Nicolas Fray (LISA)
Thursday June 16th - 11am
IRAM Seminar Room - IRAM
COSIMA - COmetary Secondary Ion Mass Analyser – is an instrument dedicated to the study of cometary particles on board the Rosetta orbiter.
Since August 2014, COSIMA is capturing cometary dust particles in the inner coma of the comet 67P/Churyumov-Gerasimenko onto metal target plates. COSIMA images and identifies the particles with an optical microscope with a resolution of 14 um per pixel and analyses their composition with a time of flight secondary ion mass spectrometer with a mass resolution of 1400 at half peak maximum at m/z =100 u.
The images allows to characterize the flux of dust and the size distribution of the particles on a daily to weekly basis. Moreover, these optical images show that the particles present different morphologies. The diversity in morphology after impact on the targets of the collected particles and particle fragments point towards diverse families of cometary dust particles.
The obtained secondary ion mass spectra contain ions of complex mixture of mineral compounds and organic molecules. The elemental abundances of the particles are determined and compared with the one of CI meteorites and interplanetary dust particles. One of the first results of these analyses have already shown that the particles are rich in sodium and likely represent the parent material of interplanetary dust particles. The mineral and molecular compositions are still under consideration, but some preliminary results will be presented.
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