Simulations of a comet impact on the Moon and associated ice deposition in polar cold traps
Simulations of a comet impact on the Moon and associated ice deposition in polar cold traps
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模拟彗星撞击月球以及相关的极地冷阱中的冰沉积
DOI：
10.1016/j.icarus.2011.03.014
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发表时间：
2011
期刊：
影响因子：
3.2
通讯作者：
L. Trafton
中科院分区：
文献类型：
--
作者：
B. Stewart;E. Pierazzo;D. Goldstein;P. Varghese;L. Trafton
给出了彗星撞击月球产生的水蒸气羽流以及由此产生的月球冷陷中的水冰沉积的模拟结果。用SOVA程序模拟了落点附近的水汽羽流，用直接模拟蒙特卡罗(DSMC)方法模拟了远场水汽羽流，计算的输入为固定半球界面的SOVA程序解。SOVA程序模拟了撞击事件的物理过程，如撞击过程中的表面变形和材料相变化。进一步的输送和滞留过程，包括重力、光破坏过程和具有局地极地冷陷的地表温度变化过程，在撞击后的几个月内用DSMC方法进行了模拟。为了跟踪水从撞击的近场进入完整的行星诱导大气，三维并行的DSMC程序使用了碰撞限制格式和非定常多域方法。给出了一颗直径2公里的彗星以30公里/S的速度45°斜撞击月球表面的三维结果。大部分彗星水在撞击后不久就会因逃逸而丢失，最初只有3%的彗星水被保留在月球上。(∼)可以观察到水蒸气羽流的早期向下聚焦，但运动较慢的后期物质随着时间的推移呈现出更对称的形状。对撞击点的几个位置进行了调查，并观察到∼最终保留率为彗星质量的0.1%。根据本模拟中使用的冷凝器的表面积，在这样一次撞击后，冷凝器中将积累1毫米∼的冰。极地冷空气陷阱中累积的总水量超过1byr的估计与最近的观测结果一致。
Modeling results of the water vapor plume produced by a comet impact on the Moon and of the resulting water ice deposits in the lunar cold traps are presented. The water vapor plume is simulated near the point of impact by the SOVA hydrocode and in the far field by the Direct Simulation Monte Carlo (DSMC) method using as input the SOVA hydrocode solution at a fixed hemispherical interface. The SOVA hydrocode models the physics of the impact event such as the surface deformation and material phase changes during the impact. The further transport and retention processes, including gravity, photodestruction processes, and variable surface temperature with local polar cold traps, are modeled by the DSMC method for months after impact. In order to follow the water from the near field of the impact to the full planetary induced atmosphere, the 3D parallel DSMC code used a collision limiting scheme and an unsteady multi-domain approach. 3D results for the 45° oblique impact of a 2km in diameter comet on the surface of the Moon at 30km/s are presented. Most of the cometary water is lost due to escape just after impact and only ∼3% of the cometary water is initially retained on the Moon. Early downrange focusing of the water vapor plume is observed but the later material that is moving more slowly takes on a more symmetric shape with time. Several locations for the point of impact were investigated and final retention rates of ∼0.1% of the comet mass were observed. Based on the surface area of the cold traps used in the present simulations, ∼1mm of ice would have accumulated in the cold traps after such an impact. Estimates for the total mass of water accumulated in the polar cold traps over 1byr are consistent with recent observations.
影响因子：
5.2
作者：
H. Noda;H. Araki;S. Goossens;Y. Ishihara;K. Matsumoto;S. Tazawa;N. Kawano;S. Sasaki
通讯作者：
H. Noda;H. Araki;S. Goossens;Y. Ishihara;K. Matsumoto;S. Tazawa;N. Kawano;S. Sasaki