Hayabusa2 Initial Analysis Organic Macromolecule team led by Professor Yabuta Hikaru (Hiroshima University) measured chemical, isotopic, and morphological compositions of macromolecular organic matter in samples of the asteroid Ryugu (37 grains ranging from 200 to 900 μm in size), which were returned by the spacecraft Hayabusa2. Their coordinated analysis by various microscopic techniques showed that the chemical compositions of macromolecular organic matter in the Ryugu sample are similar to those in primitive carbonaceous CI (Ivuna-type) and CM (Mighei-type) chondritic meteorites. The morphology of the organic matter includes nanoglobules and diffuse carbon associated with phyllosilicate and carbonate minerals, which is the evidence of the evolution of organic matter during reaction with liquid water on Ryugu’s parent body (the larger asteroid from which Ryugu is thought to be a fragment). No graphite-like material was found, which indicates that the Ryugu organic matter was not subjected to heating events on the parent body, such as long duration radiogenic thermal metamorphism and short-duration heating.
Jérémie Mathurin, Alexandre Dazzi, Ariane Deniset-Besseau from ICP have been involved in this study.