日本地球惑星科学連合2019年大会

講演情報

[E] 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-PS03] Solar System Small Bodies: A New Frontier Arising Hayabusa 2, OSIRIS-REx and Other Projects

2019年5月29日(水) 17:15 〜 18:30 ポスター会場 (幕張メッセ国際展示場 8ホール)

コンビーナ:石黒 正晃(ソウル大学物理天文学科)、中本 泰史(東京工業大学)、安部 正真(宇宙航空研究開発機構宇宙科学研究所)、Olivier S Barnouin(Johns Hopkins University Applied Physics Laboratory)

[PPS03-P03] Flyby observation of Asteroid (3200) Phaethon by DESTINY+ onboard cameras

*石橋 高1亀田 真吾2鍵谷 将人3洪 鵬1山田 学1奥平 修1荒井 朋子1吉田 二美1佐藤 峻介4石丸 貴博4岡本 尚也4岩田 隆浩4岡田 達明4高島 健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:ファエトン、デスティニー・プラス、フライバイ、カメラ

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 2023. DESTINY+ is a joint mission of technology demonstration and scientific observation. The near-Earth asteroid (3200) Phaethon, the flyby target, is known as a parent body of the Geminid meteor shower, the size of which is approximately 5 to 6 km in diameter.

In this mission, 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) during the flyby, in order to understand the nature of a meteor shower's parent body, which is one of the sources of interplanetary dust particles that are thought to be an important transport medium of organic matter to the Earth. The spacecraft flybys Phaethon with a relative speed of 30 to 40 km/s. Despite such a high flyby speed, the cameras are required to take un-blurred images of Phaethon.

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.

TCAP is a telescopic panchromatic camera for high spatial resolution imaging of the surface of Phaethon and have a rotational mirror for asteroid tracking during flyby. The rotational mirror can change the direction of the line of sight from 0 deg to 180 deg. This enables to observe Phaethon throughout the flyby with wide solar phase angles, which is extremely important to image and understand the surfaces of planetary bodies because the solar phase angle affects significantly the appearance of geological features in taken images.

MCAP is a multiband camera, the wavelengths of which are 400, 480, 550, 700, 850, and 950 nm (480 and 950 nm are optional bands) and has multiple optical systems and sensors in order to take all band images simultaneously. This is because there is not enough time to take each band image in turn with changing bandpass filters using such as a filter wheel in this high speed flyby mission. MCAP does not have a tracking mirror due to the weight limitation, and the line of sight of MCAP is fixed to the spacecraft with 40 deg off the relative velocity vector of the spacecraft.

We will explain the flyby imaging sequence of DESTINY+, and show the conceptual designs of TCAP and MCAP.