We describe the capabilities, radiometric stability, and calibration of a custom vacuum environment chamber capable of simulating the near‐surface conditions of airless bodies. Here we demonstrate the collection of spectral measurements of a suite of fine particulate asteroid analogs made using the Planetary Analogue Surface Chamber for Asteroid and Lunar Environments (PASCALE) under conditions like those found on Earth and on airless bodies. The sample suite includes anhydrous and hydrated physical mixtures, and chondritic meteorites (CM, CI, CV, CR, and L5) previously characterized under Earth‐ and asteroid‐like conditions. And for the first time, we measure the terrestrial and extra‐terrestrial mineral end members used in the olivine‐ and phyllosilicate‐dominated physical mixtures under the same conditions as the mixtures and meteorites allowing us better understand how minerals combine spectrally when mixed intimately. Our measurements highlight the sensitivity of thermal infrared emissivity spectra to small amounts of low albedo materials and the composition of the sample materials. As the albedo of the sample decreases, we observe smaller differences between Earth‐ and asteroid‐like spectra, which results from a reduced thermal gradient in the upper hundreds of microns in the sample. These spectral measurements can be compared to thermal infrared emissivity spectra of asteroid (101955) Bennu's surface in regions where similarly fine particulate materials may be observed to infer surface compositions.

中文翻译：

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使用 PASCALE 对 Bennu 类似物进行光谱表征：模拟无空气物体近地表条件的新实验装置


我们描述了能够模拟无空气物体近地表条件的定制真空环境室的功能、辐射稳定性和校准。在这里，我们展示了在类似地球和无空气天体的条件下使用小行星和月球环境行星模拟表面室 (PASCALE) 制作的一套细颗粒小行星类似物的光谱测量结果。样品套件包括无水和水合物理混合物，以及先前在类地球和类小行星条件下表征的球粒陨石（CM、CI、CV、CR 和 L5）。我们第一次在与混合物和陨石相同的条件下测量了以橄榄石和层状硅酸盐为主的物理混合物中使用的陆地和地外矿物端元，使我们能够更好地了解矿物在紧密混合时如何在光谱上结合。我们的测量强调了热红外发射率光谱对少量低反照率材料和样品材料成分的敏感性。随着样本反照率的降低，我们观察到类地球光谱和类小行星光谱之间的差异较小，这是由于样本中上层数百微米的热梯度降低所致。这些光谱测量结果可以与小行星 (101955) Bennu 表面的热红外发射率光谱进行比较，在这些区域中可以观察到类似的细颗粒材料，以推断表面成分。