Organic components of cometary nuclei and the effects of opaque phases on spectral detectability of cometary organics and minerals.

研究建议的目的是：(1)开发一种仔细的方法来鉴定和表征彗星核表面的有机物质，同时考虑到不透明相(特别是铁硫化物)的影响，以及考虑到带电粒子照射彗核表面和在近日点对有机物进行热处理可能造成的光学变化；(2)对暴露在67P/Churyumov-Gerasimenko彗星核上的有机成分进行光谱表征。这些目标将通过几种不同的方法实现，包括实验室实验、理论计算和解释彗星67/P的新的可见光-红外反射光谱。拟议的工作将包括(1)彗星难熔有机物模拟材料的光谱反射率研究(0.4-20微米)，根据先前的工作和欧空局Rosetta任务提供的最新信息精心挑选；(2)铁-硫化物与选定的与彗星有关的有机物和矿物的亲密混合物的光谱反射率研究；(3)应用辐射传输模型模拟有机-硫化物亲密混合物的反射光谱和空间风化效应；(4)分析和解释67/P彗星的VIRTIS/Rosetta光谱，从可探测性和有机和无机表面组分的相对丰度方面进行解释；(5)基于所获得的结果对彗核、暗TNO、低反照率小行星和碳质陨石之间的光谱变异性进行比较分析。预期的结果可以极大地帮助我们理解太阳系黑暗小天体之间的光谱变异性，并为整个太阳系有机物质的性质和分布提供新的见解。

The research proposal is aimed at (1) development of a careful approach to spectroscopic identification and characterization of organics on the surfaces of comet nuclei by taking into account influence of opaque phases (in particular, Fe-sulfides), as well as possible optical alteration caused by irradiation of the surfaces with charged particles and thermal processing of organics at perihelion; (2) spectroscopic characterization of organic components exposed on the nucleus of comet 67P/Churyumov-Gerasimenko. These goals will be achieved through several different approaches, including laboratory experiments, theoretical calculations, and interpretation of new VIS-IR reflectance spectra of comet 67/P. The proposed work will include (1) spectral reflectance studies (0.4-20 micrometers) of analogue materials for cometary refractory organics, carefully selected based on the previous work and the most up-to-date information provided by the ESA's Rosetta mission; (2) spectral reflectance studies of unheated and heated intimate mixtures of Fe-sulfides with selected organics and minerals relevant to comets; (3) application of radiative transfer models to simulate reflectance spectra of organic-sulfide intimate mixtures and space weathering effects; (4) analysis/interpretation of the VIRTIS/Rosetta spectra of comet 67/P in terms of detectability and relative abundances of organic and inorganic surface constituents.; (5) comparative analysis of spectral variability among comet nuclei, dark TNOs, low albedo asteroids and carbonaceous meteorites based on the obtained results. The expected results can significantly contribute to our understanding the spectral variability among dark small bodies of the solar system, and provide new insights into the nature and distribution of organic materials throughout the outer solar system.