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1. Flattened loose particles from numerical simulations compared to Rosetta collected particles

Author

Lasue, Jeremie, Maroger, Isabelle, Botet, Robert, Garnier, Philippe, Merouane, Sihane, Mannel, Thurid, Levasseur-Regourd, Anny-Chantal, and Bentley, Mark

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

Cometary dust particles are remnants of the primordial accretion of refractory material that occurred during the initial stages of the Solar System formation. Understanding their physical structure can help constrain their accretion process. We have developed a simple numerical simulation of aggregate impact flattening to interpret the properties of particles collected by COSIMA. The aspect ratios of flattened particles from both simulations and observations are compared to differentiate between initial families of aggregates characterized by different fractal dimensions $D_f$. This dimension can differentiate between certain growth modes. The diversity of aspect ratios measured by COSIMA is consistent with either two families of aggregates with different initial $D_f$ (a family of compact aggregates with fractal dimensions close to 2.5-3 and some fluffier aggregates with fractal dimensions around 2). Alternatively, the distribution of morphologies seen by COSIMA could originate from a single type of aggregation process, such as DLPA, but to explain the range of aspect ratios observed by COSIMA a large range of dust particle cohesive strength is necessary. Furthermore, variations in cohesive strength and velocity may play a role in the higher aspect ratio range detected (>0.3). Our work allows us to explain the particle morphologies observed by COSIMA and those generated by laboratory experiments in a consistent framework. Taking into account all observations from the three dust instruments on-board Rosetta, we favor an interpretation of our simulations based on two different families of dust particles with significantly distinct fractal dimensions ejected from the cometary nucleus., Comment: 9 pages, 10 figures, accepted for publication in Astronomy and Astrophysics

Published
2019
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2. Hesperos: A geophysical mission to Venus

Author

Koopmans, Robert-Jan, Białek, Agata, Donohoe, Anthony, Jiménez, María Fernández, Frasl, Barbara, Gurciullo, Antonio, Kleinschneider, Andreas, Łosiak, Anna, Mannel, Thurid, Elorza, Iñigo Muñoz, Nilsson, Daniel, Oliveira, Marta, Sørensen-Clark, Paul Magnus, Timoney, Ryan, and van Zelst, Iris

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

The Hesperos mission proposed in this paper is a mission to Venus to investigate the interior structure and the current level of activity. The main questions to be answered with this mission are whether Venus has an internal structure and composition similar to Earth and if Venus is still tectonically active. To do so the mission will consist of two elements: an orbiter to investigate the interior and changes over longer periods of time and a balloon floating at an altitude between 40 and 60\~km to investigate the composition of the atmosphere. The mission will start with the deployment of the balloon which will operate for about 25 days. During this time the orbiter acts as a relay station for data communication with Earth. Once the balloon phase is finished the orbiter will perform surface and gravity gradient mapping over the course of 7 Venus days. This mission proposal is the result of the Alpbach Summer School and the post-Alpbach week., Comment: The article was submitted to Advances in Space Research in November 2016. It was accepted with major revisions. Due to unavailability of the team after the end of the project, the paper wasn't fully revised and the submission was withdrawn. The current version includes most of the revisions

Published
2018

3. Evidence for the formation of comet 67P/Churyumov-Gerasimenko through gravitational collapse of a bound clump of pebbles

Author

Blum, Jürgen, Gundlach, Bastian, Krause, Maya, Fulle, Marco, Johansen, Anders, Agarwal, Jessica, von Borstel, Ingo, Shi, Xian, Hu, Xuanyu, Bentley, Mark S., Capaccioni, Fabrizio, Colangeli, Luigi, Della Corte, Vincenzo, Fougere, Nicolas, Green, Simon F., Ivanovski, Stavro, Mannel, Thurid, Merouane, Sihane, Migliorini, Alessandra, Rotundi, Alessandra, Schmied, Roland, and Snodgrass, Colin

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

The processes that led to the formation of the planetary bodies in the Solar System are still not fully understood. Using the results obtained with the comprehensive suite of instruments on-board ESA's Rosetta mission, we present evidence that comet 67P/Churyumov-Gerasimenko likely formed through the gentle gravitational collapse of a bound clump of mm-sized dust aggregates ("pebbles"), intermixed with microscopic ice particles. This formation scenario leads to a cometary make-up that is simultaneously compatible with the global porosity, homogeneity, tensile strength, thermal inertia, vertical temperature profiles, sizes and porosities of emitted dust, and the steep increase in water-vapour production rate with decreasing heliocentric distance, measured by the instruments on-board the Rosetta spacecraft and the Philae lander. Our findings suggest that the pebbles observed to be abundant in protoplanetary discs around young stars provide the building material for comets and other minor bodies., Comment: accepted by MNRAS

Published
2017
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4. Aggregate dust particles at comet 67P/Churyumov-Gerasimenko

Author

Bentley, Mark S., Schmied, Roland, Mannel, Thurid, Torkar, Klaus, Jeszenszky, Harald, Romstedt, Jens, Levasseur-Regourd, Anny-Chantal, Weber, Iris, Jessberger, Elmar K., Ehrenfreund, Pascale, Koeberl, Christian, and Havnes, Ove

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

Comets are thought to preserve almost pristine dust particles, thus providing a unique sample of the properties of the early solar nebula. The microscopic properties of this dust played a key part in particle aggregation during the formation of the Solar System. Cometary dust was previously considered to comprise irregular, fluffy agglomerates on the basis of interpretations of remote observations in the visible and infrared and the study of chondritic porous interplanetary dust particles that were thought, but not proved, to originate in comets. Although the dust returned by an earlier mission has provided detailed mineralogy of particles from comet 81P/Wild, the fine-grained aggregate component was strongly modified during collection. Here we report in situ measurements of dust particles at comet 67P/Churyumov-Gerasimenko. The particles are aggregates of smaller, elongated grains, with structures at distinct sizes indicating hierarchical aggregation. Topographic images of selected dust particles with sizes of one micrometre to a few tens of micrometres show a variety of morphologies, including compact single grains and large porous aggregate particles, similar to chondritic porous interplanetary dust particles. The measured grain elongations are similar to the value inferred for interstellar dust and support the idea that such grains could represent a fraction of the building blocks of comets. In the subsequent growth phase, hierarchical agglomeration could be a dominant process and would produce aggregates that stick more easily at higher masses and velocities than homogeneous dust particles. The presence of hierarchical dust aggregates in the near-surface of the nucleus of comet 67P also provides a mechanism for lowering the tensile strength of the dust layer and aiding dust release.

Published
2017
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5. MIDAS: Lessons learned from the first spaceborne atomic force microscope

Author

Bentley, Mark S., Arends, Herman, Butler, Bart, Gavira, Jose, Jeszenszky, Harald, Mannel, Thurid, Romstedt, Jens, Schmied, Roland, and Torkar, Klaus

Subjects
Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

The Micro-Imaging Dust Analysis System (MIDAS) atomic force microscope (AFM) onboard the Rosetta orbiter was the first such instrument launched into space in 2004. Designed only a few years after the technique was invented, MIDAS is currently orbiting comet 67P Churyumov-Gerasimenko and producing the highest resolution 3D images of cometary dust ever made in situ. After more than a year of continuous operation much experience has been gained with this novel instrument. Coupled with operations of the Flight Spare and advances in terrestrial AFM a set of "lessons learned" has been produced, cumulating in recommendations for future spaceborne atomic force microscopes. The majority of the design could be reused as-is, or with incremental upgrades to include more modern components (e.g. the processor). Key additional recommendations are to incorporate an optical microscope to aid the search for particles and image registration, to include a variety of cantilevers (with different spring constants) and a variety of tip geometries., Comment: To be published in Acta Astronautica

Published
2016
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6. Characterization of 67P/Churyumov-Gerasimenko cometary activity

Author

Longobardo, Andrea, primary, Kim, Minjae, additional, Pestoni, Boris, additional, Cottin, Hervé, additional, Guttler, Carsten, additional, Ivanovski, Stavro, additional, Mannel, Thurid, additional, Merouane, Sihane, additional, Rinaldi, Giovanna, additional, Rubin, Martin, additional, Tubiana, Cecilia, additional, Zakharov, Vladimir, additional, Deshapriya, Prasanna, additional, Dirri, Fabrizio, additional, Ciarniello, Mauro, additional, Della Corte, Vincenzo, additional, Fulle, Marco, additional, Palomba, Ernesto, additional, and Rotundi, Alessandra, additional

Published
2022
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7. Cometary Dust

Author

Levasseur-Regourd, Anny-Chantal, Agarwal, Jessica, Cottin, Hervé, Engrand, Cécile, Flynn, George, Fulle, Marco, Gombosi, Tamas, Langevin, Yves, Lasue, Jérémie, Mannel, Thurid, Merouane, Sihane, Poch, Olivier, Thomas, Nicolas, and Westphal, Andrew

Published
2018
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10. Aggregate dust particles at comet 67P/ChuryumovGerasimenko

Author

Bentley, Mark S., Schmied, Roland, Mannel, Thurid, Torkar, Klaus, Jeszenszky, Harald, Romstedt, Jens, Levasseur-Regourd, Anny-Chantal, Weber, Iris, Jessberger, Elmar K., Ehrenfreund, Pascale, Koeberl, Christian, and Havnes, Ove

Subjects
Comets -- Observations, Cosmic dust -- Observations, Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Author(s): Mark S. Bentley (corresponding author) [1]; Roland Schmied [1]; Thurid Mannel [1, 2]; Klaus Torkar [1]; Harald Jeszenszky [1]; Jens Romstedt [3]; Anny-Chantal Levasseur-Regourd [4]; Iris Weber [5]; Elmar [...]

Published
2016
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13. Classification of comet 67P dust at the nanometre scale with MIDAS on-board Rosetta

Author

Mannel, Thurid, Bentley, Mark, Boakes, Peter D., Jeszenszky, Harald, Ehrenfreund, Pascale, Engrand, Cecile, Koeberl, Christian, Levasseur-Regourd, Anny Chantal, Romstedt, Jens, Schmied, Roland, Torkar, Klaus, Weber, Iris, Space Research Institute of Austrian Academy of Sciences (IWF), Austrian Academy of Sciences (OeAW), Karl-Franzens-Universität [Graz, Autriche], European Space Astronomy Centre (ESAC), European Space Agency (ESA), Space Policy Institute [Washington], The George Washington University (GW), Leiden Observatory [Leiden], Universiteit Leiden [Leiden], Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Department of Lithospheric Research [Wien], Universität Wien, Natural History Museum [Vienna] (NHM), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), European Space Research and Technology Centre (ESTEC), Institut für Planetologie [Münster], Westfälische Wilhelms-Universität Münster (WWU), and Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU]Sciences of the Universe [physics]
Abstract

International audience; The properties of the smallest sub-units of cometary dust contain information on their origin and clues to the formation of planetesimals and planets. The MIDAS Atomic Force Microscope (AFM) on-board the ESA Rosetta orbiter collected dust in the coma of comet 67P/Churyumov-Gerasimenko. These particles, collected at low velocities, were analysed to measure the structural properties of minimally altered material with a known origin. This can be used to further the investigation of our early Solar System. A novel method is presented to achieve the highest spatial resolution of imaging possible with the MIDAS instrument. 3D topographic images with resolutions of down to 8 nm are analysed to determine the sub-unit sizes of particles on the nanometre scale.

Published
2019

14. Cometary dust: structure at the nanometre scale

Author

Mannel, Thurid, Bentley, Mark, Boakes, Peter, Jeszenszky, Harald, Ehrenfreund, Pascale, Engrand, Cécile, Koeberl, Christian, Levasseur-Regourd, Anny Chantal, Romstedt, Jens, Schmied, Roland, Torkar, Klaus, Weber, Iris, Space Research Institute of Austrian Academy of Sciences (IWF), Austrian Academy of Sciences (OeAW), Karl-Franzens-Universität Graz, European Space Astronomy Centre (ESAC), Agence Spatiale Européenne = European Space Agency (ESA), Leiden Observatory [Leiden], Universiteit Leiden, Space Policy Institute [Washington], The George Washington University (GW), Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Department of Lithospheric Research [Wien], Universität Wien, Natural History Museum [Vienna] (NHM), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), European Space Research and Technology Centre (ESTEC), Institut für Weltraumforschung = Space Research institute [Graz] (IWF), Osterreichische Akademie der Wissenschaften (ÖAW), Institut für Planetologie [Münster], Westfälische Wilhelms-Universität Münster = University of Münster (WWU), Karl-Franzens-Universität [Graz, Autriche], European Space Agency (ESA), Universiteit Leiden [Leiden], Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Institut für Weltraumforschung [Graz] (IWF), Westfälische Wilhelms-Universität Münster (WWU), and Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11)

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience; The Rosetta orbiter carried three dedicated dust analysis instruments to investigate the properties of the comet andits dust at smallest scales. The images with the highest resolutions were obtained by the MIDAS (Micro-ImagingDust Analysis System) atomic force microscope [1,2]. It collected dust particles of one to tens of micrometresin size and imaged their surface in 3D. Nominal images had approximately hundreds of nanometres resolutionand were used to study the particle morphology at the micrometre scale. It was shown that the majority ofcollected particles were fragile agglomerates [3] with a moderate packing density of subunits at the surface [4].Exceptions were one extremely porous particle with a fractal structure that is suggested to be pristinely preservedfrom early agglomeration processes in our Solar System [4], and the particles of about one micrometre size thatshow less fragility. To study these smallest detected particles a special scanning mode, called ‘reverse imagingmode‘, was developed that reached resolutions down to eight nanometres [5]. In the reverse imaging mode dustparticles were picked up with the tip and imaged with the help of a sharp spike on a calibration sample. Theresulting images opened the possibility to identify the agglomerate structure of the dust down to the nanometrescale and to determine smallest features with mean sizes of about 100 nanometres. Whether these smallestfeatures are surface related or true subunits comprising the dust will be discussed on the basis of comparisons tosmallest subunit sizes identified by indirect Rosetta measurements and by investigations of other cometary material.References:[1] W. Riedler, K. Torkar, H. Jeszenszky, et al., MIDAS – The Micro-Imaging Dust Analysis System for theRosetta Mission. Space Science Reviews 128, 2007.[2] M.S. Bentley, H. Arends, B. Butler, et al., MIDAS: Lessons learned from the first spaceborne atomic forcemicroscope. Acta Astronautica 125, 2016.[3] M.S. Bentley, R. Schmied, T. Mannel et al., Aggregate dust particles at comet 67P/Chruyumov-Gerasimenko,Nature, 537, 2016.[4] T. Mannel, M.S. Bentley, R. Schmied et al., Fractal cometary dust – a window into the early Solar system,MNRAS, 462, 2016.[5] T. Mannel, M.S. Bentley, P.D. Boakes, et al., MIDAS results: classification and extension to the nanometrescale, submitted to Astronomy & Astrophysics, Rosetta special issue, 2018.

Published
2019

15. The Post-Rosetta Understanding of the Fate of Cometary Dust

Author

Levasseur-Regourd, Anny Chantal, Bentley, Mark, Cottin, Hervé, Engrand, Cécile, Freissinet, Caroline, Hadamcik, Edith, Langevin, Yves, Lasue, Jérémie, Mannel, Thurid, Merouane, Sihane, PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), European Space Astronomy Centre (ESAC), European Space Agency (ESA), Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse (CSNSM), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Space Research Institute of Austrian Academy of Sciences (IWF), Austrian Academy of Sciences (OeAW), Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, Cardon, Catherine, IMPEC - LATMOS, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Agence Spatiale Européenne = European Space Agency (ESA), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), and Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], [SDU.ASTR] Sciences of the Universe [physics]/Astrophysics [astro-ph]
Abstract

International audience; Thanks to its long duration, the Rosetta mission has provided a unique insight into the properties of dust particles released by 67P/C-G nucleus, and ascertained the links between cometary dust and CP-IDPs or UCAMMs [1]. Minerals to organics proportions are quite comparable within the refractory phase, in which carbon-bearing compounds present high-molecular masses [2-4]. Dust particles consist of aggregates of smaller grains and present hierarchical structures, with morphologies ranging from extremely porous to almost compact [5-7].The refractory materials released in comae (monitored with ≈ 4-1.2 au solar distance range for 67P/C-G), subjected to gravitational and non-gravitational forces, build up dust tails and trails, and progressively become parts of the zodiacal cloud, i.e. the lenticular-shaped interplanetary dust cloud. The small dust particles spiral towards the Sun under Poynting-Robertson effect, with migration times in the 300-50000 years range for micron-sized grains with densities about 100-1000 kg m-3 released at solar distances about 4-1.2 au [8]. Such dust particles happen to encounter the Earth atmosphere. Independent approaches have established that most of the near-Earth interplanetary dust comes from Jupiter Family comets, such as 67P/C-G [9-11], which orbit in the vicinity of the ecliptic plane.Updates of our present understanding of dust in 67P/C-G will be proposed. Through various numerical and experimental simulations [e.g. 12], the changes in composition and in physical properties of cometary dust particles in the interplanetary dust cloud will be discussed, as a function of time and of solar distance. The possible implications, for the early evolution of terrestrial planets, of the properties of the cometary dust component in the interplanetary dust cloud will be tentatively addressed.1. Levasseur-Regourd et al. SSR 2018. 2. Goesmann et al. Science 2015. 3. Fray et al. Nature 2016. 4. Bardyn et al. MNRAS 2017. 5. Bentley et al. Nature 2016. 6. Langevin et al. Icarus 2016. 7. Mannel et al. MNRAS 2017. 8. Saïagh PhD Thesis UPE 2014. 9. Lasue et al. Astron. Astrophys. 2007. 10. Nesvorny et al. ApJ 2010. 11. Rowan-Robinson and May MNRAS 2013. 12. Hadamcik et al. PSS 2018.

Published
2018

16. Compacted aggregates from numerical simulations compared to Rosettacollected particles

Author

Maroger, Isabelle, Lasue, Jeremie, Botet, Robert, Garnier, Philippe, Merouane, Sihane, Mannel, Thurid, Levasseur-Regourd, Anny Chantal, Bentley, Mark, Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique des Solides (LPS), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, Space Research Institute of Austrian Academy of Sciences (IWF), Austrian Academy of Sciences (OeAW), Karl-Franzens-Universität [Graz, Autriche], PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), European Space Astronomy Centre (ESAC), and European Space Agency (ESA)

Subjects
[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph]
Abstract

International audience; The Rosetta space mission includes three main instruments for solid dust particles analysis. The combinedmicroscope and mass spectrometer COSIMA (Cometary Secondary Ion Mass Analyser) [1], the atomic forcemicroscope MIDAS (Micro-Imaging Dust Analysis System) [2], and the impact detector GIADA (Grain ImpactAnalyser and Dust Accumulator) [3]. These three instruments provide complementary insights into the dustparticles properties thanks to their different approaches and resolution ranges (10nm to 1mm). GIADA andMIDAS observed a major contribution from compact dust aggregates together with a population of porousparticles with a low fractal dimension (Df ~ 1.7 for MIDAS [4]) [5, 6]. Such a fractal dust component of thenucleus and its properties give constraints on the formation of comets in the early solar system [5].In this work, we analyse results from a simple numerical model of dust aggregates compaction and compare themwith COSIMA images of collected aggregates to assess the initial physical properties of the dust populations. Weconsider 4 different kinds of fractal aggregates presenting different initial fractal dimensions (Df ~ 1.8/2.1/2.5/3)based on their aggregation processes (diffusion limited or reaction limited aggregations, depending on the surfacesticking probabilities of the monomers, and particle-cluster or cluster-cluster aggregations).We find that the aspect ratio distribution observed by COSIMA may be explained either by compacting twodifferent initial families with low and high fractal dimensions and the same cohesive strength between monomers,or by compacting a single type of particles (with an aggregation process like DLPA) however with a large rangeof internal cohesive strengths or collection velocities.References: [1] Kissel, J. et al. (2007) SSR, 128(1), 823-867. [2] Riedler, W. et al. (2007) SSR, 128(1-4),869-904. [3] Colangeli, L. et al. (2007) SSR, 128(1-4), 803-821. [4] Mannel, T. et al. (2016) MNRAS, 462(S1),304-311. [5] Fulle, M. and Blum, J. (2017), MNRAS, 469(S2), 39-44 [6] Fulle, M. et al. (2017) MNRAS 469(S2),45–49

Published
2018

17. Compacted loose particles from numerical simulations compared to Rosetta collected particles

Author

Maroger, Isabelle, Lasue, Jeremie, Botet, Robert, Garnier, Philippe, Merouane, Sihane, Mannel, Thurid, Levasseur-Regourd, Anny Chantal, Bentley, Mark Stephen, Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique des Solides (LPS), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, Space Research Institute of Austrian Academy of Sciences (IWF), Austrian Academy of Sciences (OeAW), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), European Space Astronomy Centre (ESAC), and European Space Agency (ESA)

Subjects
[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph]
Abstract

International audience; The Rosetta space mission included three main instruments for solid dust particle analysis. The combined microscope and mass spectrometer COSIMA (Cometary Secondary Ion Mass Analyser) [1], the atomic force microscope MIDAS (Micro-Imaging Dust Analysis System) [2], and the impact detector GIADA (Grain Impact Analyser and Dust Accumulator) [3]. These three instruments provide complementary insights into dust particles properties over a wide range of sizes/masses (10nm to 1mm). GIADA and MIDAS observed a major contribution from compact dust particles together with a population of porous particles with a low fractal dimension (Df~1,7 for MIDAS [4]) [5, 6]. The fractal dust component of the nucleus and its properties give constraints on the formation of comets in the early solar system [5].In this work, we analyseresults from a simple numerical model of dust aggregates compactionto assess the initial physical properties of the dust populations.

Published
2018

19. Nucleus structure and dust morphology: Post-Rosetta understanding and implications

Author

Levasseur-Regourd, Anny Chantal, Bentley, Mark, Ciarletti, Valérie, Kofman, Woldek, Lasue, Jérémie, Mannel, Thurid, Herique, Alain, PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Space Research Institute of Austrian Academy of Sciences (IWF), Austrian Academy of Sciences (OeAW), Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), IMPEC - LATMOS, Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU]Sciences of the Universe [physics]
Abstract

International audience; The structure of cometary nuclei and the morphology of dust particles they eject have long been unknowns in cometary science. The combination of these two subjects, as revealed by the Rosetta mission at 67P/C-G, is currently providing an unprecedented insight about Solar System formation and early evolution.Rosetta has established that the bulk porosity of 67P/C-G nucleus is high, in the 70% to 85% range, both from the determination of its density and from permittivity measurements with CONSERT bistatic radar experiment [1-2]. CONSERT, through operations after Philae landing on 12-13 November 2014, has also allowed us to estimate that i) the porosity is likely to be higher inside the nucleus than on its subsurface, ii) a major component of the nucleus is refractory carbonaceous compounds, and iii) the small lobe is homogeneous at a scale of a few wavelengths (i.e., about 10 m), while heterogeneities in the 3-m range (similar to the rounded nodules noticed on walls of large pits) cannot be ruled out [2-4].Rosetta has also established, through its 26 months rendezvous with 67P/C-G, the aggregated structure of dust particles within a wide range of sizes in the inner cometary coma. The MIDAS atomic force microscope experiment has given us evidence (from 3D topographic images with nano- to micrometer resolution) for i) a hierarchical structure of aggregated dust particles, down to tens of nm-sized grains, ii) one extremely porous dust particle, with a fractal dimension of (1.7 ± 0.1) [5-6]. The accuracy of comparisons between cometary dust particles and interplanetary dust particles collected in the stratosphere (including CP-IDPs) could thus be improved.Such results should further refine the main processes (e.g., low velocity aggregation) that allowed the formation of comets in the early Solar System, and the implications of a possible late heavy bombardment on the interplanetary dust clouds and on telluric planets.References. 1. Pätzold et al. Nature 530 63 2016. 2. Kofman et al. Science 349 6247 2015. 3. Herique et al. MNRAS 462 S516 2016. 4. Ciarletti et al. A&A 583 A40 2015. 5. Bentley et al., Nature 537 73 2016. 6. Mannel et al., MNRAS 462 S304 2016.

Published
2017

20. A post-Rosetta understanding of polarimetric observations of comets

Author

Levasseur-Regourd, Anny Chantal, Ciarletti, Valérie, Hadamcik, Edith, Lasue, Jérémie, Mannel, Thurid, PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Institute of Physics [Graz], Karl-Franzens-Universität [Graz, Autriche], Space Research Institute of Austrian Academy of Sciences (IWF), Austrian Academy of Sciences (OeAW), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), and Karl-Franzens-Universität Graz

Subjects
[SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP]
Abstract

International audience; Numerous polarimetric observations of solar light scattered by dust in cometary comae have been obtained by various teams, providing phase angle and wavelength dependences for many comets and revealing different classes of comets [e.g., 1]. Besides, numerical and experimental simulations have suggested interpretations for such observations. The Rosetta long duration rendezvous with comet 67P/Churyumov-Gerasimenko (thereafter 67P/C-G) now allows us to compare our understanding of the polarimetric properties of cometary dust with the ground-truth provided by the Rosetta mission, at least for two typical results.First, some comets present a highly-polarized positive branch, the most conspicuous case being that of new comet C/1995 O1 Hale-Bopp [2], while other comets suffering a partial fragmentation or a total disruption, such as C/1995 S4 LINEAR [3], present a significant increase in polarization. We will discuss these observations in the context of evidence for changes between the porosity (and possibly the dust/ice ratio) of the subsurface and of the interior of 67P/C-G, a periodic Jupiter Family Comet, as derived from analyses [4] of the CONSERT bi-static radar measurements on board Rosetta and Philae.Secondly, numerical simulations of the phase and wavelength dependence of polarimetric observations of some comets (extensively observed on a wide range of wavelengths and phase angles) have suggested the presence of fractal, likely-porous aggregates and of compact particles within their comae [e.g., 5]. We will review such results in the context of evidence for porous and compact aggregates of submicron-sized grains in the inner coma of 67P/C-G [6], as given by 3D images (with a resolution down to tens of nanometers) of the MIDAS atomic force microscope on board Rosetta.

Published
2017

21. How MIDAS improved our understanding of micrometre- sized cometary dust

Author

Mannel, Thurid, Bentley, Mark Stephen, Boakes, Peter, Jeszenszky, Harald, Levasseur-Regourd, Anny Chantal, Schmied, Roland, Torkar, Klaus, Cardon, Catherine, Space Research Institute of Austrian Academy of Sciences (IWF), Austrian Academy of Sciences (OeAW), Institute of Physics [Graz], Karl-Franzens-Universität [Graz, Autriche], PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and Karl-Franzens-Universität Graz

Subjects
[SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [SDU.ASTR.SR] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], [SDU.ASTR.EP] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP]
Abstract

International audience; The MIDAS atomic force microscope on the Rosetta orbiter was an instrument developed to investigate, for the first time, the morphology of nearly unaltered cometary dust. It acquired the 3D topography of about 1-50 µm sized dust particles with resolutions down to a few nanometres. These images showed the agglomerate character of the dust and confirmed that the smallest subunit sizes were less than 100 nm. MIDAS acquired the first direct proof of a fractal dust particle, opening a new approach to investigate the history of our early Solar System and of comets.

Published
2017

22. The morphology of cometary dust: Subunit size distributions down to tens of nanometres

Author

Mannel, Thurid, Bentley, Mark, Boakes, Peter, Jeszenszky, Harald, Levasseur-Regourd, Anny Chantal, Schmied, Roland, Torkar, Klaus, Cardon, Catherine, Institute of Physics [Graz], Karl-Franzens-Universität [Graz, Autriche], Space Research Institute of Austrian Academy of Sciences (IWF), Austrian Academy of Sciences (OeAW), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and Karl-Franzens-Universität Graz

Subjects
Quantitative Biology::Biomolecules, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [SDU.ASTR.SR] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], [SDU.ASTR.EP] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Astrophysics::Earth and Planetary Astrophysics
Abstract

International audience; The Rosetta orbiter carried a dedicated analysis suite for cometary dust. One of the key instruments was MIDAS (Micro-Imaging Dust Analysis System), an atomic force microscope that scanned the surfaces of hundreds of (sub-)micrometre particles in 3D with resolutions down to nanometres. This provided the opportunity to study the morphology of the smallest cometary dust; initial investigation revealed that the particles are agglomerates of smaller subunits [1] with different structural properties [2]. To understand the (surface-) structure of the dust particles and the origin of their smallest building blocks, a number of particles were investigated in detail and the size distribution of their subunits determined [3].Here we discuss the subunit size distributions ranging from tens of nanometres to a few micrometres. The differences between the subunit size distributions for particles collected pre-perihelion, close to perihelion, and during a huge outburst are examined, as well as the dependence of subunit size on particle size. A case where a particle was fragmented in consecutive scans allows a direct comparison of fragment and subunit size distributions. Finally, the small end of the subunit size distribution is investigated: the smallest determined sizes will be reviewed in the context of other cometary missions, interplanetary dust particles believed to originate from comets, and remote observations. It will be discussed if the smallest subunits can be interpreted as fundamental building blocks of our early Solar System and if their origin was in our protoplanetary disc or the interstellar material.

Published
2017

23. Ground truth of (sub-)micrometre cometary dust - Results of MIDAS onboard Rosetta

Author

Mannel, Thurid, Bentley, Mark, Schmied, Roland, Torkar, Klaus, Jeszenszky, Harald, Romsted, Jens, Levasseur-Regourd, Anny Chantal, Weber, Iris, Jessberger, Elmar K., Ehrenfreund, Pascale, Köberl, Christian, Havnes, Ove, Space Research Institute of Austrian Academy of Sciences (IWF), Austrian Academy of Sciences (OeAW), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut für Planetologie [Münster], Westfälische Wilhelms-Universität Münster (WWU), Space Policy Institute [Washington], The George Washington University (GW), University of Vienna [Vienna], Department of Physics and Technology [Tromsø], University of Tromsø (UiT), Agence Spatiale Européenne = European Space Agency (ESA), and Westfälische Wilhelms-Universität Münster = University of Münster (WWU)

Subjects
[SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP]
Abstract

International audience; The investigation of comet 67P by Rosetta has allowed the comprehensive characterisation of pristine cometary dust particles ejected from the nucleus. Flying alongside the comet at distances as small as a few kilometres, and with a relative velocity of only centimetres per second, the Rosetta payload sampled almost unaltered dust. A key instrument to study this dust was MIDAS (the Micro-Imaging Dust Analysis System), a dedicated atomic force microscope that scanned the surfaces of hundreds of (sub- )micrometre sized particles in 3D with resolutions down to nanometres. This offers the unique opportunity to explore the morphology of smallest cometary dust and expand our current knowledge about cometary material.Here we give an overview of dust collected and analysed by MIDAS and highlight its most important features. These include the ubiquitous agglomerate nature of the dust, which is found at all size scales from the largest (>10 μm) through to the smallest (

Published
2016

24. Evidence for the formation of comet 67P/Churyumov-Gerasimenko through gravitational collapse of a bound clump of pebbles

Author

Blum, Jürgen, primary, Gundlach, Bastian, additional, Krause, Maya, additional, Fulle, Marco, additional, Johansen, Anders, additional, Agarwal, Jessica, additional, von Borstel, Ingo, additional, Shi, Xian, additional, Hu, Xuanyu, additional, Bentley, Mark S, additional, Capaccioni, Fabrizio, additional, Colangeli, Luigi, additional, Della Corte, Vincenzo, additional, Fougere, Nicolas, additional, Green, Simon F, additional, Ivanovski, Stavro, additional, Mannel, Thurid, additional, Merouane, Sihane, additional, Migliorini, Alessandra, additional, Rotundi, Alessandra, additional, Schmied, Roland, additional, and Snodgrass, Colin, additional

Published
2017
Full Text
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28. Cometary Dust

Author

Levasseur-Regourd, Anny-Chantal, Agarwal, Jessica, Cottin, Hervé, Engrand, Cécile, Flynn, George, Fulle, Marco, Gombosi, Tamas, Langevin, Yves, Lasue, Jérémie, Mannel, Thurid, Merouane, Sihane, Poch, Olivier, Thomas, Nicolas, and Westphal, Andrew

Subjects
13. Climate action, 520 Astronomy, Physics::Space Physics, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Earth and Planetary Astrophysics, 620 Engineering, complex mixtures, Astrophysics::Galaxy Astrophysics, respiratory tract diseases
Abstract

This review presents our understanding of cometary dust at the end of 2017. For decades, insight about the dust ejected by nuclei of comets had stemmed from remote observations from Earth or Earth’s orbit, and from flybys, including the samples of dust returned to Earth for laboratory studies by the Stardust return capsule. The long-duration Rosetta mission has recently provided a huge and unique amount of data, obtained using numerous instruments, including innovative dust instruments, over a wide range of distances from the Sun and from the nucleus. The diverse approaches available to study dust in comets, together with the related theoretical and experimental studies, provide evidence of the composition and physical properties of dust particles, e.g., the presence of a large fraction of carbon in macromolecules, and of aggregates on a wide range of scales. The results have opened vivid discussions on the variety of dust-release processes and on the diversity of dust properties in comets, as well as on the formation of cometary dust, and on its presence in the near-Earth interplanetary medium. These discussions stress the significance of future explorations as a way to decipher the formation and evolution of our Solar System.

29. Evidence for the formation of comet 67P/Churyumov-Gerasimenko through gravitational collapse of a bound clump of pebbles

Author

Blum, Jürgen, Gundlach, Bastian, Krause, Maya, Fulle, Marco, Johansen, Anders, Agarwal, Jessica, Borstel, Ingo von, Shi, Xian, Hu, Xuanyu, Bentley, Mark S., Capaccioni, Fabrizio, Colangeli, Luigi, Corte, Vincenzo Della, Fougere, Nicolas, Green, Simon F., Ivanovski, Stavro, Mannel, Thurid, Merouane, Sihane, Migliorini, Alessandra, Rotundi, Alessandra, Schmied, Roland, Snodgrass, Colin, Blum, Jürgen, Gundlach, Bastian, Krause, Maya, Fulle, Marco, Johansen, Anders, Agarwal, Jessica, Borstel, Ingo von, Shi, Xian, Hu, Xuanyu, Bentley, Mark S., Capaccioni, Fabrizio, Colangeli, Luigi, Corte, Vincenzo Della, Fougere, Nicolas, Green, Simon F., Ivanovski, Stavro, Mannel, Thurid, Merouane, Sihane, Migliorini, Alessandra, Rotundi, Alessandra, Schmied, Roland, and Snodgrass, Colin

Abstract

The processes that led to the formation of the planetary bodies in the Solar System are still not fully understood. Using the results obtained with the comprehensive suite of instruments on-board ESA’s Rosetta mission, we present evidence that comet 67P/Churyumov-Gerasimenko likely formed through the gentle gravitational collapse of a bound clump of mm-sized dust aggregates (“pebbles”), intermixed with microscopic ice particles. This formation scenario leads to a cometary make-up that is simultaneously compatible with the global porosity, homogeneity, tensile strength, thermal inertia, vertical temperature profiles, sizes and porosities of emitted dust, and the steep increase in water-vapour production rate with decreasing heliocentric distance, measured by the instruments on-board the Rosetta spacecraft and the Philae lander. Our findings suggest that the pebbles observed to be abundant in protoplanetary discs around young stars provide the building material for comets and other minor bodies.

30. Evidence for the formation of comet 67P/Churyumov-Gerasimenko through gravitational collapse of a bound clump of pebbles

Author

Blum, Jürgen, Gundlach, Bastian, Krause, Maya, Fulle, Marco, Johansen, Anders, Agarwal, Jessica, Borstel, Ingo von, Shi, Xian, Hu, Xuanyu, Bentley, Mark S., Capaccioni, Fabrizio, Colangeli, Luigi, Corte, Vincenzo Della, Fougere, Nicolas, Green, Simon F., Ivanovski, Stavro, Mannel, Thurid, Merouane, Sihane, Migliorini, Alessandra, Rotundi, Alessandra, Schmied, Roland, Snodgrass, Colin, Blum, Jürgen, Gundlach, Bastian, Krause, Maya, Fulle, Marco, Johansen, Anders, Agarwal, Jessica, Borstel, Ingo von, Shi, Xian, Hu, Xuanyu, Bentley, Mark S., Capaccioni, Fabrizio, Colangeli, Luigi, Corte, Vincenzo Della, Fougere, Nicolas, Green, Simon F., Ivanovski, Stavro, Mannel, Thurid, Merouane, Sihane, Migliorini, Alessandra, Rotundi, Alessandra, Schmied, Roland, and Snodgrass, Colin

Abstract

The processes that led to the formation of the planetary bodies in the Solar System are still not fully understood. Using the results obtained with the comprehensive suite of instruments on-board ESA’s Rosetta mission, we present evidence that comet 67P/Churyumov-Gerasimenko likely formed through the gentle gravitational collapse of a bound clump of mm-sized dust aggregates (“pebbles”), intermixed with microscopic ice particles. This formation scenario leads to a cometary make-up that is simultaneously compatible with the global porosity, homogeneity, tensile strength, thermal inertia, vertical temperature profiles, sizes and porosities of emitted dust, and the steep increase in water-vapour production rate with decreasing heliocentric distance, measured by the instruments on-board the Rosetta spacecraft and the Philae lander. Our findings suggest that the pebbles observed to be abundant in protoplanetary discs around young stars provide the building material for comets and other minor bodies.

32. Space-to-Ground Communication for Columbus: A Quantitative Analysis.

Author

Uhlig T, Mannel T, Fortunato A, and Illmer N

Subjects
Humans, Astronauts, Satellite Communications, Space Flight, Spacecraft
Abstract

The astronauts on board the International Space Station (ISS) are only the most visible part of a much larger team engaged around the clock in the performance of science and technical activities in space. The bulk of such team is scattered around the globe in five major Mission Control Centers (MCCs), as well as in a number of smaller payload operations centres. Communication between the crew in space and the flight controllers at those locations is an essential element and one of the key drivers to efficient space operations. Such communication can be carried out in different forms, depending on available technical assets and the selected operational approach for the activity at hand. This paper focuses on operational voice communication and provides a quantitative overview of the balance achieved in the Columbus program between collaborative space/ground operations and autonomous on-board activity execution. An interpretation of the current situation is provided, together with a description of potential future approaches for deep space exploration missions.

Published
2015
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