[P-PS03] 太陽系小天体研究：現状の理解と将来の展望

[PPS03-P05] Flyby observation of Asteroid Phaethon by DESTINY⁺ onboard cameras

*石橋 高¹、亀田 真吾²、鍵谷 将人³、洪 鵬¹、岡本 尚也¹、山田 学¹、奥平 修¹、荒井 朋子¹、吉田 二美¹、石丸 貴博⁴、佐藤 峻介⁴、高島 健⁴、岩田 隆浩⁴、岡田 達明⁴ (1.千葉工業大学、2.立教大学、3.東北大学、4.宇宙航空研究開発機構)

キーワード：フェートン、DESTINY+、フライバイ

DESTINY⁺ (Demonstration and Experiment of Space Technology for INterplanetary voYage, Phaethon fLy-by and dUst Science) is a mission proposed for JAXA/ISAS Epsilon class small program, currently in the pre-project phase (Phase-A) with a launch targeted for 2022. DESTINY⁺ is a joint mission of technology demonstration and scientific observation. The science mission objectives are (1) to measure physical and chemical properties of cosmic dusts around 1 au and (2) to conduct geological observation of Phaethon upon flyby and analyze dusts nearby Phaethon. Phaethon is known as a parent body of the Geminid meteor shower, the size of which is approximately 6 km in diameter. Phaethon is important as a known source for cosmic dust delivered to the Earth. During the flyby of Phaethon spatially resolved images of Phaethon will be taken by two onboard cameras, the Telescopic CAmera for Phaethon (TCAP) and the Multiband CAmera for Phaethon (MCAP). The relative flyby speed is as high as 33 km/s and the distance at the closest approach is approximately 500 km. The main purposes of the DESTINY⁺ flyby observation of Phaethon is to understand the geology of a parent body of a meteor shower, and in particular constrain the dust ejection mechanisms from active (i.e., dust-ejecting) asteroids. The specific objectives of the camera observation are taking images for (1) obtaining the light curve of Phaethon in order to estimate the rotational period, (2) measuring the outline shape of Phaeton, (3) making a 3D shape model of Phaethon, (4) observing the surface geological features of Phaethon including dust ejection features, and (5) observing the surface material distribution of Phaethon. The observations (1) to (4) will be conducted by TCAP, and (5) by MCAP. We will explain the flyby imaging sequence of DESTINY⁺, and show the conceptual designs of TCAP and MCAP.