Profiling COSIMA’s dust grain family

Rosetta’s COSIMA instrument – the Cometary Secondary Ion Mass Analyser – has detected tens of thousands of dust grains since arriving at Comet 67P/Churyumov-Gerasimenko. The grains collected from 11 August 2014 – 3 April 2015 across nine 1 cm^2 targets, when the comet was moving towards the Sun along its orbit from about 3.5 to 2 AU, provide the focus for a detailed study outlined in a paper published this month in the journal Icarus. The paper, led by Yves Langevin of the Institut d’Astrophysique Spatiale at CNRS/University of Paris-Sud, France, describes the key characteristics of the different grain families imaged under the COSIMA microscope, the COSISCOPE. The images reveal the particles are extremely diverse at scales of just a few 10s of micrometers (μm) to several 100 μm. The grains were characterized according to factors such as the complexity of its appearance and its height above target – determined by analysing its shadow –, which in turn is related to strength of particle. In general, the dust families can be divided into compact particles or clusters, with the cluster group further subdivided into shattered clusters, glued clusters and rubble piles. The clusters are differentiated based on the different size distributions of the components, their spatial relationship on the collection plate, and the existence or not of any connecting matrix. The different grain families are described below, including reconstructed anaglyph images made by combining an image at the nominal position (red) and an image obtained by shifting the target by 4mm away from the LED (blue). The particles follow a naming convention based on COSIMA team members and other Rosetta mission team colleagues. (Note: the credit line for all images is: ESA/Rosetta/MPS for COSIMA Team MPS/CSNSM/UNIBW/TUORLA/IWF/IAS/ESA/BUW/MPE/LPC2E/LCM/FMI/UTU/LISA/UOFC/vH&S/ Langevin et al (2016)) Compact particles Compact particles are defined as those with well-defined boundaries, […]

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