Life is pervasive on planet Earth, but whether life is ubiquitous in the Galaxy and sustainable over timescales comparable to stellar evolution is unknown. Evidence suggests that life first appeared on Earth more than 3.77 Gyr ago, during a period of heavy meteoric bombardment. Amino acids, the building blocks of proteins, have been demonstrated to exist in interstellar ice. As such, the contribution of space-generated amino acids to those existing on Earth should be considered. However, detection of space amino acids is challenging. In this study, we used analytical data from several meteorites and in situ measurements of the comet 67P/Churyumov-Gerasimenko collected by the Rosetta probe to evaluate the detectability of alanine by ultraviolet spectropolarimetry. Alanine is the second-most abundant amino acid after glycine and is optically active. This chirality produces a unique signature that enables reliable identification of this amino acid using the imprint of optical rotatory dispersion (ORD) and circular dichroism (CD) in the ultraviolet spectrum (130–230 nm). Here, we show that the ORD signature could be detected in comets by using ultraviolet spectropolarimetric observations conducted at middle size space observatories. These observations can also provide crucial information for the study of sources of enantiomeric imbalance on Earth.

中文翻译：

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使用紫外分光偏振法检测彗星手性氨基酸的限制

生命在地球上无处不在，但生命是否在银河系中无处不在，并且在与恒星演化相当的时间尺度上是可持续的尚不清楚。有证据表明，生命首次出现在地球上的时间超过 3.77 Gyr，当时正处于严重的流星轰击时期。氨基酸，蛋白质的组成部分，已被证明存在于星际冰中。因此，应该考虑太空产生的氨基酸对地球上存在的氨基酸的贡献。然而，空间氨基酸的检测具有挑战性。在这项研究中，我们使用了来自几个陨石和原位的分析数据Rosetta 探测器收集的彗星 67P/Churyumov-Gerasimenko 的测量值，以通过紫外分光偏振法评估丙氨酸的可检测性。丙氨酸是仅次于甘氨酸的第二丰富的氨基酸，具有光学活性。这种手性产生了独特的特征，可以使用紫外光谱（130-230 nm）中的旋光色散 (ORD) 和圆二色性 (CD) 的印记来可靠地识别这种氨基酸。在这里，我们表明可以通过使用在中型空间天文台进行的紫外分光偏振观测来检测彗星中的 ORD 特征。这些观察结果还可以为研究地球上对映体不平衡的来源提供重要信息。