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-PS04] 火星と火星圏の科学

2019年5月26日(日) 15:30 〜 17:00 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:宮本 英昭(東京大学)、臼井 寛裕(東京工業大学地球生命研究所)、松岡 彩子(宇宙航空研究開発機構 宇宙科学研究所 太陽系科学研究系)、Sushil K Atreya(University of Michigan Ann Arbor)

[PPS04-P10] Small-scale ridges newly identified on the equatorial region of the Phobos nearside

*逸見 良道1菊地 紘1宮本 英昭1 (1.東京大学)

キーワード:フォボス、HiRISE、数値標高モデル

Although the craters and grooves on Phobos are indicative of widespread and abundant surface modification during Phobos' geologic history [Basilevsky et al., 2014], little definitive evidence exists for geologically recent regolith migration other than down-slope mass-wasting [Shi et al., 2016]. Here we report newly found small-scale sinuous ridges identified in Mars Reconnaissance Orbiter's High Resolution Imaging Science Experiment (HiRISE [McEwen et al., 2007]) images of the nearside of Phobos. These ridges are spatially focused within the equatorial region (-5° to 20° N). Some of them superpose on craters and grooves, which is consistent with a geologically recent activity. They are ~200 m to ~1 km in length, several 10's m in width, and most of them are roughly parallel to each other and are generally oriented in NE-SW direction. To extract detailed topographic profiles, we constructed a high-resolution (~5-6 m/pixel; almost same as the original image) digital elevation model (DEM) by using shape-from-shading [Alexandrov and Beyer, 2018] in the selected regions of a HiRISE image and a stereo-derived HiRISE DEM (20 m/pixel) [Hemmi and Miyamoto, 2019]. Our preliminary analysis shows these ridges are less than several meters high. Their morphology and topography are unlikely to be formed by impact cratering, extensional stress fields, or mass wasting processes. In this presentation, we provide initial results of geological mapping of the small-scale ridges and discuss their possible origins.

References
Alexandrov, O., and R. A. Beyer (2018), Multiview Shape-From-Shading for Planetary Images, Earth and Space Science, 5(10).
Basilevsky, A. T., C. A. Lorenz, T. V. Shingareva, J. W. Head, K. R. Ramsley, and A. E. Zubarev (2014), The surface geology and geomorphology of Phobos, Planetary and Space Science, 102, 95-118.
Hemmi, R., and H. Miyamoto (2019), HiRISE digital elevation model of Phobos: Implications for morphological analysis of grooves, Proceedings of the 50th Lunar and Planetary Science Conference, Abstract No. 1759.
McEwen, A. S., et al. (2007), Mars Reconnaissance Orbiter's High Resolution Imaging Science Experiment (HiRISE), Journal of Geophysical Research: Planets, 112(E5), E05S02.
Shi, X., J. Oberst, and K. Willner (2016), Mass wasting on Phobos triggered by an evolving tidal environment, Geophysical Research Letters, 43(24), 12,371-312,379.