卡西尼号对土卫六大气层的紫外成像光谱仪恒星探测器。

The Cassini UVIS stellar probe of the Titan atmosphere.

作者信息

Shemansky Donald E, Stewart A Ian F, West Robert A, Esposito Larry W, Hallett Janet T, Liu Xianming

机构信息

Department of Aerospace Engineering, University of Southern California, University Park, Los Angeles, CA 90089, USA.

出版信息

Science. 2005 May 13;308(5724):978-82. doi: 10.1126/science.1111790.

DOI:10.1126/science.1111790

PMID:15890872

Abstract

The Cassini Ultraviolet Imaging Spectrometer (UVIS) observed the extinction of photons from two stars by the atmosphere of Titan during the Titan flyby. Six species were identified and measured: methane, acetylene, ethylene, ethane, diacetylene, and hydrogen cyanide. The observations cover altitudes from 450 to 1600 kilometers above the surface. A mesopause is inferred from extraction of the temperature structure of methane, located at 615 km with a temperature minimum of 114 kelvin. The asymptotic kinetic temperature at the top of the atmosphere determined from this experiment is 151 kelvin. The higher order hydrocarbons and hydrogen cyanide peak sharply in abundance and are undetectable below altitudes ranging from 750 to 600 km, leaving methane as the only identifiable carbonaceous molecule in this experiment below 600 km.

摘要

在“卡西尼”号飞越土卫六期间，紫外线成像光谱仪（UVIS）观测到土卫六大气层对两颗恒星光子的消光现象。识别并测量了六种物质：甲烷、乙炔、乙烯、乙烷、丁二炔和氰化氢。观测范围覆盖土卫六表面上方450至1600千米的高度。通过提取甲烷的温度结构推断出一个中间层顶，位于615千米处，最低温度为114开尔文。根据该实验确定的大气层顶部渐近动力学温度为151开尔文。高阶碳氢化合物和氰化氢的丰度急剧峰值，在750至600千米以下的高度无法检测到，这使得甲烷成为该实验中600千米以下唯一可识别的含碳分子。