Impact investigations will be an important aspect of the InSight mission. One of the scientific goals of the mission is a measurement of the current impact rate at Mars. Impacts will additionally inform the major goal of investigating the interior structure of Mars.In this paper, we review the current state of knowledge about seismic signals from impacts on the Earth, Moon, and laboratory experiments. We describe the generalized physical models that can be used to explain these signals. A discussion of the appropriate source time function for impacts is presented, along with spectral characteristics including the cutoff frequency and its dependence on impact momentum. Estimates of the seismic efficiency (ratio between seismic and impact energies) vary widely. Our preferred value for the seismic efficiency at Mars is 5×10−4$5 \times 10^{- 4}$, which we recommend using until we can measure it during the InSight mission, when seismic moments are not used directly. Effects of the material properties at the impact point and at the seismometer location are considered. We also discuss the processes by which airbursts and acoustic waves emanate from bolides, and the feasibility of detecting such signals.We then consider the case of impacts on Mars. A review is given of the current knowledge of present-day cratering on Mars: the current impact rate, characteristics of those impactors such as velocity and directions, and the morphologies of the craters those impactors create. Several methods of scaling crater size to impact energy are presented. The Martian atmosphere, although thin, will cause fragmentation of impactors, with implications for the resulting seismic signals.We also benchmark several different seismic modeling codes to be used in analysis of impact detections, and those codes are used to explore the seismic amplitude of impact-induced signals as a function of distance from the impact site. We predict a measurement of the current impact flux will be possible within the timeframe of the prime mission (one Mars year) with the detection of ∼ a few to several tens of impacts. However, the error bars on these predictions are large.Specific to the InSight mission, we list discriminators of seismic signals from impacts that will be used to distinguish them from marsquakes. We describe the role of the InSight Impacts Science Theme Group during mission operations, including a plan for possible night-time meteor imaging. The impacts detected by these methods during the InSight mission will be used to improve interior structure models, measure the seismic efficiency, and calculate the size frequency distribution of current impacts.

中文翻译：

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InSight 任务的冲击地震调查

影响调查将是洞察号任务的一个重要方面。该任务的科学目标之一是测量火星当前的撞击率。撞击还将为研究火星内部结构的主要目标提供信息。在本文中，我们回顾了对地球、月球和实验室实验的撞击产生的地震信号的当前知识状态。我们描述了可用于解释这些信号的广义物理模型。讨论了适当的撞击源时间函数，以及包括截止频率及其对撞击动量的依赖性在内的光谱特征。地震效率（地震和冲击能量之间的比率）的估计差异很大。我们对火星地震效率的首选值是 5×10−4$5 \times 10^{- 4}$，我们建议使用它，直到我们可以在 InSight 任务期间对其进行测量，此时不直接使用地震矩。考虑了冲击点和地震仪位置处材料特性的影响。我们还讨论了空爆和声波从火流中发出的过程，以及探测这些信号的可行性。然后我们考虑撞击火星的情况。回顾了目前火星上的陨石坑的当前知识：当前的撞击率、这些撞击物的特征（例如速度和方向）以及这些撞击物造成的陨石坑的形态。介绍了几种根据撞击能量缩放陨石坑大小的方法。火星大气虽然稀薄，但会导致撞击物碎裂，从而影响产生的地震信号。我们还对用于分析撞击检测的几种不同地震建模代码进行了基准测试，这些代码用于探索作为与撞击地点距离的函数的撞击诱发信号的地震振幅。我们预测，在主要任务的时间范围内（一个火星年），可以测量当前的撞击通量，并检测到几到几十次的撞击。然而，这些预测的误差条很大。针对洞察号任务，我们列出了撞击产生的地震信号的鉴别器，这些鉴别器将用于将它们与地震区分开来。我们描述了洞察力影响科学主题小组在任务操作期间的作用，包括可能的夜间流星成像计划。