日本地球惑星科学連合2016年大会

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インターナショナルセッション(ポスター発表)

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

2016年5月22日(日) 17:15 〜 18:30 ポスター会場 (国際展示場 6ホール)

コンビーナ:*木村 淳(東京工業大学地球生命研究所)、藤本 正樹(宇宙航空研究開発機構・宇宙科学研究本部)、笠羽 康正(東北大学大学院 理学研究科 地球物理学専攻)、佐々木 晶(大阪大学大学院理学研究科宇宙地球科学専攻)、谷川 享行(産業医科大学医学部)、関根 康人(東京大学大学院理学系研究科地球惑星科学専攻)、Sayanagi Kunio(Atmospheric and Planetary Sciences Department, Hampton University)、Vance Steven(Jet Propulsion Laboratory, Caltech)

17:15 〜 18:30

[PPS01-P11] Science Experiments with the Trojan Asteroid Lander in the Solar Powered Sail Mission

*岡田 達明1ジャンピエール ビブリン2ウラメッツ ステファン3ビール イェンス3中村 良介4矢野 創1癸生川 陽子5青木 順6河井 洋輔6薮田 ひかる6伊藤 元雄7斎藤 義文1横田 勝一郎1グラン ノエル8コティン エルベ8ティルケル ロラン9ブリオワ クリステル9岩田 隆浩1松岡 彩子1松本 純10加藤 英樹1森 治1川口 淳一郎1 (1.宇宙航空研究開発機構宇宙科学研究所、2.フランス宇宙物理学研究所、3.ドイツ航空宇宙センター、4.産業技術総合研究所、5.横浜国立大学、6.大阪大学、7.海洋研究開発機構高知コア研究所、8.パリ12大学LISA、9.フランス国立科学研究センター、10.東京大学)

キーワード:Trojan asteroid, Solar Sail, Lander, High Resolution Mass Spectrometry, Solar-Powered Sail, Subsurface sample

Scientific exploration on the Jupiter Trojan asteroid is under study for the solar-powered sail (SPS) mission. This mission includes a scientific lander jointly studied by Japanese and European engineers and scientists [1]. We present the objectives and the strawman payloads for this mission.
The SPS is a candidate as the next medium class space science mission in Japan. This engineering mission is based on the technologies such as the solar sail and the ion engine system inherited from Ikaros and Hayabusa missions, respectively. With this hybrid propulsion system, the spacecraft will cruise to the Jupiter and beyond, even if a radioisotope thermoelectric generator (RTG) is not used. A Trojan asteroid will be investigated by remote sensing after rendezvous, and then a small lander will be deployed from the mothership to conduct in situ experiments on the asteroid. As an option, sample will be returned to the Earth. Mission duration is typically 15 years to arrive at the Trojan asteroid, and 30 years in total for Earth return. The shortest one way trip to the asteroid is less than 12 years. The lander should be designed within 100 kg wet mass. Total mission payloads should be within 20 kg, including all the science payloads, sampling and sample return systems [2].
Jupiter Trojan asteroids are located around the Sun-Jupiter Lagrange points. Most of them are volatile-rich D- or P-type asteroids, and their origin and evolution, composition and physical conditions still remain unknown. In a classical model of solar system evolution, they formed around the Jupiter orbit and survive until now. But in a recent model such as Nice model [3], they formed at the far end of the solar system and transferred inward due to dynamical migration of giant planets. Physical, mineralogical, and isotopic studies of surface materials could solve their origin and evolution processes, as well as the solar system formation [4]. To achieve these goals, in situ observations using the lander is planned, as well as the asteroid global characterization with a near-infrared hyperspectral imager.
Geological, mineralogical, and geophysical observations will be conducted to characterize the landing site, by using a panoramic camera, an infrared hyperspectral imager, a magnetometer, and a thermal radiometer. The surface conditions and composition will be investigated with a close-up imager and a Raman spectrometry. The imager is also used to check the conditions whether the sampling could be done or not. If the configuration is unsuitable for sampling, the lander must relocate and change the configuration. The surface and subsurface materials will be collected into a carousel by bullet-type and pneumatic drill type samplers, respectively. Samples in the each case of carousel will be viewed by infrared microscope to identify them. Those samples will be transferred for evaporation of volatiles for high resolution mass spectrometry (HRMS). Some samples will be heated for pyrolysis for isotopic analysis. Mass resolution m/Δm > 30,000 is required to investigate isotopic ratios of D/H, 15N/14N, and 18O/16O, as well as molecules from organic matters (M = 30 to 1000).The MULTUM type in Japan and the Cosmorbitrap type in France are being investigated for the HRMS. A set of strawman payloads are now considered to meet the science, mission, and system requirements and constraints (total mass < 20kg, and total energy consumption < 600 WHr). They will be finally determined by the international announce of opportunity.
References: [1] Mori O. et al. (2015) 11th Low-Cost Planetary Missions Conf., S3-10. [2] Saiki T. et al. (2015) ISSFD2015, S19-3, #84. [3] Morbidelli A. et al. (2005) Nature 435, 462-466. [4] Yano H. et al., (2014) COSPAR 2014, B0.4-2-14. [5] Mori O. et al. (2016) Lunar Planet. Sci. Conf. , submitted.