CHO-bearing organic compounds at the surface of 67P/Churyumov-Gerasimenko revealed by Ptolemy

The surface and subsurface of comets preserve material from the formation of the solar system. The properties of cometary material thus provide insight into the physical and chemical conditions during their formation. We present mass spectra taken by the Ptolemy instrument 20 minutes after the initial touchdown of the Philae lander on the surface of comet 67P/Churyumov-Gerasimenko. Regular mass distributions indicate the presence of a sequence of compounds with additional -CH2- and -O- groups (mass/charge ratios 14 and 16, respectively). Similarities with the detected coma species of comet Halley suggest the presence of a radiation-induced polymer at the surface. Ptolemy measurements also indicate an apparent absence of aromatic compounds such as benzene, a lack of sulfur-bearing species, and very low concentrations of nitrogenous material.

[1]  F. R. Krueger,et al.  Organic Ions in the Coma of Comet Halley , 1992 .

[2]  Andrew Steele,et al.  Organic compounds on comet 67P/Churyumov-Gerasimenko revealed by COSAC mass spectrometry , 2015, Science.

[3]  F. Scholten,et al.  The landing(s) of Philae and inferences about comet surface mechanical properties , 2015, Science.

[4]  E. Kührt,et al.  Time variability and heterogeneity in the coma of 67P/Churyumov-Gerasimenko , 2015, Science.

[5]  Steven B. Charnley,et al.  The Chemical Composition of Comets—Emerging Taxonomies and Natal Heritage , 2011 .

[6]  Carl Sagan,et al.  Tholins: organic chemistry of interstellar grains and gas , 1978, Nature.

[7]  T. Owen,et al.  Molecular nitrogen in comet 67P/Churyumov-Gerasimenko indicates a low formation temperature , 2015, Science.

[8]  POLYOXYMETHYLENE AS PARENT MOLECULE FOR THE FORMALDEHYDE EXTENDED SOURCE IN COMET HALLEY , 2001 .

[9]  Cyril Szopa,et al.  Cosac, The Cometary Sampling and Composition Experiment on Philae , 2007 .

[10]  D. Mitchell,et al.  Evidence for Chain Molecules Enriched in Carbon, Hydrogen, and Oxygen in Comet Halley , 1987, Science.

[11]  K. Glassmeier,et al.  Rosetta-ESA's Mission to the Origin of the Solar System , 2009 .

[12]  W. Huebner,et al.  First Polymer in Space Identified in Comet Halley , 1987, Science.

[13]  M. Wright,et al.  Formaldehyde in Comets C/1995 O1 (Hale-Bopp), C/2002 T7 (LINEAR), and C/2001 Q4 (NEAT): Investigating the Cometary Origin of H2CO , 2006 .

[14]  Ian Wright,et al.  Ptolemy operations and results during the Lutetia flyby , 2012 .

[15]  R. Garrod,et al.  FORMATION OF HYDROXYLAMINE ON DUST GRAINS VIA AMMONIA OXIDATION , 2015, 1501.04701.

[16]  S. Sandford,et al.  An experimental study of the organic molecules produced in cometary and interstellar ice analogs by thermal formaldehyde reactions. , 1993, Icarus.

[17]  Carl Sagan,et al.  Production and Chemical Analysis of Cometary Ice Tholins , 1996 .

[18]  A. Ercoli Finzi,et al.  SD2 – How To Sample A Comet , 2007 .

[19]  M. Banaszkiewicz,et al.  Thermal and mechanical properties of the near-surface layers of comet 67P/Churyumov-Gerasimenko , 2015, Science.

[20]  J. Sauvaud,et al.  Mass spectra of heavy ions near comet Halley , 1986 .

[21]  N. Wickramasinghe.  Polyoxymethylene Polymers as Interstellar Grains , 1975 .

[22]  R. Reinhard.  The Giotto encounter with comet Halley , 1986 .

[23]  N. Fray,et al.  Distributed Sources in Comets , 2008 .