[P-PS05] 火星と火星衛星

[PPS05-01] Martian Moons Exploration MMX: An Overview of Its Progress

*倉本 圭^1,2、川勝 康弘²、藤本 正樹²、Barucci Maria³、玄田 英典⁴、平田 成⁵、今村 剛⁶、Helbert Jörn⁷、亀田 真吾⁸、小林 正規⁹、草野 広樹¹⁰、Lawrence David¹¹、松本 晃治¹²、Michel Patrick¹³、宮本 英昭⁶、中川 広務¹⁴、中村 智樹¹⁴、小川 和律²、大嶽 久志²、尾崎 正伸¹²、Russell Sara¹⁵、佐々木 晶¹⁶、千秋 博紀⁹、寺田 直樹¹⁴、Ulamec Stephan⁷、臼井 寛裕²、和田 浩二⁹、横田 勝一郎¹⁶ (1.北海道大学、2.宇宙航空研究開発機構、3.Paris Observatory、4.東京工業大学、5.会津大学、6.東京大学、7.DLR、8.立教大学、9.千葉工業大学、10.量子科学技術研究開発機構、11.Johns Hopkins University APL、12.国立天文台、13.Université Côte d’azur、14.東北大学、15.Natural History Museum、16.大阪大学)

キーワード：フォボス、ダイモス、サンプルリターン、MMX、火星、惑星形成

The Martian Moons Exploration (MMX), to be the world's first sample return mission from the Martian system, has almost completed its critical design review (as of February 2023), and its development is moving toward the manufacturing phase of the spacecraft. The designs of spacecraft system, mission instruments, ground system, orbit, and spacecraft operation are going completed. The mission scenario is kept unchanged from the original plan: launch next year, about one year cruise to Mars, three years stay near the moons, and one year on the way back. This includes detailed observation of Phobos, rover drop to Phobos, two landings and sample collection, fly-by observation of Deimos, and Mars atmosphere observation during the period of stay. The onboard science instruments, telescopic camera TENGOO, light detection and ranging LIDAR, wide angle multiband visible camera OROCHI, near-infrared spectrometer MIRS, gamma-ray, neutron spectrometer MEGANE, ion mass spectrometer MSA, dust monitor CMDM, rover, and samplers are achieving the performance required to elucidate the origin of Mars satellites, early solar system processes leading to the formation of habitable planets, and the evolution of the Mars atmosphere. One of the bus instruments, the CAM-T telescopic camera, is identical in design to TENGOO and, when used together, will enhance Phobos' terrain mapping imaging, which is essential for landing site selection. The engineering requirements for a landing site include sunlight availability, earth visibility, reachability from orbit, small surface undulation, and a small slope. On the other hand, the accessibility of less-weathered, Phobos indigenous materials is the most important scientific requirement for landing site selection. The currently available shape model of Phobos and the analysis of possible landing sequences have shown that there are multiple areas on the anti-Mars and Mars sides of Phobos that could meet the engineering requirements. Local slopes and surface undulations on horizontal scales same and below the size of the spacecraft (about 4 m between landing legs), which are necessary to ensure a safe landing of the spacecraft, cannot be specified even in the highest resolution images available at this time. The actual landing sites will be selected based on the results of detailed proximity observations from orbit for about one year from the arrival to the proximity of Phobos. Deimos flyby observations and continuous observations of the Martian atmosphere will be concentrated on the period immediately after insertion into the areocentric orbit and just before escape from the Martian sphere of gravity. For returned samples with a targeting total weight > 20 g, the early curation phase will involve the characterization of optical, mechanical, and thermal properties of the sample as an aggregate that can be compared with close-up observation data of Phobos. Preliminary analyses will be intensified before the initiation of the initial analyses to make a guide promoting the detailed analyses. Because achieving the science objectives of the mission requires cross-investigation of data from multiple instruments and sample analysis, five science strategy teams (SSTs: Origin of Phobos and Deimos, Early solar system evolution, Surface science and geology, Mars science, and Geodesy) are collaborating also with the working teams responsible for instrument development, operational design, data processing, landing site selection, and sample analysis to promote preparatory activities to generate science results.