Abstract The interior structures of small planetary bodies such as asteroids and comets are an enigma. Determining the internal structure is important for understanding the formation and evolution of the solar system and also has implications for in-situ resource exploitation and planetary defense. Despite the immense value, no detailed investigation of the interior properties of an asteroid has yet been made. Although orbital radar and lander based seismological approaches have been proposed to make direct interior observations, it has not yet been demonstrated that radar could transmit through a rocky asteroid, nor that landing multiple seismometers is feasible or affordable. An elegant alternative to landed seismometers is orbital laser Doppler vibrometry, which could record seismic shaking of a small body without contact with the surface. Laser Doppler vibrometers (LDVs) are mature instruments for terrestrial applications and could be adapted for a space environment. However, when incident on a rough surface like an asteroid regolith, an LDV is subject to laser speckle noise which may be misinterpreted as seismic shaking. We address the challenge of making LDV measurements on naturally rough surfaces by quantifying the laser speckle noise that an orbital LDV would encounter during a hypothetical orbital measurement. Specifically, we simulate an LDV measurement of a seismic signal generated by an impact source on the asteroid 101955 Bennu. We demonstrate that speckle noise can be attenuated by combining multiple signals recorded by an orbital seismometer equipped with multiple LDV sensors. By mitigating laser speckle, we demonstrate that an orbital LDV can record seismic signals on a natural asteroid surface, which would enable an orbital seismometer to achieve the dense global coverage necessary for high resolution interior imaging.

中文翻译：

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轨道激光测振仪地震学中的散斑噪声衰减

摘要 小行星、彗星等小型行星体的内部结构是一个谜。确定内部结构对于理解太阳系的形成和演化很重要，对原位资源开发和行星防御也有影响。尽管价值巨大，但尚未对小行星的内部特性进行详细调查。尽管已经提出了基于轨道雷达和着陆器的地震学方法来进行直接的内部观测，但尚未证明雷达可以通过岩石小行星进行传输，也没有证明登陆多个地震仪是可行的或负担得起的。着陆地震仪的一个优雅替代品是轨道激光多普勒测振仪，它可以在不接触地表的情况下记录小天体的地震震动。激光多普勒测振仪 (LDV) 是用于地面应用的成熟仪器，可适用于空间环境。然而，当入射到像小行星风化层这样的粗糙表面时，LDV 会受到激光散斑噪声的影响，这可能会被误解为地震震动。我们通过量化轨道 LDV 在假设轨道测量期间遇到的激光散斑噪声来解决在自然粗糙表面上进行 LDV 测量的挑战。具体来说，我们模拟了由小行星 101955 Bennu 上的撞击源产生的地震信号的 LDV 测量。我们证明可以通过组合由配备多个 LDV 传感器的轨道地震仪记录的多个信号来衰减散斑噪声。通过减轻激光散斑，