Investigating the contribution of methane produced by ablating micrometeorites to the atmosphere of Mars
Investigating the contribution of methane produced by ablating micrometeorites to the atmosphere of Mars
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研究微陨石烧蚀产生的甲烷对火星大气的贡献
DOI：
10.1016/j.epsl.2009.09.041
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发表时间：
2009
影响因子：
5.3
通讯作者：
Court R
中科院分区：
文献类型：
--
作者：
Court R
火星大气中存在的甲烷被认为是生命存在的证据，因为甲烷在火星大气中的寿命很短，只有几百年，需要通过连续或间歇的机制来替代，例如生物学、火山作用、超镁铁质地壳的蛇纹石化或大型彗星或小行星撞击。碳质陨石中游离甲烷的丰度较低，限制了陨石坠落释放大量甲烷的潜力。然而，将陨石物质输送到行星表面是一个充满能量的过程，并且碳质陨石在进入大气层期间烧蚀时产生甲烷的能力尚未被考虑到。在这里，我们使用分析热解来模拟碳质微陨石进入大气层时的烧蚀和热解，并使用傅里叶变换红外光谱来量化随后的甲烷产量。我们表明，烧蚀产生的甲烷产量比默奇森 CM2 碳质球粒陨石中测得的游离甲烷大约高两个数量级，但这种以前被忽视的甲烷来源每年只能产生不到 10 公斤甲烷，这个质量远低于维持在火星大气中观察到的甲烷丰度所需的质量。我们的数据支持在红色星球上寻找生命和探索地下化学过程的尝试。
The presence of methane in the atmosphere of Mars has been suggested as evidence of life, as methane has a short lifetime in the atmosphere of Mars of just a few hundred years, requiring replacement by mechanisms, continuous or episodic, such as biology, volcanism, serpentinization of ultramafic crust or large cometary or asteroidal impacts. The potential of meteoritic infall to deliver significant quantities of methane is restricted by the low abundance of free methane in carbonaceous meteorites. However, the delivery of meteoritic material to the surface of a planet is an energetic process, and the ability of carbonaceous meteorites to generate methane upon ablation during atmospheric entry has not been previously considered. Here, we use analytical pyrolysis to simulate the ablation and pyrolysis of carbonaceous micrometeorites upon atmospheric entry, and Fourier-transform infrared spectroscopy to quantify the subsequent yield of methane. We show that ablation produces a yield of methane that is approximately two orders of magnitude greater than the measured free methane present in the CM2 carbonaceous chondrite, Murchison, but that this previously overlooked source of methane can only account for less than 10kg of methane annually, a mass far below that required to maintain the abundance of methane observed in the atmosphere of Mars. Our data support attempts to search for life and explore subsurface chemical processes on the Red Planet.
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影响因子：
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作者：
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DOI：
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发表时间：
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期刊：
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影响因子：
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作者：
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影响因子：
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作者：
Flynn, GJ
通讯作者：
Flynn, GJ