Dibb S D, Bell J F, Elkins-Tanton L T, Williams D A
Bay Area Environmental Research Institute NASA Ames Research Center Moffett Field CA USA.
School of Earth and Space Exploration Arizona State University Tempe AZ USA.
Earth Space Sci. 2023 Jan;10(1):e2022EA002694. doi: 10.1029/2022EA002694. Epub 2023 Jan 26.
The NASA Psyche mission will explore the structure, composition, and other properties of asteroid (16) Psyche to test hypotheses about its formation. Variations in radar reflectivity, density, thermal inertia, and visible to near-infrared (VNIR) reflectance spectra of Psyche suggest a highly metallic composition with mafic silicate minerals (e.g., pyroxene) heterogeneously distributed on the surface in low abundance (<10 vol.%). The Psyche spacecraft's Multispectral Imager is designed to map ≥80% of the surface at high spatial resolution (≤20 m/pixel) through a panchromatic filter and provide compositional information for about ≥80% of the surface using seven narrowband filters at VNIR wavelengths (∼400-1,100 nm) and at spatial scales of ≤500 m/pixel. We analyzed 359 reflectance spectra from samples consistent with current uncertainties in Psyche's composition and compared them to published reflectance spectra of the asteroid using a chi-square test for goodness of fit. The best matches for Psyche include iron meteorite powder, powders from the sulfide minerals troilite and pentlandite, and powder from the CH/CBb chondrite Isheyevo. Comparison of absorption features support the interpretation that Psyche's surface is a metal-silicate mixture, although the exact abundance and chemistry of the silicate component remains poorly constrained. We convolve our spectra to the Imager's spectral throughput to demonstrate preliminary strategies for mapping the surface composition of the asteroid using filter ratios and reconstructed band parameters. Our results provide predictions of the kinds of surface compositional information that the Psyche mission could reveal on the solar system's largest M-type asteroid.
美国国家航空航天局（NASA）的“心灵号”任务将探索小行星（16）“心灵”的结构、成分及其他特性，以检验有关其形成的假设。“心灵”的雷达反射率、密度、热惯量以及可见光至近红外（VNIR）反射光谱的变化表明，其成分高度金属化，镁铁硅酸盐矿物（如辉石）以低丰度（<10体积%）不均匀地分布在表面。“心灵号”航天器的多光谱成像仪旨在通过全色滤光片以高空间分辨率（≤20米/像素）绘制≥80%的表面，并使用七个VNIR波长（约400 - 1100纳米）的窄带滤光片在≤500米/像素的空间尺度上为约≥80%的表面提供成分信息。我们分析了359个与“心灵”当前成分不确定性相符的样本的反射光谱，并使用卡方拟合优度检验将它们与已发表的该小行星反射光谱进行比较。与“心灵”最佳匹配的包括铁陨石粉末、硫化物矿物陨硫铁和镍黄铁矿的粉末，以及CH/CBb球粒陨石伊谢耶沃的粉末。吸收特征的比较支持了“心灵”表面是金属 - 硅酸盐混合物的解释，尽管硅酸盐成分的确切丰度和化学性质仍受约束不足。我们将我们的光谱与成像仪的光谱通量进行卷积，以展示使用滤光片比率和重建波段参数绘制小行星表面成分的初步策略。我们的结果提供了关于“心灵号”任务可能在太阳系最大的M型小行星上揭示的表面成分信息种类的预测。
