Formation and evolution of carbonaceous asteroid Ryugu
Direct evidence from returned samples
T. Nakamura (Tohoku University)
M. Matsumoto (Tohoku University)
K. Amano (Tohoku University)
Y. Enokido (Tohoku University)
M. E. Zolensky (NASA Johnson Space Center)
T. Mikouchi (University of Tokyo)
H. Genda (Tokyo Institute of Technology)
M. Y. Zolotov (School of Earth and Space Exploration)
S. M. Potin (Observatoire de Paris, TU Delft - Aerospace Engineering)
undefined More Authors (External organisation)
More Info
expand_more
Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.
Abstract
Samples of the carbonaceous asteroid Ryugu were brought to Earth by the Hayabusa2 spacecraft. We analyzed 17 Ryugu samples measuring 1 to 8 millimeters. Carbon dioxide-bearing water inclusions are present within a pyrrhotite crystal, indicating that Ryugu's parent asteroid formed in the outer Solar System. The samples contain low abundances of materials that formed at high temperatures, such as chondrules and calcium- and aluminum-rich inclusions. The samples are rich in phyllosilicates and carbonates, which formed through aqueous alteration reactions at low temperature, high pH, and water/rock ratios of <1 (by mass). Less altered fragments contain olivine, pyroxene, amorphous silicates, calcite, and phosphide. Numerical simulations, based on the mineralogical and physical properties of the samples, indicate that Ryugu's parent body formed ~2 million years after the beginning of Solar System formation.