Impact and intrusion experiments on the deceleration of low-velocity impactors by small-body regolith
Impact and intrusion experiments on the deceleration of low-velocity impactors by small-body regolith
复制标题
小体风化层对低速撞击体减速的撞击与侵入实验
DOI：
10.1016/j.icarus.2013.02.023
复制
发表时间：
2012
期刊：
影响因子：
3.2
通讯作者：
K. et al.
中科院分区：
文献类型：
--
作者：
Nakamura;A. M.;Setoh;M.;Wada;K. et al.
小的原始体在形成时可能是高度多孔的，有些仍然具有低密度，这表明孔隙含量很高。因此，在它们形成后，撞击在它们表面的行星际尘埃可能因为它们的多孔结构而被捕获。因此，尘埃穿透机制对于理解小天体的演化及其内部尘埃粒子的起源具有重要意义。烧结玻璃珠靶的冲击实验特征为80%，87%和94%的体积孔隙率，使用金属和玄武岩弹丸在1.6至7.2kms-1的冲击速度范围内进行。轨道形态和渗透过程进行了分析，使用X射线断层扫描和闪光X射线系统。观察到两种类型的轨迹，正如以前在星尘气凝胶中发现的那样：一种细长的轨迹（胡萝卜形轨迹）和一种带尾巴的“灯泡”（灯泡形轨迹）。初始动压的变化会改变轨道的形状。我们发现，“胡萝卜”和“灯泡”之间的过渡发生在大约20倍的弹丸的拉伸强度的压力。利用与弹丸速度平方成正比的惯性阻力和与靶板抗压强度成正比的常阻力组成的阻力方程，再现了弹丸在没有严重变形和破碎的情况下的减速过程。我们应用这个减速方程的硅酸盐尘埃渗透到假设的多孔冰体是均匀的小得多的尺度上比撞击尘埃颗粒。对于孔隙率为90%的物体，穿透深度约为射弹直径的100倍。
Small primitive bodies were presumably highly porous when they formed and some still have low densities that are indicative of a high pore content. Therefore, after their formation, interplanetary dust impacting on their surface may have been captured because of their porous structure. The mechanism of dust penetration is thus of importance to understand the evolution of small bodies and the origin of their internal dust particles. Impact experiments of sintered glass-bead targets characterized by 80%, 87%, and 94% bulk porosity were conducted using metal and basalt projectiles at impact velocities ranging from 1.6 to 7.2kms−1. Track morphology and penetration processes were analyzed using both X-ray tomography and a flash X-ray system. Two types of track were observed, as previously also found in the Stardust aerogel: a thin and long track (carrot-shaped track), and a “bulb” with tails (bulb-shaped track). The track shape changed with initial dynamic pressure. We found that the transition between “carrot” and “bulb” occurred at a pressure of roughly 20 times the projectile’s tensile strength. The deceleration process of projectiles without severe deformation and fragmentation was reproduced by a drag equation composed of an inertia drag that was proportional to the square of the projectile’s velocity and a constant drag proportional to the target’s compressive strength. We applied this deceleration equation to silicate dust penetrating into hypothetical porous icy bodies which were homogeneous on much smaller scales than the impacting dust particles. The penetration depth was approximately 100 times the projectile diameter for the bodies with 90% porosity.