Japan Geoscience Union Meeting 2019

Presentation information

[E] Oral

P (Space and Planetary Sciences ) » P-PS Planetary Sciences

[P-PS03] Solar System Small Bodies: A New Frontier Arising Hayabusa 2, OSIRIS-REx and Other Projects

Tue. May 28, 2019 1:45 PM - 3:15 PM A01 (TOKYO BAY MAKUHARI HALL)

convener:Masateru Ishiguro(Department of Physics and Astronomy, Seoul National University), Taishi Nakamoto(Tokyo Institute of Technology), Masanao Abe(Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency), Olivier S Barnouin(Johns Hopkins University Applied Physics Laboratory), Chairperson:Olivier Barnouin(Johns Hopkins University Applied Physics Laboratory)

2:45 PM - 3:00 PM

[PPS03-11] Geomorphological characteristics of asteroid Ryugu: implications to its evolutional history

*Hideaki Miyamoto1, Ryodo Hemmi1, Hiroshi Kikuchi1, Goro Komatsu2, Chikatoshi Honda3, Tatsuhiro Michikami4, Tomokatsu Morota5, Yuichiro Cho1, Olivier S Barnouin6, Sho Sasaki7, Naru Hirata3, Naoyuki Hirata8, Rie Honda10, Shingo Kameda11, ERI TATSUMI1, Yasuhiro Yokota12, Toru Kouyama13, Hidehiko Suzuki14, Manabu Yamada15, Naoya Sakatani12, Masahiko Hayakawa12, Kazuo Yoshioka1, Moe Matsuoka12, Masatoshi Hirabayashi9, Hirotaka Sawada12, Seiji Sugita1 (1.University of Tokyo, 2.D'Annunzio University, 3.Aizu University, 4.Kinki University, 5.Nagoya University, 6.Johns Hopkins University, 7.Osaka University, 8.Kobe University, 9.Auburn University, 10.Kouchi University, 11.Rikkyo University, 12.ISAS/JAXA, 13.AIST, 14.Meiji University, 15.Chiba Inst Tech)

Keywords:asteroid, Hayabusa 2, Ryugu

Observations by Hayabusa 2 spacecraft indicate that Ryugu is a highly porous C-type asteroid. Ryugu’s surface is covered by numerous boulders. These are consistent with the idea that Ryugu is a rubble-pile asteroid. Interestingly, Itokawa, the only other similarly-sized rubble-pile asteroid closely observed by spacecraft, is different from Ryugu in many aspects. For example, while the shape of Ryugu is a top-shape, that of Itokawa is somehow elongated cigar-like. Though Ryugu is generally homogeneous in terms of roughness, Itokawa has two distinctive areas such as smooth and rough terrains. Ryugu has an almost continuous equatorial ridge, though Itokawa does not have such a large-scale topographic feature.

These differences may come from the difference in evolutional processes; a top-shape of rubble pile asteroid is believed to result of rotationally induced deformation or from re-accumulation. Another possibility is that the differences may come from variations in mechanical properties of asteroid forming materials. We are investigating geological characteristics of Ryugu, which may hold clues for these aspects. In this talk, we report initial results of geological investigations mostly using visible images obtained by the Optical Navigation Camera (ONC) onboard the Hayabusa2 spacecraft, and discuss about their implications to evolutional history of Ryugu..