Abundant molecular oxygen in the coma of comet 67P/Churyumov-Gerasimenko.
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.
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.
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Bieler
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.
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Altwegg
Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.
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Balsiger
Department of Geosciences, Tel-Aviv University, Ramat-Aviv, 6997801 Tel-Aviv, Israel.
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Bar-Nun
LATMOS/IPSL-CNRS-UPMC-UVSQ, 4 Avenue de Neptune, F-94100 Saint-Maur, France.
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Berthelier
Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.
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Bochsler
Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), UMR 6115 CNRS - Université d'Orléans, 45071 Orléans, France.
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Briois
Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.
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Calmonte
Department of Climate and Space Science and Engineering, University of Michigan, 2455 Hayward Street, Ann Arbor, Michigan 48109, USA.
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Combi
Belgian Institute for Space Aeronomy, BIRA-IASB, Ringlaan 3, B-1180 Brussels, Belgium.
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De Keyser
Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands.
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van Dishoeck
Institute of Computer and Network Engineering (IDA), TU Braunschweig, Hans-Sommer-Straße 66, D-38106 Braunschweig, Germany.
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Fiethe
Space Science and Engineering Division, Southwest Research Institute, 6220 Culebra Road, San Antonio, Texas 78228, USA.
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Fuselier
Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.
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Gasc
Department of Climate and Space Science and Engineering, University of Michigan, 2455 Hayward Street, Ann Arbor, Michigan 48109, USA.
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Gombosi
Department of Climate and Space Science and Engineering, University of Michigan, 2455 Hayward Street, Ann Arbor, Michigan 48109, USA.
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Hansen
Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.|Space Science and Engineering Division, Southwest Research Institute, 6220 Culebra Road, San Antonio, Texas 78228, USA.
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Hässig
Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.
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Jäckel
Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.
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Kopp
Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany.
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Korth
Center for Space and Habitability, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.
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Le Roy
Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany.
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Mall
Belgian Institute for Space Aeronomy, BIRA-IASB, Ringlaan 3, B-1180 Brussels, Belgium.
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Maggiolo
Centre de Recherches Pétrographiques et Géochimiques, CRPG-CNRS, Université de Lorraine, 15 rue Notre Dame des Pauvres, BP 20, 54501 Vandoeuvre lès Nancy, France.
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Marty
Aix Marseille Université, CNRS, LAM (Laboratoire d'Astrophysique de Marseille) UMR 7326, 13388 Marseille, France.
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Mousis
Institute for Astronomy, University of Hawaii, Honolulu, Hawaii 96822, USA.
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Owen
Université de Toulouse-UPS-OMP-IRAP, 31400 Toulouse, France.|CNRS-IRAP, 9 avenue du Colonel Roche, BP 44346, F-31028 Toulouse Cedex 4, France.
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Rème
Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.
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Rubin
Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.
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Sémon
Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.
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Tzou
Space Science and Engineering Division, Southwest Research Institute, 6220 Culebra Road, San Antonio, Texas 78228, USA.
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Waite
Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands.
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Walsh
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.
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Wurz
D002248:Carbon Monoxide / Q000032:analysis; D005118:Extraterrestrial Environment / Q000737:chemistry; D007053:Ice / Q000032:analysis; D019110:Meteoroids; D009584:Nitrogen / Q000032:analysis; D010100:Oxygen / Q000032:analysis* / Q000528:radiation effects; D010782:Photolysis; D016082:Solar System / Q000737:chemistry; D018531:Spacecraft; D014867:Water / Q000032:analysis
D007053:Ice; D014867:Water; D002248:Carbon Monoxide; D009584:Nitrogen; D010100:Oxygen