木卫二疑似喷射水流——或成下一个生命绿洲

The Galileo spacecraft may be dead, but it still has stories to tell.

伽利略号航天器已经报废了，不过它还有些故事要告诉我们。

Fifteen years after the NASA probe burned up in Jupiter’s atmosphere, newly analyzed magnetic and plasma data from the mission have bolstered evidence that Europa, the planet’s ice-bound moon, is likely venting water into space.

这颗美国航空航天局的探测器在木星大气层中焚毁的十五年之后，该任务最新分析的磁场和等离子数据支持了木卫二欧罗巴，这颗木星的冰封的卫星很可能朝太空中喷射过水柱。

Researchers have long believed that Europa is home to a vast saltwater ocean, trapped beneath a thick crust of ice, making the moon potentially habitable for life and a focus of upcoming robotic exploration.

研究人员们很久以来一直相信欧罗巴上有一片广阔的咸水海洋，被冰封在冰壳之下，这使得该卫星有承载生命的潜能，也是接下来开展的机器人探索的目标。

Over the past decade, scientists using the Hubble Space Telescope have made observations that seemed to support the notion that Europa is venting some of this water to space, much like Saturn’s moon Enceladus.

在过去的几十年里，使用哈勃望远镜的科学家们观测到了一些似乎能够支持欧罗巴朝太空喷射水柱的发现，这跟土卫二恩克拉德斯很相似。

But many other attempted observations have turned up dry.

不过很多其他的观测尝试都是无功而返。

So scientists instead returned to Galileo, which on 16 December 1997 made its closest approach to Europa, flying only 400 kilometers above its surface.

因此科学家们转而研究伽利略号，它于1997年12月16日到达最接近欧罗巴的地点，于其上空仅400千米的高空飞过。

Over the course of 5 minutes, spikes the spacecraft recorded with its magnetic and plasma sensors reflected the alterations that a veil of ejected water, from one or many vents, could cause in a region matching the telescope observations, they report today in Nature Astronomy.

在飞过的这五分钟内，航天器的磁场和等离子体探测器记录的峰值反应了从一个或者多个地点喷射出水柱的雾气，表示可能会有一片跟望远镜观测相符的区域，他们在今天的《自然天文学》杂志上进行了报道。

This indicates that a region of the moon potentially 1000 kilometers long could host such activity, though it is impossible to say whether this is a single plume or many, like the complex system of fractures and vents seen on Enceladus.

这表明了这颗卫星的该区域可能会有长达1000千米的范围会有这种活动，不过还说不清楚这是一次单一的喷发还是会有很多次，复杂的系统的裂缝和喷发，就像恩德拉克斯一样。

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