Atmospheric and Surface Composition of Titan from Specular Reflections

这个项目是为了限制土星的卫星泰坦的表面和大气组成。对土卫六表面的光谱观测，无论是从原位航天器还是地球上的望远镜，都因为土卫六厚厚的大气层而变得复杂，因为光线必须穿过大气层，而大气层的组成和结构却鲜为人知。该项目的关键要素是通过卡西尼号航天器上的视觉和红外测绘光谱仪（VIMS）从泰坦的一个碳氢化合物湖观测太阳的掠角镜面反射。首席研究员（PI）打算利用镜面反射的波长无关性来分离大气对总光谱的贡献。提出的工作包括三个具体任务：(1)利用镜面反射获得的透射光谱探索土卫六极地大气的组成；(2)利用VIMS光谱在校正大气效应后的5微米透射窗口中约束可能的地表有机物种的组成；(3)利用校正后的光谱绘制地表水冰暴露的程度。该项目将支持一名研究生和一名本科生的工作，这所大学以前在天文学研究方面并不活跃，为扩大爱达荷州居民对科学的参与提供了机会。该项目由天文科学部和刺激竞争性研究实验计划办公室（EPSCoR）联合资助。

This project is an effort to constrain the surface and atmospheric composition of Saturn's moon Titan. Spectroscopic observations of the surface, whether from in situ spacecraft or Earth-based telescopes, are complicated by Titan's thick atmosphere, through which the light must traverse, and the composition and structure of which are poorly known. The key element of this project is the observation of a grazing-angle specular reflection of the Sun from one of Titan's hydrocarbon lakes by the Visual and Infrared Mapping Spectrometer (VIMS) on the Cassini spacecraft. The Principal Investigator (PI) intends to exploit the wavelength independence of the specular reflection to isolate the atmospheric contributions to the total spectrum. The proposed work consists of three specific tasks: (1) to explore the composition of Titan's polar atmosphere using the transmission spectrum obtained from the specular reflection; (2) to constrain the composition of possible surface organic species using VIMS spectra in the 5-micron transmission window corrected for atmospheric effects, and (3) to map the extent of surface water ice exposures using the corrected spectra. The project would support the work of a graduate student and an undergraduate student at an institution that has not previously been active in astronomy research, providing an opportunity to broaden participation in science among residents of Idaho. This project is jointly funded by the Division of Astronomical Sciences and the Office of the Experimental Program to Stimulate Competitive Research (EPSCoR).