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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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