ALBERT

Description: Observations of the green and red-doublet emission lines have previously been realized for several comets. We present here a chemistry-emission coupled model to study the production and loss mechanisms of the O( 1 S) and O( 1 D) states, which are responsible for the emission lines of interest, for comet 67P/Churyumov-Gerasimenko. The recent discovery of O 2 in significant abundance relative to water (3.7±1.5 %) within the coma of 67P has been taken into consideration for the first time in such models. We evaluate the effect of the presence of O 2 on the green to red-doublet emission intensity ratio, which is traditionally used to assess the CO 2 abundance within cometary atmospheres. Model simulations, solving the continuity equation with transport, show that not taking O 2 into account leads to an underestimation of the CO 2 abundance within 67P, with a relative error of about 25 %. This strongly suggests that the green to red-doublet emission intensity ratio alone is not a proper tool for determining the CO 2 abundance, as previously suggested. Indeed, there is no compelling reason why O 2 would not be a common cometary volatile, making revision of earlier assessments regarding the CO 2 abundance in cometary atmospheres necessary. The large uncertainties of the CO 2 photodissociation cross section imply that more studies are required in order to better constrain the O( 1 S) and O( 1 D) production through this mechanism. Space weather phenomena, such as powerful solar flares, could be used as tools for doing so, providing additional information on a good estimation of the O 2 abundance within cometary atmospheres.

Description: Comets are composed of dust and frozen gases. The ices are mixed with the refractory material either as an icy conglomerate, or as an aggregate of pre-solar grains (grains that existed prior to the formation of the Solar System), mantled by an ice layer. The presence of water-ice grains in periodic comets is now well established. Modelling of infrared spectra obtained about ten kilometres from the nucleus of comet Hartley 2 suggests that larger dust particles are being physically decoupled from fine-grained water-ice particles that may be aggregates, which supports the icy-conglomerate model. It is known that comets build up crusts of dust that are subsequently shed as they approach perihelion. Micrometre-sized interplanetary dust particles collected in the Earth's stratosphere and certain micrometeorites are assumed to be of cometary origin. Here we report that grains collected from the Jupiter-family comet 67P/Churyumov-Gerasimenko come from a dusty crust that quenches the material outflow activity at the comet surface. The larger grains (exceeding 50 micrometres across) are fluffy (with porosity over 50 per cent), and many shattered when collected on the target plate, suggesting that they are agglomerates of entities in the size range of interplanetary dust particles. Their surfaces are generally rich in sodium, which explains the high sodium abundance in cometary meteoroids. The particles collected to date therefore probably represent parent material of interplanetary dust particles. This argues against comet dust being composed of a silicate core mantled by organic refractory material and then by a mixture of water-dominated ices. At its previous recurrence (orbital period 6.5 years), the comet's dust production doubled when it was between 2.7 and 2.5 astronomical units from the Sun, indicating that this was when the nucleus shed its mantle. Once the mantle is shed, unprocessed material starts to supply the developing coma, radically changing its dust component, which then also contains icy grains, as detected during encounters with other comets closer to the Sun.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Schulz, Rita -- Hilchenbach, Martin -- Langevin, Yves -- Kissel, Jochen -- Silen, Johan -- Briois, Christelle -- Engrand, Cecile -- Hornung, Klaus -- Baklouti, Donia -- Bardyn, Anais -- Cottin, Herve -- Fischer, Henning -- Fray, Nicolas -- Godard, Marie -- Lehto, Harry -- Le Roy, Lena -- Merouane, Sihane -- Orthous-Daunay, Francois-Regis -- Paquette, John -- Ryno, Jouni -- Siljestrom, Sandra -- Stenzel, Oliver -- Thirkell, Laurent -- Varmuza, Kurt -- Zaprudin, Boris -- England -- Nature. 2015 Feb 12;518(7538):216-8. doi: 10.1038/nature14159. Epub 2015 Jan 26.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉European Space Agency, Scientific Support Office, Keplerlaan 1, Postbus 299, 2200 AG Noordwijk, The Netherlands. ; Max-Planck-Institut fur Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Gottingen, Germany. ; Institut d'Astrophysique Spatiale, CNRS/Universite Paris Sud, Batiment 121, 91405 Orsay, France. ; Finnish Meteorological Institute, Observation services, Erik Palmenin aukio 1, FI-00560 Helsinki, Finland. ; Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), CNRS/Universite d'Orleans, 45071 Orleans, France. ; Centre de Sciences Nucleaires et de Sciences de la Matiere, CNRS/IN2P3-Universite Paris Sud-UMR8609, Batiment 104, 91405 Orsay campus, France. ; Universitat der Bundeswehr, LRT-7, Werner Heisenberg Weg 39, 85577 Neubiberg, Germany. ; 1] Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), CNRS/Universite d'Orleans, 45071 Orleans, France [2] Laboratoire Interuniversitaire des Systemes Atmospheriques (LISA), UMR CNRS 7583, Universite Paris Est Creteil et Universite Paris Diderot, Institut Pierre Simon Laplace, 94000 Creteil, France. ; Laboratoire Interuniversitaire des Systemes Atmospheriques (LISA), UMR CNRS 7583, Universite Paris Est Creteil et Universite Paris Diderot, Institut Pierre Simon Laplace, 94000 Creteil, France. ; University of Turku, Department of Physics and Astronomy, Tuorla Observatory Vaisalantie 20, 21500 Piikkio, Finland. ; Center for Space and Habitability (CSH), University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland. ; Universite Grenoble Alpes/CNRS, Institut de Planetologie et d'Astrophysique de Grenoble, 414 Rue de la Piscine, Domaine Universitaire, 38000 Grenoble, France. ; Department of Chemistry, Materials and Surfaces, SP Technical Research Institute of Sweden, Box 857, 50115 Boras, Sweden. ; Institut fur Statistik und Wahrscheinlichkeitstheorie, Technische Universitat Wien, Wiedner Hauptstrasse 7, 1040 Wien, Austria.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25624103" target="_blank"〉PubMed〈/a〉

Description: Molecular nitrogen (N2) is thought to have been the most abundant form of nitrogen in the protosolar nebula. It is the main N-bearing molecule in the atmospheres of Pluto and Triton and probably the main nitrogen reservoir from which the giant planets formed. Yet in comets, often considered the most primitive bodies in the solar system, N2 has not been detected. Here we report the direct in situ measurement of N2 in the Jupiter family comet 67P/Churyumov-Gerasimenko, made by the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis mass spectrometer aboard the Rosetta spacecraft. A N2/CO ratio of (5.70 +/- 0.66) x 10(-3) (2sigma standard deviation of the sampled mean) corresponds to depletion by a factor of ~25.4 +/- 8.9 as compared to the protosolar value. This depletion suggests that cometary grains formed at low-temperature conditions below ~30 kelvin.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉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 -- Hassig, M -- Jackel, A -- Kopp, E -- Korth, A -- Le Roy, L -- Mall, U -- Marty, B -- Mousis, O -- Owen, T -- Reme, H -- Semon, T -- Tzou, C-Y -- Waite, J H -- Wurz, P -- New York, N.Y. -- Science. 2015 Apr 10;348(6231):232-5. doi: 10.1126/science.aaa6100. Epub 2015 Mar 19.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland. martin.rubin@space.unibe.ch. ; Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland. Center for Space and Habitability, University of Bern, Sidlerstrasse. 5, CH-3012 Bern, Switzerland. ; Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland. ; Department of Geoscience, Tel-Aviv University, Ramat-Aviv, Tel-Aviv, Israel. ; Laboratoire Atmospheres, Milieux, Observations Spatiales (LATMOS)/Institute Pierre Simon Laplace-CNRS-UPMC-UVSQ, 4 Avenue de Neptune F-94100, Saint-Maur, France. ; Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland. Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, 2455 Hayward, Ann Arbor, MI 48109, USA. ; Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), UMR 6115 CNRS-Universite d'Orleans, Orleans, France. ; Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, 2455 Hayward, Ann Arbor, MI 48109, USA. ; Belgian Institute for Space Aeronomy, Belgisch Instituut voor Ruimte-Aeronomie-Institut d'Aeronomie Spatiale de Belgique (BIRA-IASB), Ringlaan 3, B-1180 Brussels, Belgium. ; Institute of Computer and Network Engineering, Technische Universitat Braunschweig, Hans-Sommer-Strasse 66, D-38106 Braunschweig, Germany. ; Department of Space Science, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78228, USA. ; Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland. Department of Space Science, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78228, USA. ; Max-Planck-Institut fur Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Gottingen, Germany. ; Center for Space and Habitability, University of Bern, Sidlerstrasse. 5, CH-3012 Bern, Switzerland. ; Centre de Recherches Petrographiques et Geochimiques (CRPG)-CNRS, Universite de Lorraine, 15 rue Notre Dame des Pauvres, Boite Postale 20, 54501 Vandoeuvre les Nancy, France. ; Aix Marseille Universite, CNRS, Laboratoire d'Astrophysique de Marseille UMR 7326, 13388, Marseille, France. ; Institute for Astronomy, University of Hawaii, Honolulu, HI 96822, USA. ; Universite de Toulouse; UPS-OMP; Institut de Recherche en Astrophysique et Planetologie (IRAP), Toulouse, France. CNRS; IRAP; 9 Avenue du Colonel Roche, Boite Postale 44346, F-31028 Toulouse Cedex 4, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25791084" target="_blank"〉PubMed〈/a〉

Description: 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.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hassig, 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 -- Jackel, A -- Keller, H U -- Kopp, E -- Korth, A -- Kuhrt, E -- Le Roy, L -- Mall, U -- Marty, B -- Mousis, O -- Neefs, E -- Owen, T -- Reme, H -- Rubin, M -- Semon, T -- Tornow, C -- Tzou, C-Y -- Waite, J H -- Wurz, P -- New York, N.Y. -- Science. 2015 Jan 23;347(6220):aaa0276. doi: 10.1126/science.aaa0276. Epub 2015 Jan 22.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland. Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238, USA. myrtha.haessig@swri.org. ; Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland. Center for Space and Habitability (CSH), University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland. ; Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland. ; Department of Geosciences, Tel-Aviv University, Ramat-Aviv, Tel-Aviv, Israel. ; Laboratoire Atmospheres, Milieux, Observations Spatiales (LATMOS), Institute Pierre Simon Laplace (IPSL), Centre national de recherche scientifique (CNRS), Universite Pierre et Marie Curie (UPMC), Universite de Versailles Saint-Quentin-en-Yvelines (UVSQ), BP 102, UPMC, 4 Place Jussieu, F-75252 Paris Cedex 05, France. ; Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland. Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, 2455 Hayward Street, Ann Arbor, MI 48109, USA. ; Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), UMR 7328 CNRS - Universite d'Orleans, France. ; Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, 2455 Hayward Street, Ann Arbor, MI 48109, USA. ; Belgian Institute for Space Aeronomy (BIRA-IASB), Ringlaan 3, B-1180 Brussels, Belgium. Center for Plasma Astrophysics, KULeuven, Celestijnenlaan 200D, 3001 Heverlee, Belgium. ; Institute of Computer and Network Engineering (IDA), TU Braunschweig, Hans-Sommer-Strasse 66, D-38106 Braunschweig, Germany. ; Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238, USA. ; Department of Physics, Imperial College London, Prince Consort Road, London SW7 2AZ, UK. ; Institute for Geophysics and Extraterrestrial Physics, Technische Universitat (TU) Braunschweig, 38106 Braunschweig, Germany. German Aerospace Center, Institute of Planetary Research, Asteroids and Comets, Rutherfordstrasse 2, 12489 Berlin, Germany. ; Max-Planck-Institut fur Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Gottingen, Germany. ; German Aerospace Center, Institute of Planetary Research, Asteroids and Comets, Rutherfordstrasse 2, 12489 Berlin, Germany. ; Center for Space and Habitability (CSH), University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland. ; Centre de Recherches Petrographiques et Geochimiques (CRPG), 15 Rue Notre Dame des Pauvres, BP 20, 54501 Vandoeuvre les Nancy, France. ; Aix Marseille Universite, CNRS, LAM (Laboratoire d'Astrophysique de Marseille), UMR 7326, 13388, Marseille, France. ; Engineering Division, BIRA-IASB, Ringlaan 3, B-1180 Brussels, Belgium. ; Institute for Astronomy, University of Hawaii, Honolulu, HI 96822, USA. ; Universite de Toulouse, Universite Paul Sabathier (UPS), Observatoire de Midi-Pyrenees (OMP), Institut de Recherche en Astrophysique et Planetologie (IRAP), Toulouse, France. CNRS, IRAP, 9 Avenue du Colonel Roche, BP 44346, F-31028 Toulouse Cedex 4, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25613892" target="_blank"〉PubMed〈/a〉

Description: The provenance of water and organic compounds on Earth and other terrestrial planets has been discussed for a long time without reaching a consensus. One of the best means to distinguish between different scenarios is by determining the deuterium-to-hydrogen (D/H) ratios in the reservoirs for comets and Earth's oceans. Here, we report the direct in situ measurement of the D/H ratio in the Jupiter family comet 67P/Churyumov-Gerasimenko by the ROSINA mass spectrometer aboard the European Space Agency's Rosetta spacecraft, which is found to be (5.3 +/- 0.7) x 10(-4)-that is, approximately three times the terrestrial value. Previous cometary measurements and our new finding suggest a wide range of D/H ratios in the water within Jupiter family objects and preclude the idea that this reservoir is solely composed of Earth ocean-like water.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉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 -- Hassig, M -- Jackel, A -- Kopp, E -- Korth, A -- LeRoy, L -- Mall, U -- Marty, B -- Mousis, O -- Neefs, E -- Owen, T -- Reme, H -- Rubin, M -- Semon, T -- Tzou, C-Y -- Waite, H -- Wurz, P -- New York, N.Y. -- Science. 2015 Jan 23;347(6220):1261952. doi: 10.1126/science.1261952. Epub 2014 Dec 10.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland. altwegg@space.unibe.ch. ; Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland. ; Department of Geosciences, Tel-Aviv University, Ramat-Aviv, Tel-Aviv, Israel. ; Laboratoire Atmospheres, Milieux, Observations Spatiales (LATMOS), 4 Avenue de Neptune, F-94100 Saint-Maur, France. ; Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland. Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, 2455 Hayward, Ann Arbor, MI 48109, USA. ; Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), UMR 6115 CNRS-Universite d'Orleans, France. ; Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, 2455 Hayward, Ann Arbor, MI 48109, USA. ; Space Physics Division, Belgisch Instituut voor Ruimte-Aeronomie (BIRA)-Institut d'Aeronomie Spatiale de Belgique (IASB), Ringlaan 3, B-1180 Brussels, Belgium. ; Institute of Computer and Network Engineering (IDA), Technicsche Universitat Braunschweig, Hans-Sommer-Strasse 66, D-38106 Braunschweig, Germany. ; Department of Space Science, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78228, USA. ; Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland. Department of Space Science, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78228, USA. ; Max-Planck-Institut fur Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Gottingen, Germany. ; Centre de Recherches Petrographiques et Geochimiques, Centre de Recherches Petrographiques et Geochimiques (CRPG)-CNRS, Universite de Lorraine, 15 rue Notre Dame des Pauvres, BP 20, 54501 Vandoeuvre les Nancy, France. ; Universite de Franche-Comte, Institut Univers, Transport, Interfaces, Nanostructures, Atmosphere et Environnement, Molecules (UTINAM), CNRS/Institut National des Sciences de l'Univers (INSU), UMR 6213 Besancon Cedex, France. ; Institute for Astronomy, University of Hawaii, Honolulu, HI 96822, USA. ; Universite de Toulouse, Universite Paul Sabatier (UPS)-Observatoire Midi-Pyrenees (OMP), Institut de Recherche en Astrophysique et Planetologie (IRAP), Toulouse, France. CNRS, IRAP, 9 Avenue du Colonel Roche, BP 44346, F-31028 Toulouse cedex 4, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25501976" target="_blank"〉PubMed〈/a〉

Description: The composition of the neutral gas comas of most comets is dominated by H2O, CO and CO2, typically comprising as much as 95 per cent of the total gas density. In addition, cometary comas have been found to contain a rich array of other molecules, including sulfuric compounds and complex hydrocarbons. Molecular oxygen (O2), however, despite its detection on other icy bodies such as the moons of Jupiter and Saturn, has remained undetected in cometary comas. Here we report in situ measurement of O2 in the coma of comet 67P/Churyumov-Gerasimenko, with local abundances ranging from one per cent to ten per cent relative to H2O and with a mean value of 3.80 +/- 0.85 per cent. Our observations indicate that the O2/H2O ratio is isotropic in the coma and does not change systematically with heliocentric distance. This suggests that primordial O2 was incorporated into the nucleus during the comet's formation, which is unexpected given the low upper limits from remote sensing observations. Current Solar System formation models do not predict conditions that would allow this to occur.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉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 -- Le Roy, L -- Mall, U -- Maggiolo, R -- Marty, B -- Mousis, O -- Owen, T -- Reme, H -- Rubin, M -- Semon, T -- Tzou, C-Y -- Waite, J H -- Walsh, C -- Wurz, P -- England -- Nature. 2015 Oct 29;526(7575):678-81. doi: 10.1038/nature15707.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Climate and Space Science and Engineering, University of Michigan, 2455 Hayward Street, Ann Arbor, Michigan 48109, USA. ; Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland. ; Center for Space and Habitability, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland. ; Department of Geosciences, Tel-Aviv University, Ramat-Aviv, 6997801 Tel-Aviv, Israel. ; LATMOS/IPSL-CNRS-UPMC-UVSQ, 4 Avenue de Neptune, F-94100 Saint-Maur, France. ; Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), UMR 6115 CNRS - Universite d'Orleans, 45071 Orleans, France. ; Belgian Institute for Space Aeronomy, BIRA-IASB, Ringlaan 3, B-1180 Brussels, Belgium. ; Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands. ; Institute of Computer and Network Engineering (IDA), TU Braunschweig, Hans-Sommer-Strasse 66, D-38106 Braunschweig, Germany. ; Space Science and Engineering Division, Southwest Research Institute, 6220 Culebra Road, San Antonio, Texas 78228, USA. ; Max-Planck-Institut fur Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Gottingen, Germany. ; Centre de Recherches Petrographiques et Geochimiques, CRPG-CNRS, Universite de Lorraine, 15 rue Notre Dame des Pauvres, BP 20, 54501 Vandoeuvre les Nancy, France. ; Aix Marseille Universite, CNRS, LAM (Laboratoire d'Astrophysique de Marseille) UMR 7326, 13388 Marseille, France. ; Institute for Astronomy, University of Hawaii, Honolulu, Hawaii 96822, USA. ; Universite de Toulouse-UPS-OMP-IRAP, 31400 Toulouse, France. ; CNRS-IRAP, 9 avenue du Colonel Roche, BP 44346, F-31028 Toulouse Cedex 4, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26511578" target="_blank"〉PubMed〈/a〉

Description: 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 13 C 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.

Description: Comets have been considered to be representative of icy planetesimals that may have contributed a significant fraction of the volatile inventory of the terrestrial planets. For example, comets must have brought some water to Earth. However, the magnitude of their contribution is still debated. We report the detection of argon and its relation to the water abundance in the Jupiter family comet 67P/Churyumov-Gerasimenko by in situ measurement of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) mass spectrometer aboard the Rosetta spacecraft. Despite the very low intensity of the signal, argon is clearly identified by the exact determination of the mass of the isotope 36 Ar and by the 36 Ar/ 38 Ar ratio. Because of time variability and spatial heterogeneity of the coma, only a range of the relative abundance of argon to water can be given. Nevertheless, this range confirms that comets of the type 67P/Churyumov-Gerasimenko cannot be the major source of Earth’s major volatiles.

Description: The Rosetta Orbiter Spectrometer for Ion and Neutral Analysis mass spectrometer Double Focusing Mass Spectrometer on board the European Space Agency’s Rosetta spacecraft detected the major isotopes of the noble gases argon, krypton, and xenon in the coma of comet 67P/Churyumov-Gerasimenko. Earlier, it was found that xenon exhibits an isotopic composition distinct from anywhere else in the solar system. However, argon isotopes, within error, were shown to be consistent with solar isotope abundances. This discrepancy suggested an additional exotic component of xenon in comet 67P/Churyumov-Gerasimenko. We show that krypton also exhibits an isotopic composition close to solar. Furthermore, we found the argon to krypton and the krypton to xenon ratios in the comet to be lower than solar, which is a necessity to postulate an addition of exotic xenon in the comet.

Description: 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 H 3 O + /H 2 O + ratio in the outer and inner regions at 67P/ Churyumov–Gerasimenko. The H 3 O + /H 2 O + ratio and the H 3 O + signal are observed to increase in the transition from the outer to the inner region and the H 3 O + 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 H 3 O + /H 2 O + ratio appear to be driven largely by transport properties and only weakly by neutral composition in the coma.