7月28日报道（张微 编译）科学家说，“菲莱”着陆器收集的数据支持彗星可以作为宇宙实验室这一理论，因为彗星上存在构成生命中的一些基本元素。

“菲莱”是欧洲宇航局罗塞塔号彗星探测器的着陆器，它去年11月在彗星67P/Churyumov-Gerasimenko上颠簸着陆时，利用两个独立的仪器寻找分子。

本周四发表在《科学》杂志的一篇论文中，研究人员说，他们花了几个月的时间分析了数据，并得出了67P上包含至少16种有机化合物的结论。其中的四种，包括丙酮，之前在彗星上没有被发现过。

“彗星上含有的所有原材料，比如水，二氧化碳，甲烷，氨气，都是形成更加复杂的有机分子所需要的，也许通过来自太阳或宇宙射线的紫外线来引发，或者通过彗星撞击行星表面(比如早期的地球)来产生，”欧洲航天局高级科学顾问Mark McCaughrean说。

目前尚不清楚在67P上发现的复杂分子是否在太阳系诞生初期就形成了，然后进入彗星，或者在此之后形成，他说。“无论是哪种方式，彗星都是一个探索生命起源的很理想的地方。

McCaughrean并没有直接参与研究，他也澄清了最近有关彗星上发现存在生命的证据的报道。但是他表示，检测到的生命起源前化合物通过行星的碰撞可能形成更加复杂的分子，如氨基酸。

蛋白质，构成生命体的基本物质，由一个长链氨基酸、一个简单氨基酸和谷氨酸构成，几年前另一个彗星探索任务美国航空航天局“星尘”任务时，在彗星彗尾收集的物质中被发现。

菲莱项目的科学家们尚未在67P上发现任何氨基酸，但这并不是说它们不存在。因为菲莱在电池耗尽之前，只能够进行60个小时的科学实验，科学家们无法完成一些他们希望开展的工作。

菲莱上个月从冬眠中醒过来了，但是德国航空航天中心控制的菲莱还不能重启科学实验。不过，科学家们仍然对探测器寄予希望，因为菲莱的母船罗塞塔正在围绕彗星运转，陪伴者彗星67P在太空的旅程。

本次任务的下一个大事件将发生在8月13日，当彗星接近太阳的时候，这个点称为近日点。

随着他们对彗星化学成分的研究，科学家们也对其岩石地形和异常坚硬的表面发表了新的见解，这对未来的彗星任务是至关重要的。

“这个首次着陆彗星任务至少让我们确定了一件事：着陆彗星时的弹跳，比起陷入地面是更加棘手问题，”菲莱项目经理Stephan Ulamec说。
 

英文原文：

Philae probe finds evidence that comets can be cosmic labs

Scientists say the Philae space probe has gathered data supporting the theory that comets can serve as cosmic laboratories in which some of the essential elements for life are assembled.

Philae, which is part of the European Space Agency's Rosetta mission, used two separate instruments to 'sniff' for molecules during its bumpy landing on comet67P/Churyumov-Gerasimenko last November.

In an article published Thursday in the journal Science, researchers said they spent months analyzing the data and concluded that 67P contains at least 16 organic compounds. Four of them, including acetone, hadn't been detected on a comet before.

"Comets are loaded with all the raw materials like water, CO2, methane, ammonia, needed to assemble more complex organic molecules, perhaps sparked by UV-photons from the Sun or cosmic rays, or in the shock that occurs when a comet hits the surface of a planet like the young Earth," said Mark McCaughrean, a senior scientific adviser at the European Space Agency.

It's not yet known whether the complex molecules found in 67P were made in the early solar system and then incorporated into the comet or formed there later, he said. "Either way, it seems that comets are pretty good places to find the building blocks of molecules which later on could be used for life."

McCaughrean, who wasn't directly involved in the study, dismissed recent reports that evidence of life itself had been found on the comet. But he said the prebiotic compounds that were detected might be coaxed into even more complex molecules such as amino acids, including by a planetary impact.

Proteins, fundamental to living organisms, are made from long chains of amino acids, and the simplest one, glycine, was even detected in material collected from the tail of another comet by NASA's Stardust mission a few years ago.

The Philae scientists have not found any amino acids on 67P yet, but that's not to say they aren't there. As Philae was only able to perform experiments for 60 hours before its batteries were depleted, scientists were unable to complete some of the work they had hoped to carry out.

The space probe woke up from hibernation last month, but the German space agency DLR that operates Philae has not yet been able to establish a robust connection to restart the scientific experiments. Still, scientists are hopeful that this will be possible as the probe and its mother ship Rosetta, which is orbiting the comet, accompany 67P on its journey through space.

The next important event in the mission will take place on Aug. 13, when the comet comes closest to the sun, a point known as perihelion.

Along with their findings on the comet's chemical composition, scientists also published new insights about its rocky terrain and its unexpectedly hard surface, which may prove crucial to future comet missions.

"We have definitely learned at least one thing with this first comet landing: Bouncing is a bigger problem than a possible sinking into the ground," said Philae to project manager Stephan Ulamec.