This movie presents X-ray computed tomographic (CT) data for Chelyabinsk fragment 3-3-4. The first rotation shows surface rendering of the collected CT data, with both the fusion crust and fractures prominent on its exterior. Upon the second rotation, the surface is made transparent to reveal the interior components of the sample presented in a blue-green volume rendering (color bar shown). This visualization is achieved by adjusting the threshold over the nominal full range from 0 to 65,535 that scales with the absorption coefficient of the material. The lower threshold for the volume rendering starts low and is increased to 22,000 to hide the fine grain matrix materials made of low density, low Z elements. The upper threshold was adjusted to 55,670 to provide the best contrast for objects of interest. When the lower threshold is static at 22,000 in the movie, components displayed are metal (FeNi alloy) and troilite (FeS) (shown in green collectively), and finely disseminated FeNi and FeS grains intermingled with silicates (shown in blue). Finally the sample is rotated showing the peak end of the stone towards the viewer. The sample is then cut through the rock virtually showing the individual X-ray CT slices (a total of 1,176 slices encompass the sample in this slice direction; the CT data was reconstructed into 5.46 micron isotropic voxels). Typical ordinary chondritic textures can be discerned readily, such as chondrules (seen as dark rounded objects in the serial slices, rich in low-Z elements, e.g. O, Mg and Si), as well as metal and troilite grains (bright white, irregularly shaped grains). A network of fractures, likely due to the highly shocked nature of the meteorite, is also apparent throughout the rock's interior. The X-ray CT imaging was performed at the Center for Molecular and Genomic Imaging at the University of California, Davis, with a MicroXCT-200 scanner (Xradia, Inc.) The X-ray CT data is rendered using the software Amira 5.4 (VSG Inc.).
Scientific details on Chelyabinsk meteorite is found in the accompanying paper in Science by Popova et al published first in Science Express online on Nov. 7, 2013 (happens to be the day of anniversary of October Revolution). doi:10.1126/science.1242642
Music by Tchaikovsky, Giselle Act II: Ensemble des WIlis (Philharmonia Cassovia)
