Search

Your search keyword '"Gasc, S."' showing total 120 results
Start Over Author "Gasc, S."

Refine your results

more »

more »

more »

more »
120 results on '"Gasc, S."'

1. Evidence for depletion of heavy silicon isotopes at comet 67P/Churyumov-Gerasimenko

Author

Rubin, M., Altwegg, K., Balsiger, H., Berthelier, J. -J., Bieler, A., Calmonte, U., Combi, M., De Keyser, J., Engrand, C., Fiethe, B., Fuselier, S. A., Gasc, S., Gombosi, T. I., Hansen, K. C., Hässig, M., Roy, L. Le, Mezger, K., Tzou, C. -Y., Wampfler, S. F., and Wurz, P.

Subjects
Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Solar and Stellar Astrophysics
Abstract

Context. The Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) was designed to measure the composition of the gas in the coma of comet 67P/Churyumov-Gerasimenko, the target of the European Space Agency's Rosetta mission. In addition to the volatiles, ROSINA measured refractories sputtered off the comet by the interaction of solar wind protons with the surface of the comet. Aims. The origin of different solar system materials is still heavily debated. Isotopic ratios can be used to distinguish between different reservoirs and investigate processes occurring during the formation of the solar system. Methods. ROSINA consisted of two mass spectrometers and a pressure sensor. In the ROSINA Double Focusing Mass Spectrometer (DFMS), the neutral gas of cometary origin was ionized and then deflected in an electric and a magnetic field that separated the ions based on their mass-to-charge ratio. The DFMS had a high mass resolution, dynamic range, and sensitivity that allowed detection of rare species and the known major volatiles. Results. We measured the relative abundance of all three stable silicon isotopes with the ROSINA instrument on board the Rosetta spacecraft. Furthermore, we measured $^{13}$C/$^{12}$C in C$_2$H$_4$, C$_2$H$_5$, and CO. The DFMS in situ measurements indicate that the average silicon isotopic composition shows depletion in the heavy isotopes $^{29}$Si and $^{30}$Si with respect to $^{28}$Si and solar abundances, while $^{13}$C to $^{12}$C is analytically indistinguishable from bulk planetary and meteorite compositions. Although the origin of the deficiency of the heavy silicon isotopes cannot be explained unambiguously, we discuss mechanisms that could have contributed to the measured depletion of the isotopes $^{29}$Si and $^{30}$Si., Comment: Accepted for publication in Astronomy & Astrophysics

Published
2017
Full Text
View/download PDF

2. Impact of radiogenic heating on the formation conditions of comet 67P/Churyumov-Gerasimenko

Author

Mousis, O., Drouard, A., Vernazza, P., Lunine, J. I., Monnereau, M., Maggiolo, R., Altwegg, K., Balsiger, H., Berthelier, J. -J., Cessateur, G., De Keyser, J., Fuselier, S. A., Gasc, S., Korth, A., Deun, T. Le, Mall, U., Marty, B., Rème, H., Rubin, M., Tzou, C. -Y., Waite, J. H., and Wurz, P.

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

Because of the high fraction of refractory material present in comets, the heat produced by the radiogenic decay of elements such as aluminium and iron can be high enough to induce the loss of ultravolatile species such as nitrogen, argon or carbon monoxide during their accretion phase in the protosolar nebula. Here, we investigate how heat generated by the radioactive decay of 26Al and 60Fe influences the formation of comet 67P/Churyumov-Gerasimenko, as a function of its accretion time and size of parent body. We use an existing thermal evolution model that includes various phase transitions, heat transfer in the ice-dust matrix, and gas diffusion throughout the porous material, based on thermodynamic parameters derived from Rosetta observations. Two possibilities are considered: either, to account for its bilobate shape, 67P/Churyumov-Gerasimenko was assembled from two primordial ~2 kilometer-sized planetesimals, or it resulted from the disruption of a larger parent body with a size corresponding to that of comet Hale-Bopp (~70 km). To fully preserve its volatile content, we find that either 67P/Churyumov-Gerasimenko's formation was delayed between ~2.2 and 7.7 Myr after that of Ca-Al-rich Inclusions in the protosolar nebula or the comet's accretion phase took place over the entire time interval, depending on the primordial size of its parent body and the composition of the icy material considered. Our calculations suggest that the formation of 67P/Churyumov-Gerasimenko is consistent with both its accretion from primordial building blocks formed in the nebula or from debris issued from the disruption of a Hale-Bopp-like body., Comment: Accepted for publication in The Astrophysical Journal Letters

Published
2017
Full Text
View/download PDF

3. Spatial distribution of low-energy plasma around comet 67P/CG from Rosetta measurements

Author

Edberg, N. J. T., Eriksson, A. I., Odelstad, E., Henri, P., Lebreton, J. -P., Gasc, S., Rubin, M., André, M., Gill, R., Johansson, E. P. G., Johansson, F., Vigren, E., Wahlund, J. E., Carr, C. M., Cupido, E., Glassmeier, K. -H., Goldstein, R., Koenders, C., Mandt, K., Nemeth, Z., Nilsson, H., Richter, I., Wieser, G. Stenberg, Szego, K., and Volwerk, M.

Subjects
Physics - Space Physics, Astrophysics - Earth and Planetary Astrophysics
Abstract

We use measurements from the Rosetta plasma consortium (RPC) Langmuir probe (LAP) and mutual impedance probe (MIP) to study the spatial distribution of low-energy plasma in the near-nucleus coma of comet 67P/Churyumov-Gerasimenko. The spatial distribution is highly structured with the highest density in the summer hemisphere and above the region connecting the two main lobes of the comet, i.e. the neck region. There is a clear correlation with the neutral density and the plasma to neutral density ratio is found to be about 1-2x10^-6, at a cometocentric distance of 10 km and at 3.1 AU from the sun. A clear 6.2 h modulation of the plasma is seen as the neck is exposed twice per rotation. The electron density of the collisonless plasma within 260 km from the nucleus falls of with radial distance as about 1/r. The spatial structure indicates that local ionization of neutral gas is the dominant source of low-energy plasma around the comet., Comment: 7 pages, 3 figures

Published
2016
Full Text
View/download PDF

4. D₂O and HDS in the coma of 67P/Churyumov—Gerasimenko

Author

Altwegg, K., Balsiger, H., Berthelier, J. J., Bieler, A., Calmonte, U., De Keyser, J., Fiethe, B., Fuselier, S. A., Gasc, S., Gombosi, T. I., Owen, T., Le Roy, L., Rubin, M., Sémon, T., and Tzou, C.-Y.

Published
2017

5. Xenon isotopes in 67P/Churyumov-Gerasimenko show that comets contributed to Earth's atmosphere

Author

Marty, B., Altwegg, K., Balsiger, H., Bar-Nun, A., Bekaert, D. V., Berthelier, J.-J., Bieler, A., Briois, C., Calmonte, U., Combi, M., De Keyser, J., Fiethe, B., Fuselier, S. A., Gasc, S., Gombosi, T. I., Hansen, K. C., Hässig, M., Jäckel, A., Kopp, E., Korth, A., Le Roy, L., Mall, U., Mousis, O., Owen, T., Rème, H., Rubin, M., Sémon, T., Tzou, C.-Y., Waite, J. H., and Wurz, P.

Published
2017

6. Molecular nitrogen in comet 67P/Churyumov-Gerasimenko indicates a low formation temperature

Author

Rubin, M., Altwegg, K., Balsiger, H., Bar-Nun, A., Berthelier, J.-J., Bieler, A., Bochsler, P., Briois, C., Calmonte, U., Combi, M., De Keyser, J., Dhooghe, F., Eberhardt, P., Fiethe, B., Fuselier, S. A., Gasc, S., Gombosi, T. I., Hansen, K. C., Hässig, M., Jäckel, A., Kopp, E., Korth, A., Le Roy, L., Mall, U., Marty, B., Mousis, O., Owen, T., Réme, H., Sémon, T., Tzou, C.-Y., Waite, J. H., and Wurz, P.

Published
2015

7. Time variability and heterogeneity in the coma of 67P/Churyumov-Gerasimenko

Author

Hässig, M., Altwegg, K., Balsiger, H., Bar-Nun, A., Berthelier, J. J., Bieler, A., Bochsler, P., Briois, C., Calmonte, U., Combi, M., De Keyser, J., Eberhardt, P., Fiethe, B., Fuselier, S. A., Galand, M., Gasc, S., Gombosi, T. I., Hansen, K. C., Jäckel, A., Keller, H. U., Kopp, E., Korth, A., Kührt, E., Le Roy, L., Mall, U., Marty, B., Mousis, O., Neefs, E., Owen, T., Rème, H., Rubin, M., Sémon, T., Tornow, C., Tzou, C.-Y., Waite, J. H., and Wurz, P.

Published
2015

8. 67P/Churyumov-Gerasimenko, a Jupiter family comet with a high D/H ratio

Author

Altwegg, K., Balsiger, H., Bar-Nun, A., Berthelier, J. J., Bieler, A., Bochsler, P., Briois, C., Calmonte, U., Combi, M., De Keyser, J., Eberhardt, P., Fiethe, B., Fuselier, S., Gasc, S., Gombosi, T. I., Hansen, K.C., Hässig, M., Jäckel, A., Kopp, E., Korth, A., LeRoy, L., Mall, U., Marty, B., Mousis, O., Neefs, E., Owen, T., Rème, H., Rubin, M., Sémon, T., Tzou, C.-Y., Waite, H., and Wurz, P.

Published
2015

9. Abundant molecular oxygen in the coma of comet 67P/Churyumov-Gerasimenko

Author

Bieler, A., Altwegg, K., Balsiger, H., Bar-Nun, A., Berthelier, J.-J., Bochsler, P., Briois, C., Calmonte, U., Combi, M., De Keyser, J., van Dishoeck, E.F., Fiethe, B., Fuselier, S.A., Gasc, S., Gombosi, T.I., Hansen, K.C., Hassig, M., Jackel, A., Kopp, E., Korth, A., Roy, L. Le, Mall, U., Maggiolo, R., Marty, B., Mousis, O., Owen, T., Reme, H., Rubin, M., Semon, T., Tzou, C.-Y., Waite, J.H., Walsh, C., and Wurz, P.

Subjects
Comets -- Chemical properties -- Observations, Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

The composition of the neutral gas comas of most comets is dominated by [H.sub.2]O, CO and C[O.sub.2], typically comprising as much as 95 per cent of the total gas density (1). In addition, cometary comas have been found to contain a rich array of other molecules, including sulfuric compounds and complex hydrocarbons. Molecular oxygen ([O.sub.2]), however, despite its detection on other icy bodies such as the moons of Jupiter and Saturn (2,3), has remained undetected in cometary comas. Here we report in situ measurement of [O.sub.2] in the coma of comet 67P/Churyumov-Gerasimenko, with local abundances ranging from one per cent to ten per cent relative to [H.sub.2]O and with a mean value of 3.80 ± 0.85 per cent. Our observations indicate that the [O.sub.2]/[H.sub.2]O ratio is isotropic in the coma and does not change systematically with heliocentric distance. This suggests that primordial [O.sub.2] was incorporated into the nucleus during the comet's formation, which is unexpected given the low upper limits from remote sensing observations (4). Current Solar System formation models do not predict conditions that would allow this to occur., Measurements of the coma of 67P/Churyumov-Gerasimenko (hereafter 67P) were made between September 2014 and March 2015 with the ROSINA-DFMS mass spectrometer (5) on board the Rosetta spacecraft. For the present [...]

Published
2015

10. COMETARY FORMATION: Molecular nitrogen in comet 67P/Churyumov-Gerasimenko indicates a low formation temperature

Author

Rubin, M., Altwegg, K., Balsiger, H., Bar-Nun, A., Berthelier, J.-J., Bieler, A., Bochsler, P., Briois, C., Calmonte, U., Combi, M., De Keyser, J., Dhooghe, F., Eberhardt, P., Fiethe, B., Fuselier, S. A., Gasc, S., Gombosi, T. I., Hansen, K. C., Hässig, M., Jäckel, A., Kopp, E., Korth, A., Le Roy, L., Mall, U., Marty, B., Mousis, O., Owen, T., Rème, H., Sémon, T., Tzou, C.-Y., Waite, J. H., and Wurz, P.

Published
2015
Full Text
View/download PDF

11. ALMA and ROSINA detections of phosphorus-bearing molecules: The interstellar thread between star-forming regions and comets

Author

Rivilla, V. M., Drozdovskaya, M. N., Altwegg, K., Caselli, P., Beltrán, M. T., Fontani, F., Van, Der, Tak, F. F. S., Cesaroni, R., Vasyunin, A., Rubin, M., Lique, F., Marinakis, S., Testi, L., Balsiger, H., Berthelier, J. J., De Keyser, J., Fiethe, B., Fuselier, S. A., Gasc, S., Gombosi, T. I., Sémon, T., Tzou, C. -Y., Rivilla, V. M., Drozdovskaya, M. N., Altwegg, K., Caselli, P., Beltrán, M. T., Fontani, F., Van, Der, Tak, F. F. S., Cesaroni, R., Vasyunin, A., Rubin, M., Lique, F., Marinakis, S., Testi, L., Balsiger, H., Berthelier, J. J., De Keyser, J., Fiethe, B., Fuselier, S. A., Gasc, S., Gombosi, T. I., Sémon, T., and Tzou, C. -Y.

Abstract

To understand how phosphorus (P)-bearing molecules are formed in star-forming regions, we have analysed the Atacama Large Millimeter/Submillimeter Array (ALMA) observations of PN and PO towards the massive star-forming region AFGL 5142, combined with a new analysis of the data of the comet 67P/Churyumov-Gerasimenko taken with the Rosetta Orbiter Spectrometer for Ion and NeutralAnalysis (ROSINA) instrument onboard Rosetta. TheALMA maps show that the emission of PN and PO arises from several spots associated with lowvelocity gas with narrow linewidths in the cavity walls of a bipolar outflow. PO is more abundant than PN in most of the spots, with the PO/PN ratio increasing as a function of the distance to the protostar. Our data favour a formation scenario in which shocks sputter phosphorus from the surface of dust grains, and gas-phase photochemistry induced by UV photons from the protostar allows efficient formation of the two species in the cavity walls. Our analysis of the ROSINA data has revealed that PO is the main carrier of P in the comet, with PO/PN > 10. Since comets may have delivered a significant amount of prebiotic material to the early Earth, this finding suggests that PO could contribute significantly to the phosphorus reservoir during the dawn of our planet. There is evidence that PO was already in the cometary ices prior to the birth of the Sun, so the chemical budget of the comet might be inherited from the natal environment of the Solar system, which is thought to be a stellar cluster including also massive stars. © 2019 The Author(s).

Published
2020

12. ALMA and ROSINA detections of phosphorus-bearing molecules: the interstellar thread between star-forming regions and comets

Author

Rivilla, V. M., Drozdovskaya, M. N., Altwegg, K., Caselli, P., BELTRAN SOROLLA, MARIA TERESA, FONTANI, FRANCESCO, van der Tak, F. F. S., CESARONI, Riccardo, Vasyunin, A., Rubin, M., Lique, F., Marinakis, S., TESTI, Leonardo, Rosina Team, Balsiger, H., Berthelier, J. J., de Keyser, J., Fiethe, B., Fuselier, S. A., Gasc, S., Gombosi, T. I., Sémon, T., Tzou, C. -Y., INAF - Osservatorio Astrofisico di Arcetri (OAA), Istituto Nazionale di Astrofisica (INAF), Center for Space and Habitability (CSH), University of Bern, Physikalisches Institut [Bern], Universität Bern [Bern], Max-Planck-Institut für Extraterrestrische Physik (MPE), SRON Netherlands Institute for Space Research (SRON), Kapteyn Astronomical Institute [Groningen], University of Groningen [Groningen], Ural Federal University [Ekaterinburg] (UrFU), Laboratoire Ondes et Milieux Complexes (LOMC), Centre National de la Recherche Scientifique (CNRS)-Université Le Havre Normandie (ULH), Normandie Université (NU)-Normandie Université (NU), School of Health, Sport and Bioscience (HSB), University of East London (UEL), School of Biological and Chemical Sciences, Queen Mary University of London (QMUL), European Southern Observatory (ESO), 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), Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique (BIRA-IASB), Institute of Computer and Network Engineering [Braunschweig] (IDA), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Southwest Research Institute [San Antonio] (SwRI), Department of Atmospheric, Oceanic, and Space Sciences [Ann Arbor] (AOSS), University of Michigan [Ann Arbor], University of Michigan System-University of Michigan System, and Astronomy

Subjects
Solar System, PN, Astrochemistry, molecular data, 530 Physics, Comet, SULFUR, FOS: Physical sciences, Astrophysics, 01 natural sciences, Submillimeter Array, ABUNDANCES, CHEMISTRY, Planet, FORMATION [STARS], Bipolar outflow, EXCITATION, 0103 physical sciences, Protostar, POTENTIAL-ENERGY SURFACES, 010306 general physics, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Physics, ASTROCHEMISTRY, PHOSPHINE, stars: formation, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], astrochemistry, 520 Astronomy, comets: general, 67P/CHURYUMOV-GERASIMENKO, PROTOSTELLAR, Astronomy and Astrophysics, MOLECULAR DATA, 620 Engineering, Astrophysics - Astrophysics of Galaxies, ISM: molecules, Stars, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, MOLECULES [ISM], Astrophysics of Galaxies (astro-ph.GA), EMISSION, GENERAL [COMETS]
Abstract

To understand how Phosphorus-bearing molecules are formed in star-forming regions, we have analysed ALMA observations of PN and PO towards the massive star-forming region AFGL 5142, combined with a new analysis of the data of the comet 67P/Churyumov-Gerasimenko taken with the ROSINA instrument onboard Rosetta. The ALMA maps show that the emission of PN and PO arises from several spots associated with low-velocity gas with narrow linewidths in the cavity walls of a bipolar outflow. PO is more abundant than PN in most of the spots, with the PO/PN ratio increasing as a function of the distance to the protostar. Our data favor a formation scenario in which shocks sputter phosphorus from the surface of dust grains, and gas-phase photochemistry induced by UV photons from the protostar allows efficient formation of the two species in the cavity walls. Our analysis of the ROSINA data has revealed that PO is the main carrier of P in the comet, with PO/PN>10. Since comets may have delivered a significant amount of prebiotic material to the early Earth, this finding suggests that PO could contribute significantly to the phosphorus reservoir during the dawn of our planet. There is evidence that PO was already in the cometary ices prior to the birth of the Sun, so the chemical budget of the comet might be inherited from the natal environment of the Solar System, which is thought to be a stellar cluster including also massive stars., Accepted in MNRAS (20 pages, 12 figures)

Published
2019
Full Text
View/download PDF

13. CLUPI, a high-performance Imaging System on the rover of theExoMars Mission 2020 to doscover biofabrics on MARS. Science objectives and development status

Author

Josset, J.-L., Westall, F., Hofmann, B. A., Spray, J., Cockell, C., Kempe, S., Griffiths, A. D., De Sanctis, Maria Cristina, Colangeli, Luigi, Koschny, D., Föllmi, Karl, Verrecchia, Eric, Diamond, Larryn, Josset, Marie, Javaux, Emmanuelle J., Esposito, F., Gunn, M., Gasc, S., Bontognali, Tomaso R. R., Korablev, Oleg, Erkman, Suren, Paar, G., Ulamec, Stephan, Foucher, F., Kuhn, N., Tanevski, M., Martin, P., and Yago, J.

Subjects
ExoMars, CLUPI
Published
2018

14. Two years with comet 67P/Churyumov-Gerasimenko: H2O, CO2, and CO as seen by the ROSINA/RTOF instrument of Rosetta

Author

Hoang, M., primary, Garnier, P., additional, Gourlaouen, H., additional, Lasue, J., additional, Rème, H., additional, Altwegg, K., additional, Balsiger, H., additional, Beth, A., additional, Calmonte, U., additional, Fiethe, B., additional, Galli, A., additional, Gasc, S., additional, Jäckel, A., additional, Korth, A., additional, Le Roy, L., additional, Mall, U., additional, Rubin, M., additional, Sémon, T., additional, Tzou, C.-Y., additional, Waite, J. H., additional, and Wurz, P., additional

Published
2019
Full Text
View/download PDF

16. 2 years with comet 67P/Churyumov-Gerasimenko: H2O, CO2, CO as seen by ROSINA RTOF

Author

Hoang, M., Garnier, P., Lasue, J., Reme, H., Altwegg, K., Balsiger, H. R., Bieler, A. M., Calmonte, U., CAPRIA, MARIA TERESA, Combi, M. R., De Keyser, J. M., Fiethe, B., Fougere, N., Fuselier, S. A., Galli, A., Gasc, S., Gombosi, T. I., Hansen, K. C., Jäckel, A., Korth, A., Mall, U., MIGLIORINI, Alessandra, Rubin, M., Sémon, T., Tzou, C. Y., Waite, J. H., Jr., Wurz, P., ITA, USA, FRA, DEU, BEL, and CHE

Abstract

The Rosetta space mission investigated comet 67P/Churyumov-Gerasimenko (67P) over two years from August 2014 to September 2016. Onboard the spacecraft, the ROSINA experiment included two mass spectrometers to derive the composition of neutrals and ions, and a COmet Pressure Sensor (COPS) to monitor the density and velocity of the neutrals in the coma. We will here analyse and discuss data from the Reflectron-type Time-Of-Flight instrument during the comet escort phase. The RTOF mass spectrometer possessed a wide mass range and a high temporal resolution (Balsiger et al., 2007). The analysis of 67P/C-G's coma major molecules over the mission showed strong variability of the comet coma's main volatiles concentrations (H2O, CO2, CO) and their relative abundances. The 2 years long Rosetta mission allowed us to observe the seasonal evolution in the atmosphere of 67P, in particular the change occurring during the equinoxes and at perihelion. In this work, we analyze the asymmetry in the outgassing rate before and after the perihelion (13/08/2015), the evolution of abundance ratios through the whole mission, and in particular the behavior of the very volatile CO molecules. Density maps projected on the surface of 67P demonstrate the evolution of the three main coma species after the outbound equinox. We will present first results of our comet nucleus thermal modelling used to simulate the internal structure and temperature evolution of 67P at characteristic surface areas. These results will be compared with the coma composition measurements obtained by ROSINA....

Published
2017

17. Ion composition at comet 67P near perihelion : Rosetta observations and model-based interpretation

Author

Heritier, K. L., Altwegg, K., Balsiger, H., Berthelier, J. -J, Beth, A., Bieler, A., Biver, N., Calmonte, U., Combi, M. R., De Keyser, J., Eriksson, Anders I., Fiethe, B., Fougere, N., Fuselier, S. A., Galand, M., Gasc, S., Gombosi, T. I., Hansen, K. C., Hassig, M., Kopp, E., Odelstad, Elias, Rubin, M., Tzou, C. -Y, Vigren, Erik, Vuitton, V., Heritier, K. L., Altwegg, K., Balsiger, H., Berthelier, J. -J, Beth, A., Bieler, A., Biver, N., Calmonte, U., Combi, M. R., De Keyser, J., Eriksson, Anders I., Fiethe, B., Fougere, N., Fuselier, S. A., Galand, M., Gasc, S., Gombosi, T. I., Hansen, K. C., Hassig, M., Kopp, E., Odelstad, Elias, Rubin, M., Tzou, C. -Y, Vigren, Erik, and Vuitton, V.

Abstract

We present the ion composition in the coma of comet 67P with newly detected ion species over the 28-37 u mass range, probed by Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA)/Double Focusing Mass Spectrometer (DFMS). In summer 2015, the nucleus reached its highest outgassing rate and ion-neutral reactions started to take place at low cometocentric distances. Minor neutrals can efficiently capture protons from the ion population, making the protonated version of these neutrals a major ion species. So far, only NH4+ has been reported at comet 67P. However, there are additional neutral species with proton affinities higher than that of water (besides NH3) that have been detected in the coma of comet 67P: CH3OH, HCN, H2CO and H2S. Their protonated versions have all been detected. Statistics showing the number of detections with respect to the number of scans are presented. The effect of the negative spacecraft potential probed by the Rosetta Plasma Consortium/LAngmuir Probe on ion detection is assessed. An ionospheric model has been developed to assess the different ion density profiles and compare them to the ROSINA/DFMS measurements. It is also used to interpret the ROSINA/DFMS observations when different ion species have similar masses, and their respective densities are not high enough to disentangle them using the ROSINA/DFMS high-resolution mode. The different ion species that have been reported in the coma of 67P are summarized and compared with the ions detected at comet 1P/Halley during the Giotto mission.

Published
2017
Full Text
View/download PDF

18. Noble gases Ar, Kr and Xe measured in the coma of Comet 67P/Churyumov-Gerasimenko: implications to early solar system formation

Author

Balsiger, H. R., Altwegg, K., Bar-Nun, A., Berthelier, Jean-Jacques, Bieler, A. M., Bochsler, P., Briois, C., Calmonte, U., Combi, M. R., de Keyser, J., Fiethe, B., Fuselier, S. A., Gasc, S., Gombosi, T. I., Hansen, K. C., Hässig, M., Kopp, E., Korth, A., Le Roy, L., Mall, U., Marty, B., Mousis, O., Owen, T. C., Reme, H., Rubin, M., Semon, T., Tzou, C. Y., Waite, J. H., Wurz, P., Physikalisches Institut [Bern], Universität Bern [Bern] (UNIBE), Center for Space and Habitability (CSH), University of Bern, Tel Aviv University (TAU), 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), University of Michigan [Ann Arbor], University of Michigan System, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique (BIRA-IASB), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Southwest Research Institute [San Antonio] (SwRI), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, Centre de Recherches Pétrographiques et Géochimiques (CRPG), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), University of Hawai‘i [Mānoa] (UHM), Institut de recherche en astrophysique et planétologie (IRAP), 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 POTHIER, Nathalie

Subjects
[SDU] Sciences of the Universe [physics], Surfaces, Plasma, [SDU]Sciences of the Universe [physics], Ices, Physics::Space Physics, Comets, Astrophysics::Solar and Stellar Astrophysics, Dust, Astrophysics::Earth and Planetary Astrophysics, MHD instabilities, Small Bodies
Abstract

International audience; The role of comets in the formation of solar system planets, in particular their contribution to the volatiles of the terrestrial planets has been the subject of numerous models and speculations. Having kept at least partially the volatile constituents of the solar nebula, comets are among the most primitive objects in the solar system. Noble gases in the cometary coma are key tracers for assessing origin and processing of planetary atmospheres. We report the detection of Ar, Kr and Xe in the coma of Comet 67P during the same period (May 2016) by the Double Focusing Mass Spectrometer (DFMS) of the ROSINA experiment on ESA's Rosetta spacecraft, their relative abundance and isotopic composition. First implications for the volatile inventory of terrestrial planets and for solar system formation scenarios are discussed.

Published
2016

19. Evolution of water production of 67P/Churyumov-Gerasimenko

Author

Hansen, Kenneth C., Altwegg, K., Berthelier, J. -J., Bieler, A., Biver, N., Bockelee-Morvan, D., Calmonte, U., Capaccioni, F., Combi, M. R., De Keyser, J., Fiethe, B., Fougere, N., Fuselier, S. A., Gasc, S., Gombosi, T. I., Huang, Z., Le Roy, L., Lee, S., Nilsson, H., Rubin, Martin, Shou, Y., Snodgrass, C., Tenishev, V., Tzou, C.-Y., Wedlund, C. Simon, Toth, Gabor, ROSINA Team, University of Michigan, Ann Arbor, University of Bern, Observatoire de Paris, Istituto Nazionale Astrofisica - Italy, Royal Belgian Institute for Space Aeronomy, TU Braunschweig, University of Texas at San Antonio, Jet Propulsion Laboratory, Swedish Institute of Space Physics, Open University, Department of Radio Science and Engineering, Aalto-yliopisto, and Aalto University

Subjects
individual: 67P/CG [comets], SIMULATION, DUST, CO2, PREPERIHELION, ROSINA, PERIHELION, miscellaneous [methods], ATMOSPHERE, ROSETTA ORBITER, TARGET COMET 67P/CHURYUMOV-GERASIMENKO, general [comets], HALE-BOPP
Abstract

We examine the evolution of the water production of comet 67P/Churyumov-Gerasimenko during the Rosetta mission (2014 June-2016 May) based on in situ and remote sensing measurements made by Rosetta instruments, Earth-based telescopes and through the development of an empirical coma model. The derivation of the empirical model is described and the model is then applied to detrend spacecraft position effects from the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) data. The inter-comparison of the instrument data sets shows a high level of consistency and provides insights into the water and dust production. We examine different phases of the orbit, including the early mission (beyond 3.5 au) where the ROSINA water production does not show the expected increase with decreasing heliocentric distance. A second important phase is the period around the inbound equinox, where the peak water production makes a dramatic transition from northern to southern latitudes. During this transition, the waterdistribution is complex, but is driven by rotation and active areas in the north and south. Finally, we consider the perihelion period, where there may be evidence of time dependence in the water production rate. The peak water production, as measured by ROSINA, occurs 18-22 d after perihelion at 3.5 +/- 0.5 x 10(28) water molecules s(-1). We show that the water production is highly correlated with ground-based dust measurements, possibly indicating that several dust parameters are constant during the observed period. Using estimates of the dust/gas ratio, we use our measured water production rate to calculate a uniform surface loss of 2-4 m during the current perihelion passage.

Published
2016

20. Isotopic composition of CO2in the coma of 67P/Churyumov-Gerasimenko measured with ROSINA/DFMS

Author

Hässig, M., primary, Altwegg, K., additional, Balsiger, H., additional, Berthelier, J. J., additional, Bieler, A., additional, Calmonte, U., additional, Dhooghe, F., additional, Fiethe, B., additional, Fuselier, S. A., additional, Gasc, S., additional, Gombosi, T. I., additional, Le Roy, L., additional, Luspay-Kuti, A., additional, Mandt, K., additional, Rubin, M., additional, Tzou, C.-Y., additional, Wampfler, S. F., additional, and Wurz, P., additional

Published
2017
Full Text
View/download PDF

21. Ion composition at comet 67P near perihelion: Rosetta observations and model-based interpretation

Author

Heritier, K. L., primary, Altwegg, K., additional, Balsiger, H., additional, Berthelier, J.-J., additional, Beth, A., additional, Bieler, A., additional, Biver, N., additional, Calmonte, U., additional, Combi, M. R., additional, De Keyser, J., additional, Eriksson, A. I., additional, Fiethe, B., additional, Fougere, N., additional, Fuselier, S. A., additional, Galand, M., additional, Gasc, S., additional, Gombosi, T. I., additional, Hansen, K. C., additional, Hassig, M., additional, Kopp, E., additional, Odelstad, E., additional, Rubin, M., additional, Tzou, C.-Y., additional, Vigren, E., additional, and Vuitton, V., additional

Published
2017
Full Text
View/download PDF

22. Sulphur isotope mass-independent fractionation observed in comet 67P/Churyumov–Gerasimenko by Rosetta/ROSINA

Author

Calmonte, U, primary, Altwegg, K, additional, Balsiger, H, additional, Berthelier, J-J, additional, Bieler, A, additional, De Keyser, J, additional, Fiethe, B, additional, Fuselier, S A, additional, Gasc, S, additional, Gombosi, T I, additional, Le Roy, L, additional, Rubin, M, additional, Sémon, T, additional, Tzou, C-Y, additional, and Wampfler, S F, additional

Published
2017
Full Text
View/download PDF

23. Organics in comet 67P – a first comparative analysis of mass spectra from ROSINA–DFMS, COSAC and Ptolemy

Author

Altwegg, Kathrin, primary, Balsiger, H., additional, Berthelier, J.J., additional, Bieler, A., additional, Calmonte, U., additional, Fuselier, S.A., additional, Goesmann, F., additional, Gasc, S., additional, Gombosi, T. I., additional, Le Roy, L., additional, de Keyser, J., additional, Morse, A., additional, Rubin, M., additional, Schuhmann, M., additional, Taylor, M. G. G. T, additional, Tzou, C.-Y., additional, and Wright, I., additional

Published
2017
Full Text
View/download PDF

24. Evidence for depletion of heavy silicon isotopes at comet 67P/Churyumov-Gerasimenko

Author

Rubin, M., primary, Altwegg, K., additional, Balsiger, H., additional, Berthelier, J.-J., additional, Bieler, A., additional, Calmonte, U., additional, Combi, M., additional, De Keyser, J., additional, Engrand, C., additional, Fiethe, B., additional, Fuselier, S. A., additional, Gasc, S., additional, Gombosi, T. I., additional, Hansen, K. C., additional, Hässig, M., additional, Le Roy, L., additional, Mezger, K., additional, Tzou, C.-Y., additional, Wampfler, S. F., additional, and Wurz, P., additional

Published
2017
Full Text
View/download PDF

25. Impact of Radiogenic Heating on the Formation Conditions of Comet 67P/Churyumov–Gerasimenko

Author

Mousis, O., primary, Drouard, A., additional, Vernazza, P., additional, Lunine, J. I., additional, Monnereau, M., additional, Maggiolo, R., additional, Altwegg, K., additional, Balsiger, H., additional, Berthelier, J.-J., additional, Cessateur, G., additional, De Keyser, J., additional, Fuselier, S. A., additional, Gasc, S., additional, Korth, A., additional, Le Deun, T., additional, Mall, U., additional, Marty, B., additional, Rème, H., additional, Rubin, M., additional, Tzou, C.-Y., additional, Waite, J. H., additional, and Wurz, P., additional

Published
2017
Full Text
View/download PDF

26. The heterogeneous coma of comet 67P/Churyumov-Gerasimenko as seen by ROSINA: H2O, CO2, and CO from September 2014 to February 2016

Author

Hoang, M., primary, Altwegg, K., additional, Balsiger, H., additional, Beth, A., additional, Bieler, A., additional, Calmonte, U., additional, Combi, M. R., additional, De Keyser, J., additional, Fiethe, B., additional, Fougere, N., additional, Fuselier, S. A., additional, Galli, A., additional, Garnier, P., additional, Gasc, S., additional, Gombosi, T., additional, Hansen, K. C., additional, Jäckel, A., additional, Korth, A., additional, Lasue, J., additional, Le Roy, L., additional, Mall, U., additional, Rème, H., additional, Rubin, M., additional, Sémon, T., additional, Toublanc, D., additional, Tzou, C.-Y., additional, Waite, J. H., additional, and Wurz, P., additional

Published
2017
Full Text
View/download PDF

27. First in-situ detection of the cometary ammonium ion NH$_4^{+}$ (protonated ammonia NH 3 ) in the coma of 67P/C-G near perihelion

Author

Beth, A., primary, Altwegg, K., additional, Balsiger, H., additional, Berthelier, J.-J., additional, Calmonte, U., additional, Combi, M.R., additional, De Keyser, J., additional, Dhooghe, F., additional, Fiethe, B., additional, Fuselier, S.A., additional, Galand, M., additional, Gasc, S., additional, Gombosi, T.I., additional, Hansen, K.C., additional, Hässig, M., additional, Héritier, K.L., additional, Kopp, E., additional, Le Roy, L., additional, Mandt, K.E., additional, Peroy, S., additional, Rubin, M., additional, Sémon, T., additional, Tzou, C.-Y., additional, and Vigren, E., additional

Published
2017
Full Text
View/download PDF

28. The volatile inventory of comet 67P/Churyumov-Gerasimenko from Rosetta/ROSINA at 3 AU

Author

Le Roy, L., Altwegg, K., Berthelier, Jean-Jacques, Bieler, A., Briois, C., Calmonte, U., Combi, M. R., de Keyser, J., Dhooghe, F., Fiethe, B., Fuselier, S. A., Gasc, S., Gombosi, T. I., Hässig, M., Jäckel, A., Rubin, M., Tzou, C. -Y., Center for Space and Habitability (CSH), University of Bern, Space Research and Planetary Sciences [Bern) (WP), Physikalisches Institut [Bern], Universität Bern [Bern] (UNIBE)-Universität Bern [Bern] (UNIBE), HELIOS - 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), Department of Atmospheric, Oceanic, and Space Sciences [Ann Arbor] (AOSS), University of Michigan [Ann Arbor], University of Michigan System-University of Michigan System, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique (BIRA-IASB), Institute of Computer and Network Engineering [Braunschweig] (IDA), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], and Southwest Research Institute [San Antonio] (SwRI)

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

International audience; Comets are believed to be the most pristine bodies in the solar system. The study of their composition can therefore give us important clues about the processes that occurred during the solar system formation. We will report abundances of the major observed species with focus on the hydrocarbons detected by ROSINA/DFMS in the coma of 67P/Churyumov-Gerasimenko in October 2014 at 3 AU.

Published
2015

30. Statistical analysis of suprathermal electron drivers at 67P/Churyumov-Gerasimenko

Author

Broiles, Thomas W., Burch, J. L., Chae, K., Clark, G., Cravens, T. E., Eriksson, Anders, Fuselier, S. A., Frahm, R. A., Gasc, S., Goldstein, R., Henri, P., Koenders, C., Livadiotis, G., Mandt, K. E., Mokashi, P., Nemeth, Z., Odelstad, Elias, Rubin, M., Samara, M., Broiles, Thomas W., Burch, J. L., Chae, K., Clark, G., Cravens, T. E., Eriksson, Anders, Fuselier, S. A., Frahm, R. A., Gasc, S., Goldstein, R., Henri, P., Koenders, C., Livadiotis, G., Mandt, K. E., Mokashi, P., Nemeth, Z., Odelstad, Elias, Rubin, M., and Samara, M.

Abstract

We use observations from the Ion and Electron Sensor (IES) on board the Rosetta spacecraft to study the relationship between the cometary suprathermal electrons and the drivers that affect their density and temperature. We fit the IES electron observations with the summation of two kappa distributions, which we characterize as a dense and warm population (similar to 10 cm(-3) and similar to 16 eV) and a rarefied and hot population (similar to 0.01 cm(-3) and similar to 43 eV). The parameters of our fitting technique determine the populations' density, temperature, and invariant kappa index. We focus our analysis on the warm population to determine its origin by comparing the density and temperature with the neutral density and magnetic field strength. We find that the warm electron population is actually two separate sub-populations: electron distributions with temperatures above 8.6 eV and electron distributions with temperatures below 8.6 eV. The two sub-populations have different relationships between their density and temperature. Moreover, the two sub-populations are affected by different drivers. The hotter sub-population temperature is strongly correlated with neutral density, while the cooler sub-population is unaffected by neutral density and is only weakly correlated with magnetic field strength. We suggest that the population with temperatures above 8.6 eV is being heated by lower hybrid waves driven by counterstreaming solar wind protons and newly formed, cometary ions created in localized, dense neutral streams. To the best of our knowledge, this represents the first observations of cometary electrons heated through wave-particle interactions., QC 20200602

Published
2016
Full Text
View/download PDF

31. Ion chemistry in the coma of comet 67P near perihelion

Author

Fuselier, S. A., Altwegg, K., Balsiger, H., Berthelier, J. J., Beth, A., Bieler, A., Briois, C., Broiles, T. W., Burch, J. L., Calmonte, U., Cessateur, G., Combi, M., De Keyser, J., Fiethe, B., Galand, M., Gasc, S., Gombosi, T. I., Gunell, H., Hansen, K. C., Hassig, M., Heritier, K. L., Korth, A., Le Roy, L., Luspay-Kuti, A., Mall, U., Mandt, K. E., Petrinec, S. M., Reme, H., Rinaldi, M., Rubin, M., Semon, T., Trattner, K. J., Tzou, C. -Y, Vigren, Erik, Waite, J. H., Wurz, P., Fuselier, S. A., Altwegg, K., Balsiger, H., Berthelier, J. J., Beth, A., Bieler, A., Briois, C., Broiles, T. W., Burch, J. L., Calmonte, U., Cessateur, G., Combi, M., De Keyser, J., Fiethe, B., Galand, M., Gasc, S., Gombosi, T. I., Gunell, H., Hansen, K. C., Hassig, M., Heritier, K. L., Korth, A., Le Roy, L., Luspay-Kuti, A., Mall, U., Mandt, K. E., Petrinec, S. M., Reme, H., Rinaldi, M., Rubin, M., Semon, T., Trattner, K. J., Tzou, C. -Y, Vigren, Erik, Waite, J. H., and Wurz, P.

Abstract

The coma and the comet-solar wind interaction of comet 67P/Churyumov-Gerasimenko changed dramatically from the initial Rosetta spacecraft encounter in 2014 August through perihelion in 2015 August. Just before equinox (at 1.6 au from the Sun), the solar wind signal disappeared and two regions of different cometary ion characteristics were observed. These 'outer' and 'inner' regions have cometary ion characteristics similar to outside and inside the ion pileup region observed during the Giotto approach to comet 1P/Halley. Rosetta/Double-Focusing Mass Spectrometer ion mass spectrometer observations are used here to investigate the H3O+/H2O+ ratio in the outer and inner regions at 67P/Churyumov-Gerasimenko. The H3O+/H2O+ ratio and the H3O+ signal are observed to increase in the transition from the outer to the inner region and the H3O+ signal appears to be weakly correlated with cometary ion energy. These ion composition changes are similar to the ones observed during the 1P/Halley flyby. Modelling is used to determine the importance of neutral composition and transport of neutrals and ions away from the nucleus. This modelling demonstrates that changes in the H3O+/H2O+ ratio appear to be driven largely by transport properties and only weakly by neutral composition in the coma.

Published
2016
Full Text
View/download PDF

32. First in situ detection of the cometary ammonium ion NH4+ (protonated ammonia NH3) in the coma of 67P/C-G near perihelion

Author

Beth, A., Altwegg, K., Balsiger, H., Berthelier, J. -J, Calmonte, U., Combi, M. R., De Keyser, J., Dhooghe, F., Fiethe, B., Fuselier, S. A., Galand, M., Gasc, S., Gombosi, T. I., Hansen, K. C., Hassig, M., Heritier, K. L., Kopp, E., Le Roy, L., Mandt, K. E., Peroy, S., Rubin, M., Semon, T., Tzou, C. -Y, Vigren, Erik, Beth, A., Altwegg, K., Balsiger, H., Berthelier, J. -J, Calmonte, U., Combi, M. R., De Keyser, J., Dhooghe, F., Fiethe, B., Fuselier, S. A., Galand, M., Gasc, S., Gombosi, T. I., Hansen, K. C., Hassig, M., Heritier, K. L., Kopp, E., Le Roy, L., Mandt, K. E., Peroy, S., Rubin, M., Semon, T., Tzou, C. -Y, and Vigren, Erik

Abstract

In this paper, we report the first in situ detection of the ammonium ion NH4+ at 67P/Churyumov-Gerasimenko (67P/C-G) in a cometary coma, using the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA)/Double Focusing Mass Spectrometer (DFMS). Unlike neutral and ion spectrometers onboard previous cometary missions, the ROSINA/DFMS spectrometer, when operated in ion mode, offers the capability to distinguish NH4+ from H2O+ in a cometary coma. We present here the ion data analysis of mass-to-charge ratios 18 and 19 at high spectral resolution and compare the results with an ionospheric model to put these results into context. The model confirms that the ammonium ion NH4+ is one of the most abundant ion species, as predicted, in the coma near perihelion.

Published
2016
Full Text
View/download PDF

33. Statistical analysis of suprathermal electron drivers at 67P/Churyumov–Gerasimenko

Author

Broiles, Thomas W., primary, Burch, J. L., additional, Chae, K., additional, Clark, G., additional, Cravens, T. E., additional, Eriksson, A., additional, Fuselier, S. A., additional, Frahm, R. A., additional, Gasc, S., additional, Goldstein, R., additional, Henri, P., additional, Koenders, C., additional, Livadiotis, G., additional, Mandt, K. E., additional, Mokashi, P., additional, Nemeth, Z., additional, Odelstad, E., additional, Rubin, M., additional, and Samara, M., additional

Published
2016
Full Text
View/download PDF

34. Sulphur-bearing species in the coma of comet 67P/Churyumov–Gerasimenko

Author

Calmonte, U., primary, Altwegg, K., additional, Balsiger, H., additional, Berthelier, J. J., additional, Bieler, A., additional, Cessateur, G., additional, Dhooghe, F., additional, van Dishoeck, E. F., additional, Fiethe, B., additional, Fuselier, S. A., additional, Gasc, S., additional, Gombosi, T. I., additional, Hässig, M., additional, Le Roy, L., additional, Rubin, M., additional, Sémon, T., additional, Tzou, C.-Y., additional, and Wampfler, S. F., additional

Published
2016
Full Text
View/download PDF

35. Mass spectrometric characterization of the Rosetta Spacecraft contamination

Author

Bieler, A., additional, Altwegg, K., additional, Balsiger, H., additional, Berthelier, J.-J., additional, Calmonte, U., additional, Combi, M., additional, De Keyser, J., additional, Fiethe, B., additional, Fuselier, S. A., additional, Gasc, S., additional, Gombosi, T., additional, Hansen, K. C., additional, Hässig, M., additional, Korth, A., additional, Le Roy, L., additional, Mall, U., additional, Rème, H., additional, Rubin, M., additional, Sémon, T., additional, Tenishev, V., additional, Tzou, C.-Y., additional, Waite, J. H., additional, and Wurz, P., additional

Published
2016
Full Text
View/download PDF

36. Ion chemistry in the coma of comet 67P near perihelion

Author

Fuselier, S. A., primary, Altwegg, K., additional, Balsiger, H., additional, Berthelier, J. J., additional, Beth, A., additional, Bieler, A., additional, Briois, C., additional, Broiles, T. W., additional, Burch, J. L., additional, Calmonte, U., additional, Cessateur, G., additional, Combi, M., additional, De Keyser, J., additional, Fiethe, B., additional, Galand, M., additional, Gasc, S., additional, Gombosi, T. I., additional, Gunell, H., additional, Hansen, K. C., additional, Hässig, M., additional, Heritier, K. L., additional, Korth, A., additional, Le Roy, L., additional, Luspay-Kuti, A., additional, Mall, U., additional, Mandt, K. E., additional, Petrinec, S. M., additional, Rème, H., additional, Rinaldi, M., additional, Rubin, M., additional, Sémon, T., additional, Trattner, K. J., additional, Tzou, C.-Y., additional, Vigren, E., additional, Waite, J. H., additional, and Wurz, P., additional

Published
2016
Full Text
View/download PDF

38. HIGH-TIME RESOLUTION IN SITU INVESTIGATION OF MAJOR COMETARY VOLATILES AROUND 67P/C–G AT 3.1–2.3 au MEASURED WITH ROSINA-RTOF

Author

Mall, U., primary, Altwegg, K., additional, Balsiger, H., additional, Bar-Nun, A., additional, Berthelier, J.-J., additional, Bieler, A., additional, Bochsler, P., additional, Briois, C., additional, Calmonte, U., additional, Combi, M. R., additional, Dabrowski, B., additional, Keyser, J. De, additional, Dhooghe, F., additional, Fiethe, B., additional, Fuselier, S. A., additional, Galli, A., additional, Garnier, P., additional, Gasc, S., additional, Gombosi, T. I., additional, Hansen, K. C., additional, Hässig, M., additional, Hoang, M., additional, Jäckel, A., additional, Kopp, E., additional, Korth, A., additional, Roy, L. Le, additional, Magee, B., additional, Marty, B., additional, Mousis, O., additional, Rème, H., additional, Rubin, M., additional, Sémon, T., additional, Tzou, C.-Y., additional, Waite, J. H., additional, and Wurz, P., additional

Published
2016
Full Text
View/download PDF

39. Spatial distribution of low-energy plasma around comet 67P/CG from Rosetta measurements

Author

Edberg, Niklas J. T., Eriksson, Anders I., Odelstad, Elias, Henri, P., Lebreton, J. -P, Gasc, S., Rubin, M., André, Mats, Gill, Reine, Johansson, Erik P. G., Johansson, Fredrik, Vigren, Erik, Wahlund, Jan-Erik, Carr, C. M., Cupido, E., Glassmeier, K. -H, Goldstein, R., Koenders, C., Mandt, K., Nemeth, Z., Nilsson, H., Richter, I., Wieser, G. Stenberg, Szego, K., Volwerk, M., Edberg, Niklas J. T., Eriksson, Anders I., Odelstad, Elias, Henri, P., Lebreton, J. -P, Gasc, S., Rubin, M., André, Mats, Gill, Reine, Johansson, Erik P. G., Johansson, Fredrik, Vigren, Erik, Wahlund, Jan-Erik, Carr, C. M., Cupido, E., Glassmeier, K. -H, Goldstein, R., Koenders, C., Mandt, K., Nemeth, Z., Nilsson, H., Richter, I., Wieser, G. Stenberg, Szego, K., and Volwerk, M.

Abstract

We use measurements from the Rosetta plasma consortium Langmuir probe and mutual impedance probe to study the spatial distribution of low-energy plasma in the near-nucleus coma of comet 67P/Churyumov-Gerasimenko. The spatial distribution is highly structured with the highest density in the summer hemisphere and above the region connecting the two main lobes of the comet, i.e., the neck region. There is a clear correlation with the neutral density and the plasma to neutral density ratio is found to be approximate to 1-210(-6), at a cometocentric distance of 10km and at 3.1AU from the Sun. A clear 6.2h modulation of the plasma is seen as the neck is exposed twice per rotation. The electron density of the collisionless plasma within 260km from the nucleus falls off with radial distance as approximate to 1/r. The spatial structure indicates that local ionization of neutral gas is the dominant source of low-energy plasma around the comet., QC 20200818

Published
2015
Full Text
View/download PDF

40. ROSINA/DFMS and IES observations of 67P : Ion-neutral chemistry in the coma of a weakly outgassing comet

Author

Fuselier, S. A., Altwegg, K., Balsiger, H., Berthelier, J. J., Bieler, A., Briois, C., Broiles, T. W., Burch, J. L., Calmonte, U., Cessateur, G., Combi, M., De Keyser, J., Fiethe, B., Galand, M., Gasc, S., Gombosi, T. I., Gune, H., Hansen, K. C., Haessig, M., Jaeckel, A., Korth, A., Le Roy, L., Mall, U., Mandt, K. E., Petrinec, S. M., Raghuram, S., Reme, H., Rinaldi, M., Rubin, M., Semon, T., Trattner, K. J., Tzou, C. -Y, Vigren, Erik, Waite, J. H., Wurz, P., Fuselier, S. A., Altwegg, K., Balsiger, H., Berthelier, J. J., Bieler, A., Briois, C., Broiles, T. W., Burch, J. L., Calmonte, U., Cessateur, G., Combi, M., De Keyser, J., Fiethe, B., Galand, M., Gasc, S., Gombosi, T. I., Gune, H., Hansen, K. C., Haessig, M., Jaeckel, A., Korth, A., Le Roy, L., Mall, U., Mandt, K. E., Petrinec, S. M., Raghuram, S., Reme, H., Rinaldi, M., Rubin, M., Semon, T., Trattner, K. J., Tzou, C. -Y, Vigren, Erik, Waite, J. H., and Wurz, P.

Abstract

Context. The Rosetta encounter with comet 67P/Churyumov-Gerasimenko provides a unique opportunity for an in situ, up-close investigation of ion-neutral chemistry in the coma of a weakly outgassing comet far from the Sun. Aims. Observations of primary and secondary ions and modeling are used to investigate the role of ion-neutral chemistry within the thin coma. Methods. Observations from late October through mid-December 2014 show the continuous presence of the solar wind 30 km from the comet nucleus. These and other observations indicate that there is no contact surface and the solar wind has direct access to the nucleus. On several occasions during this time period, the Rosetta/ROSINA/Double Focusing Mass Spectrometer measured the low-energy ion composition in the coma. Organic volatiles and water group ions and their breakup products (masses 14 through 19), COP, and CO, (masses 28 and 44) and other mass peaks (at masses 26, 27, and possibly 30) were observed. Secondary ions include H3O+ and HCO+ (masses 19 and 29). These secondary ions indicate ion-neutral chemistry in the thin coma of the comet. A relatively simple model is constructed to account for the low H3O /H2O+ and HCO /CO+ ratios observed in a water dominated coma. Results from this simple model are compared with results from models that include a more detailed chemical reaction network. Results. At low outgassing rates, predictions from the simple model agree with observations and with results from more complex models that include much more chemistry. At higher outgassing rates, the ion-neutral chemistry is still limited and high HCO /CO+ ratios are predicted and observed. However, at higher outgassing rates, the model predicts high H3O /H2O+ ratios and the observed ratios are often low. These low ratios may be the result of the highly heterogeneous nature of the coma, where CO and CO2 number densities can exceed that of water.

Published
2015
Full Text
View/download PDF

41. Prebiotic chemicals--amino acid and phosphorus--in the coma of comet 67P/Churyumov-Gerasimenko

Author

Altwegg K., Balsiger H., Bar-Nun A., Berthelier J.-J., Bieler A., Bochsler P., Briois C., Calmonte U., Combi M. R., Cottin H., De Keyser J., Dhooghe F., Fiethe B., Fuselier S. A., Gasc S., Gombosi T. I., Hansen K. C., Haessig M., Ja ckel A., Kopp E., Korth A., Le Roy L., Mall U., and Marty B.

Abstract

The importance of comets for the origin of life on Earth has been advocated for many decades. Amino acids are key ingredients in chemistry leading to life as we know it. Many primitive meteorites contain amino acids and it is generally believed that these are formed by aqueous alterations. In the collector aerogel and foil samples of the Stardust mission after the flyby at comet Wild 2 the simplest form of amino acids glycine has been found together with precursor molecules methylamine and ethylamine. Because of contamination issues of the samples a cometary origin was deduced from the C 13 isotopic signature. We report the presence of volatile glycine accompanied by methylamine and ethylamine in the coma of 67P/Churyumov Gerasimenko measured by the ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) mass spectrometer confirming the Stardust results. Together with the detection of phosphorus and a multitude of organic molecules this result demonstrates that comets could have played a crucial role in the emergence of life on Earth.

Published
2016
Full Text
View/download PDF

42. ROSINA/DFMS and IES observations of 67P: Ion-neutral chemistry in the coma of a weakly outgassing comet

Author

Fuselier, S. A., primary, Altwegg, K., additional, Balsiger, H., additional, Berthelier, J. J., additional, Bieler, A., additional, Briois, C., additional, Broiles, T. W., additional, Burch, J. L., additional, Calmonte, U., additional, Cessateur, G., additional, Combi, M., additional, De Keyser, J., additional, Fiethe, B., additional, Galand, M., additional, Gasc, S., additional, Gombosi, T. I., additional, Gunell, H., additional, Hansen, K. C., additional, Hässig, M., additional, Jäckel, A., additional, Korth, A., additional, Le Roy, L., additional, Mall, U., additional, Mandt, K. E., additional, Petrinec, S. M., additional, Raghuram, S., additional, Rème, H., additional, Rinaldi, M., additional, Rubin, M., additional, Sémon, T., additional, Trattner, K. J., additional, Tzou, C.-Y., additional, Vigren, E., additional, Waite, J. H., additional, and Wurz, P., additional

Published
2015
Full Text
View/download PDF

43. Composition-dependent outgassing of comet 67P/Churyumov-Gerasimenko from ROSINA/DFMS

Author

Luspay-Kuti, A., primary, Hässig, M., additional, Fuselier, S. A., additional, Mandt, K. E., additional, Altwegg, K., additional, Balsiger, H., additional, Gasc, S., additional, Jäckel, A., additional, Le Roy, L., additional, Rubin, M., additional, Tzou, C.-Y., additional, Wurz, P., additional, Mousis, O., additional, Dhooghe, F., additional, Berthelier, J. J., additional, Fiethe, B., additional, Gombosi, T. I., additional, and Mall, U., additional

Published
2015
Full Text
View/download PDF

44. Spatial distribution of low‐energy plasma around comet 67P/CG from Rosetta measurements

Author

Edberg, N. J. T., primary, Eriksson, A. I., additional, Odelstad, E., additional, Henri, P., additional, Lebreton, J.‐P., additional, Gasc, S., additional, Rubin, M., additional, André, M., additional, Gill, R., additional, Johansson, E. P. G., additional, Johansson, F., additional, Vigren, E., additional, Wahlund, J. E., additional, Carr, C. M., additional, Cupido, E., additional, Glassmeier, K.‐H., additional, Goldstein, R., additional, Koenders, C., additional, Mandt, K., additional, Nemeth, Z., additional, Nilsson, H., additional, Richter, I., additional, Wieser, G. Stenberg, additional, Szego, K., additional, and Volwerk, M., additional

Published
2015
Full Text
View/download PDF

45. Physical Characterization of Asteroids Candidates of Marco Polo Mission

Author

Birlan, Mirel, Binzel, Richard P., Nedelcu, Dan Alin, Vernazza, Pierre, Barucci, Maria Antonella, Gasc, S., Fulchignoni, Marcello, Dotto, Elisabetta, Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Department of Earth Atmospheric and Planetary Sciences, MIT, AIRA, Romania, ESTEC / ESA, Netherlands, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Planétologie du LESIA, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Université Paris Cité (UPCité), and INAF/OAR, Italy

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

International audience; The principal scientific objective of the Marco Polo mission is to return unaltered NEO materials. Marco Polo will allow us to analyze the samples in terrestrial laboratories, thereby obtaining measurements that cannot yet beperformed from a robotic spacecraft. The selection of the target asteroids for the mission has important consequences in terms of mission design, constraints, and operational requirements. A list of asteroids as possible targets for the Marco Polo mission has been drawn, taken into account both dynamical and physical constraints. The key parameters of this list were the accessibility of the object (the delta-V amount for the encounter with the target) and the desirable, primitive composition requirements of the target deduced from the groundbased data (mainly from colors and spectroscopy).

Published
2009

46. Les changements institutionnels dans la prise en charge des enfants handicapés en milieu ordinaire : les applications des lois de la réforme de la protection de l’enfance du 5 mars 2007 et du 11 février 2005 pour l’égalité des droits et des chances, la participation et la citoyenneté des personnes handicapées

Author

Atticot, Maurice, Bertrand, M., Besson, M., Blaison, M., Egly, C., Gasc, S., Heitz, JS., Levesque, E., MAURY, N., Milachon, N., Savoure, C., Bréhaux, Karine, brehaux, karine, Centre de recherches politiques de Sciences Po (Sciences Po, CNRS) (CEVIPOF), Sciences Po (Sciences Po)-Centre National de la Recherche Scientifique (CNRS), EHESP, and Centre de recherches politiques de Sciences Po (CEVIPOF)

Subjects
[SHS] Humanities and Social Sciences, [SHS]Humanities and Social Sciences
Published
2008

47. Cometary science. Time variability and heterogeneity in the coma of 67P/Churyumov-Gerasimenko

Author

Hässig M, Altwegg K, Balsiger H, Bar-Nun A, Berthelier J J, Bieler A, Bochsler P, Briois C, Calmonte U, Combi M, De Keyser J, Eberhardt P, Fiethe B, Fuselier S A, Galand M, Gasc S, Gombosi T I, Hansen K C, Jäckel A, Keller H U, Kopp E, Korth A, Kührt E, Le Roy L, and Mall U

Subjects
food and beverages, sense organs
Abstract

Comets contain the best preserved material from the beginning of our planetary system. Their nuclei and comae composition reveal clues about physical and chemical conditions during the early solar system when comets formed. ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) onboard the Rosetta spacecraft has measured the coma composition of comet 67P/Churyumov Gerasimenko with well sampled time resolution per rotation. Measurements were made over many comet rotation periods and a wide range of latitudes. These measurements show large fluctuations in composition in a heterogeneous coma that has diurnal and possibly seasonal variations in the major outgassing species: water carbon monoxide and carbon dioxide. These results indicate a complex coma nucleus relationship where seasonal variations may be driven by temperature differences just below the comet surface.

Published
2015
Full Text
View/download PDF

48. Isotopic composition of CO2 in the coma of 67P/Churyumov-Gerasimenko measured with ROSINA/DFMS.

Author

Hässig, M., Altwegg, K., Balsiger, H., Berthelier, J. J., Bieler, A., Calmonte, U., Dhooghe, F., Fiethe, B., Fuselier, S. A., Gasc, S., Gombosi, T. I., Le Roy, L., Luspay-Kuti, A., Mandt, K., Rubin, M., Tzou, C.-Y., Wampfler, S. F., and Wurz, P.

Subjects
COMET formation, ISOTOPIC fractionation, SOLAR evolution, SOLAR system, PROTOPLANETARY disks, ISOTOPOLOGUES
Abstract

Context. Measurements of isotopic abundances in cometary ices are key to understanding and reconstructing the history and origin of material in the solar system. Comets are considered the most pristine material in the solar system. Isotopic fractionation (enrichment of an isotope in a molecule compared to the initial abundance) is sensitive to environmental conditions at the time of comet formation. Therefore, measurements of cometary isotope ratios can provide information on the composition, density, temperature, and radiation during formation of the molecules, during the chemical evolution from the presolar cloud to the protosolar nebula, and the protoplanetary disk before accretion in solid bodies. Most isotopic abundances of 12C/13C and 16O/18O in comets to date are in agreement with terrestrial abundances. Prior to the Rosetta mission, measurements of 12C/13C in comets were only available for HCN, CN, and C2 and for 16O/18O in H2O. Measurements of 12C/13C in comets were only available from ground based observations and remote sensing, while 16O/18O in H2O had also been measured in-situ. To date, no measurements of the CO2 isotopologues in comets were available. Aims. This paper presents the first measurements of the CO2 isotopologues in the coma of 67P/Churyumov-Gerasimenko (67P). Methods. We analyzed measurements taken by the Double Focusing Mass Spectrometer (DFMS) of the ROSINA experiment on board the ESA spacecraft Rosetta in the coma of 67P. Results. The CO2 isotopologues results for 67P are: 12C/13C = 84 ± 4, 16O/18O = 494 ± 8, and 13C16O2/16C18O16O = 5.87 ± 0.07. The oxygen isotopic ratio is within error bars compatible with terrestrial abundances but not with solar wind measurements. Conclusions. The carbon isotopic ratio and the combined carbon and oxygen isotopic ratio are slightly (14%) enriched in 13C, within 1σ uncertainty, compared to solar wind abundances and solar abundances. The small fractionation of 12C/13C in CO2 is probably compatible with an origin of the material in comets from the native cloud. [ABSTRACT FROM AUTHOR]

Published
2017
Full Text
View/download PDF

49. The heterogeneous coma of comet 67P/Churyumov-Gerasimenko as seen by ROSINA: H2O, CO2, and CO from September 2014 to February 2016.

Author

Hoang, M., Altwegg, K., Balsiger, H., Beth, A., Bieler, A., Calmonte, U., Combi, M. R., De Keyser, J., Fiethe, B., Fougere, N., Fuselier, S. A., Galli, A., Garnier, P., Gasc, S., Gombosi, T., Hansen, K. C., Jäckel, A., Korth, A., Lasue, J., and Le Roy, L.

Subjects
CHURYUMOV-Gerasimenko comet, CARBON dioxide, PRESSURE sensors, COMETS spectra, MONTE Carlo method
Abstract

Context. The ESA Rosetta mission has been investigating the environment of comet 67P/Churyumov-Gerasimenko (67P) since August 2014. Among the experiments on board the spacecraft, the ROSINA experiment (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) includes two mass spectrometers to analyse the composition of neutrals and ions and a COmet Pressure Sensor (COPS) to monitor the density and velocity of neutrals in the coma. Aims. We study heterogeneities in the coma during three periods starting in October 2014 (summer in the northern hemisphere) and ending in February 2016 (end of winter in the northern hemisphere).We provide a detailed description of the main volatiles dynamics (H2O, CO2, CO) and their abundance ratios. Methods. We analysed and compared the data of the Reflectron-type Time-Of-Flight (RTOF) mass spectrometer with data from both the Double Focusing Mass Spectrometer (DFMS) and COPS during the comet escort phase. This comparison has demonstrated that the observations performed with each ROSINA sensor are indeed consistent. Furthermore, we used a Direct Simulation Monte Carlo (DSMC) model to compare modelled densitites with in situ detections. Results. Our analysis shows how the active regions of the main volatiles evolve with the seasons with a variability mostly driven by the illumination conditions; this is the case except for an unexpected dichotomy suggesting the presence of a dust layer containing water deposited in the northern hemisphere during previous perihelions hiding the presence of CO2. The influence of various parameters is investigated in detail: distance to the comet, heliocentric distance, longitude and latitude of sub-satellite point, local time, and phase angle. [ABSTRACT FROM AUTHOR]

Published
2017
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results