The Hayabusa2 mission successfully collected samples from the asteroid Ryugu last year and will return these to Earth in December 2020. It is anticipated that the samples will enable the analysis of terrestrially uncontaminated organic matter and minerals. Such analyses are in turn expected to elucidate the evolution of organic matter through Solar System history, including the origination and processing of biogenically important molecules, which could have been utilized by the first organisms on Earth. In anticipation, studies have made predictions concerning the properties of Ryugu, including its composition. The spectral characteristics of Ryugu, such as albedo, have been employed to relate the asteroid to members of the carbonaceous chondrite group that have been identified on Earth. However, the recent Hayabusa2 touchdown highlights a disparity between the color of surfaces of displaced platy fragments, indicating a brightening trend for the surface exposed to space compared to that facing into the body. Here we present a mass balance calculation with reference to data from the literature, which indicates that Ryugu may contain a significantly higher abundance of organic matter (likely >50%) than the currently most accepted meteorite analogues. A high organic content may result in high levels of extractable organic matter for the second touchdown site, where the spacecraft sampled freshly exposed material. However, high abundances of insoluble aromatic/graphitic rich organic matter may be present in the first touchdown site, which sampled the surface of Ryugu that had been exposed to space. Moreover, we suggest that the potentially high organic abundance and the rubble-pile nature of Ryugu may originate from the capture of rocky debris by a comet nucleus and subsequent water-organic-mineral interactions and sublimation of water ice.

中文翻译：

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Ryugu的反照率：从Hayabusa2着陆演习中推断出的高有机丰度的证据。

去年，Hayabusa2任务成功从小行星Ryugu收集了样本，并将于2020年12月将它们送回地球。预计这些样本将能够对未受污染的有机物和矿物进行分析。反过来，这些分析有望通过太阳系历史阐明有机物质的演化，包括生物上重要分子的起源和加工，这可能是地球上的第一批生物利用的。预料之中，研究已对龙y的特性，包括其成分作出了预测。Ryugu的光谱特征（例如反照率）已被用于将小行星与地球上已发现的碳质球粒陨石群成员联系起来。然而，最近的Hayabusa2触地得分突出显示了置换后的板状碎片表面的颜色之间的差异，这表明暴露于空间的表面与面对人体的表面相比有变亮的趋势。在这里，我们参考文献中的数据进行质量平衡计算，这表明琉球可能比目前最被接受的陨石类似物包含更高的有机质含量（可能> 50％）。高有机物含量可能导致第二个着陆点的高水平可提取有机物含量，航天器在那里对新鲜暴露的物质进行采样。但是，在第一个着陆点可能会存在大量不溶的芳香/富含石墨的有机物，该点对暴露于太空的Ryugu表面进行了采样。此外，