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Balsiger H, Altwegg K, Bar-Nun A, Berthelier JJ, Bieler A, Bochsler P, Briois C, Calmonte U, Combi M, De Keyser J, Eberhardt P, Fiethe B, Fuselier SA, Gasc S, Gombosi TI, Hansen KC, Hässig M, Jäckel A, Kopp E, Korth A, Le Roy L, Mall U, Marty B, Mousis O, Owen T, Rème H, Rubin M, Sémon T, Tzou CY, Waite JH, Wurz P. Detection of argon in the coma of comet 67P/Churyumov-Gerasimenko. SCIENCE ADVANCES 2015; 1:e1500377. [PMID: 26601264 PMCID: PMC4643765 DOI: 10.1126/sciadv.1500377] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 06/22/2015] [Indexed: 05/15/2023]
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.
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Affiliation(s)
- Hans Balsiger
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
- Corresponding author:
| | - Kathrin Altwegg
- 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
| | - Akiva Bar-Nun
- Department of Geoscience, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel
| | - Jean-Jacques Berthelier
- 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
| | - Andre Bieler
- 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
| | - Peter Bochsler
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - Christelle Briois
- Laboratoire de Physique et Chimie de l’Environnement et de l’Espace (LPC2E), UMR 6115 CNRS–Université d’Orléans, 45071 Orléans, France
| | - Ursina Calmonte
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - Michael Combi
- Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, 2455 Hayward, Ann Arbor, MI 48109, USA
| | - Johan De Keyser
- Belgian Institute for Space Aeronomy (BIRA-IASB), Ringlaan 3, B-1180 Brussels, Belgium
| | - Peter Eberhardt
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - Björn Fiethe
- Institute of Computer and Network Engineering (IDA), Technische Universität (TU) Braunschweig, Hans-Sommer-Straße 66, D-38106 Braunschweig, Germany
| | - Stephen A. Fuselier
- Department of Space Science, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78228, USA
| | - Sébastien Gasc
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - Tamas I. Gombosi
- Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, 2455 Hayward, Ann Arbor, MI 48109, USA
| | - Kenneth C. Hansen
- Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, 2455 Hayward, Ann Arbor, MI 48109, USA
| | - Myrtha Hässig
- 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
| | - Annette Jäckel
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - Ernest Kopp
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - Axel Korth
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| | - Lena Le Roy
- Center for Space and Habitability, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - Urs Mall
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| | - Bernard Marty
- CRPG (Centre de Recherches Pétrographiques et Géochimiques)–CNRS, Université de Lorraine, 15 rue Notre Dame des Pauvres, BP 20, 54501 Vandoeuvre lès Nancy, France
| | - Olivier Mousis
- Aix Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, 13388 Marseille, France
| | - Tobias Owen
- Institute for Astronomy, University of Hawaii, Honolulu, HI 96822, USA
| | - Henri Rème
- Université de Toulouse; UPS (Université Paul Sabatier)–OMP (L’Observatoire Midi-Pyrénées); IRAP (L’Institut de Recherche en Astrophysique et Planétologie), 31400 Toulouse, France
| | - Martin Rubin
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - Thierry Sémon
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - Chia-Yu Tzou
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - J. Hunter Waite
- Department of Space Science, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78228, USA
| | - Peter Wurz
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
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Prettyman TH, Mittlefehldt DW, Yamashita N, Lawrence DJ, Beck AW, Feldman WC, McCoy TJ, McSween HY, Toplis MJ, Titus TN, Tricarico P, Reedy RC, Hendricks JS, Forni O, Le Corre L, Li JY, Mizzon H, Reddy V, Raymond CA, Russell CT. Elemental mapping by Dawn reveals exogenic H in Vesta's regolith. Science 2012; 338:242-6. [PMID: 22997135 DOI: 10.1126/science.1225354] [Citation(s) in RCA: 186] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Using Dawn's Gamma Ray and Neutron Detector, we tested models of Vesta's evolution based on studies of howardite, eucrite, and diogenite (HED) meteorites. Global Fe/O and Fe/Si ratios are consistent with HED compositions. Neutron measurements confirm that a thick, diogenitic lower crust is exposed in the Rheasilvia basin, which is consistent with global magmatic differentiation. Vesta's regolith contains substantial amounts of hydrogen. The highest hydrogen concentrations coincide with older, low-albedo regions near the equator, where water ice is unstable. The young, Rheasilvia basin contains the lowest concentrations. These observations are consistent with gradual accumulation of hydrogen by infall of carbonaceous chondrites--observed as clasts in some howardites--and subsequent removal or burial of this material by large impacts.
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Affiliation(s)
- Thomas H Prettyman
- Planetary Science Institute, 1700 East Fort Lowell, Suite 106, Tucson, AZ 85719-2395, USA.
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