Data returned by the OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer) spacecraft have shown that asteroid (101955) Bennu has a globally low-albedo surface covered in boulders with diverse texture, color, and albedo properties, and an aqueously altered composition dominated by phyllosilicates. To test whether Bennu’s color and albedo diversity could be caused by texture and/or composition variations, we performed a laboratory-based study using simple two-component mixtures (called “mudpies”) of the phyllosilicate saponite and carbon-rich opaques. Each mudpie is prepared in four different textures: fine powder, coarse particles, sanded slab, and textured rock. We find that a sanded slab made from 90% saponite and 10% lampblack is a good analog for Bennu, and the color and albedo changes due to texture variations are substantial. At 550 nm, texture changes alone can create up to 36% brightness contrast, and in color measured as a 473 nm/847 nm ratio, texture changes can provide up to 18% color contrast. In comparison, Bennu shows approximately 25% albedo and <1% color contrasts from boulder type to boulder type. These findings suggest that if texture contributes to color on Bennu, the texture variations are typically more subtle than what we simulated in the laboratory. According to our study, the color and albedo properties of different boulder types on Bennu are consistent with different concentrations of carbon-rich opaques (and possibly consistent with variations in carbonate concentration). The variations within each boulder group are consistent with textural differences.

中文翻译：

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两分量“泥饼”模拟中不同质地和成分的光谱效应：小行星洞察 (101955) Bennu

OSIRIS-REx（起源、光谱解释、资源识别和安全-风化层探测器）航天器返回的数据表明，小行星 (101955) Bennu 的全球低反照率表面覆盖着具有不同纹理、颜色和反照率特性的巨石，以及以层状硅酸盐为主的水化成分。为了测试 Bennu 的颜色和反照率多样性是否是由质地和/或成分变化引起的，我们使用页硅酸盐皂石和富​​含碳的不透明材料的简单双组分混合物（称为“泥浆”）进行了一项基于实验室的研究。每个泥饼都以四种不同的质地制成：细粉、粗颗粒、砂板和纹理岩石。我们发现由 90% 的皂石和 10% 的油烟制成的砂板是 Bennu 的一个很好的类似物，并且由于纹理变化而导致的颜色和反照率变化很大。在 550 nm 处，仅纹理变化就可以产生高达 36% 的亮度对比度，在以 473 nm/847 nm 比率测量的颜色中，纹理变化可以提供高达 18% 的颜色对比度。相比之下，Bennu 显示了大约 25% 的反照率和 <1% 的巨石类型之间的颜色对比度。这些发现表明，如果纹理对 Bennu 的颜色有影响，则纹理变化通常比我们在实验室中模拟的更微妙。根据我们的研究，Bennu 上不同类型巨石的颜色和反照率特性与不同浓度的富碳不透明物质一致（并且可能与碳酸盐浓度的变化一致）。每个巨石组内的变化与质地差异一致。