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首页> 外文期刊>Planetary and space science >Low-speed impact simulations into regolith in support of asteroid sampling mechanism design Ⅰ: Comparison with 1-g experiments
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Low-speed impact simulations into regolith in support of asteroid sampling mechanism design Ⅰ: Comparison with 1-g experiments

机译：支持小行星采样机制设计的低速撞击硬粒岩模拟Ⅰ：与1-g实验的比较

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摘要

This study is carried out in the framework of sample-return missions to asteroids that use a low-speed projectile as the primary component of its sampling mechanism (e.g., JAXA's Hayabusa and Hayabusa2 missions). We perform numerical simulations of such impacts into granular materials using different projectile shapes under Earth's gravity. We then compare the amounts of ejected mass obtained in our simulations against what was found in experiments that used similar setups, which allows us to validate our numerical approach. We then investigate the sensitivity of various parameters involved in the contacts between grains on the amount of mass that is ejected. For the targets, we consider 2 different monodisperse grain-diameter sizes: 5 mm and 3 mm. The impact speed of the projectile is 11 m s~(-1), and is directed downward, perpendicular to the surface of the targets. Using an implementation of the soft-sphere discrete element method (SSDEM) in the N-body gravity tree code pkdgrav, previously validated in the context of low-speed impacts into sintered glass bead agglomerates, we find a noticeable dependence of the amount of ejected mass on the projectile shape. As found in experiments, in the case of the larger target grain size (5 mm), a conically shaped projectile ejects a greater amount of mass than do projectiles of other shapes, including disks and spheres. We then find that numerically the results are sensitive to the normal coefficient of restitution of the grains, especially for impacts into targets comprising smaller grains (3 mm). We also find that static friction plays a more important role for impacts into targets comprising the larger grains. As a preliminary demonstration, one of these considered setups is simulated in a microgravity environment As expected, a reduction in gravity increases both the amount of ejected mass and the timescale of the impact process. A dedicated quantitative study in microgravity is the subject of future work. We also plan to study other aspects of the ejection process such as velocity distributions and crater properties, and to adapt our methodology to the conditions of sampling mechanisms included in specific mission designs.
机译：这项研究是在对以低速弹丸作为其采样机制主要成分的小行星进行样本返回任务的框架内进行的（例如JAXA的Hayabusa和Hayabusa2任务）。我们在地球重力作用下使用不同的弹丸形状对颗粒材料进行这种冲击的数值模拟。然后，我们将在模拟中获得的弹出质量与使用类似设置的实验中发现的质量进行比较，这使我们能够验证我们的数值方法。然后，我们研究了颗粒之间接触中涉及的各种参数对所排出的质量的敏感性。对于目标，我们考虑2种不同的单分散晶粒直径尺寸：5 mm和3 mm。弹丸的撞击速度为11 m s〜（-1），垂直于目标表面向下定向。使用N体重力树代码pkdgrav中的软球离散元方法（SSDEM）的实现（先前已在低速撞击烧结玻璃珠附聚物的情况下进行了验证），我们发现射出量的显着依赖性弹丸形状上的质量。如在实验中发现的，在较大的目标晶粒尺寸（5毫米）的情况下，圆锥形弹丸比其他形状的弹丸（包括圆盘和球形）弹丸发射的质量更大。然后，我们发现从数值上讲，结果对晶粒的正常恢复系数敏感，尤其是对于冲入包含较小晶粒（3毫米）的目标的冲击时。我们还发现，静摩擦对于冲击包含较大晶粒的目标具有更重要的作用。作为初步演示，可以在微重力环境中模拟这些考虑的设置之一。如预期的那样，重力的减小既增加了射出质量的数量，又增加了撞击过程的时间尺度。微重力的专门定量研究是未来工作的主题。我们还计划研究弹射过程的其他方面，例如速度分布和弹坑特性，并使我们的方法适应特定任务设计中包含的采样机制的条件。

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  • 来源
    《Planetary and space science》 |2014年第11期|174-183|共10页
  • 作者

    Stephen R. Schwartz; Patrick Michel; Derek C. Richardson; Hajime Yano;

  • 作者单位

    Department of Astronomy, University of Maryland, College Park, 20740-2421, United States,Lagrange Laboratory, University of Nice Sophia Antipolis, CNRS, Observatoire de la Cote d'Azur, C.S. 34229, 06304 Nice Cedex 4, France,UMR 7293 Lagrange/CNRS, Observatoire de la Cote d'Azur, C.S. 34229,06304 Nice Cedex 4, France;

    Lagrange Laboratory, University of Nice Sophia Antipolis, CNRS, Observatoire de la Cote d'Azur, C.S. 34229, 06304 Nice Cedex 4, France;

    Department of Astronomy, University of Maryland, College Park, 20740-2421, United States;

    Department of Interdisciplinary Space Science, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210, Japan;

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  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    Asteroids; Surfaces; Collisional physics; Granular material; Sampling mechanism; Geological processes; Regoliths;

    机译：小行星;表面;大学物理;粒状材料;采样机制;地质过程;雷哥利斯;

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