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A never-ending story in the sky: The secrets of chemical evolution

机译：天空中永无止境的故事：化学进化的秘密

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Cosmic evolution is the tale of progressive transition from simplicity to complexity. The newborn universe started with the simplest atoms formed after the Big Bang and proceeded toward the formation of the so-called 'astronomical complex organic molecules' (aCOMs), most of them showing a clear prebiotic character. Understanding the chemical evolution of the universe is one of the main aims of Astrochemistry, with the starting point being the knowledge whether a molecule is present in the astronomical environment under consideration and, if so, its abundance. However, the interpretation of astronomical detections and the identification of molecules are not at all straightforward. Indeed, the extraterrestrial chemical inventory has been obtained by means of astronomical observations based on spectroscopic signatures determined in laboratory (either experimental or computational) studies. Even though the presence of aCOMs has been known for decades, the processes that lead to their synthesis are still hotly debated or even unknown. It is often assumed that aCOMs are mostly synthesized on grain surfaces during the so-called warm-up phase, when various radicals trapped in the grain mantles acquire mobility and recombine into large molecules. However, recent detections of aCOMs in cold environments have challenged this exclusive role of grain-surface chemistry. Clearly, gas-phase chemistry is at work in cold environments. Moving to Titan's atmosphere, prior to the Cassini-Huygens arrival in the Saturn system, it was generally believed that Earth and interstellar space are the two places where organic molecules are/were synthesized extensively. However, the experimental measurements by the instruments on board the Cassini orbiter spacecraft and the Huygens probe lander have changed this view.
机译：宇宙演变是从简单到复杂性的渐进过渡的故事。新生宇宙从大爆炸后形成的最简单原子开始，并朝着形成所谓的“天文学综合有机分子”（ACOMS）的形成，大多数显示出明显的益生元特征。了解宇宙的化学演变是星体化学的主要目标之一，目的点是知识在所考虑的天文环境中存在分子，如果是的话，其丰富。然而，对天文检测的解释和分子的鉴定并不简单。实际上，通过基于实验室（实验或计算）研究中确定的光谱签名来获得外星物化化学品。即使ACOM的存在已知几十年来，导致其合成的流程仍然是热烈的争论甚至未知。通常假设在所谓的预热阶段期间，当捕获在谷物幔中的各种自由基获取迁移率并将其重组成大分子时，Acoms在所谓的预热阶段中合成。然而，近期寒冷环境中的Acoms检测挑战了谷物表面化学的这种独家作用。显然，气相化学在寒冷环境中工作。在Cassini-Huygens抵达土星系统之前，搬到泰坦的氛围，人们普遍认为，地球和星际空间是有机分子被广泛合成的两个地方。然而，仪器上的实验测量仪器上的Cassini轨道飞船和Huygens Probe Lander已经改变了这个观点。

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