Composition of Titan's lower atmosphere and simple surface volatiles as measured by the Cassini-Huygens probe gas chromatograph mass spectrometer experiment
Composition of Titan's lower atmosphere and simple surface volatiles as measured by the Cassini-Huygens probe gas chromatograph mass spectrometer experiment
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DOI：
10.1029/2010je003659
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发表时间：
2010-12-10
影响因子：
4.8
通讯作者：
Raulin, F.
中科院分区：
文献类型：
--
作者：
Niemann, H. B.;Atreya, S. K.;Raulin, F.
卡西尼-惠更斯探测器气相色谱质谱仪（GCMS）确定了土卫六大气层的组成，从大约140公里的高度到表面。着陆后，它返回了从表面蒸发的气体成分数据。分子氮（N-2），甲烷（CH 4），和分子氢（H-2）的高度分布进行了测定。在蒸发的甲烷、乙烷（C2 H6）、乙炔（C2 H2）、氰（C2 N2）和二氧化碳（CO2）的表面上检测到痕量。甲烷数据表明甲烷沉淀是最近发生的。平流层下部（139.8-75.5公里）的甲烷摩尔分数为（1.48 +/- 0.09）x 10（-2），近地表（距地表6.7公里）的甲烷摩尔分数为（5.65 +/- 0.18）x 10（-2）。大气中氢分子的摩尔分数为（1.01 +/- 0.16）x 10（-3），表面上为（9.90 +/- 0.17）x 10（-4）。在分子氮中，N-14/N-15的同位素比为167.7 +/- 0.6，在甲烷中，C-12/C-13的同位素比为91.1 +/- 1.4，在分子氢中，D/H的同位素比为（1.35 +/- 0.30）x 10（-4）。Ar-36和放射成因Ar-40的摩尔分数分别为（2.1 +/- 0.8）× 10（-7）和（3.39 +/- 0.12）× 10（-5）。Ne-22的摩尔分数为（2.8 +/- 2.1）x 10（-7）。氪和氙低于1 × 10（-8）摩尔分数的检测阈值。由于大气和地面上有机痕量气体的丰度没有达到检测阈值，因此没有从气相色谱分系统检索科学数据。先前发表的GCMS实验结果被本出版物取代。
The Cassini-Huygens probe gas chromatograph mass spectrometer (GCMS) determined the composition of the Titan atmosphere from similar to 140 km altitude to the surface. After landing, it returned composition data of gases evaporated from the surface. Height profiles of molecular nitrogen (N-2), methane (CH4), and molecular hydrogen (H-2) were determined. Traces were detected on the surface of evaporating methane, ethane (C2H6), acetylene (C2H2), cyanogen (C2N2), and carbon dioxide (CO2). The methane data showed evidence that methane precipitation occurred recently. The methane mole fraction was (1.48 +/- 0.09) x 10(-2) in the lower stratosphere (139.8-75.5 km) and (5.65 +/- 0.18) x 10(-2) near the surface (6.7 km to the surface). The molecular hydrogen mole fraction was (1.01 +/- 0.16) x 10(-3) in the atmosphere and (9.90 +/- 0.17) x 10(-4) on the surface. Isotope ratios were 167.7 +/- 0.6 for N-14/N-15 in molecular nitrogen, 91.1 +/- 1.4 for C-12/C-13 in methane, and (1.35 +/- 0.30) x 10(-4) for D/H in molecular hydrogen. The mole fractions of Ar-36 and radiogenic Ar-40 are (2.1 +/- 0.8) x 10(-7) and (3.39 +/- 0.12) x 10(-5), respectively. Ne-22 has been tentatively identified at a mole fraction of (2.8 +/- 2.1) x 10(-7). Krypton and xenon were below the detection threshold of 1 x 10(-8) mole fraction. Science data were not retrieved from the gas chromatograph subsystem as the abundance of the organic trace gases in the atmosphere and on the ground did not reach the detection threshold. Results previously published from the GCMS experiment are superseded by this publication.