An Interplanetary Dust Particle (IDP) of cometary origin provided by NASA was analyzed in the laboratory with infrared spectroscopy (2 ¬ 60 µm), Raman, and FESEM-EDX analyses, in the framework of the analysis of cometary materials performed by the “Institut d’Astrophysique Spatiale” (IAS, Orsay) in the Astrochimie et Origines team, in collaboration with the SMIS beamline at SOLEIL and Università di Napoli “Parthenope” (Italy).
 | Figure 1: Interplanetary dust particle. |
This chondritic* porous aggregate IDP was pressed between diamond windows (Fig. 1) to increase the quality of the spectral data by overcoming the diffraction limitation and minimizing light scattering effects from particles of a global size similar to the wavelength of the observation. This combination of techniques has enabled a mineralogical, organic and compositional description of the compressed particle. Raman spectra detected carbonaceous structures with different degrees of order, and the combination of the three techniques indicates that the particle experienced only mild flash heating on atmospheric entry.
Figure 2: Comparison of the Hale-Bopp ISO-SWS spectrum (bottom) to the studied dust particle spectrum. The IDP spectrum has been multiplied by a 180K Planck function, corresponding to the "average" temperature of particles ejected by the comet.
IR spectra strikingly match the small silicate grains emission of comet Hale-Bopp (Fig. 2). This result, other than stressing once again the importance of IDP laboratory studies to interpret the astronomical data, indicates that most information extractable from the remote sensing comet observations may be included in the physical and chemical properties of a ~20 µm IDP. In other words, this IDP already represents a sort of well-sampled ³miniature comet², fallen on the Earth and finally delivered to our laboratory.
*chondrite: a stony meteorite consisting mainly of silicate minerals, with less than 35% of metal.
From the IAS website
References:
These results are published in the following article:
Brunetto, R., et al., Mid-IR, Far-IR, Raman micro-spectroscopy, and FESEM-EDX study of IDP L2021C5: clues to its origin, Icarus (2011), doi:10.1016/j.icarus.2011.01.038
http://dx.doi.org/10.1016/j.icarus.2011.01.038
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