise those new technologies and to highlight their special application areas. In addition, the paper presents a roadmap and an EU level biomethane structural analysis as the groundwork for a more detailed strategy for market implementation of innovative technologies for small- to medium scale upgrading of biogas to biomethane.
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| 4. |
- Bienert, K., et al.
(författare)
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The biomethane map - Research coordination for a low-cost biomethane production at small and medium scale applications
- 2017
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Ingår i: European Biomass Conf. Exhib. Proc.. - : ETA-Florence Renewable Energies. ; , s. 1097-1104
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Konferensbidrag (refereegranskat)abstract
- The European Horizon 2020 project “Research Coordination for a Low-Cost Biomethane Production at Small and Medium Scale Applications”, short Record Biomap, aims to build up a knowledge transfer platform to foster the use of research outcomes which are often insufficiently exploited after the end of a research project. In the focus are technology solutions for a cost efficient biomethane production at small to medium scale, which is not yet economically competitive compared to large scale applications. Technology developments along the biomethane supply chain, from substrate pre-treatment, digestion systems up to gas upgrading processes, especially for those technologies which are yet in the first phases of their development are monitored and supported during the project duration. The present paper will give an overview of the project´s focus. The current status of collected technology profiles is presented. The promising innovative technologies “ultra-sound and hydrodynamic cavitation” for substrate pre-treatment, the “high organic loading plug-flow digestion system” and the “in-situ methane enrichment in combination with a wood ash filter” to upgrade the biogas to biomethane are explained in detail. Furthermore, the first findings on R&D needs and framework conditions are highlighted. © 2017, ETA-Florence Renewable Energies. All rights reserved.
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| 5. |
- Fray, Nicolas, et al.
(författare)
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High-molecular-weight organic matter in the particles of comet 67P/Churyumov–Gerasimenko
- 2016
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Ingår i: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 538:7623, s. 72-74
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Tidskriftsartikel (refereegranskat)abstract
- The presence of solid carbonaceous matter in cometary dust was established by the detection of elements such as carbon, hydrogen, oxygen and nitrogen in particles from comet 1P/Halley1, 2. Such matter is generally thought to have originated in the interstellar medium3, but it might have formed in the solar nebula—the cloud of gas and dust that was left over after the Sun formed4. This solid carbonaceous material cannot be observed from Earth, so it has eluded unambiguous characterization5. Many gaseous organic molecules, however, have been observed6, 7, 8, 9; they come mostly from the sublimation of ices at the surface or in the subsurface of cometary nuclei8. These ices could have been formed from material inherited from the interstellar medium that suffered little processing in the solar nebula10. Here we report the in situ detection of solid organic matter in the dust particles emitted by comet 67P/Churyumov–Gerasimenko; the carbon in this organic material is bound in very large macromolecular compounds, analogous to the insoluble organic matter found in the carbonaceous chondrite meteorites11, 12. The organic matter in meteorites might have formed in the interstellar medium and/or the solar nebula, but was almost certainly modified in the meteorites’ parent bodies11. We conclude that the observed cometary carbonaceous solid matter could have the same origin as the meteoritic insoluble organic matter, but suffered less modification before and/or after being incorporated into the comet.
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| 6. |
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