Organic Matter Responses to Radiation under Lunar Conditions.
Organic Matter Responses to Radiation under Lunar Conditions.
复制标题
有机物在月球条件下对辐射的反应。
DOI：
10.1089/ast.2015.1442
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发表时间：
2016-11
期刊：
影响因子：
4.2
通讯作者：
Sephton MA
中科院分区：
文献类型：
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作者：
Matthewman R;Crawford IA;Jones AP;Joy KH;Sephton MA
像月球这样的大型天体，在很长一段时间内保持相对不变，有可能保存太阳系早期历史上有机化学过程的记录。挥发物和撞击物的记录可能保存在被保护性熔岩流覆盖的埋藏月球风化层中。特别令人感兴趣的是，可能保存其他天体的抛射碎片，包括来自早期地球表面的碎片所提供的生命前有机物质。熔岩流层将保护下面的风化层和其中的任何含碳材料免受空间风化的大部分影响，但封装的有机材料在被风化层掩埋并被熔岩覆盖之前仍将受到辐照。我们进行了一项研究，以模拟太阳辐射对各种有机材料与月球和陨石模拟基板混合的影响。在4-13 MeV能量下，103 × 1013质子cm−2的能量密度（代表太阳高能粒子）对低分子量（≤C30）碳氢化合物结构（可用于指示生物活性（生物标志物）或高分子量碳氢化合物聚合物聚（苯乙烯-二乙烯基苯））几乎没有可检测到的影响，并且对氨基酸（≤C9）的选择几乎没有明显的影响。不可避免的是，暴露在太阳高能粒子下的时间越长，可能会产生越多的有害影响，而快速掩埋和封装总是更有利于有机物的保存。我们的数据表明，可用于推断其母行星上生物活动的生物标志物化合物可以相对抵抗辐射的影响，并且在月球的古风化层中可能具有很高的保存潜力。关键词：辐射-月球-风化层-氨基酸-生物标志物。Astrobiology 16，900-912.
Large bodies, such as the Moon, that have remained relatively unaltered for long periods of time have the potential to preserve a record of organic chemical processes from early in the history of the Solar System. A record of volatiles and impactors may be preserved in buried lunar regolith layers that have been capped by protective lava flows. Of particular interest is the possible preservation of prebiotic organic materials delivered by ejected fragments of other bodies, including those originating from the surface of early Earth. Lava flow layers would shield the underlying regolith and any carbon-bearing materials within them from most of the effects of space weathering, but the encapsulated organic materials would still be subject to irradiation before they were buried by regolith formation and capped with lava. We have performed a study to simulate the effects of solar radiation on a variety of organic materials mixed with lunar and meteorite analog substrates. A fluence of ∼3 × 1013 protons cm−2 at 4–13 MeV, intended to be representative of solar energetic particles, has little detectable effect on low-molecular-weight (≤C30) hydrocarbon structures that can be used to indicate biological activity (biomarkers) or the high-molecular-weight hydrocarbon polymer poly(styrene-co-divinylbenzene), and has little apparent effect on a selection of amino acids (≤C9). Inevitably, more lengthy durations of exposure to solar energetic particles may have more deleterious effects, and rapid burial and encapsulation will always be more favorable to organic preservation. Our data indicate that biomarker compounds that may be used to infer biological activity on their parent planet can be relatively resistant to the effects of radiation and may have a high preservation potential in paleoregolith layers on the Moon. Key Words: Radiation—Moon—Regolith—Amino acids—Biomarkers. Astrobiology 16, 900–912.