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R. Schulz, M. Hilchenbach, J. Kissel, Y. Langevin, J. Silén, C. Briois, C. Engrand, K. Hornung, D. Baklouti, A. Bardyn, H. Cottin, H. Fischer, N. Fray, K. Varmuza et al.:
"On the Dust of Comet 67P/Churyumov-Gerasimenko measured by COSIMA (Paper FM9p.29)";
Poster: IAU XXIX General Assembly, Honolulu, Hawaii, USA; 2015-08-03 - 2015-08-15; in: "IAU XXIX General Assembly, Honolulu, HI, August, 2015 - Meeting Abstracts", astronomy2015.org, (2015), 2 pages.

The composition of a comet nucleus cannot be directly determined by astronomical observations with ground-based telescopes. For the icy component some information can usually be inferred from gas coma observations, assuming certain conditions in the nearnucleus environment. However, the composition of comet dust can only be determined by in-situ measurements. Key information is provided by the results of the measurements obtained with COSIMA (COmetary Secondary Ion Mass Analyser) which is one of the scientific instruments on the Rosetta spacecraft currently investigating Jupiter-family comet 67P/Churyumov-Gerasimenko. COSIMA is collecting the dust grains released from the comet nucleus onto special target plates and subsequently images them and analyses their composition. For the latter a secondary ion mass spectrometer (TOF-SIMS) with an Indium ion source is used. The obtained high resolution mass spectra contain ions of complex mixtures of mineral compounds and organic molecules (molecular peaks, fragments and elements) released from the surface of these grains. We are making progress in extracting the scientific content of the SIMS data, which is a tedious and laborious effort, as automatic procedures are not applicable. The first results of the
COSIMA analyses have shown that the particles are rich in sodium and likely represent the parent material of interplanetary dust particles 1 . Here we report the latest results of our in-situ analysis of cometary grains as COSIMA monitors the evolution of the comet
dust component as a function of increasing solar flux input while the comet is moving towards its perihelion. A special emphasis is put on how we can transfer what we have learnt also to other comets, not investigated by a space mission. This provides new means to distinguish whether differences between comets, observed in their comae by groundbased methods, reflect differences of their nuclei or are related to different environmental conditions of the comets at the time of observation. This in turn has important implications to the question of how and where comets were formed in the early solar
system.

http://astronomy2015.org/sites/default/files/Abstracts%20for%20web%208.11.pdf