20241022|木星卫星上可能存在生命（下）

If plumes do not exist, then Europa Clipperwill have to content itself with examining the moon's surface.

如果不存在羽状物，那么欧罗巴快船就只能满足于检测卫星表面。

That surface is notably smooth and relatively free from impact craters, which suggests it is regularly renewed by processes a bit like plate tectonics on Earth.

欧罗巴表面非常光滑，相对没有撞击坑，这表明它定期通过类似地球板块构造的过程进行更新。

That, in turn, suggests that chemicals that form on Europa's surface might have a way down to the ocean, and vice versa.

这反过来又表明，欧罗巴表面形成的化学物质可能有通往海洋的途径，反之亦然。

Studying Europa's surface may, therefore, give valuable clues as to what lies beneath.

因此，研究欧罗巴表面可能会为了解其下方情况提供有价值的线索。

The final ingredient for a habitable world is a source of energy for life to exploit.

宜居世界的最后一个要素是可供生命利用的能量来源。

Whatever that might be on Europa-far from the Sun, and beneath kilometres of ice-it will not be sunlight. That is a bit of a problem.

欧罗巴远离太阳，在数公里厚的冰层之下，因此，无论欧罗巴上有什么，它都不会有阳光。这有点问题。

On Earth almost every living thing ultimately depends on photosynthesis for its energy,

在地球上，几乎所有生物最终都依赖光合作用获取能量，

including the rich ecosystems in the ocean depths, discovered in the 1980s and which helped the idea of life on Europa gain a foothold.

包括20世纪80年代发现的丰富的海洋深处生态系统，这有助于欧罗巴上存在生命的观点获得立足点。

Their inhabitants do not benefit from sunlight directly, but their metabolisms are powered by chemicals created in the photosynthesising, oxygen-rich surface oceans far above.

那里的居民并不直接受益于阳光，但他们的新陈代谢是由远在天上、进行光合作用、氧气丰富的海洋表面产生的化学物质提供能量的。

There's none of that on Europa. But there does not have to be.

欧罗巴上没有这些。但也不一定要有。

Some of the microbes living in fissures in the earth's sea bed make use of chemicals that come entirely from below, rather than above.

一些生活在地球海床裂缝中的微生物利用完全来自下方而不是上方的化学物质。

It is a scant source of energy, but a real one. And Europa might offer much the same.

这是一种稀少的能量来源，但却是真实存在的。欧罗巴可能也提供类似的能量。

Analysing Europa's surface chemistry may give clues as to whether something similar could, at least in principle, be happening on its ocean floor.

分析欧罗巴的表面化学成分可能会提供线索，说明类似的事情是否至少在原则上可能发生在其海底。

And Europa Clipperwill not be the only probe hanging out at Jupiter.

欧罗巴快船将不是唯一在木星上停留的探测器。

Last year saw the launch of a European probe called the Jupiter Icy Moons Explorer (JUICE).

去年，欧洲发射了一个名为木星冰卫星探测器(JUICE)的探测器。

It will likewise examine Europa, as well as Callisto and Ganymede, two other moons that are also thought to have oceans.

它还将研究欧罗巴，以及另外两颗被认为也拥有海洋的卫星木卫四和木卫三。

The vagaries of orbital mechanics mean that, despite its later departure, Europa Clipperwill arrive in 2030, a year before JUICE.

轨道力学的变化意味着，尽管欧罗巴快船较晚离开，但它将于2030年抵达，比JUICE早一年。

If the findings from the two missions are sufficiently exciting, then the next step could be to send a lander.

如果这两次任务的发现足够令人兴奋，那么下一步可能是发射着陆器。

Scouting for landing sites on Europa is another of Europa Clipper's goals.

寻找欧罗巴上的着陆点是欧罗巴快船的另一个目标。

But the probe will not be able to build a perfect map of the moon's surface.

但探测器无法绘制出完美的月球表面地图。

Jupiter's powerful magnetic field produces areas of intense radiation near the planet, enough to fry any spacecraft that lingers too long.

木星强大的磁场在木星附近产生强烈辐射区，足以摧毁任何停留时间过长的航天器。

Europa Clipper will, instead, make 49 looping flybys, gathering as much data as possible each time before retreating to a safe distance.

相反，欧罗巴快船将进行49次循环飞行，每次在撤退到安全距离之前收集尽可能多的数据。

The world's alien-hunters will be hoping it survives.

全世界的外星人猎人都希望它能幸存下来。