Permalink : http://hdl.handle.net/2115/34720

氷衛星上の衝突クレーターや外惑星領域における惑星・衛星の衝突集積過程に関連して，氷を用いた高速度衝突実験が行われている．氷の衝突実験は融けやすい氷の取り扱いに問題が生じ精度の高い実験をすることが難しかったが，衝突実験装置自体を大型の低温室に設置することによりその問題が解 決され，研究が飛躍的に進歩した．特に氷中を伝播する衝撃波や破壊素過程の理解が進み，さらに弾丸にも氷を用いた高速度衝突実験が衝突速度700m/sまで可能となった．その結果，氷クレーターの形態変化やスケール則及び氷の衝突破壊強度が明らかになった．
Impact experiments on water ice have been conducted to study impact crater formation on icy satellites and collisional accretion process of icy bodies. It was difficult to use water ice for collisional experiments in a laboratory because it was easy to melt at room temperature. In order to overcome this difficulty, an impact facility was set in a large cold room below 0℃, and this method is successful to advance the impact study on water ice. Elementary physical processes related to impact disruption were especially studied to achieve a good progress. Furthermore, it was enabled that an ice projectile was accelerated at the impact velocity higher than 700m/s. As a result, the impact strength of water ice was obtained to be one order of magnitude smaller than that of basalt, and a systematic change of crater morphologies with the impact velocity and the scaling law on the impact crater was extensively studied.