评论
打印
Last week, NASA did a thing that, for us in the science communication world, is always a little bit of a mixed bag.
上周，美国宇航局做了一件让普通大众情绪复杂的事情。
They were like, We've got some really big Mars news, and then the entire world goes crazy and there's like, There's life on M...!
他们表现出发现与火影有关的重大消息的样子，然后整个世界都为之疯狂，因为他们给人的感觉就是"火星上发现了生命！"
And then you're like, No, they probably would do this a different way if there was life on Mars, but we'll listen, and it will be exciting, but probably not in precisely the way you're thinking.
看到这种情况，我们就会觉得：不，如果火星上有生命，他们就不会这样了。但我们还是会在兴奋的氛围里相信这一切，觉得不应该持怀疑态度。
And it was cool!
这种情况非常棒！
But let's get this out of the way in the beginning: The Curiosity rover did not find evidence of past or present life on Mars.
但如果我们抽离出一开始的情景：好奇号并未发现火星上有过去或者现在存在生命的迹象。
And when the headlines said ‘Organic Matter on Mars', for non-science speakers that can be confusing, and they're like, "So, like, organic matter like a little bit of, like, snot?
所以，头条若是刊登《火星上惊现有机物》的标题，就会对普通大众产生困惑，大家就会疑惑"有机物？是鼻涕那样的有机物吗？"
Like, what is this on Mars? No, it's carbon compounds.
火星上到底发现了什么呢？不，只是碳水化合物而已。
If there was life on Mars, you would find out about it in a really big way, I promise. And we'd be here.
如果火星上发现了生命的话，就会大张旗鼓地报道了，我打赌。反正肯定不是现在这种方式。
But, Curiosity did find even more evidence to indicate the planet could've been habitable billions of years ago.
但好奇号确实发现了不止于此的证据，表明火星在数十亿年前是宜居的。
The results came in two papers published last Friday in the journal Science.
这个结果是上周五在《科学》杂志的两篇论文中指出的。
And while they don't prove anything about life on the Red Planet, they do show some of the strides Curiosity is making in understanding Mars' history.
虽然这样的发现并不能证明火星上有生命存在，但确实可以证明好奇号在发现火星历史方面取得了重大进展。
Since it landed on Mars in 2012, Curiosity has been hanging out in Gale Crater, which planetary scientists are pretty sure is an ancient lake bed.
自从2012年着陆火星以来，好奇号就一直在盖尔陨坑附近活动。科学家非常确定的一点是：盖尔陨坑在古代火星曾是一片湖泊沉积矿。
Among its duties, the rover has been drilling into rocks and sniffing the atmosphere to detect organic molecules.
好奇号的使命还包括钻取岩石，探测火星大气层中是否存在有机分子。
These are carbon-containing compounds that, on Earth, are often produced by life.
有机分子是含碳化合物，是通常情况下地球上生命的来源。
So finding them on Mars might suggest life once existed there, too, although they can also be made by non-biological processes.
所以，有机分子的发现或许可以证明火星上曾经有过生命，虽然非生物进程也可以产生有机分子。
A key one is methane.
关键点在于甲烷。
We've known that there's methane in Mars's atmosphere for a while.
众所周知，甲烷在火星上出现已经有段时日了。
But now, Curiosity has shown that the amount, at least in the vicinity of Gale Crater, varies seasonally.
但现在，好奇号发现，甲烷的含量是会随季节变化的，至少在盖尔陨坑附近是如此。
In the northern hemisphere, it peaks in summer months and drops near the winter.
在火星的北半球，甲烷含量会在夏季达到巅峰，在临近冬季的时候下降。
The paper's authors suspect the variations come from methane being stored deep underground, and from temperature changes on Mars's surface that allow it to flow upward.
本文作者猜测，甲烷含量之所以会变化是因为甲烷是储藏在火星地底深层的，而火星表面的气温变化会让甲烷向上流动。
For example, the gas could get trapped underground in icy crystals called clathrates, which melt come summer to free the gas.
比如，甲烷有可能封锁于冰晶笼子之中，而冰晶笼子在夏季融化后会释放甲烷。
At the moment, it's impossible to know if this methane comes from biological or non-biological sources.
目前的技术尚无法确认甲烷是否是由生物进程产生的。
But we do know it's getting replenished somehow.
但我们可以确认的是：甲烷含量得到了补充。
The molecules only survive for a few hundred years before sunlight breaks them down, so something has to be making more methane.
就算没有日光照射，甲烷分子也只能存在数百年时间，所以一定有什么供给了甲烷含量。
Even if there is no life producing it, though, this is still very cool news.
即便不是生命体产生了甲烷，也很令人兴奋了。
For one, Earth's atmosphere doesn't have a seasonal variation of many molecules, so Mars gets to be kind of special that way.
一方面，地球大气层不会随季节的变化而产生甲烷含量的变化，所以火星的这种表现算是一种特质了。
Also, if the variation does come from geologic processes, it would mean that Mars's interior isn't as dead as we thought.
另一方面，如果甲烷季节性变化是由地质作用导致的，那么就可以证明火星内部并不是一片死寂。
There would likely have to be some kind of heat source down there to drive those methane-producing reactions.
一定是有什么热源驱动了产生甲烷的反应。
So it's probably not aliens, but it's probably some very cool geology.
所以，很有可能不是外星人，而是温度较低的地质作用。
And that's the result of one of the papers.
这就是其中一篇论文的研究结果。
The other involved organic molecules more complex than methane.
另一篇论文讨论了比甲烷更为复杂的有机分子。
A few years ago, Curiosity ran tests that suggested larger organics existed on Mars's surface, but the data was contaminated by other chemicals.
几年前，好奇号经过测试发现，火星表面存在更大的有机物，但这个数据受到了其他化学物质的污染。
Now, we have some clearer results.
现在，我们有了更为清晰的结果。
Curiosity found these new compounds by drilling into 3.5 billion-year-old rocks called mudstone.
好奇号在钻入35亿年泥石后发现了这些化合物。
Mudstone is a sedimentary rock that forms from silt accumulating at the bottom of a lake.
泥石是一种沉积岩，它是由聚集在湖底的淤泥形成的。
Unlike other rocks on Mars, it's likely a better place to store organic compounds.
跟火星上其他岩石不同的是：泥石很擅长储存有机化合物。
Now, this could be because of a few reasons, including, like, protective interactions with other molecules.
现在看来，可能有几个原因，比如，与其他分子之间保护性的相互作用。
After Curiosity powderized and extracted the samples, its tool suite, called SAM, heated them to more than 500°C.
在好奇号萃取出样本后，其火星样本分析设备(SAM)就会把样本加热到500℃以上。
That was more than enough to get them to release their organics.
这个温度足以让样本释放出其有机物。
Then, SAM could analyze exactly what molecules came out.
然后，火星样本分析设备就可以分析出样本释放的分子。
Some of the compounds identified included thiophenes, benzene, toluene, and small carbon chains.
经确认，其中含有噻吩、苯、甲苯、小碳链。
But they likely started off as something else.
不过，这些成分很有可能是从某种物质衍生而来的。
See, Curiosity collected its samples from less than 5 centimeters below the ground.
因为好奇号是从地表以下5厘米处萃取的样本。
Anything that close to the surface is affected by radiation from space, which, along with other chemicals in the dirt, breaks down organic matter over time.
近地表的物体都会受到空间辐射的影响，因为辐射加上泥土中的化学物质会随着时间的流逝分解有机物。
So most likely, the compounds Curiosity found are really pieces of larger organic molecules, although we don't know what they started out as.
所以，最有可能的情况是：好奇号发现的化合物是更大的有机分子形成的，虽然我们尚不清楚它们一开始是什么。
If it were capable of drilling farther down, where radiation isn't a problem, maybe the rover could have found some of the original organics.
如果好奇号能钻得更深，那么辐射就不再是影响因素，所以好奇号可能就会发现其最开始的有机物是什么。
But the fact that some bits and pieces survived long enough to be detected reveals that Gale Crater might have once held all the necessary chemical building blocks for life.
但是鉴于这些细碎的物质历经这么久还能被好奇号探测到，所以盖尔陨坑可能曾经具备形成生命的所有基本化学物质。
Whether or not life actually existed, though, that's still up in the air.
至于火星上到底是否曾有生命存在过，还不确定。
Just like the methane, there's no way to know where these organic molecules came from.
就跟甲烷的情况一样，我们没法知道这些有机分子从何而来。
Many of them are found elsewhere in the solar system, like in interplanetary dust and on meteoroids.
很多有机分子在太阳系的其他地方也能发现，比如行星际尘埃和流星体中。
So it could be that Curiosity happened to find the remnants of a meteorite impact, not of life.
所以，好奇号发现的可能是流星体撞击的残留物，而非生命存在的迹象。
At a minimum, the study shows that traces of Martian organics, whether they come from tiny Martians or just chemistry, can survive for billions of years, to some degree.
至少这项研究可以表明：火星上的有机物，无论其来自于生命体还是非生命体，从某种程度上来说，都可以存在数十亿年的时间。
Luckily for us, we have a lot of future missions planned that can help us dig into that matter. Or, rather, drill into it.
好在我们未来还有一些太空任务可以帮助我们更深入地研究有机分子。就算没结论，也能钻取更多的样本。
NASA's InSight lander, which launched back in May, will land on Mars in late November.
美国宇航局的洞察号5月已着陆回到地球，并将在11月下旬着陆火星。
While it won't be able to determine chemical compositions, it will be able to drill down farther than ever before: 5 meters, to lower a heat probe.
虽然洞察号无法确定化学组成，但它可以比以往任何一次任务都钻入得更深：5米，从而将探热仪放得更深。
So it might be able to help us figure out some of that seasonal methane puzzle.
所以，洞察号或许能帮助我们弄清楚甲烷季节性波动的谜题。
Also, the ESA's ExoMars Rover is slated to launch in 2020, and while it will only be able to drill down 2 meters, it'll have the tools to extract rocks and analyze what they're made of.
此外，欧洲航天局的欧洲火星探测任务计划于2020年发射。虽然其钻入深度只有2米，但它配备的工具可以萃取并分析其岩石成分。
So hopefully, the fact that it will be able to go, like, 40 times deeper than Curiosity means we'll be able to find more intact organic molecules.
所以，我们希望，钻取深度是好奇号40倍的它可以发现更多未受污染的有机分子。
Finally, NASA's 2020 Rover won't be doing any deep drilling, but it will have technology to hunt for and understand any Martian organics it comes across on or near the surface.
最后我想说的是：美国宇航局的火星2020年探测车没有深钻作业，但其技术可以追踪到其遇到的以及地表的任何有机物，并分析其成分。
So hang on you tiny, probably dead Martians!
所以，不管火星上是否存在生命，还是要持续关注火星上的有机分子哦！
If you ever existed, we're coming for you!
如果真有生命存在的话，就静候地球人的光临吧！
Thanks for watching this episode of SciShow Space!
感谢收看本期的《太空科学秀》！
If you'd like to keep following the latest discoveries in astronomy and planetary science, we make a news episode like this every Friday!
如果您想持续关注有关天文和行星科学的发现的话，我们本周五有新的一集哦！
To make sure you never miss one, you can go to youtube.com/scishowspace to subscribe.
为了不漏掉您可能感兴趣的节目，就请订阅youtube.com/scishowspace吧！
