Production, processing and characterization techniques for cosmic dust analogues

Abstract

Abstract-The laboratory analyses of cosmic dust analogues-that in the context ofthis paper include interstellar, circumstellar as well as cometary dust-have a critical role in the study of circumstellar and cometary dust. The morphological, structural and chemical characterization of these analogues are critical for comparisons oftheir infrared and ultraviolet spectra with those obtained by astronomical observations, as well as for modeling purposes. Besides, the results from these laboratory studies are important to the success of space missions to comets when testing and calibrating the payload instruments. The interpretations of returned scientific data would benefit from the comparison with data recorded by the instruments in a laboratory setting for different classes ofpreviously characterized analogues. We produced various types ofcondensed samples: (1) Mg,Fe-silicates, (olivine, pyroxene), (2) carbon-rich dust, and (3) mixed carbon-silicate dust. The samples were prepared using different techniques, viz. (1) laser bombardment of solid targets in an Ar and 02 atmosphere, (2) arc discharge in an Ar and H2 atmosphere, and (3) grinding powders of natural minerals. We simulated various post-condensation processes, such as thermal annealing, ultraviolet irradiation, ion bombardment and exposure to atomic hydrogen. These processes produced compound samples of a wide range of physico-chemical properties. To identify their textures, morphologies, grain compositions and crystallographic properties we used electron microscopy and far-ultraviolet to far-infrared (millimeter range) spectroscopy.

Laboratory hydration of condensed magnesiosilica smokes with implications for hydrated silicates in IDPs and comets

“…These successful and maturing experiments use combinations of sophisticated analytical tools, e.g., infrared spectroscopy and transmission electron microscopy, to determine the properties of the original and processed dust analogues (Nuth et al , 2002Rotundi et al 2002). For example, but without an attempt to be comprehensive, such laboratory studies, including this study, define condensation and thermal annealing of Fe-and Mg-silicates (Carrez et al 2002;Fabian et al 2000;Hallenbeck et al 1998;Rietmeijer et al 2002a;Thompson and Tang 2001) and carbon dust analogues (Jäger et al 1999;Rietmeijer et al Forthcoming;Rotundi et al 1998) as well as hydration of condensed silicates.…”

Rotating dust particles in the coma of comet 67P/Churyumov-Gerasimenko

“…All these models assume that the dust grains are spherical. However, the stratospheric interplanetary dust particles (IDPs; Rotundi et al 2007Rotundi et al , 2014 or the samples brought by the Stardust mission from comet 81P/Wild (Brownlee et al 2006;Zolensky et al 2006;Rotundi & Rietmeijer 2008) imply strongly irregular dust shapes by origin.…”

Raman spectroscopy of ion‐irradiated astrophysically relevant materials

“…50 In almost all Raman analyses on IDPs, the only features seen are the AC G and D bands superimposed upon a fluorescence background of variable intensity, although features due to minerals have been detected in a few cases. 51,52 The non-detection of minerals in almost all Raman spectra of IDPs could be due to the opaque nature of the samples which prevents deep visiblelaser penetration and/or to the very high Raman scattering efficiency of the AC bands with respect to minerals. 35 The G and D band profiles changes among different IDPs, 11,35 indicating the existence of different degrees of order, which could be due to a different evolution and/or origin.…”

“…The degree of order of AC in IDPs is distinctly different from the ordering in carbon compounds found in carbonaceous chondrite meteorites. 52,53 That is, the carbon phase of IDPs is, on average, more distortrd (wider G and D bands) than in meteorites. Some IDPs derive from the less altered, carbon-rich outer asteroid belt (icy) asteroids and comet nuclei in the solar system.…”