研究表明：木卫二仍是探索地外生命的首要选择

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重新审视旧数据让科学家重新有理由将木卫二列为寻找地球外生命的首要候选

木卫二

A fresh look at old data is giving scientists a new reason to consider Europa, a moon orbiting the planet Jupiter, as a leading candidate in the search for life beyond Earth.

重新审视旧数据让科学家重新有理由将木卫二列为寻找地球外生命的首要候选。

The reason: evidence of water from the moon shooting into space.

理由是：有证据显示木卫二上的水喷射到了太空中。

NASA, the American space agency, noted an unusual shape -- a bend -- in Europa’s magnetic field in 1997.

美国宇航局1997年提到木星磁场中出现过不同寻常的弯曲。

That was the year when NASA’s Galileo spacecraft passed close to the moon.

那一年美国宇航局伽利略号航天器从月球近处划过。

For a time, it was about 200 kilometers above the surface.

该航天器一度只距该星球表面200公里远。

Scientists reported earlier this month on their reexamination of the Galileo data.

本月早些时候科学家报告称他们再次检测了伽利略号的数据。

They now think this bend in the magnetic field could be explained by an active geyser in an underground ocean.

目前，他们认为，磁场中出现的这道弯曲可以用地下海洋间歇性喷泉解释。

The scientists believe the spacecraft traveled through a plume of water.

科学家认为，该航天器当时穿过了羽毛状的水蒸气。

Elizabeth Turtle is a planetary scientist with the Johns Hopkins University Applied Physics Laboratory.

伊丽莎白·泰托是约翰霍普金斯大学应用物理实验室的行星科学家。

She told reporters that Europa does have a lot of the qualities that are necessary for life was we know it.

她告诉记者说，据我们所知，木卫二确实存在许多生命存在所需的必要特质。

“There’s water. There’s energy. There’s some amount of carbon material.

“那里有水，有能量，还有一定数量的碳物质。

But the habitability of Europa is one of the big questions that we want to understand,” said Turtle.

但是，木卫二的可居住性是我们想要理解的主要问题之一，”泰托表示。

“And one of the really exciting things about detection of a plume is that that means there may be ways that the material from the ocean

“探测到羽状水汽让人真正激动的是，这意味着海洋下的物质可以从冰壳下喷发出来，

— which is likely the most habitable part of Europa because it’s warmer and it’s protected… to come out above the ice shell,” she added.

海洋可能是木卫二上最适宜居住的地方，因为那里更暖和，并且受到了保护，”她补充说道。

University of Michigan space physicist Xianzhe Jia led the latest study, which was published in the journal Nature Astronomy.

密西根大学空间物理学家贾现哲领导了最近的这项研究，文章发表在《自然天文学》杂志上。

The findings support other evidence of plumes from Europa, whose ocean may contain two times as much water as all of Earth’s oceans.

这些发现支持了其他证明木卫二上有羽状水汽的证据，木卫二上的海洋水量可能是地球上所有海洋水量的两倍。

In 2012, NASA’s Hubble Space Telescope collected evidence of ultraviolet radiation which suggests a plume.

2012年，美国宇航局哈勃太空望远镜收集到了紫外线辐射证据，暗示存在羽状水汽。

NASA will get a close-up look from a new spacecraft as part of the space agency’s Europa Clipper mission.

美国宇航局将通过新的宇航器进行近距离观察，以此作为宇航局木卫二飞艇任务的一部分。

That spacecraft could be launched as soon as June 2022.

该宇航器最快将于2022年6月发射。

The agency says this could provide a chance to examine plumes for signs of life from Europa’s ocean, some of which may be microscopic.

宇航局称，这可为探测羽状水汽，寻找木卫二上海洋迹象提供机会，甚至还可找到微型迹象。

Experts consider Europa to be among the top candidates for life in our solar system.

专家认为木卫二是他们所在的太阳系最有可能存在生命的星球之一。

But it is not the only one.

但并不是唯一一个。

For example, NASA’s Cassini spacecraft examined plumes from Enceladus, a moon of the planet Saturn.

例如，美国宇航局卡西尼号宇航器探测到过土卫二上存在羽状水汽。

The water from Enceladus’s ocean contained hydrogen from hydrothermal vents, an environment that may have given rise to life on Earth.

土卫二海洋中的水蒸气中含有深海热泉氢气，这种环境可能可以产生地球上的生命。

Europa is a little smaller than Earth’s moon.

木卫二比地球卫星月球略小。

Its ocean is buried under about 15 to 25 kilometers of ice.

木卫二上的海洋可能埋藏在15到25公里深的冰层下。

Experts believe the ocean itself to be anywhere from 60 to 150 kilometers deep.

专家认为，那里的海洋本身也能有60到150公里深。