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OATS-DAUT SEMINAR
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Speaker: Alessandra Rotundi (Università di Napoli "Parthenope")

Title: Stardust: the first laboratory analyses of cometary dust

Date: Wednesday, March 21th, 2007
Time: 16:00
Venue: Villa Bazzoni

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Abstract: LANDS (Laboratory ANalyses of Dust from Space): the only Italian project selected by NASA to do the first measurements on the dust samples collected at comet 81P Wild-2 by the Stardust/NASA spacecraft and returned to Earth on Jan the 15th, 2006. The project is developed in Napoli, at the Laboratorio di Fisica Cosmica e Planetologia - (Università Parthenope/INAF-OAC), and in Catania, at the Laboratorio di Astrofisica Sperimentale (INAF-OACT). For the analysis of Stardust samples NASA settled a preliminary analysis phase, from March to September 2006, to be performed by a Preliminary Examination Team (PET) formed after a worldwide selection, composed of about 200 researchers. The PET includes teams focused on mineralogy, chemical composition, isotopic measurements, organic analysis, cratering and optical properties. The main PET goals were to provide for the returned samples: an initial characterization with an emphasis on the effects of the capture process; a comparison to other meteoritic materials; the abundance of pre-solar materials. In this frame the LANDS team performed combined micro-IR, micro-Raman, and Field Emission Scanning Electron Microscope analyses bulk particles. We present mid IR spectra collected on Stardust particles, which are rendered in some cases difficult to interpret because of the presence of molten aerogel mixed with the grain. The CH2/CH3 ratios inferred from the infrared data are greater than those seen in organics in the diffuse interstellar medium, possibly indicating the presence of longer or less branched aliphatic chains. The Micro-Raman data offer insights on the state of order of the amorphous carbon component present in the particles and we compare them to similar data obtained from IDPs and meteorites. The carbonaceous material appears more primitive with respect to IDPs and meteorites for most of the particles analyzed. Both the IR and Raman data seem to imply the presence of a very labile component to the carbonaceous matter, mixed with the refractory minerals.
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