Interior structure of the moon and planets by VLBI observation of spacecraft: Size, state and the origin of metallic core

2014 Fiscal Year Final Research Report

• Project/Area Number: 24244072
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Solid earth and planetary physics
• Research Institution: Osaka University
• Principal Investigator: SASAKI Sho 大阪大学, 理学(系)研究科(研究院), 教授 (10183823)
• Co-Investigator(Kenkyū-buntansha): MATSUMOTO Koji 国立天文台, RISE月惑星探査検討室, 准教授 (30332167) ; KIKUCHI Fuyuhiko 国立天文台, RISE月惑星探査検討室, 専門研究職員 (30465926) ; KAWAGUCHI Noriyuki 国立天文台, 水沢VLBI観測所, 名誉教授 (90214618) ; KONO Yusuke 国立天文台, 水沢VLBI観測所, 助教 (00370106)
• Co-Investigator(Renkei-kenkyūsha): ARAKI Hiroshi 国立天文台, RISE月惑星探査検討室, 助教 (10290884) ; NODA Hirotomo 国立天文台, RISE月惑星探査検討室, 助教 (10353426) ; HANADA Hideo 国立天文台, RISE月惑星探査検討室, 准教授 (60132677) ; KAMEYA Osamu 国立天文台, 水沢VLBI観測所, 助教 (70202025) ; JIKE Takaaki 国立天文台, 水沢VLBI観測所, 助教 (40425400) ; OYAMA Tomoaki 国立天文台, 水沢VLBI観測所, 専門研究職員 (70425403) ; IWATA Takahiro 独立行政法人宇宙航空研究開発機構, 宇宙科学研究所, 准教授 (20201949) ; MOROTA Tomokatsu 名古屋大学, 大学院環境学研究科, 助教 (30415898) ; HEKI Kosuke 北海道大学, 大学院理学研究科, 教授 (30280564)
• Research Collaborator: YAMADA Ryuhei 国立天文台, RISE月惑星探査検討室, 研究員 (60647379)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 月内部構造 / 重力 / VLBI / 潮汐ラブ数 / 金属核 / 月の起源

Outline of Final Research Achievements

In order to clarify the state of metallic core and lower mantle, we developed wideband radio signal receiving system for observing VLBI resources and we construct plausible models from geodetic and seismic data. We considered a spherically symmetric elastic Moon with eight layers including a low-velocity zone.The thickness, density, and elastic parameters in each layer were estimated using Markov Chain Monte Carlo method. Mean crustal thickness, the radii of the outer fluid core and the solid inner core were estimated to be 43 ± 10 km, 310 + 90 km, and 0 - 270 km, respectively. If we take into account the upper bound of the fluid core size of 400 km which is 200 indicated by magnetic observation, the thickness of the low-velocity - partially molten) zone at the bottom of the mantle is at least about 200 km. The inferred density of the lowermost mantle suggests lunar magmas with high TiO2 content which prefer mantle overturn scenario.

Free Research Field

惑星科学