双语|火星上发现了湖！Liquid water 'lake'revealed on Mars
火星上首次发现了液态水湖！
可是···是一个又冷又咸的湖
不知道火星鱼好不好吃呢···
Researchers have found evidence of an existingbody of liquid water on Mars.
科学家们发现火星上存在一个液态水湖。
他们认为这个湖处于火星的南极冰川之下，大约有20公里宽。之前的研究认为火星表面可能有间歇性的液态水流，但这回的发现首次说明目前有持续性的水就存在于火星上。
Lake beds like those explored by Nasa's Curiosity rover show water waspresent on the surface of Mars in the past.
NASA的好奇者号探测器曾经发现了湖床，这可以证实火星表面上在过去有水的存在。
However, the planet's climate has since cooled due to its thin atmosphere,leaving most of its water locked up in ice.
但是，因为火星稀薄的大气层，它的气候逐渐变得寒冷，导致大部分的水结成了冰。
The result is exciting because scientists have long searched for signs of present-day liquid water on Mars, but these have come up empty or yielded ambiguous findings. It will also interest those studying the possibilities forlife beyond Earth - though it does not yet raise the stakes in the search for biology.
之所以得出这个结论，是因为科学家长久以来就在寻找火星上的现存液态水，可是要么无功而返，要么只能得出模糊的结论。这次发现也将使寻找外星生命的人浮想联翩——尽管这并没有给寻找火星生物增加多少成功的概率。
The discovery was made using Marsis, a radar instrument on board theEuropean Space Agency's (Esa) Mars Express orbiter.
这次发现是由欧洲航天局的火星快车号搭载的雷达装置Marsis完成的。
"It's probably not a very large lake," said Prof Roberto Oroseifrom the Italian National Institute for Astrophysics, who led the study.
“这可能不是一个很大的湖，”主导这次研究的意大利国家天体物理研究所Roberto Orosei教授说。
Marsis wasn't able to determine how thick the layer of water might be, butthe research team estimate that it is a minimum of one metre.
Marsis并不能测定湖水的深度，但是科学家团队估算水深至少有1米。
"This really qualifies this as a body of water. A lake, not some kindof meltwater filling some space between rock and ice, as happens in certainglaciers on Earth," Prof Orosei added.
“这的确可以算做是一个湖了，而不是像地球冰川上那样，只是岩石和冰之间融化的一点水。” Roberto Orosei教授补充说。
How was it found?
怎么发现的？
Radar instruments like Marsis examine the surface and immediate subsurfaceof the planet by sending out a signal and examining what is bounced back.
Marsis这样的雷达装置会通过发射信号来检测星球表面及地下，然后检测反弹回来的信号。
The continuous white line at the top of the radar results above marks thebeginning of the South Polar Layered Deposit; a filo pastry-like accumulationof water ice and dust.
如上图，雷达结果上面连续的白线标记了南极层状矿床，一种像点心酥皮一样的冰和灰尘的混合物。
Beneath this, researchers spotted something unusual 1.5km under the ice.
再往下，科学家在冰下1.5公里处发现了一些不寻常的东西。
"In light blue you can see where the reflections from the bottom arestronger than surface reflection. This is something that is to us the tell talesign of the presence of water," says Prof Orosei.
“你可以看到浅蓝色的部分，也就是从底部反射回来的，比表面反射回来的更强。这就是水存在的证据了。” RobertoOrosei教授说。
What does this mean for life?
这对火星生命有什么启示？
Nothing definitive. Yet.
到现在为止还没有确切结论。
Dr Manish Patel from the Open University explained: "We have longsince known that the surface of Mars is inhospitable to life as we know it, sothe search for life on Mars is now in the subsurface.
英国开放大学的Manish Patel博士解释：“以我们目前所知，火星表面并不适合生命生存，所以现在对火星生命的寻找都集中在地下。”
"This is where we get sufficient protection from harmful radiation,and the pressure and temperature rise to more favourable levels. Mostimportantly, this allows liquid water, essential for life."
“在那里我们可以获得足够的屏障以抵抗有害的辐射，大气压和温度也回到更合适的程度。更重要的是，那里可以有液态水的存在，这对于生命是关键的。”
This principle of following the water is key to astrobiology - the studyof potential life beyond Earth.
对于研究外星潜在生命的天体生物学来说，追踪水的存在是基本要素。
So while the findings suggest water is present, they don't confirm anything further.
所以研究是推测了水的存在，他们并没有再进一步证实任何事。
"We are not closer to actually detecting life," Dr Patel toldBBC News, "but what this finding does is give us the location of where to lookon Mars. It is like a treasure map - except in this case, there will be lots of'X's marking the spots."
“我们并没有很近距离的去探测生命，” Patel博士告诉BBC新闻，“但是这个发现告诉了我们去火星的哪里寻找。这就像一个藏宝图——不过这张图上将有很多X点。”
The water's temperature and chemistry could also pose a problem for anypotential martian organisms.
水的温度和化学成分也将为任何潜在的火星有机生命带来问题。
In order to remain liquid in such cold conditions (the research teamestimate between -10 and -30 Celsius where it meets the ice above), the waterlikely has a great many salts dissolved in it.
为了将液态水温维持在这么低的状态（科学家团队估计在冰面下，水温在-10到-30摄氏度），水里可能溶解有大量的盐。
"It's plausible that the water may be an extremely cold, concentratedbrine, which would be pretty challenging for life," explained Dr ClaireCousins, an astrobiologist from the University of St Andrews, UK.
“似乎水可能非常冷而且极咸，对生命来说有很大挑战，”圣安德鲁斯大学的天体生物学家Claire Cousins博士解释道。
What next?
接下来呢？
While its existence provides a tantalising prospect for those interestedin the possibility of past or present life on Mars, the lake's characteristics must first be verified by further research.
虽然对热衷于探究火星过去或现在是否存有生命的人来说，液态水湖的存在为其提供了急切的希望，但湖水的性状必须被进一步论证。
"What needs to be done now," explained Dr Matt Balme from theOpen University, "is for the measurements to be repeated elsewhere to lookfor similar signals, and, if possible, for all other explanation to be examinedand - hopefully - ruled out.
“现在需要做的是，”英国开放大学的Matt Balme博士解释，“在其他地方重复探测以寻找类似的信号，如果可能的话，希望经过检验可以排除其他可能。”
"Maybe this could even be the trigger for an ambitious new Marsmission to drill into this buried water-pocket - like has been done forsub-glacial lakes in Antarctica on Earth," he added.
“或许这将启动一项野心勃勃的新火星任务，就像探索南极洲的冰下湖一样，去深入这些埋藏的水塘。”他补充说。
科学家之前在南极洲的Vostok湖深处发现了细菌生命，但是在火星上发掘将是一项浩大的工程。
"Getting there and acquiring the final evidence that this is indeed a lake will not be an easy task," said Prof Orosei.
“到达那里并获得最终证据来证实这确实是个湖，将不是一个简单的任务，” Orosei说。
"It will require flying a robot there which is capable of drilling through 1.5km of ice. This will certainly require some technological developments that at the moment are not available."
“这需要运送一个能够掘穿1.5公里厚冰面的机器人飞过去。这其中所需要的一些科技发展是目前所还达不到的。”
（原文来自BBC NEWS，玛斯特翻译整理）