著者

Eizo NAKAMURA Katsura KOBAYASHI Ryoji TANAKA Tak KUNIHIRO Hiroshi KITAGAWA Christian POTISZIL Tsutomu OTA Chie SAKAGUCHI Masahiro YAMANAKA Dilan M. RATNAYAKE Havishk TRIPATHI Rahul KUMAR Maya-Liliana AVRAMESCU Hidehisa TSUCHIDA Yusuke YACHI Hitoshi MIURA Masanao ABE Ryota FUKAI Shizuho FURUYA Kentaro HATAKEDA Tasuku HAYASHI Yuya HITOMI Kazuya KUMAGAI Akiko MIYAZAKI Aiko NAKATO Masahiro NISHIMURA Tatsuaki OKADA Hiromichi SOEJIMA Seiji SUGITA Ayako SUZUKI Tomohiro USUI Toru YADA Daiki YAMAMOTO Kasumi YOGATA Miwa YOSHITAKE Masahiko ARAKAWA Atsushi FUJII Masahiko HAYAKAWA Naoyuki HIRATA Naru HIRATA Rie HONDA Chikatoshi HONDA Satoshi HOSODA Yu-ichi IIJIMA Hitoshi IKEDA Masateru ISHIGURO Yoshiaki ISHIHARA Takahiro IWATA Kosuke KAWAHARA Shota KIKUCHI Kohei KITAZATO Koji MATSUMOTO Moe MATSUOKA Tatsuhiro MICHIKAMI Yuya MIMASU Akira MIURA Tomokatsu MOROTA Satoru NAKAZAWA Noriyuki NAMIKI Hirotomo NODA Rina NOGUCHI Naoko OGAWA Kazunori OGAWA Chisato OKAMOTO Go ONO Masanobu OZAKI Takanao SAIKI Naoya SAKATANI Hirotaka SAWADA Hiroki SENSHU Yuri SHIMAKI Kei SHIRAI Yuto TAKEI Hiroshi TAKEUCHI Satoshi TANAKA Eri TATSUMI Fuyuto TERUI Ryudo TSUKIZAKI Koji WADA Manabu YAMADA Tetsuya YAMADA Yukio YAMAMOTO Hajime YANO Yasuhiro YOKOTA Keisuke YOSHIHARA Makoto YOSHIKAWA Kent YOSHIKAWA Masaki FUJIMOTO Sei-ichiro WATANABE Yuichi TSUDA

出版者

The Japan Academy

雑誌

Proceedings of the Japan Academy, Series B (ISSN:03862208)

巻号頁・発行日

vol.98, no.6, pp.227-282, 2022-06-10 (Released:2022-06-10)

参考文献数

245

被引用文献数

90

---

Presented here are the observations and interpretations from a comprehensive analysis of 16 representative particles returned from the C-type asteroid Ryugu by the Hayabusa2 mission. On average Ryugu particles consist of 50% phyllosilicate matrix, 41% porosity and 9% minor phases, including organic matter. The abundances of 70 elements from the particles are in close agreement with those of CI chondrites. Bulk Ryugu particles show higher δ18O, Δ17O, and ε54Cr values than CI chondrites. As such, Ryugu sampled the most primitive and least-thermally processed protosolar nebula reservoirs. Such a finding is consistent with multi-scale H-C-N isotopic compositions that are compatible with an origin for Ryugu organic matter within both the protosolar nebula and the interstellar medium. The analytical data obtained here, suggests that complex soluble organic matter formed during aqueous alteration on the Ryugu progenitor planetesimal (several 10’s of km), <2.6 Myr after CAI formation. Subsequently, the Ryugu progenitor planetesimal was fragmented and evolved into the current asteroid Ryugu through sublimation.

著者

Hiroshi ARAKI Ko ISHIBASHI Noriyuki NAMIKI Hirotomo NODA Masanori KOBAYASHI Keigo ENYA Masanobu OZAKI Takahide MIZUNO Yoshifumi SAITO Kazuyuki TOUHARA Shoko OSHIGAMI Shingo KASHIMA Jun KIMURA Shingo KOBAYASHI Gregor STEINBRUEGGE Alexander STARK Christian ALTHAUS Simone Del TOGNO Kay LINGENAUBER Hauke HUSSMANN

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN (ISSN:18840485)

巻号頁・発行日

vol.17, no.2, pp.150-154, 2019 (Released:2019-03-04)

参考文献数

10

被引用文献数

1

---

GALA (GAnymede Laser Altimeter) is one of the payload instruments of the JUICE (JUpiter ICy moons Explorer) project to be launched in 2022 to the Jovian icy moons Ganymede, Europa, and Callisto. GALA is developed through an international collaboration between Germany, Japan, Switzerland, and Spain. With the performance model of GALA, we have sought to create the interface conditions that satisfy the science requirements on the probability of false detection (PFD) and the range accuracy. The science requirements on GALA performance can be summarized as involving the following four criteria: [1] for Europa fly-by, PFD is less than 0.2 from an altitude of 1300 km or lower, [2] under the worst observation condition for albedo and surface slope of GCO500 (Ganymede Circular Orbit whose height is 500 km), the accuracy of ranging is less than 10 m and PFD is less than 0.2, [3] under the nominal observation condition of GCO500, the accuracy of ranging is less than 2 m and PFD is less than 0.1, and [4] under the best observation condition of GCO500, the accuracy of ranging is less than 1 m and PFD is less than 0.1. For the assessment, however, we had used literature data as the characteristics of the laser detector of GALA, avalanche photodiode (APD), which should be degraded due to the severe radiation environment around Jupiter. Then we carried out a more realistic model simulation of GALA by incorporating these degradation effects of APD. Characteristics of APD, such as gain, quantum efficiency, excess noise index, surface dark current, and bulk dark current, were re-evaluated through radiation tests using the data of dark and photo current of the APD irradiated with 2-MeV-electron and 50-MeV-proton beams, which are the radiation conditions assumed for JUICEGALA around Jupiter. These degraded characteristics of APD by radiation were introduced to our performance model of GALA. As a result, our performance simulation of GALA showed again that the science requirements are satisfied even after taking into account the degraded characteristics of APD. The remaining matter is the effect of noise or digitization in the Analog Electronics Module (AEM), which must be taken into account for the final specifications of GALA.