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Hayabusa2 Arrives at the Carbonaceous Asteroid 162173 Ryugu-A Spinning Top-shaped Rubble Pile

Overview
Journal Science
Specialty Science
Date 2019 Mar 21
PMID 30890588
Citations 33
Authors
S Watanabe
M Hirabayashi
N Hirata
Na Hirata
R Noguchi
Y Shimaki
H Ikeda
E Tatsumi
M Yoshikawa
S Kikuchi
H Yabuta
T Nakamura
S Tachibana
Y Ishihara
T Morota
K Kitazato
N Sakatani
K Matsumoto
K Wada
H Senshu
C Honda
T Michikami
H Takeuchi
T Kouyama
R Honda
S Kameda
T Fuse
H Miyamoto
G Komatsu
S Sugita
T Okada
N Namiki
M Arakawa
M Ishiguro
M Abe
R Gaskell
E Palmer
O S Barnouin
P Michel
A S French
J W McMahon
D J Scheeres
P A Abell
Y Yamamoto
K Shirai
M Matsuoka
M Yamada
Y Yokota
H Suzuki
K Yoshioka
Y Cho
S Tanaka
N Nishikawa
T Sugiyama
H Kikuchi
R Hemmi
T Yamaguchi
N Ogawa
G Ono
Y Mimasu
K Yoshikawa
T Takahashi
Y Takei
A Fujii
C Hirose
T Iwata
M Hayakawa
S Hosoda
O Mori
H Sawada
T Shimada
S Soldini
H Yano
R Tsukizaki
M Ozaki
Y Iijima
K Ogawa
M Fujimoto
T-M Ho
A Moussi
R Jaumann
J-P Bibring
C Krause
F Terui
T Saiki
S Nakazawa
Y Tsuda
Affiliations
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Abstract

The Hayabusa2 spacecraft arrived at the near-Earth carbonaceous asteroid 162173 Ryugu in 2018. We present Hayabusa2 observations of Ryugu's shape, mass, and geomorphology. Ryugu has an oblate "spinning top" shape, with a prominent circular equatorial ridge. Its bulk density, 1.19 ± 0.02 grams per cubic centimeter, indicates a high-porosity (>50%) interior. Large surface boulders suggest a rubble-pile structure. Surface slope analysis shows Ryugu's shape may have been produced from having once spun at twice the current rate. Coupled with the observed global material homogeneity, this suggests that Ryugu was reshaped by centrifugally induced deformation during a period of rapid rotation. From these remote-sensing investigations, we identified a suitable sample collection site on the equatorial ridge.

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