| Project/Area Number |
08454134
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Space and upper atmospheric physics
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| Research Institution | HOKKAIDO UNIVERSITY |
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Principal Investigator |
ARAKAWA Masahiko Institute of Low Temperature Science, Hokkaido University, Ins., 低温科学研究所, 助手 (10222738)
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| Co-Investigator(Kenkyū-buntansha) |
KOUCHI Akira Institute of Low Temperature Science, Hokkaido University, Prof., 低温科学研究所, 教授 (60161866)
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| Project Period (FY) |
1996 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥7,800,000 (Direct Cost: ¥7,800,000)
Fiscal Year 1998: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1997: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1996: ¥5,900,000 (Direct Cost: ¥5,900,000)
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| Keywords | Icy satellite / Impact process / Shock-wave attenuation / Catastrophic disputation / Reaccumulation / 衝突破壊 / 二段式軽ガス銃 / 多結晶氷 / 衝撃波 / 最大破片 / クレーター / 微惑星 / 惑星集積過程 / 氷衛星 / 衝突破片 |
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| Research Abstract |
High velocity impact among icy planets is an important physical phenomenon related to the planetary accretion process in the outer solar system. Then, an impact experiment on water ice was made by using a micro two-stage light gas gun installed in a cold room (-10ﾟC) to clarify elementary processes of the collisional disruption and to study reaccumulation condition of the impact fragments. As a result, we clarified that the shock pressure attenuated in the ice target according to the relation of P = a (Lp/d)^2 irrespective of the mass ratio between 10^-3 to 10^-5, where Lp is a projectile size and d is a propagation distance. We also observed that the shock wave propagated with the velocity of 4.4 km/s at the shock pressure from 10 to 200 GPa ; 2.6 km/s at 200 MPa. Below 200 MPa, the shear fracture region expanded with the velocity of 1.7 km/s until the shock pressure decreased lower than 60 MPa. The reaccumulation condition of icy planets in the high velocity collisions was estimated to show that fragments disrupted from parent bodies with the radius larger than 500 km could reaccumulate at any conditions of the impact velocity from 500 m/s to 5 km/s and the mass ratio from 10^-2 to l0^-5.
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