Hayabusa2 arrives at the carbonaceous asteroid 162173 Ryugu-A spinning top-shaped rubble pile

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; S Tanaka; 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

doi:10.1126/science.aav8032

Hayabusa2 arrives at the carbonaceous asteroid 162173 Ryugu-A spinning top-shaped rubble pile

Science. 2019 Apr 19;364(6437):268-272. doi: 10.1126/science.aav8032. Epub 2019 Mar 19.

Authors

S Watanabe^{1

2}, M Hirabayashi³, N Hirata⁴, Na Hirata⁵, R Noguchi², Y Shimaki², H Ikeda⁶, E Tatsumi⁷, M Yoshikawa^{2

8}, S Kikuchi², H Yabuta⁹, T Nakamura¹⁰, S Tachibana^{7

2}, Y Ishihara², T Morota¹¹, K Kitazato⁴, N Sakatani², K Matsumoto^{12

8}, K Wada¹³, H Senshu¹³, C Honda⁴, T Michikami¹⁴, H Takeuchi^{2

8}, T Kouyama¹⁵, R Honda¹⁶, S Kameda¹⁷, T Fuse¹⁸, H Miyamoto⁷, G Komatsu^{19

13}, S Sugita⁷, T Okada^{2

7}, N Namiki^{12

8}, M Arakawa⁵, M Ishiguro²⁰, M Abe^{2

8}, R Gaskell²¹, E Palmer²¹, O S Barnouin²², P Michel²³, A S French²⁴, J W McMahon²⁴, D J Scheeres²⁴, P A Abell²⁵, Y Yamamoto^{2

8}, S Tanaka^{2

8}, K Shirai², M Matsuoka², M Yamada¹³, Y Yokota^{2

16}, H Suzuki²⁶, K Yoshioka⁷, Y Cho⁷, S Tanaka⁵, N Nishikawa⁵, T Sugiyama⁴, H Kikuchi⁷, R Hemmi⁷, T Yamaguchi², N Ogawa², G Ono⁶, Y Mimasu², K Yoshikawa⁶, T Takahashi², Y Takei², A Fujii², C Hirose⁶, T Iwata^{2

8}, M Hayakawa², S Hosoda², O Mori², H Sawada², T Shimada², S Soldini², H Yano^{2

8}, R Tsukizaki², M Ozaki^{2

8}, Y Iijima², K Ogawa⁵, M Fujimoto², T-M Ho²⁷, A Moussi²⁸, R Jaumann²⁹, J-P Bibring³⁰, C Krause³¹, F Terui², T Saiki², S Nakazawa², Y Tsuda^{2

8}

Affiliations

¹ Nagoya University, Nagoya 464-8601, Japan. [email protected].
² Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan.
³ Auburn University, Auburn, AL 36849, USA.
⁴ University of Aizu, Aizu-Wakamatsu 965-8580, Japan.
⁵ Kobe University, Kobe 657-8501, Japan.
⁶ Research and Development Directorate, JAXA, Sagamihara 252-5210, Japan.
⁷ University of Tokyo, Tokyo 113-0033, Japan.
⁸ SOKENDAI (The Graduate University for Advanced Studies), Hayama 240-0193, Japan.
⁹ Hiroshima University, Higashi-Hiroshima 739-8526, Japan.
¹⁰ Tohoku University, Sendai 980-8578, Japan.
¹¹ Nagoya University, Nagoya 464-8601, Japan.
¹² National Astronomical Observatory of Japan, Mitaka 181-8588, Japan.
¹³ Chiba Institute of Technology, Narashino 275-0016, Japan.
¹⁴ Kindai University, Higashi-Hiroshima 739-2116, Japan.
¹⁵ National Institute of Advanced Industrial Science and Technology, Tokyo 135-0064 Japan.
¹⁶ Kochi University, Kochi 780-8520, Japan.
¹⁷ Rikkyo University, Tokyo 171-8501, Japan.
¹⁸ National Institute of Information and Communications Technology, Kashima 314-8501, Japan.
¹⁹ Università d'Annunzio, 65127 Pescara, Italy.
²⁰ Seoul National University, Seoul 08826, Korea.
²¹ Planetary Science Institute, Tucson, AZ 85710, USA.
²² Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA.
²³ Université Côte d'Azur, Observatoire de la Côte d'Azur, Centre National de la Recherche Scientifique (CNRS), Laboratoire Lagrange, 06304 Nice, France.
²⁴ University of Colorado, Boulder, CO 80309, USA.
²⁵ NASA Johnson Space Center, Houston, TX 77058, USA.
²⁶ Meiji University, Kawasaki 214-8571, Japan.
²⁷ DLR (German Aerospace Center), Institute of Space Systems, 28359 Bremen, Germany.
²⁸ Centre National d'Etudes Spatiales (CNES), 31401 Toulouse, France.
²⁹ DLR, Institute of Planetary Research, 12489 Berlin-Adlershof, Germany.
³⁰ Institute d'Astrophysique Spatiale, 91405 Orsay, France.
³¹ DLR, Microgravity User Support Center, 51147 Cologne, Germany.

PMID: 30890588
DOI: 10.1126/science.aav8032

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.

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.