日本地球惑星科学連合2023年大会

講演情報

[E] 口頭発表

セッション記号 P (宇宙惑星科学) » P-PS 惑星科学

[P-PS01] Outer Solar System Exploration Today, and Tomorrow

2023年5月25日(木) 09:00 〜 10:15 304 (幕張メッセ国際会議場)

コンビーナ:木村 淳(大阪大学)、佐柳 邦男 M(NASA Langley Research Center)、土屋 史紀(東北大学大学院理学研究科惑星プラズマ・大気研究センター)、座長:斎藤 義文(宇宙航空研究開発機構・宇宙科学研究所・太陽系科学研究系)、関根 康人(東京工業大学地球生命研究所)

09:30 〜 09:45

[PPS01-03] Radio & Plasma Wave Investigation (RPWI) aboard JUICE: Post launch status and its expected sciences for Jupiter and Icy Moons

*笠羽 康正1土屋 史紀1三澤 浩昭1熊本 篤志1加藤 雄人1北 元2木村 智樹3安田 陸人1佐藤 晋之祐1堺 正太朗1三好 由純4北原 理弘1笠原 禎也5松田 昇也5八木谷 聡5尾崎 光紀5小嶋 浩嗣6栗田 怜6Cecconi Baptiste7、Wahlund Jan-Erik8、JUICE RPWI team (1.東北大学、2.東北工業大学、3.東京理科大学、4.名古屋大学、5.金沢大学、6.京都大学、7.パリ天文台、8.IRF Uppsala)

キーワード:木星、氷衛星、RPWI、JUICE、電波、プラズマ波動

JUpiter ICy moons Explorer (JUICE), ESA's first L-class mission, will be launched in April 2023. This talk shows a view of Radio & Plasma Wave Investigation (RPWI) aboard JUICE which provides a unique and first opportunity in this huge mission, especially the view from Japanese contributors. We, JUICE RPWI Japan team, mainly provide the high frequency radio observation capabilities.
The RPWI will investigate electromagnetic fields and plasma environment around Jupiter and icy moons with passive and active soundings by 4 Langmuir probes (LP-PWI; 3-axis E-field -1.6 MHz by four 10 cm diameter probes on the 3-m booms) and a search coil magnetometer (SCM; 3-axis B-field -20 kHz) + a tri-dipole antenna system (RWI; 3-axis E-field 0.08-45 MHz, 2.5-m tip-to-tip length) on the long MAG-Boom with JMAG. For lower frequency side, RPWI enables to investigate electric field and electromagnetic interactions governing Jupiter - moon systems, cold plasmas in the ionospheres of icy moons for investigations of surfaces and salty conductive sub-surface oceans., and cold micrometeorite impacts.

The RPWI Japan team provides the high frequency part of this system, i.e., Preamp of RWI and its High Frequency Receiver (HF), under the collaboration with the colleagues in France, Poland, and Sweden. This part will enable characterization of Jovian radio emissions (including gonio-polarimetry), passive radio sounding of the ionospheric densities of icy moons, and passive sub-surface radar measurements. In this paper, we provide the performance and operation concepts with their feasibilities, including the test and emulation results on the ground, the deployment operations executed after the launch, and planned activities in commissioning and cruise phases, and the full observations around Jupiter and icy moon system.
We have confirmed that the HF part of RPWI has high sensitivity reaching close to the galactic background enough for the detection of Jovian radio emissions from magnetosphere (aurora etc.), atmosphere (lightning), and icy moons. Direction and polarization capabilities are first enabled in the Jovian system, to identify their source locations and characteristics. RPWI with other instruments covers the survey of harsh environment around Jupiter, environments and interaction with icy moons, and their surface and subsurface characteristics.
The most key part of the HF part is the sensing of the ionospheres, surface, and subsurface of icy moons during the flybys and on the orbit around Ganymede. Our 'High frequency part of RPWI' can do unique remote observations of the ionospheres below the spacecraft orbit by the radio occultation and reflection of Jovian radio signals, It has a capability to detect the ionospheric density not only in usual status but also episodic plume ejections triggered by expected crustal activities.
The sensing of surface and subsurface are more challenging topics, based on the passive subsurface radar (PSSR) concept which sounds the icy crusts of Galilean satellites by the reflections of penetrated Jovian radio emissions (HOM/DAM).
We will introduce their possibility and the evidences of achieved performance taken before and after the launch.