title: Detection of argon in the coma of comet 67P/Churyumov-Gerasimenko.
abstract: 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.
authors.affiliation: Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.
authors.forename: Hans
authors.initials: H
authors.lastname: Balsiger
authors.affiliation: 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.
authors.forename: Kathrin
authors.initials: K
authors.lastname: Altwegg
authors.affiliation: Department of Geoscience, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel.
authors.forename: Akiva
authors.initials: A
authors.lastname: Bar-Nun
authors.affiliation: LATMOS (Laboratoire Atmosphères, Milieux, Observations Spatiales)/IPSL (Institut Pierre Simon Laplace)-CNRS-UPMC (University Pierre et Marie Curie)-UVSQ (Université de Versailles Saint-Quentin-en-Yvelines), 4 Avenue de Neptune, F-94100 Saint-Maur, France.
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Berthelier
authors.affiliation: 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.
authors.forename: Andre
authors.initials: A
authors.lastname: Bieler
authors.affiliation: Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.
authors.forename: Peter
authors.initials: P
authors.lastname: Bochsler
authors.affiliation: Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), UMR 6115 CNRS-Université d'Orléans, 45071 Orléans, France.
authors.forename: Christelle
authors.initials: C
authors.lastname: Briois
authors.affiliation: Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.
authors.forename: Ursina
authors.initials: U
authors.lastname: Calmonte
authors.affiliation: Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, 2455 Hayward, Ann Arbor, MI 48109, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Combi
authors.affiliation: Belgian Institute for Space Aeronomy (BIRA-IASB), Ringlaan 3, B-1180 Brussels, Belgium.
authors.forename: Johan
authors.initials: J
authors.lastname: De Keyser
authors.affiliation: Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.
authors.forename: Peter
authors.initials: P
authors.lastname: Eberhardt
authors.affiliation: Institute of Computer and Network Engineering (IDA), Technische Universität (TU) Braunschweig, Hans-Sommer-Straße 66, D-38106 Braunschweig, Germany.
authors.forename: Björn
authors.initials: B
authors.lastname: Fiethe
authors.affiliation: Department of Space Science, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78228, USA.
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Fuselier
authors.affiliation: Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Gasc
authors.affiliation: Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, 2455 Hayward, Ann Arbor, MI 48109, USA.
authors.forename: Tamas I
authors.initials: TI
authors.lastname: Gombosi
authors.affiliation: Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, 2455 Hayward, Ann Arbor, MI 48109, USA.
authors.forename: Kenneth C
authors.initials: KC
authors.lastname: Hansen
authors.affiliation: 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.
authors.forename: Myrtha
authors.initials: M
authors.lastname: Hässig
authors.affiliation: Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.
authors.forename: Annette
authors.initials: A
authors.lastname: Jäckel
authors.affiliation: Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.
authors.forename: Ernest
authors.initials: E
authors.lastname: Kopp
authors.affiliation: Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany.
authors.forename: Axel
authors.initials: A
authors.lastname: Korth
authors.affiliation: Center for Space and Habitability, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.
authors.forename: Lena
authors.initials: L
authors.lastname: Le Roy
authors.affiliation: Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany.
authors.forename: Urs
authors.initials: U
authors.lastname: Mall
authors.affiliation: CRPG (Centre de Recherches Pétrographiques et Géochimiques)-CNRS, Université de Lorraine, 15 rue Notre Dame des Pauvres, BP 20, 54501 Vandoeuvre lès Nancy, France.
authors.forename: Bernard
authors.initials: B
authors.lastname: Marty
authors.affiliation: Aix Marseille Université, CNRS, LAM (Laboratoire d'Astrophysique de Marseille) UMR 7326, 13388 Marseille, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Mousis
authors.affiliation: Institute for Astronomy, University of Hawaii, Honolulu, HI 96822, USA.
authors.forename: Tobias
authors.initials: T
authors.lastname: Owen
authors.affiliation: Université de Toulouse; UPS (Université Paul Sabatier)-OMP (L'Observatoire Midi-Pyrénées); IRAP (L'Institut de Recherche en Astrophysique et Planétologie), 31400 Toulouse, France.
authors.forename: Henri
authors.initials: H
authors.lastname: Rème
authors.affiliation: Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.
authors.forename: Martin
authors.initials: M
authors.lastname: Rubin
authors.affiliation: Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.
authors.forename: Thierry
authors.initials: T
authors.lastname: Sémon
authors.affiliation: Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.
authors.forename: Chia-Yu
authors.initials: CY
authors.lastname: Tzou
authors.affiliation: Department of Space Science, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78228, USA.
authors.forename: J Hunter
authors.initials: JH
authors.lastname: Waite
authors.affiliation: Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.
authors.forename: Peter
authors.initials: P
authors.lastname: Wurz
keywords: 67P/Churyumov-Gerasimenko; Rosetta; Space science; comets; noble gas