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The near-Earth carbonaceous asteroid (162173) Ryugu is expected to contain volatile chemical species that could provide information on the origin of Earth's volatiles. Samples of Ryugu were retrieved by the Hayabusa2 spacecraft. We measured noble gas and nitrogen isotopes in Ryugu samples and found that they are dominated by presolar and primordial components, incorporated during Solar System formation. Noble gas concentrations are higher than those in Ivuna-type carbonaceous (CI) chondrite meteorites. Several host phases of isotopically distinct nitrogen have different abundances among the samples. Our measurements support a close relationship between Ryugu and CI chondrites. Noble gases produced by galactic cosmic rays, indicating a ~5 million year exposure, and from implanted solar wind record the recent irradiation history of Ryugu after it migrated to its current orbit. ISSN:0036-8075 ISSN:1095-9203

Full list of authors: Enya, Keigo; Kobayashi, Masanori; Kimura, Jun; Araki, Hiroshi; Namiki, Noriyuki; Noda, Hirotomo; Kashima, Shingo; Oshigami, Shoko; Ishibashi, Ko; Yamawaki, T.; Tohara, Kazuyuki; Saito, Yoshifumi; Ozaki, Masanobu; Mizuno, Takahide; Kamata, Shunichi; Matsumoto, Koji; Sasaki, Sho; Kuramoto, Kiyoshi; Sato, Yuki; Yokozawa, Takeshi; Numata, Tsutomu; Mizumoto, Satoko; Mizuno, Hiroyuki; Nagamine, Kenta; Sawamura, Akihiko; Tanimoto, Kazuo; Imai, Hisato; Nakagawa, Hiroyuki; Kirino, Okiharu; Green, David; Fujii, Masayuki; Iwamura, Satoru; Fujishiro, Naofumi; Matsumoto, Yoshiaki; Lingenauber, Kay; Kallenbach, Reinald; Althaus, Christian; Behnke, Thomas; Binger, Jan; Daurskikh, Anna; Eisenmenger, Henri; Heer, Ulrich; Hüttig, Christian; Lara, Luisa M.; Lichopoj, Alexander; Lötzke, Horst-Georg; Lüdicke, Fabian; Michaelis, Harald; Pablo Rodriguez Garcia, Juan; Rösner, Kerstin; Stark, Alexander; Steinbrügge, Gregor; Thabaut, Pascal; Thomas, Nicolas; del Togno, Simone; Wahl, Daniel; Wendler, Belinda; Wickhusen, Kai; Willner, Konrad; Hussmann, Hauke.--This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/ by-nc-nd/4.0/)., The Jupiter Icy Moons Explorer (JUICE) is a science mission led by the European Space Agency, being developed for launch in 2023. The Ganymede Laser Altimeter (GALA) is an instrument onboard JUICE, whose main scientific goals are to understand ice tectonics based on topographic data, the subsurface structure by measuring tidal response, and small-scale roughness and albedo of the surface. In addition, from the perspective of astrobiology, it is imperative to study the subsurface ocean scientifically. The development of GALA has proceeded through an international collaboration between Germany (the lead), Japan, Switzerland, and Spain. Within this framework, the Japanese team (GALA-J) is responsible for developing three receiver modules: the Backend Optics (BEO), the Focal Plane Assembly (FPA), and the Analog Electronics Module (AEM). Like the German team, GALA-J also developed software to simulate the performance of the entire GALA system (performance model). In July 2020, the Proto-Flight Models of BEO, FPA, and AEM were delivered from Japan to Germany. This paper presents an overview of JUICE/GALA and its scientific objectives and describes the instrumentation, mainly focusing on Japan's contribution. © 2021 COSPAR., NSO/Kitt Peak data (synoptic maps of He I Å intensity) used here are produced cooperatively by NSF/NOAO, NASA/GSFC, and NOAA/SEL. Sunspot number (version 2) comes from the Sunspot Index and Long-term Solar Observations at Royal Observatory of Belgium, Brussels. All used data are courtesy to be downloaded from their web sites. The authors would like to express their deep thanks to the staffs of these web sites. This work is supported by the National Natural Science Foundation of China (11973085, 11903077, 11803086, and 11633008), the Yunnan Ten-Thousand Talents Plan (the Yunling-Scholar Project), the national project for large scale scientific facilities (2019YFA0405001), and the Chinese Academy of Sciences., With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709.

著者人数: 16名, 資料番号: SA1004954000

著者人数: 25名, Accepted: 2011-05-05, 資料番号: SA1003063000

The SELENE mission, consisting of three separate satellites that use different terrestrial-based tracking systems, presents a unique opportunity to evaluate the contribution of these tracking systems to orbit determination precision. The tracking data consist of four-way Doppler between the main orbiter and one of the two sub-satellites while the former is over the far side, and of same-beam differential VLBI tracking between the two sub-satellites. Laser altimeter data are also used for orbit determination. The contribution to orbit precision of these different data types is investigated through orbit overlap analysis. It is shown that using four-way and VLBI data improves orbit consistency for all satellites involved by reducing peak values in orbit overlap differences that exist when only standard two-way Doppler and range data are used. Including laser altimeter data improves the orbit precision of the SELENE main satellite further, resulting in very smooth total orbit errors at an average level of 18 m. The multi-satellite data have also resulted in improved lunar gravity field models, which are assessed through orbit overlap analysis using Lunar Prospector tracking data. Improvements over a pre-SELENE model are shown to be mostly in the along-track and cross-track directions. Orbit overlap differences are at a level between 13 and 21 m with the SELENE models, depending on whether 1-day data overlaps or 1-day predictions are used.

著者人数: 15名, Accepted: 2010-08-03, 資料番号: SA1002891000

著者人数: 14名, Accepted: 2010-05-19, 資料番号: SA1002806000

著者人数: 22名, Accepted: 2011-05-09, 資料番号: SA1004347000

On December 27, 2004, plasma particle detectors on the GEOTAIL spacecraft detected an extremely strong signal of hard X-ray photons from the giant flare of SGR1806-20, a magnetar candidate. While practically all gamma-ray detectors on any satellites were saturated during the first ~500 ms interval after the onset, one of the particle detectors on GEOTAIL was not saturated and provided unique measurements of the hard X-ray intensity and the profile for the first 600 ms interval with 5.48 ms time resolution. After ~50 ms from the initial rapid onset, the peak photon flux (integrated above ~50 keV) reached the order of 10^7 photons sec^{-1} cm^{-2}. Assuming a blackbody spectrum with kT=175 keV, we estimate the peak energy flux to be 21 erg sec^{-1} cm^{-2} and the fluence (for 0-600 ms) to be 2.4 erg cm^{-2}. The implied energy release comparable to the magnetic energy stored in a magnetar (~10^{47} erg) suggests an extremely efficient energy release mechanism., Comment: 6 pages, 2 color figures, submitted to Nature

著者人数: 15名, 資料番号: SA1003662000

著者人数：11名, 資料番号: SA1000905000