Titan's inventory of organic surface materials
Titan's inventory of organic surface materials
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Titan 有机表面材料库存
DOI：
10.1029/2007gl032118
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发表时间：
2008
影响因子：
5.2
通讯作者：
E. Stofan
中科院分区：
文献类型：
--
作者：
R. Lorenz;K. Mitchell;R. Kirk;A. Hayes;O. Aharonson;H. Zebker;Phillipe Paillou;J. Radebaugh;J. Lunine;M. Janssen;S. Wall;R. Lopes;B. Stiles;S. Ostro;G. Mitri;E. Stofan
卡西尼号雷达观测现在允许对土卫六表面物质的两类（假定为有机物）清单进行初步评估：极地湖泊液体和赤道沙丘砂。人们已经观察到数百个湖泊或海洋，其中数十个估计含有比地球上所有已知的石油和天然气储量更多的碳氢化合物液体。黑色沙丘覆盖了泰坦表面的20%，其物质体积是地球煤炭储量的几百倍。然而，总的来说，已确定的表面存量（>3 × 104 km3的液体和>2 × 105 km3的沙丘砂）与太阳系年龄期间土卫六上估计的光化学生产相比是很小的。沙子的体积太大，不能简单地用观测到的河道侵蚀或观测到的撞击坑喷出物来解释。这些湖泊的范围足以在短期内缓冲大气中的甲烷，防止其光解，但所含的甲烷不足以维持整个地质时期的大气。除非来自内部的频繁补给以正确的速度缓冲这种温室气体，否则泰坦的过去，现在和未来都可能发生剧烈的气候变化。
Cassini RADAR observations now permit an initial assessment of the inventory of two classes, presumed to be organic, of Titan surface materials: polar lake liquids and equatorial dune sands. Several hundred lakes or seas have been observed, of which dozens are each estimated to contain more hydrocarbon liquid than the entire known oil and gas reserves on Earth. Dark dunes cover some 20% of Titan's surface, and comprise a volume of material several hundred times larger than Earth's coal reserves. Overall, however, the identified surface inventories (>3 × 104 km3 of liquid, and >2 × 105 km3 of dune sands) are small compared with estimated photochemical production on Titan over the age of the solar system. The sand volume is too large to be accounted for simply by erosion in observed river channels or ejecta from observed impact craters. The lakes are adequate in extent to buffer atmospheric methane against photolysis in the short term, but do not contain enough methane to sustain the atmosphere over geologic time. Unless frequent resupply from the interior buffers this greenhouse gas at exactly the right rate, dramatic climate change on Titan is likely in its past, present and future.