中国的月球样本世界首次揭示月球背面“年轻”的火山活动

For the first time, Chinese scientists and their US collaborators have been able to precisely measure the age of volcanic eruptions on the far side of the moon.

中国科学家及其美国合作者首次成功精确测量了月球背面火山喷发的年龄。

Previously this was only estimated through remote sensing observations.

此前，这一信息仅通过遥感观测进行估算。

Two research teams led by scientists from the Chinese Academy of Sciences, based in Beijing and Guangzhou, used radiometric dating to analyse isotope decay in basalts, a type of volcanic rock brought back to Earth by China’s Chang’e-6 mission in June.

由中国科学院北京和广州的科学家领导的两支研究团队，利用放射性定年法分析了玄武岩（由中国嫦娥六号任务于六月带回地球的一种火山岩）中的同位素衰变。
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Their studies, published on Friday in journals Nature and Science, both found that the moon’s oldest and deepest crater on its far side was volcanically active around 2.8 billion years ago.

他们的研究成果于周五分别在《自然》和《科学》期刊上发表，均发现月球背面最古老和最深的陨石坑在大约28亿年前曾有火山活动。
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In comparison, samples returned by the Apollo, Luna and Chang’e-5 missions – all from the near side – established that lunar volcanism occurred between 4 billion and 2 billion years ago.

与阿波罗、Luna和嫦娥五号任务从月球正面带回的样品相比，这些样品证实月球火山活动发生在40亿到20亿年前。

The Nature paper highlighted that the 2.8 billion-year age was “surprisingly young” as volcanic activities on the far side were traditionally thought to have ended much earlier. Most volcanic eruptions were associated with the near side and believed to have ceased by around 3 billion years ago.

《自然》杂志的论文指出，28亿年的年龄“出人意料地年轻”，因为传统上认为月球背面的火山活动结束得更早。大多数火山喷发与月球正面有关，并被认为大约在30亿年前已停止。

Meanwhile, authors of the Science paper were less surprised, noting that similar younger volcanism, such as the Chang’e-5 basalt samples measured at around 2 billion years old, had already suggested that lunar volcanism may have persisted longer than previously believed on both sides of the moon.

同时，《科学》杂志论文的作者不那么惊讶，他们指出，类似的年轻火山活动，如嫦娥五号玄武岩样本测量出的约20亿年的年龄，就已经表明月球两侧的火山活动可能比之前认为的持续时间更长。

Qian Yuqi, a planetary geologist at the University of Hong Kong and a co-author of the Science paper, expressed his excitement about being part of the initial studies on the unique Chang’e-6 samples.

香港（特区）大学行星地质学家、《科学》论文的合作者钱煜奇对参与对嫦娥六号样本的初步研究感到非常兴奋。

He said there was a “high readiness” among scientists to study these valuable rocks, thanks to the expertise built up through analyses of Chang’e-5 samples in recent years.

他说，由于近年来对嫦娥五号样品的分析积累了丰富的经验，科学家们对研究这些宝贵岩石的“准备度很高”。
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“The study of Chang’e-5 samples has led to an explosive growth in China’s planetary science community. Thanks to the Chang’e-5 and Chang’e-6 missions, we are now in a golden era for lunar and planetary science in China,” he said.

“对嫦娥五号样本的研究促使中国行星科学界的爆炸式增长。感谢嫦娥五号和嫦娥六号任务，我们现在处于中国月球和行星科学的黄金时代，”他说。

Both studies analysed Chang’e-6 samples distributed to sext teams for initial pre-research. Last week, China’s national space agency officially opened up the first round of applications for domestic scientists to borrow the samples.

两项研究均分析了嫦娥六号分发给选定团队用于初步预研究的样本。上周，中国国家航天局正式开启了国内科学家申请借用样本的第一轮。

Earlier this year, China launched the complex, 53-day-long Chang’e-6 mission to collect rocks from the far side of the moon. The spacecraft scooped and drilled materials from the Apollo basin, located within the 2,500km-wide (1,553 mile-wide) South Pole-Aitken basin, and successfully brought nearly 2kg (4.4 pounds) of samples back to Earth.

今年早些时候，中国发射了复杂的、为期53天的嫦娥六号任务，以收集月球背面的岩石。航天器从南极-艾特肯盆地内的阿波罗盆地收集并钻取了材料，成功将近2公斤（4.4磅）的样本带回地球。

In September, preliminary findings from the Chang’e-6 samples were published in National Science Review. Researchers reported that the samples had a looser and more porous structure – among other unique characteristics – compared to those retrieved from the near side.

九月，嫦娥六号样本的初步发现发表在《国家科学评论》上。研究人员报告称，相较于从月球正面回收的样本，这些样本具有更松散和多孔的结构——以及其他独特特征。

At the time, Jim Head, a planetary geologist at Brown University in Rhode Island and a long-time collaborator with Chinese scientists, congratulated the country on the mission’s success.

当时，罗德岛布朗大学的行星地质学家、与中国科学家长期合作的吉姆·赫德，祝贺中国取得任务的成功。

“The Chang’e-6 mission was well worth the wait for the international community,” he said. “It made the scientific dreams of lunar and planetary scientists a reality.”

“嫦娥六号任务值得国际社会的等待，”他说。“它实现了月球和行星科学家们的科学梦想。”

Returning samples from the lunar far side and analysing them in high-precision labs on Earth offers a much deeper understanding of their nature, including age and formation processes, than is possible through remote sensing or in situ measurements on the moon, according to Head, who co-authored the Science paper.

根据这篇《科学》论文的合著者赫德的说法，从月球背面返回样本并在地球上的高精度实验室中进行分析，提供了比遥感或月球上的原位测量更深入的了解其性质的机会，包括年龄和形成过程。

“Indeed, there are many reasons to suspect that the lunar far side differs in its history from the near side,” he said.

“实际上，有很多理由怀疑月球背面的历史与正面不同，”他说。

In the current research, the two teams analysed 108 and 35 basalt fragments, respectively, to determine their ages. While most samples consistently dated to around 2.8 billion years old, the Beijing-based team reported an “outlier” in their Nature paper – a fragment with a high aluminium content that dated to about 4.2 billion years.

在当前研究中，两支团队分别分析了108和35块玄武岩碎片，以确定其年龄。尽管大多数样本的一致测定年龄约为28亿年，但北京研究团队在《自然》论文中报告了一个“离群值”——一个含铝量高的碎片，其年代约为42亿年。

The team noted that at such an age, it was among the oldest lunar materials ever obtained, along with sext Apollo samples and a lunar meteorite recovered in Botswana in 1999 that dated to 4.36 billion years.

该研究团队指出，这样的年龄使其成为迄今为止获得的最古老的月球材料之一，与某些阿波罗样品以及1999年在博茨瓦纳发现的月球陨石一起，其年代可追溯至43.6亿年前。
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After confirming it was likely that the fragment originated from the sampling region, the researchers concluded that volcanism on the far side of the moon persisted for more than 1.4 billion years.

在确认碎片很可能来自采样区域后，研究人员得出结论，月球背面的火山活动持续了超过14亿年。

Meanwhile, both groups found that the mantle source of the Chang’e-6 samples contained a low abundance of elements that produce radioactive heat, which is crucial for sustaining volcanic eruptions.

与此同时，两个小组都发现嫦娥六号样本的地幔源含有低丰度的能产生放射性热量的元素，而这些元素对维持火山喷发至关重要。

This could help explain why the lunar far side had far fewer dark basalt plains than the near side, despite the South Pole-Aitken basin having the thinnest crust to facilitate volcanism, the researchers suggested.

研究人员认为，这可以帮助解释为什么尽管南极-艾特肯盆地的地壳最薄，有利于火山活动，但月球的背面比正面拥有更少的黑色玄武岩平原。

“We anticipate a tsunami of important new insights into lunar formation and evolution, as subsequent detailed analyses of the Chang’e-6 samples are reported in the literature,” Head said.

“我们预计，随着对嫦娥六号样本的详细分析结果在文献中发表，将会迎来关于月球形成和演化的重要新见解的浪潮，”赫德说。